An encompassed representation of timescale hierarchies in first-order reaction network

Complex networks are pervasive in various fields such as chemistry, biology, and sociology. In chemistry, first-order reaction networks are represented by a set of first-order differential equations, which can be constructed from the underlying energy landscape. However, as the number of nodes increases, it becomes more challenging to understand complex kinetics across different timescales. Hence, how to construct an interpretable, coarse-graining scheme that preserves the underlying timescales of overall reactions is of crucial importance. Here, we develop a scheme to capture the underlying hierarchical subsets of nodes, and a series of coarse-grained (reduced-dimensional) rate equations between the subsets as a function of time resolution from the original reaction network. Each of the coarse-grained representations guarantees to preserve the underlying slow characteristic timescales in the original network. The crux is the construction of a lumping scheme incorporating a similarity measure in deciphering the underlying timescale hierarchy, which does not rely on the assumption of equilibrium. As an illustrative example, we apply the scheme to four-state Markovian models and Claisen rearrangement of allyl vinyl ether (AVE), and demonstrate that the reduced-dimensional representation accurately reproduces not only the slowest but also the faster timescales of overall reactions although other reduction schemes based on equilibrium assumption well reproduce the slowest timescale but fail to reproduce the second-to-fourth slowest timescales with the same accuracy. Our scheme can be applied not only to the reaction networks but also to networks in other fields, which helps us encompass their hierarchical structures of the complex kinetics over timescales.

Phase space geometry of isolated to condensed chemical reactions

The complexity of gas and condensed phase chemical reactions has generally been uncovered either approximately through transition state theories or exactly through (analytic or computational) integration of trajectories. These approaches can be improved by recognizing that the dynamics and associated geometric structures exist in phase space, ensuring that the propagator is symplectic as in velocity-Verlet integrators and by extending the space of dividing surfaces to optimize the rate variationally, respectively. The dividing surface can be analytically or variationally optimized in phase space, not just over configuration space, to obtain more accurate rates. Thus, a phase space perspective is of primary importance in creating a deeper understanding of the geometric structure of chemical reactions. A key contribution from dynamical systems theory is the generalization of the transition state (TS) in terms of the normally hyperbolic invariant manifold (NHIM) whose geometric phase-space structure persists under perturbation. The NHIM can be regarded as an anchor of a dividing surface in phase space and it gives rise to an exact non-recrossing TS theory rate in reactions that are dominated by a single bottleneck. Here, we review recent advances of phase space geometrical structures of particular relevance to chemical reactions in the condensed phase. We also provide conjectures on the promise of these techniques toward the design and control of chemical reactions.

Identifying reaction pathways in phase space via asymptotic trajectories

In this paper, we revisit the concepts of the reactivity map and the reactivity bands as an alternative to the use of perturbation theory for the determination of the phase space geometry of chemical reactions. We introduce a reformulated metric, called the asymptotic trajectory indicator, and an efficient algorithm to obtain reactivity boundaries. We demonstrate that this method has sufficient accuracy to reproduce phase space structures such as turnstiles for a 1D model of the isomerization of ketene in an external field. The asymptotic trajectory indicator can be applied to higher dimensional systems coupled to Langevin baths as we demonstrate for a 3D model of the isomerization of ketene.

Reactivity boundaries for chemical reactions associated with higher-index and multiple saddles

Reactivity boundaries that divide the origin and destination of trajectories are of crucial importance to reveal the mechanism of reactions, which was recently found to exist robustly even at high energies for index 1 saddles [Phys. Rev. Lett. 105, 048304 (2010)]. Here we revisit the concept of the reactivity boundary and propose a more general definition that can involve a single reaction associated with a bottleneck composed of higher-index saddles and/or several saddle points with different indices, where the normal form theory, based on expansion around a single stationary point, does not work. We numerically demonstrate the reactivity boundary by using a reduced model system of the H(5)(+) cation where the proton exchange reaction takes place through a bottleneck composed of two index 2 saddle points and two index 1 saddle points. The cross section of the reactivity boundary in the reactant region of the phase space reveals which initial conditions are effective in making the reaction happen and thus sheds light on the reaction mechanism.

Reactivity boundaries to separate the fate of a chemical reaction associated with an index-two saddle

Reactivity boundaries that divide the destination and the origin of trajectories are of crucial importance to reveal the mechanism of reactions. We investigate whether such reactivity boundaries can be extracted for higher index saddles in terms of a nonlinear canonical transformation successful for index-one saddles by using a model system with an index-two saddle. It is found that the true reactivity boundaries do not coincide with those extracted by the transformation taking into account a nonlinearity in the region of the saddle even for small perturbations, and the discrepancy is more pronounced for the less repulsive direction of the index-two saddle system. The present result indicates an importance of the global properties of the phase space to identify the reactivity boundaries, relevant to the question of what reactant and product are in phase space, for saddles with index more than one.

Laparoscopic lower anterior resection is equivalent to laparotomy for lower rectal cancer at the distal line of resection

BACKGROUND

Procedures that involve resection of the distal rectum challenge the current limitations of laparoscopic technology, because of lack of compact articulating stapling instruments.

METHOD

We improve the procedure with the aid of a Lap disk, an abdominal wall sealing device that was developed for hand-assisted manipulation. A linear stapler capable of changing its stop angle is inserted through the disk, and the rectum is transected by the disk during a second pneumoperitoneum.

RESULTS

The transection line becomes equivalent to that obtained with laparotomy.

CONCLUSION

This new technique made laparoscopic lower anterior resection possible to transect the lower rectum in the same way as is done with laparotomy.

Role of platelet activating factor on severity of ischemic colitis

PURPOSE

Ischemic colitis develops after a sudden decrease in colonic blood supply and has a variety of clinical manifestations. The aim of this study was to assess the role of platelet activating factor in the pathogenesis of ischemic colitis with use of the platelet activating factor antagonist TCV-309.

METHODS

Rats were randomly divided into four groups. Rats in Group RV underwent ring attachment around the rectum to induce partial obstruction and ligation of the marginal vessels of the left colon. As control, rats in Group R underwent the ring attachment and rats in Group V underwent the vascular ligation. Rat in Group C underwent sham operation. The effects of TCV-309 on lesion formation in the colon were evaluated. Thiobarbituric acid reactant level was determined in colonic mucosa, and the incidence and severity of ischemic lesions were also determined.

RESULTS

Lesions of colitis were frequently observed in Group RV. TCV-309 did not prevent lesion formation, nor did it suppress the increase in thiobarbituric acid reactant level in Group RV. However, TCV-309 mitigated the severity of the lesion.

CONCLUSIONS

Partial obstruction of the colon tends to induce ischemic colitis, and additional ischemia completes lesion formation. Platelet activating factor may play a role in the progression of ischemic lesions.

Helicobacter pylori may cause "reflux" gastritis after gastrectomy

Patients with "reflux" gastritis after gastrectomy suffer from a variety of symptoms, and this type of gastritis may sometimes compromise the quality of life of these patients. Since Helicobacter pylori is considered to be one of the most important pathogenetic factors in gastritis, the association between H. pylori and reflux gastritis was investigated in this study. A total of 145 patients with gastrectomy were entered into the study. Five biopsy specimens from the gastric remnant were taken at upper gastrointestinal endoscopy. One specimen was examined pathohistologically, and the remaining four were examined for H. pylori infection. Fifty-two patients (36%) demonstrated H. pylori infection. The prevalence of H. pylori was significantly higher in patients who had a partial gastrectomy, and it was significantly lower in patients who had undergone gastrectomy more than 4 years previously. The histologic gastritis score in patients with H. pylori infection was significantly higher. Furthermore, H. pylori was eradicated in patients with some symptoms of gastritis and no bile reflux to the residual stomach at endoscopy; in these patients the symptoms were relieved and the histologic gastritis score decreased significantly. In conclusion, possible involvement of H. pylori is suspected in the pathogenesis of "nonreflux" gastritis after gastrectomy.

Impaired response of gastric vessels to prostaglandin E2 in rats with persistent obstructive jaundice

We investigated the response of gastric vessels to prostaglandin (PG) E2 after intra-duodenal release of bile in rats with obstructive jaundice. The animals were divided in four groups according to duration of bile duct obstruction (BDO): control and 1 week (W), 2W, and 3W groups. Prolonged BDO decreased gastric mucosal blood flow (BF) significantly. The BF recovered after the release of BDO in the 1W and 2W groups, but not in the 3W group. BDO decreased PGE2 content in gastric mucosa in the 1W, 2W, and 3W groups. PGE2 decreased vascular perfusion pressure of the isolated stomach in the control and 2W groups, but not in the 3W group. The response of gastric vessels to PGE2 was poor in the 3W group compared with the control and 2W groups. Decreased PGE2 in the gastric mucosa and decreased response of gastric vessels to PGE2 may affect gastric blood flow in obstructive jaundice.

Etiological involvement of Helicobacter pylori in "reflux" gastritis after gastrectomy

OBJECTIVES

"Reflux" gastritis after gastrectomy is associated with various symptoms that are often detrimental to the patients' quality of life. However, prevention of the reflux does not always bring relief from the symptoms of gastritis. Helicobacter pylori (H. pylori) is now considered one of the most important pathogenetic factors in gastritis. The association between H. pylori infection and reflux gastritis after gastrectomy was investigated in the present study.

METHODS

In total, 115 patients who had undergone gastrectomy were entered in this study. Five biopsy specimens from the gastric remnant were taken during upper GI endoscopy. One specimen was examined pathohistologically, and the remaining four were examined for H. pylori infection. The histological degree of gastritis was determined according to the score system of Rauws et al.

RESULTS

Forty-six patients (40%) demonstrated H. pylori infection in their stomachs. The prevalence of the infection was significantly higher in patients with conventional gastrectomy than in those with subtotal gastrectomy. The prevalence of H. pylori infection was significantly lower in patients who had undergone gastrectomy more than 4 yr ago. The histological gastritis score in patients with H. pylori infection was significantly higher than in those without H. pylori infection. Furthermore, the eradication of H. pylori in patients with both serious gastritis symptoms and no bile reflux improved the symptoms and significantly decreased the histological gastritis score.

CONCLUSIONS

The results suggest that H. pylori is a factor in the pathogenesis of reflux gastritis after gastrectomy.

[Role of platelet activating factor on the formation of ischemic colitis]

Role of platelet activating factor (PAF) on the formation of rat ischemic colitis was investigated. High incidence of the formation of ischemic colitis was observed after ligation of marginal vessels of the rat with stricture of the rectum, however, administration of PAF-inhibitor (TCV) decreased incidence of the lesion. Only the lesion in the mucosa occurred after clamping of the marginal vessels of the rat with stricture of the rectum and administration of TCV did not affect the incidence of the lesion. In conclusion, the etiological involvement of PAF on deterioration of the ischemic colitis was suspected.

Inhibitory effect of dopamine on gastric motility in rats

BACKGROUND

There is disagreement with regard to the involvement of dopamine (DA) receptors in gastric motility. The mechanisms of the inhibitory effect of DA on rat gastric motility was investigated in association with acetylcholine (Ach) release in the present study.

METHODS

In vivo vagotomized, splanchnicectomized rats and control rats were used, and gastric movement was determined as the gastric motility index after DA administration. In vitro study of Ach release from the circular muscle strips of the gastric corpus was investigated after administration of domperidone, SCH23390, phentolamine, or propranolol.

RESULTS

In the in vivo study DA inhibited gastric motility in a dose-dependent manner. Vagotomy and splanchnicectomy had no effect on the inhibitory effect of DA. In vitro study DA inhibited [3H]-Ach release in a dose-dependent manner. The inhibitory effect of DA was antagonized by domperidone but not by phentolamine, propranolol, or SCH23390.

CONCLUSIONS

Inhibition of gastric motility by dopamine is independent of extrinsic innervation and seems to be mediated by DA2 receptors in the gastric wall.

[Residual gastritis after gastrectomy and Helicobacter pylori--its clinical significance]

Residual gastritis after gastrectomy brings the various symptoms such as abdominal pain, nausea, emesis and loss of appetite, and often hazards quality of life of the patient. Bile reflux to the stomach is believed as one of the important pathogenesis of residual gastritis, however the prevention for bile reflux cannot always heal the gastritis. Helicobacter pylori (H. pylori) is considered as one of the most important pathogenesis of gastroduodenal ulcer and gastritis, and H. pylori may possibly cause residual gastritis after gastrectomy. However, the association between infection with H. pylori and the residual gastritis has not revealed yet. In the present study, the association with H. pylori and the residual gastritis after gastrectomy was investigated in 56 patients who had undergone gastrectomy before. Twenty-four patients (42.9%) had H. pylori infection at their stomachs and the incidence of the infection in the patients with gastrectomy was significantly higher with subtotal gastrectomy. As for the histological gastritis score of Rauws (Rauws' score), Rauws' score of H. pylori positive group was significantly higher than H. pylori negative group. Furthermore, the eradication of H. pylori for the patients with serious symptoms of gastritis improved the symptoms and decreased significantly Rauws' score. These results suggest that H. pylori was associated with the pathogenesis of residual gastritis after gastrectomy.

[A case of spontaneous mesenteric fibromatosis occurred from the mesentery of the small intestine]

The fibromatosis is benign tumor which is characterized by the remarkable proliferation and the invasive growth of fibrous tissue and no distant metastasis. It usually occurs from the abdominal wall or the extremities, and rarely from the mesentery. A 54-year-old male complained of an epigastralgia and emesis. He was diagnosed through imaging as the obstructive ileus by abdominal tumor. The laparotomy was performed and a round, egg sized tumor was found wear by dilated ileum. The tumor was considered to occur from the mesentery, and the iliectomy with the tumor was completed. It was suggested that ileus occurred in the early stage because the tumor was located just by the ileum.

Protein kinase C alpha-, beta- and gamma-subspecies in basal granulated cells of rat duodenal mucosa

Protein kinase C [cPKC: alpha, beta (beta I, beta II), gamma], a Ca(2+)- and phospholipid-dependent enzyme, has been thought to play a critical role in the synthesis and secretion of gut hormones in gastrointestinal mucosa. However, the localization of PKC has not yet been clarified at the cellular level in the gastrointestinal epithelium. The present study was made to identify cPKC-containing cells immunohistochemically in the rat duodenal epithelium by light and electron microscopy and by confocal laser scanning microscopy. Special attention was paid to the demonstration of cPKC in basal granulated cells. By light microscopy, some duodenal epithelial cells were demonstrated to be immunopositive for PKC alpha-, beta- and gamma-subspecies. Their distribution and incidence were almost similar to those of cells stained by the silver impregnation method of Grimelius. By electron microscopy, profiles of secretory granules were found at the basal region of the PKC-immunopositive epithelial cells. When the cells were double-immunostained for gastrin, serotonin or somatostatin and for PKC alpha-, beta- or gamma-subspecies, these gut hormones and PKC subspecies were shown to colocalize as examined by confocal laser scanning microscopy. These findings show that cPKC (alpha, beta, gamma) is present in basal granulated cells such as G-, EC- and D-cells, presumably playing some important role in regulation of gut hormones, including their synthesis and/or secretion.

[The mechanism of development of acute gastric ulceration following biliary drainage in obstructive jaundice]

Upper gastrointestinal hemorrhage occurs occasionally in the time of surgery or biliary infection in patients with obstructive jaundice. In the present study, the influence of obstructive jaundice and biliary drainage on the rat gastric mucosa was examined. Serum t-Bil, GOT and Alp increased during obstructive jaundice, but decreased following biliary drainage. Hexose and fucose levels in gastric mucosa decreased during obstructive jaundice; both of them increased in the 1- and 2-week jaundiced groups, however, neither increased in the 3-week jaundiced group following biliary drainage. Prolonged obstructive jaundice demonstrated a marked increase of ulcer index (UI) and decrease of gastric mucosal blood flow (BF) following water immersion and restraint stress. Biliary drainage induced these changes in the 1- and 2-week jaundiced groups, but induced neither of these changes towards recovery in the 3-week jaundice group. Prostaglandin (PG) E2 induced significant decrease in isolated gastric vascular perfusion pressure in the 2-week jaundiced group; it did not, however, have this effect in the 3-week jaundiced group. In conclusion, it was speculated that differences between the 3-week and 2-week jaundiced groups were present in sensitivity to PGE2 in the gastric vascular system, and that different reactions of the gastric microcirculation resulted in different changes in the gastric mucosal state following biliary drainage.

Immunohistochemical study of dopamine in rat gastric mucosa with acute gastric ulcer

Recent studies have shown the presence of dopamine (DA) in gastric and duodenal mucosa, and changes in gastric mucosal DA content have been observed in patient with acute ulcers. Immunohistochemical demonstration of the distribution of DA in gastric mucosa under stress was studied by light and electron microscopy. In the control group, DA was present in the gastric gland proper in the gastric corpus and antrum on light microscopy, and on the surface of mucous granules in chief cells, mucous neck cells, and surface epithelium on electron microscopy. In the stress group, DA in gastric mucosa was almost undetectable on light and electron microscopy. Further, in this group serum DA concentration was significantly higher in the portal vein than in the abdominal aorta. Endogenous DA in gastric mucosal cells may affect gastric mucosa differently from exogenous DA, and stress may release endogenous intracellular DA into extracellular spaces.

An immunohistochemical study of glucagonoma conducted on the metastatic lymph nodes from a patient with recurrent metastatic glucagonoma: report of a case

In this report, we briefly present the case of a 67-year-old woman who developed recurrent glucagonoma with lymph node metastasis. An immunohistochemical study of the metastatic tumor revealed immunoreactivity of glucagon and protein kinase C (PKC)-alpha, -beta, and -gamma in the tumor cells, two types of which were seen by electron microscopy. One type had abundant secretory granules and mitochondria, while the other had few granules and mitochondria. Some granules were similar to typical A cell granules and others were atypical. An immunoelectron microscopic demonstration revealed PKC-alpha, -beta, and -gamma immunostaining in the cytoplasm of all the tumor cells, while some secretory granules had PKC immunostaining, and others had no immunostaining. Thus, it appears that metastatic glucagonoma and its associated granules are composed of two types of mature and immature cells or granules. As immunoreactivity of PKC-alpha and -gamma was found in the tumor cells, but not in the normal A cells of the islets of Langerhans, the PKC subspecies alpha and gamma, which are not present in normal pancreatic A cells, may exist in human glucagonoma cells.

[A case report of allergic granulomatous angitis with the perforation of ileum]

A case of allergic granulomatous angitis (AGA) complicated with the perforation of the ileum was described. A 52-year-old male had suffered from bronchial asthma since 1990, and two years later he had severe attack of asthma and manifestation of systemic vasculitis. He was diagnosed a AGA with the symptom of vascultitis, history of asthma, and the abnormal hematological findings (WBC 13000/mm3, eosinophilia 11.1%, IgE 1290U/ml, RA 2+). The treatment with adrenal corticoid hormone was started. In April 1992, he complained of severe right lower abdominal pain. He was diagnosed the gastrointestinal perforation by the abdominal X-ray examination and emergency operation was performed. Two ileal perforations were found at the operation and the ileectomy was carried out. Only 11 cases of AGA complicated with the gastrointestinal perforation have ever been reported in Japan. The perforation occurred often at the small intestine and the poor prognosis was referred. The administration of adrenal corticoid hormone should be continued after operation.

[Experimental study on the etiology of ischemic colitis]

A reliable experimental model for ischemic colitis in rat could be obtained by ligating the marginal vessels of the colon 3 days after attaching the ring to induce partial colon obstruction. This model has the advantage of enabling to observe the chronic progress and the organ of the sideration to clarify the cause of ischemic colitis. The decrease of blood flow within the colonic mucosa continued up to 7 days after ligation in rat with partial obstruction, while no apparent abnormal changes were observed, and the previous level for several hours in the rats with out attaching the ring. This fact proved that the RT group is in a state easily developing sideration due to the sustained partial colon obstruction. The reactant reacting with thiobarbituric acid (TBA) was found to increase, in particular, 6 or more hours after ligation of vessels. A superoxide scavenger, liposomal-encapsulated superoxide dismutase (1-SOD) suppressed development of the ischemic lesion. The change in free radicals is therefore, considered to be involved in the occurrence of ischemic colitis.

A case of benign schwannoma of the thoracic wall mimicking a malignant tumor

A fist-sized tumor mainly locating in the right thoracic wall of a 73 year-old woman was found by ultrasonography and computed tomography, although a definitive diagnosis was not obtained because of the tumor extension to the abdominal cavity from the right internal thoracic wall, precluding biopsy. Angiography of the right eleventh intercostal artery demonstrated irregular tumor vessels, indicating malignant nature of the tumor. Therefore en-block resection of the tumor with the right eleventh rib was performed under a thoracotomy. Postoperative histopathological examination showed that the tumor was a benign schwannoma of Antoni type A. Since schwannoma is usually difficult to diagnose preoperatively without histopathological study, it is suggested that patients with schwannoma-like tumors, as represented by the present case, should be treated carefully to avoid excessive surgery including an extensive resection of the surrounding tissue.

Effect of pirenzepine on postoperative gastric secretion

Post surgical stress ulcers of the upper digestive tract, once developed, is difficult to control depending on the primary disease and associated complications. As to the cause of postoperative stress ulcers, decreased defensive factors such as gastric mucosal blood flow and increased gastric secretions have been pointed out. Recently, pirenzepine hydrochloride has been shown to be a specific antagonist of muscarinic cholinergic M1 receptors and a suppressant of gastric acid secretion. Therefore we studied its effect on gastric secretions in postoperative patients. Twenty one patients admitted for abdominal surgery, excluding gastric surgery, were selected and randomly assigned to the pirenzepine group (10 cases) or control group (11 cases). Since the serum half life of pirenzepine is 10 hours, 20mg of pirenzepine was administered intravenously immediately after the operation and twice daily (9 a.m. and 9 p.m.) from postoperative day 1 until day 7. Gastric secretions and gastric pH were measured preoperatively and daily until day 7. In the control group, significant increases in the volume of secretion and significant decreases in gastric pH were observed after the operation. In contrast, the pirenzepine group had a significantly decreased amount of gastric secretion and the gastric pH was higher than those in the control group. Thus we conclude that pirenzepine decreases gastric secretion and increases gastric pH in postoperative patients. Pirenzepine can be regarded as an effective agent for the control of postoperative gastric hypersecretion and possibly a good prophylactic for postoperative stress ulcers.

The effect of dopamine on rat gastric motility

The inhibitory mechanism of dopamine (DA) on rat gastric motility was investigated in association with DA receptors. Gastric movement was assessed according to the method of Jacoby et al and was expressed with the system of Ludwick et al. (1968). DA inhibited gastric movement in both the corpus and antrum in a dose-dependent manner. Domperidone, a specific antagonist of DA2 receptor, suppressed DA-induced inhibition of gastric movement in a dose-dependent manner. SCH23390, a specific antagonist of DA1 receptor did not affect DA-induced inhibition of gastric movement. LY171555, a specific agonist of DA2 receptor, inhibited gastric movement in both the corpus and antrum in a dose-dependent manner. SKF38393, a specific agonist of DA1 receptor, did not affect gastric movement. These results indicate that DA plays an important role in the inhibitory regulation of gastric motility, through DA2 receptor but not DA1 receptor.

[Inhibitory effect of peptide YY on gastric acid output in rats]

The purpose of this study was to elucidate the effect of Peptide YY (PYY) on gastric acid output in association with gastric mucosal blood flow (GMBF), acetylcholine (ACh) release in the gastric wall and gastric vascular perfusion pressure in rats. Baclofen stimulated the gastric acid output and GMBF in a dose-dependent manner. Both atropine sulfate and truncal vagotomy completely abolished the effect of baclofen. PYY caused inhibition of baclofen-stimulated gastric acid output and reduction in baclofen-stimulated GMBF in a dose-dependent manner, however PYY didn't cause inhibition of pentagastrin- and histamine-induced acid output completely. But PYY had no effect on bethanechol-induced acid output. PYY inhibited the [3H] ACh release from cholinergic nerve endings of gastric body evoked by electrical transmural stimulation. PYY had little effect on gastric vascular perfusion pressure in the basal state, and basal gastric acid output. In the present study, it was concluded that the mechanism of the inhibitory effect of PYY on gastric acid output seems to involve reduced ACh release from cholinergic nerves.

Effect of dopamine on prostaglandin E2 content in gastric mucosa

The effects of dopamine (DA) on the prostaglandin (PG) E2 content of rat gastric mucosa was investigated. There was a 17.5% increase in gastric mucosal blood flow (BF) after administration of DA (5 micrograms/kg/min iv). After pretreatment with fusaric acid (FA), an antagonist of dopamine beta hydroxylase, DA increased BF by 27.8%. The PGE2 content in DA and DA + FA groups increased at rates of 45.8% and 42.4%, respectively. The PGE2 content in gastric mucosa after incubation following Basso's method, increased in the DA, DA + FA and noradrenaline (NA) groups to 3.32 +/- 0.40 micrograms/g, 3.30 +/- 0.39 micrograms/g and 3.37 +/- 0.42 micrograms/g respectively. It is concluded that there are no differences in PGE2 content among the DA, DA + FA and NA groups. The mechanism by which PGE2 content increases after administration of DA is the direct action of DA and/or increasing BF. It is suspected that DA directly affects PGE2 synthesis, however the possibility that DA is metabolized to NA, which secondarily results in increased PGE2 synthesis, cannot be excluded.

[An experimental study of the action of dopamine in suppressing pentagastrin stimulated gastric acid secretion and its mechanism in rats]

The action of dopamine (DA, 10 micrograms/kg/min) on pentagastrin (16 micrograms/kg/hr) stimulated gastric acid secretion was studied by use of Ghosh-Schild's rats. DA suppressed pentagastrin-stimulated gastric acid secretion 44.6 percent compared with the level before administration. This decrease in acid was inhibited by pretreatment with beta 1 and beta 1 + beta 2 blockers and pretreatment with DA1 + DA2 and DA1 antagonists. The gastric acid secretion with DA1 agonist decreased 36.4 percent from the level at the time of pentagastrin administration. This decrease was inhibited by pretreatment with beta 1 blocker, but suppression of gastric acid secretion by beta 1 + beta 2 stimulator was not inhibited by pretreatment with DA1 antagonist. These results suggest that DA stimulated beta 1 adrenalin receptor via DA1 receptor and thereby suppresses pentagastrin-stimulated gastric acid secretion.

Study of 16,16-dimethyl prostaglandin E2 for prevention of stress ulcer after hepatectomy of experimental cirrhotic liver and its influence on hepatic regeneration

The influence of 16,16-dimethyl prostaglandin E2 (16,16-dm PGE2; an agent used for the prevention of stress ulcer after hepatectomy of the cirrhotic liver) on liver regeneration after hepatectomy was studied in rats. The following results were obtained. Ulceration after the stress of 6 h of water immersion was markedly suppressed in rats treated with 30 r/kg of 16,16-dmPGE2 as compared with the untreated controls. In animals that received hepatectomy alone, the gastric pH and gastric mucosal blood flow showed significant reduction from the preoperative levels. In animals that received hepatectomy plus 16,16-dmPGE2 treatment the postoperative reduction in the gastric pH and gastric mucosal blood flow was suppressed, suggesting the effectiveness of 16,16-dmPGE2 treatment in the prevention of stress ulcer after hepatectomy of the cirrhotic liver. The 3H-thymidine uptake percentage and thymidine activity 24 h after hepatectomy and the DNA content 30 h after hepatectomy were significantly higher in animals treated with 16,16-dmPGE2 than in the untreated controls. In animals that were treated intraperitoneally with 50 mg/kg of indomethacin 6 h before hepatectomy the mitotic index 30 h after hepatectomy was markedly lower than that in untreated controls. This indomethacin-induced reduction in the mitotic index tended to be normalized by treatment with 16,16-dmPGE2. These results suggest that 16,16-dmPGE2 treatment effectively prevents stress ulcer and favorably affects hepatic regeneration after hepatectomy of the cirrhotic liver.

[Effects of dopamine on stress ulcer]

Preventive effect of dopamine on stress ulcer formation was investigated in rats. Dopamine 1-10 micrograms/kg/min suppressed the elevation of ulcer index significantly after water immersion and restraint stress in a dose-dependent fashion, however ulcer indices of 25 micrograms/kg/min of dopamine were higher than 10 micrograms/kg/min. Dopamine 1-10 micrograms/kg/min suppressed the decrease of gastric mucosal blood flow, gastric mucosal prostaglandin E2 content and gastric transmucosal potential difference during stress loading in a dose-dependent manner, although the suppression of them in 25 micrograms/kg/min of dopamine was smaller than in 10 micrograms/kg/min also. Dopamine suppressed the increase of gastric acid secretion and gastric motility during stress loading in a dose-dependent fashion up to 25 micrograms/kg/min. These results indicates that dopamine suppresses the formation of stress ulcer by increasing defensive factors and decreasing aggressive factors.

[A study of bleeding peptic ulcer in the elderly in the view of risk factors]

We treated 448 patients for peptic ulcer from 1970 to 1988. Among them, 52 cases were bleeding peptic ulcer in the elderly. 32 cases (61.6%) had a duration of illness of less than 3 months, and the most common symptom was abdominal pain (51.9%). 22 cases (44.0%) were in shock and 32 cases (62.7%) had accessory diseases. Twelve cases were treated medically, while 40 cases were treated surgically. Elective operations were performed in 15 cases, and their mortality was 6.7%. Emergent operations were performed in 25 cases, and their mortality was 28.0%. The mortality of of cases involving both shock and accessory diseases was 57.1%, and of this group, all 3 cases treated medically died. When bleeding exceeded 2000cc was the mortality 46.7%. Regarding cases of emergent operation involving shock or accessory diseases, the mortality was 18.2% in the cases treated medically for less than 4 days and had the episodes of massive bleeding less than 3 times, but 62.5% in other cases. The results of this study suggest that aggressive surgical treatment in an early stage may reduce the mortality in elderly patients with peptic ulcer.

[The effect of cimetidine to suppress the reduction of gastric mucosal blood flow caused by immobilization in water--its relationship to noradrenaline]

Reduction of gastric mucosal blood flow has been regarded as being the most important event for the gastric defensive mechanisms. In male Wistar rats immobilized in water, the authors recently studied the effect of cimetidine on the gastric mucosal blood flow and the mechanism for that action of cimetidine. In vivo, animals were divided into four groups (PGE2-treated, PGI2-treated and cimetidine-treated groups and an untreated control group), and mucosal blood flow before and 4 hours after the start of immobilization was determined with the electrolytic hydrogen gas clearance technique. In vitro involving perfusion of the isolated gastric blood vessels, the effect of treatment with PGE2, PGI1 or cimetidine in the presence of stimulation with noradrenaline was assessed. The stress-caused blood flow reduction was significantly suppressed in the PGE2-treated group (26.9% reduction in blood flow), the PGI2-treated group (15.7%) and also in the cimetidine-treated group (39.2%) as compared to the controls in which blood flow was reduced by 58.0% following immobilization. In vitro, cimetidine treatment resulted in a reduction of gastric perfusion pressure by 36.6% at maximum although the reduction was more marked following treatment with PGE2 (44.9% reduction) or PGI2 (49.4%). This result suggests that cimetidine also has a vasodilative action.

[Pathological features and treatment of ulcerative lesions of the duodenum associated with Crohn's disease]

Among a total of 22 patients with Crohn's disease, eight patients with duodenal ulcerative lesions were investigated for pathological features and treatment. All duodenal ulcerative lesions of the eight patients were difficult to be distinguished morphologically from peptic duodenal ulcers at the beginning. But during the course of observation six of eight lesions revealed different pathological features from peptic duodenal ulcers: One showed highly edematous mucosa. Four granular mucosa, and another one longitudinal ulcers and cobblestone appearance. Gastric analysis of these patients showed 6.6 +/- 4.0 mEq/L of BAO and 21.3 +/- 3.4 mEq/L of MAO which was comparable to high acidity of peptic duodenal ulcers. Effectiveness of administration of anti-peptic ulcer drugs only and both anti-peptic ulcer drugs plus drugs against Crohn's disease were 40.0% and 57.1%, respectively. Two patients underwent distal partial gastrectomy. Recurrence was not observed. In conclusion, high acidity would be a cause of duodenal ulcerative lesions associated with Crohn's disease, and the pathological features of them would be affected by Crohn's disease itself. Anti-peptic ulcer drugs should to be administered as well as drugs against Crohn's disease. The method which has hypoacidity effect should be selected in operative therapy to such patients as to have stenosis of the duodenum.

The mechanism of acute gastric ulcer after induced hemorrhagic shock

Changes in gastric mucosal blood flow were investigated for their relationship to gastric mucosal prostaglandin E2 (PGE2) and noradrenaline (NA) in rats with hemorrhagic shock. The results were as follows: 1) Gastric mucosal blood flow and NA decreased after hemorrhage. Gastric mucosal PGE2 initially increased after exsanguination and then markedly decreased. 2) Administration of NA before hemorrhage resulted in an increase of PGE2. However, the PGE2 value for animals receiving NA after hemorrhage was not different from that of non-NA-treated group. 3) Pre-treatment with PGE2 suppressed the reduction in both gastric mucosal blood flow and NA and the development of ulcer. These results suggest that the increase in gastric mucosal PGE2 in the early stage of shock might represent a phenomenon of adaptation by the adrenergic activation, and the decrease in PGE2 in the late stage might result from impaired synthesis of PGE2 due to persistent hypoxia and might be one of the possible factors in ulcer formation.

Inhibitory effect of peptide YY on gastric acid output in rats

The administration of peptide YY (PYY: 0.8, 1.6 and 3.2 nmol/kg/h, i.v.) to fasting rats inhibited not only baclofen (2 mg/kg, s.c.)-stimulated gastric acid output and gastric mucosal blood flow, but also pentagastrin (8 micrograms/kg/h, i.v.)-stimulated gastric acid output. PYY (3.2 nmol/kg/h) reduced baclofen-induced acid output more than pentagastrin-induced acid output, i.e., by 61.8 +/- 11.5% compared to 35.3 +/- 8.2%. PYY inhibited acetylcholine (ACh) release from cholinergic nerve endings of gastric body evoked by electrical transmural stimulation (ETS: 1 msec, 10 V, 3 Hz, 30 sec) by 47.2 +/- 3.5%. The mechanism of the inhibitory effect of PYY on gastric acid output seems to involve decreased gastric mucosal blood flow and reduced ACh release from cholinergic nerves.

Experimental study of vagotomy for prevention of stress ulcer after hepatectomy of cirrhotic livers. Its influence on hepatic regeneration

We experimentally studied the influence of vagotomy on hepatic regeneration in rats after hepatectomy of cirrhotic livers. In animals that underwent hepatectomy plus vagotomy the reduction in gastric pH was suppressed, but gastric mucosal blood flow was less than that in control animals that received hepatectomy alone. The suppression of 3H-thymidine uptake percentage and thymidine kinase activity after hepatectomy was more marked in animals treated with hepatectomy plus vagotomy than in controls treated with hepatectomy alone. Hepatic DNA level tended to be lower in animals treated with hepatectomy plus vagotomy than in controls. In animals treated with hepatectomy plus vagotomy, the peak level of the mitotic index was lower and the hepatic regeneration rate was evidently suppressed. These results suggest that it is not appropriate to apply vagotomy, during hepatectomy of cirrhotic livers, for the prevention of postoperative stress ulcer because it causes a marked reduction in gastric mucosal blood flow and suppresses hepatic regeneration.

An approach to the mechanism of acute ulceration in obstructive jaundice

Changes of noradrenaline (NA) and prostaglandin (PG) E2 in gastric mucosa and gastric wall blood flow (GWBF) were investigated after stress load in rats with obstructive jaundice. We found that water immersion and restraint stress more easily increased the ulcer index and decreased GWBF, corresponding to a decrease of the NA and PGE2 contents in the gastric mucosa, as the duration of jaundice increased. Administration of PGE2 reduced the increase of the ulcer index and the decrease of the GWBF and NA contents in the gastric mucosa. It is suspected that the rapid decrease of NA and PGE2 is connected with the rapid decrease of GWBF after stress load in obstructive jaundice, and we reached the hypothesis that both PGE2 and NA mutually regulate local GWBF.

[Efficacy of vagotomy on liver regeneration in the prevention of stress ulcer after partial hepatectomy in the cirrhotic rat]

Possible effects of vagotomy (a means of preventing stress ulcers after partial hepatectomy in cirrhotic liver) on liver regeneration were explored. Cirrhosis was induced in rats by means of intraperitoneally administering 4% thioacetamide for 10 consecutive weeks. These rats were subjected to partial hepatectomy (ca. 68% resection) and vagotomy at the same time. Normal rats of consistent age served as controls after receiving hepatectomy. In controls, which received hepatectomy alone, both gastric pH and gastric wall blood flow showed a significant reduction on the third day after surgery. In animals which received both hepatectomy and vagotomy, postoperative reduction in gastric pH was suppressed, but postoperative reduction in gastric wall blood flow was more marked compared to those of controls. In animals which received both hepatectomy and vagotomy, postoperative 3H-thymidine intake and thymidine kinase activity were markedly suppressed compared to controls. In animals which received both hepatectomy and vagotomy, the peak level of mitotic index and the hepatic regeneration rate were markedly suppressed compared to those of controls. The above results indicate that vagotomy is not advantageous to liver regeneration and prevention of stress ulcer after partial hepatectomy in cirrhotic rat because of its potency of inducing marked reduction in gastric wall blood flow and impediment of liver regeneration.

[Experimental study on the pathogenesis of acute ulceration in obstructive jaundice--with reference to gastric mucosal blood flow]

We prepared obstructive jaundice models in rats in order to study the mechanism of acute ulceration in obstructive jaundice centering on impediments to gastric wall blood flow and changes in gastric mucosal NA and PGE2 when the rats were subjected to water immersion restraint stress. The results were: In the obstructive jaundice 2 weeks group, when subjected to water immersion restraint stress, gastric mucosal NA reached a dried up stage from the incipient stage, causing gastric mucosal impediments at the same time, showing a significant decrease of gastric mucosal PGE2. Intragastric pH was at a similar level of excessive acidity in all groups; gastric acid is believed to be a secondary factor promoting ulceration. Gastric mucosal PGE2 showed a significant decrease coinciding with the increase in ulceration index, being a possible factor of ulceration; it is also presumed to regulate gastric wall blood flow alternatively with gastric mucosal NA. Pre-treatment with PGE2 prior to loading stress resulted in a decrease in gastric wall blood flow being significantly controlled. The administration of PGE2 brought about an improvement in gastric wall blood flow and a consequent increase in gastric mucosal NA, being judged effective for acute ulceration in obstructive jaundice.