Sudden natural death in driving: case studies in the western area of Kanagawa

To assess their incidence and implications, we made a retrospective study of sudden unexpected natural deaths during driving that occurred in the five year-period between 1992 and 1997. During that period, 188 postmortem examinations were performed on driver victims of traffic accidents. Of these, 15 (8%) were found to have died of natural causes such as heart disease or cerebral hemorrhage. Marked findings in this study were that no persons over 70 years of age and more occupational drivers suffered natural death. Although no passengers or pedestrians were injured, as many as eight vehicles collided with another object or vehicle. Sudden natural death, particularly from cerebral hemorrhage, of drivers might be hazardous to other road users.

Determination of Aconitum alkaloids in blood and urine samples. II. Capillary liquid chromatographic-frit fast atom bombardment mass spectrometric analysis

Determination of fourteen alkaloids, toxic Aconitum alkaloids, aconitine, mesaconitine, jesaconitine, hypaconitine and deoxyaconitine, and their hydrolysis products, benzoylaconines and aconines, have been established using capillary liquid chromatography (LC) fast atom bombardment mass spectrometry (FAB-MS) with a frit interface. Protonated molecular ions were observed as base peaks in the FAB-MS for these fourteen alkaloids. All the alkaloids were simultaneously quantified with linear gradient LC elution by solvent mixture of acetonitrile and 0.3% trifluoroacetic acid using selected ion monitoring of the protonated molecular ions. The calibration curves of these alkaloids were linear in injection amounts ranging from 5 to 500 pg, and their detection limits were 1 pg per injection (S/N=3). Solid-phase extraction using Sep-Pak Plus PS-1 was also investigated to clean-up and concentrate alkaloids in blood and urine samples, and showed satisfactory recoveries. This capillary LC-frit-FAB-MS method enables determination of low levels of Aconitum alkaloids in blood and urine samples, coupled with solid-phase extraction.

Occlusive effects of lactic acid-glycolic acid copolymer membrane on gingival fibroblasts in vitro

The cell occlusive effects on human gingival fibroblasts of degradable lactic acid-glycolic acid copolymer membranes (noncoated membranes) and membranes coated with a sucrose ester of fatty acid (coated membranes) were studied and compared with those of expanded polytetrafluoroethylene (e-PTFE) membranes. The membranes were immersed in a culture medium periodically for 21 days and interposed into a chemotaxis chamber, and the fibroblasts then were cultured in the chamber for another 7 days. The passage rate of cells through the membranes was calculated and the change in surface structure of each membrane after immersion for 28 days was observed by an environmental scanning electron microscope. The passage rate of coated membranes (3.4+/-2.2%) was significantly lower than that of noncoated (25.7+/-5.1%) at the 28th day whereas the passage rate of e-PTFE membranes was 0.8-1.5%. Many pores were observed on the noncoated membranes before immersion while the coating material covered most of the pores on the coated membranes. The average pore size of the noncoated membranes was larger than that of the coated membranes at day 28. The structure of the e-PTFE membranes underwent no change. The passage rate of the coated membranes was not different from the e-PTFE membranes, suggesting an effect that might be useful for a guided tissue regeneration procedure.

Percutaneous fenestration of type B aortic dissection for decompression of false lumen pressure: case report

We describe our experience with percutaneous treatment by transfemoral balloon fenestration of the abdominal aorta in a patient with type B aortic dissection. Percutaneous fenestration was effective in reducing the pressure in the false lumen and equalizing the pressure between the two lumens. The patient was doing well at three-year follow-up.

Epitope analysis of monoclonal antibodies to human Gc globulin (vitamin D-binding protein)

Gc globulin, also called vitamin D-binding protein, is a human 56 kDa plasma protein. Antigenic epitopes of the protein recognized by 12 different monoclonal antibodies (MoAbs), including the previously prepared MoAb E12 of which binding to Gc is inhibited by actin, were analyzed in relation to the functional domains of the protein. To map the epitopes recognized by the respective antibody, the reactivities of the MoAbs were tested by immunoblotting against the recombinant Gc fragments expressed in E. coli cells, and then a competitive ELISA was performed. The results showed that the antibodies were classified into at least six groups. Furthermore, in addition to E12, actin inhibited the reactivity of MoAb 21, of which the epitope was located within residues Asp320 to Glu379, in an ELISA in the presence of the ligand. This result must indicate that this antibody-binding site is near the site that interacts with actin. In contrast, no inhibitory effect by 25-hydroxyvitamin D to any antibodies was observed. Furthermore, all antibodies, including E12 and 21, reacted with membrane-bound Gc of lymphocytes by an immunofluorescence study, suggesting that Gc is unlikely to bind to the plasma membrane in its interaction with actin.

Supplementation of Bifidobacterium longum to a high-fat, low-calcium diet lowers cytolytic activity of fecal water in rats injected with 1,2-dimethylhydrazine dihydrochloride

The effects of supplementing Bifidobacterium longum SBT 2928 and Lactobacillus acidophilus SBT 2062 to a high-fat, low-calcium diet on bile acid concentration, fatty acid concentration, cytolytic activity and intestinal alkaline phosphatase (ALP) activity of fecal water in rats injected with and without 1,2-dimethylhydrazine dihydrochloride (DMH) were examined. Male Wistar rats at 8 weeks of age were fed a diet containing 18% coconut oil, 2% corn oil and 0.1% calcium for 15 d. Lyophilized cultures were supplemented to test diets at a concentration of 1%. The feeding of a high-fat, low-calcium diet elevated the bile acid concentration, cytolytic activity and ALP activity of fecal water as compared to the AIN-76A diet, whereas the fatty acid concentration was not changed. None of the cultures had any effect on these parameters. Furthermore, 8 week-old rats were given a single subcutaneous injection of DMH at 40 mg/kg body weight, and fed the same diets for 15 d. The DMH injection had no effect on the bile acid concentration but increased the fatty acid concentration and cytolytic activity of fecal water. In contrast, ALP activity was lower in the DMH-treated rats than in the non-treated rats. The ingestion of B. longum lowered cytolytic activity but had no effect on the bile acids, fatty acids and ALP activity of fecal water. L. acidophilus had no effect on these parameters.

Antinociceptive and antidepressant-like profiles of BL-2401, a novel enkephalinase inhibitor, in mice and rats

To clarify the properties of BL-2401 ((+/-)-3-[2-benzyl-3-(propionylthio) propionyl]amino-5-methylbenzoic acid), a novel enkephalinase inhibitor, we examined its antinociceptive and antidepressant-like activities after oral administration, along with their association with endogenous opioid systems. BL-2401 produced an antinociceptive effect after oral administration in the mouse phenylbenzoquinone writhing test (ED50: 12.4 mg/kg) and the rat acetic acid writhing test (ED50: 55.8 mg/kg), the antinociceptive effect being antagonized by naloxone hydrochloride. BL-2401 also relieved arthritis-induced hyperalgesia in rats. In the mouse hot-plate and tail pressure tests, BL-2401 showed significant but modest antinociception at higher doses (200 and 400 mg/kg). In addition, BL-2401 (100 mg/kg) produced a naloxone-reversible antidepressant-like effect in the mouse forced swimming test. As for the mechanism of the action, the active metabolite of BL-2401, BL-2240 ((+/-)-3-(2-benzyl-3-mercaptopropionyl) amino-5-methylbenzoic acid), selectively inhibited enkephalinase in vitro (IC50: 5.2 nM). Oral administration of BL-2401 to mice significantly inhibited the enkephalinase activity in the striatum and also potentiated the antinociceptive effect of (D-Ala2,Met5)-enkephalin given intracisternally. These findings indicate that BL-2401 is an orally active enkephalinase inhibitor and may produce antinociceptive and antidepressant-like effects in association with endogenous opioid systems.

Correlation of patient immune responses with genetically characterized small round-structured viruses involved in outbreaks of nonbacterial acute gastroenteritis in the United States, 1990 to 1995

Small round-structured viruses (SRSVs) are a genetically and antigenically diverse group of caliciviruses that are the most common cause of outbreaks of acute nonbacterial gastroenteritis. We have applied both molecular techniques to characterize SRSVs in fecal specimens and serologic assays using four different expressed SRSV antigens to examine the distribution of outbreak strains in the United States and determine if the immune responses of patients were strain specific. Strains from 23 outbreaks of SRSV gastroenteritis were characterized by reverse transcription-PCR and nucleotide sequencing of a 277-base region of the capsid gene. These strains segregated into two distinct genogroups, I and II, comprising four and six clusters of strains respectively, each representing a distinct phylogenetic lineage. Serum IgG responses in patients were measured by enzyme immunoassay using expressed capsid antigens of Norwalk virus (NV), Toronto virus (TV), Hawaii virus (HV), and Lordsdale virus (LV), representing four of the 10 clusters. While strains in genogroups I and II were antigenically distinct, within genogroups, the specificity of the immune response varied greatly. Patients infected with genogroup I strains which had as much as 38.5% aa divergence from NV demonstrated relatively homologous seroresponses to the single NV antigen. In contrast, in genogroup II, homologous seroresponses to TV and HV were only present when the infecting strains showed less than 6.5% aa divergence from these antigens. These results suggest that TV and HV represent not only separate genetic clusters in genogroup II but also separate antigenic groups, each of which is related but distinguishable. In addition, two genetically distinct SRSV strains were identified for which we have no homologous antigen. This study suggests that while current molecular diagnostics are capable of detecting the full range of SRSVs, additional expressed antigens will be required to detect an immune response to SRSV infection caused by all the antigenically diverse strains.

Congenital metacarpal synostosis treated by longitudinal osteotomy and placement of a silicone wedge

Three cases of congenital metacarpal synostosis are reported. Two had congenital synostosis between the fourth and fifth metacarpal, and one between the third and fourth metacarpal. Both hands were involved in the former cases, while only one unilateral hand was involved in the latter case. An abnormal abduction position of the finger was noted in early infancy, and this gradually progressed as the patients grew. Operations were performed between the ages of three to eleven years. Fused metacarpal bases were longitudinally osteotomized with a chisel, and a silicone wedge was inserted between the metacarpal bases. After the operation, the hand was immobilized with a plaster cast for four weeks. The follow-up periods range from two to sixteen years. The postoperative function and appearance of the hand were remarkably improved.

Effects of alpha 2-adrenergic agonism, imidazolines, and G-protein on insulin secretion in beta cells

It is well known that alpha 2-adrenergic agonism inhibits insulin secretion and stimulates glucagon secretion in both animal and human studies. Recently, alpha 2-adrenergic blockers (DG-5128, MK-912, and SL 84.0418) have been studied as antihyperglycemic agents in human subjects. To clarify the action mechanism(s) of these agents, we investigated the effects of alpha 2 agonists and antagonists (10(-10) to 10(-4) mol/L) and pretreatment by pertussis toxin (PTX) on glucose-stimulated insulin secretion using the hamster insulinoma cell line HIT-T15. The imidazoline-derivative alpha 2-adrenoceptor agonists clonidine and oxymetazoline at concentrations as low as 10(-8) mol/L significantly inhibited glucose-stimulated insulin secretion by 63% and 65%, respectively (P < .01 for both). These inhibitory effects were abolished by 20-hour preincubation of these cells with PTX 100 ng/mL. The imidazoline-derivative alpha 2-adrenoceptor antagonist DG-5128 at a concentration of 10(-4) mol/L doubled insulin secretion with or without pretreatment by PTX (P < .01 for both). Furthermore, both clonidine and oxymetazoline at a high concentration of 10(-4) mol/L stimulated insulin secretion with pretreatment of the cells by PTX (P < .05 for both). These results indicate that glucose-stimulated insulin secretion is inhibited by alpha 2-adrenoceptor agonists through PTX-sensitive G-protein in HIT-T15 cells. It is also suggested that imidazoline compounds at high concentrations directly stimulate insulin secretion.

An experience of treatment for patients with thoracic esophageal cancer invading adjacent organs

The treatment of patients with thoracic esophageal cancer invading adjacent organs is controversial. The effect, on survival, of esophagectomy with regional node dissection after combined chemotherapy and radiotherapy was studied in six patients with the esophageal cancer. Two patients undergoing esophagectomy survived > 39 months without relapse. Postoperative complications were not observed in patients undergoing esophagectomy with a two-step surgical procedure (interval of several weeks between esophagectomy and reconstruction), while complications were observed in all patients undergoing a one-stage surgical procedure. Two-step esophagectomy with regional node dissection after combined chemo- and radiotherapy is a promising option for patients with esophageal cancer invading adjacent organs.

Nicotinamide derivatives as a new class of gastric (H+/K+)-ATPase inhibitors. III. Synthesis and gastric antisecretory activity of 2-[(2- and 4-aminobenzyl, and alpha-methylbenzyl)sulfinyl]-N-(4-pyridinyl) -3-pyridinecarboxamides

A new series of 2-[(2-aminobenzyl, 4-aminobenzyl, and alpha-methylbenzyl) sulfinyl]-N-(4-pyridinyl)-3-pyridinecarboxamides. was synthesized and evaluated for gastric antisecretory activities. Several of the compounds synthesized exhibited potent inhibitory activities against [14C]aminopyrine accumulation stimulated by dibutyryl cyclic AMP in isolated rabbit parietal cells and histamine-induced gastric acid secretion in pylorus-ligated rats by intraduodenal administration. In particular, the more polar diastereoisomer of 2-[(4-methoxy-alpha-methylbenzyl)sulfinyl] -N-(4-pyridinyl)-3-pyridinecarboxamide (13b) showed in vivo inhibitory activity equivalent or superior to that of omeprazole and was a more selective (H+/K+)-ATPase inhibitor than omeprazole.

Results of extended lymph node dissection for gastric cancer cases with N2 lymph node metastasis

The therapeutic value of extended lymph node dissection (D2) for gastric cancer remains controversial. Limited lymph node dissection, however, leaves cancer cells in the second tier of nodes (N2) in patients with N2 metastasis. This retrospective study was, therefore, undertaken to clarify which patients would be most likely to benefit from D2 dissection, even with N2 metastasis. Two groups, N2 cases with (n = 40) and without (n = 24) the development of recurrence after curative surgery, were compared. Borrmann type IV and serosal invasion were significantly related to recurrence. The number of metastatic nodes did not differ significantly between the two groups. All (7/7) of the Borrmann type IV cases with N2 metastasis developed recurrence and died. However, one quarter (7/30) of the cases with serosal invasion and N2 metastasis showed no sign of recurrence. D2 dissection is a surgical treatment which offers the potential to cure gastric cancers, other than Borrmann type IV tumor, with N2 metastasis.

Nicotinamide derivatives as a new class of gastric (H+/K+)-ATPase inhibitors II. Synthesis and structure-activity relationships of 2[(2,4-dimethoxybenzyl)sulfinyl]-N-(4-pyridinyl)pyridine-3-carboxamides

Members of a new series of 2-[(2,4-dimethoxybenzyl)sulfinyl]-N-(4-pyridinyl)pyridine-3-carboxamides were synthesized and evaluated for their gastric antisecretory activity and the ability to inhibit cytochrome P450-dependent O-dealkylation of 7-ethoxycoumarin (7-EC) in rat liver microsomes. Several of the compounds synthesized exhibited potent inhibitory activities against both [14C]aminopyrine accumulation stimulated by dibutyryl cyclic AMP in isolated rabbit parietal cells and histamine-induced gastric acid secretion in pylorus-ligated rats when administered intraduodenally; their inhibitory activities were equivalent to or superior to those of the parent compound [2- [(2,4-dimethoxybenzyl)sulfinyl]-N-(4-pyridinyl)pyridine-3-carboxamide] and omeprazole. Among the compounds having potent antisecretory activity in vitro and in vivo, 2-[(2,4-dimethoxybenzyl)sulfinyl]-N-(2,5-dimethyl-4-pyridinyl) pyridine-3-carboxamide and 2-[(2,4-dimethoxybenzyl)sulfinyl]-N-(2,6-dimethyl-4-pyridinyl)pyridine-3 - carboxamide in particular showed lower inhibitory activity against the 7-EC deethylase than omeprazole. It seems probable that, unlike omeprazole, these compounds do not interact with a metabolism of other drugs in vivo. These compounds, therefore, are considered to be more promising candidate agents for treating acid-related gastrointestinal disorders than the parent compound reported previously.

Intra-operative diagnosis of N2 lymph node metastasis of gastric cancer

BACKGROUND/AIMS

Limited lymph node dissection for gastric cancer, which is prevalent in Western countries, leaves cancer cells in the second tier of nodes in patients who have metastasis in those nodes. It is, however, difficult to correctly diagnose nodal status during surgery. The present study was, therefore, designed to examine how to detect N2 metastasis intra-operatively.

METHODOLOGY

Five hundred and eight patients undergoing extended lymph node dissections for gastric cancer were retrospectively analyzed. Accuracy of the intraoperative diagnosis of node involvement based on macroscopic findings was investigated, according to the N stage and histological type of the tumor. Furthermore, the distributions of N2 metastasis were clarified, according to tumor site.

RESULTS

Intra-operative macroscopic findings were frequently assessed as being less severe than histological findings in cases with N2 metastasis (61.9%, 39/63). Intra-operative recognition of N2 metastasis was significantly lower in the cases with undifferentiated adenocarcinoma (28.2%, 11/39) than in those with differentiated adenocarcinoma (56.5%, 13/23). The distributions of N2 metastasis revealed nodes along the left gastric and common hepatic arteries to be the key junctions for lymphatic flow from the middle and lower thirds of the stomach, respectively.

CONCLUSIONS

Intra-operative diagnosis of N2 metastasis is difficult to make based on macroscopic findings, especially in undifferentiated tumors. To detect N2 metastasis intra-operatively, the nodes along the left gastric or common hepatic artery should be submitted to frozen section examination for primary tumors located in the middle or lower third of the stomach, respectively.

Determination of Aconitum alkaloids in blood and urine samples. I. High-performance liquid chromatographic separation, solid-phase extraction and mass spectrometric confirmation

Determination of four toxic Aconitum alkaloids, aconitine, mesaconitine, hypaconitine and jesaconitine, in blood and urine samples has been established using high-performance liquid chromatography (HPLC) combined with ultraviolet absorbance detection, solid-phase extraction and mass spectrometry (MS). These alkaloids were hydrolyzed rapidly in alkaline solution (half lives (t1/2)<one day), were stable in solutions of acetonitrile, tetrahydrofuran and diluted hydrochloric acid (t1/2>five months) and were unstable in solutions of methanol and ethanol (t1/2<one month). These alkaloids were separated on an octadecylsilica column with isocratic elution using a solvent mixture of tetrahydrofuran and 0.2% trifluoroacetic acid (14:86, v/v), which was found to be the optimal solvent of the elution systems examined. Calibration curves with UV detection were linear on injection of amounts ranging from 2.5 to 500 ng, and the limit of detection was 1 ng (S/N=3). These four alkaloids in aqueous solution were recovered almost totally by solid-phase extraction using the styrene polymer resin, Sep-Pak Plus PS-1, and were eluted using a mixture of acetonitrile and hydrochloric acid. These Aconitum alkaloids were confirmed by HPLC coupled with fast atom bombardment MS, giving their protonated molecular ions as base peaks. These alkaloids were detected by HPLC with UV detection from blood samples spiked with more than 50 ng ml(-1) of alkaloids, but were not detectable from urine samples spiked with 5 microg ml(-1) of alkaloids because of severe sample interference.

[Potentiating effect of ethanol on alpha 1 adrenergic receptor mediated contraction of thoracic aorta from guinea pig]

Using aortic strips isolated from guinea pigs, effects of ethanol on vascular smooth muscle tonus were studied. 50mM of ethanol significantly potentiated the contractions induced by norepinephrine and phenylephrine, but did not influence those induced by KCl and clonidine. Furthermore, ethanol significantly augmented the contraction induced by phenylephrine in the presence of verapamil, and did not have any effects on the contractions induced by A23187, Ba2+, PDBu and BAY K 8644. These results indicate that ethanol potentiates the alpha 1 adrenergic receptor-mediated contraction, depending on the extracellular calcium influx via the receptor-operated calcium channel.

Relation between stable glycated hemoglobin A1C and plasma glucose levels in diabetes-model mice

In an IDDM model mouse which was inoculated with a diabetogenic variant, DK-27, of encephalomyocarditis (EMC) virus, the relation between a stable glycated hemoglobin A1C (St-HbA1C) level and plasma glucose level (PGL) in the progress of diabetes was studied. The St-HbA1C level and PGL were examined every 2 weeks for 10 weeks in normal male DBA/2 and IDDM-onset mice. PGLs of normal control mice did not change, but their St-HbA1C levels were slightly increased by 0.52 to 1.03%. On the other hand, in IDDM mice, their PGLs were greatly increased (> 400 mg/dl) and hyperglycemia was maintained throughout this observation period, with their St-HbA1C noticeably increased to 3.8% according to the progress of diabetes for 10 weeks. A highly significant correlation between St-HbA1C levels and averaged PGLs for the past weeks was found in IDDM mice. To examine the reflection of St-HbA1C levels to delicately varied PGLs, we also estimated both values in IDDM mice which were treated with insulin at a minimal effective dose once a day for 4 weeks. The St-HbA1C levels in insulin-injected IDDM mice were significantly lower than those in control IDDM mice. These findings suggest that the estimation of the St-HbA1C level is useful in following up blood glucose control in a long-term therapeutical study with small laboratory animals.

Prognostic significance of non-gastric malignancy after treatment of early gastric cancer

BACKGROUND

The recurrence rate of early gastric cancer is low and so second malignancies developing after treatment of this cancer have potential prognostic significance.

METHODS

Some 633 patients with early gastric cancer were studied. The median observation time was 123 months. To examine the characteristics of patients with early gastric cancer and subsequent malignancy, two groups of patients, those with and those without non-gastric malignancy, were compared using univariate analysis with respect to various clinicopathological factors. To determine which parameters were independently significant, computer-based multivariate discriminant function analysis was applied. To estimate the prognostic significance of non-gastric malignancy, death rates from these diseases in patients treated for early gastric cancer were compared with the mortality rates attributable to the same diseases in the general population of Japan.

RESULTS

The frequency of other malignancies, 9.6 per cent (61 of 633), was significantly higher than those gastric cancer recurrence rate of 2.4 per cent (15 of 633). After treatment for early gastric cancer patients with subsequent non-gastric malignancy had a significantly poorer outcome than those free from other cancers. Lung cancers were the major neoplasms occurring after the treatment of early gastric cancer. Univariate and multivariate analysis revealed male sex to be an independent risk factor for the subsequent development of non-gastric malignancy. Comparison of mortality rates revealed that men with early gastric cancer have a higher risk of death from non-gastric malignancy than the general male population.

CONCLUSION

These results suggest that systemic surveillance is particularly important for male patients after the treatment of early gastric cancer.

Microvascular anastomosis for additional blood flow in reconstruction after intrathoracic esophageal carcinoma surgery

Microvascular anastomosis, designed to achieve additional blood flow to the reconstructed site, was carried out in nine patients with intrathoracic esophageal cancer. This procedure prevents the major complications of esophagogastric and esophagocolic anastomotic leaks after subtotal esophagectomy.

Impact of lymph node metastasis on survival with early gastric cancer

The impact of lymph node metastasis on the survival of early gastric cancer (EGC) cases remains controversial. A retrospective study of 621 patients with EGC undergoing gastrectomy with lymphadenectomy during the period 1966-1993 was performed to evaluate the influence of node involvement on long-term outcomes. Lymph node metastasis was observed in 63 cases (10.1%). Two groups, EGC with and without node involvement, were compared with respect to long-term results and various clinicopathologic factors. The median observation period was 123 months. EGC cases without metastatic nodes had significantly better outcomes than those with node involvement in terms of overall survival as well as survival excluding deaths due to diseases unrelated to the primary EGC. Survival rates for EGC patients with node involvement did not, however, differ significantly according to the number of metastatic nodes. Three factors-submucosal invasion, large tumor size, and recurrence-were significantly related to lymph node metastasis. Age, sex, family history of malignancy, histologic type, and multiple occurrence of gastric cancer were unrelated to the prevalence of node involvement. The frequency of recurrence in EGC cases without node involvement was low (1.8%, 10 of 558). Recurrence was not, however, exceptional in those with metastatic nodes (9.5%, 6 of 63). EGC patients with lymph node metastasis, even with only a single positive node, constitute a high risk group for EGC recurrence.

Nicotinamide derivatives as a new class of gastric H+/K(+)-ATPase inhibitors. 1. Synthesis and structure-activity relationships of N-substituted 2-(benzhydryl- and benzylsulfinyl)nicotinamides

A new series of N-Substituted 2-(benzhydryl- and benzylsulfinyl)nicotinamides 7 and 8 were synthesized. Upon acid activation in the acidic environment of the parietal cell, these compounds are converted into their active forms, 2,3-dihydro-3-oxoisothiazolo[5,4-b]pyridines 5, which inhibit gastric H+/K(+)-ATPase. Inhibitory activities against [14C]aminopyrine accumulation stimulated by dibutyryl cAMP in isolated rabbit parietal cells in vitro and histamine-induced gastric acid secretion in pylorus-ligated rats by intraduodenal administration in vivo were evaluated, and the structure-activity relationships were examined. Among the compounds synthesized, 2-[(2,4-dimethoxybenzyl)sulfinyl]-N-(4-pyridyl)nicotinamide (8b) showed potent inhibitory activities in vitro and in vivo equivalent to those of omeprazole, a typical H+/K(+)-ATPase inhibitor. Moreover, 8b was much more stable at neutral and weakly acidic pH than omeprazole, lansoprazole, and pantoprazole. Compound 8b is considered to be a promising agent for treating acid-related gastrointestinal disorders.