To evaluate the contribution of thromboxane (Tx) A2-prostaglandin (PG) H2 in two-kidney, one-clip Goldblatt hypertension (GH), 26 GH rats were chronically treated (GHT) with a specific TxA2-PGH2 receptor antagonist, CGS-22652 (30 mg.kg-1.24 h-1 sc); 28 others as well as 17 sham-clipped (SC) rats received vehicle. Twelve GH and 3 GHT rats developed malignant hypertension and died. After 6 wk of treatment, GH rats exhibited higher mean blood pressure (BP; 189 +/- 3 vs. 118 +/- 2 mmHg) and an increased vascular reactivity to the main pressor agents compared with SC rats. Chronic TxA2-PGH2 receptor blockade lowered mean BP in 13 GHT rats (125 +/- 3 mmHg) and decreased their vascular reactivity compared with GH rats. However, 10 GHT rats remained hypertensive (190 +/- 9 mmHg) and differed from the former by an increased vascular reactivity to vasopressin. It is concluded that renal artery clipping induces either benign or malignant hypertension. In benign forms, TxA2-PGH2 blockade normalizes BP through decreasing the vascular responsiveness to the main pressor agents. In malignant forms, it limits the elevation of BP and markedly reduces mortality.

OBJECTIVE

Mechanisms that underlie the relaxant response to histamine were examined in dog external (a branch of external carotid artery) and internal (a branch of internal carotid artery) ophthalmic arteries (EOA and IOA).

METHODS

Changes in isometric tensions were recorded in helical strips of the arteries with and without the endothelium.

RESULTS

Histamine predominantly produced relaxations in EOA and IOA, partially contracted with prostaglandin (PG) F2 alpha. The relaxation of IOA almost was abolished by treatment with cimetidine (10(-5) mol/l), whereas the response of EOA was partially attenuated by treatment with cimetidine or chlorpheniramine (10(-6) mol/l) and was abolished with their combined treatment. Endothelium denudation depressed the relaxation in EOA but did not affect the response of IOA. The response to histamine of EOA was inhibited by treatment with indomethacin (10(-6) mol/l) or tranylcypromine (10(-4) mol/l), a PGI2 synthesis inhibitor, only when the endothelium was present, but additional treatment with chlorpheniramine did not further inhibit relaxation. On the other hand, IOA's response to histamine was not inhibited by indomethacin, despite the presence of endothelium.

CONCLUSIONS

The histamine-induced relaxation in EOA may be associated with the release of vasodilator PGI2 through the activation of H1 receptors in the endothelium and with the direct action on H2 receptors in smooth muscle, whereas the relaxation in IOA is mediated exclusively by H2 receptors in smooth muscle.

Earlier studies on HL-60 cells induced to differentiate into macrophages by phorbol esters have shown a selective stimulation of thromboxane (Tx) formation from endoperoxide prostaglandin (PG) H2, indicating that Tx synthesis is regulated at the level of Tx synthase (TxS), one of the peripheral enzymes of the PGH-synthase pathway. We now report on the regulation of TxS during HL-60 macrophage differentiation using monoclonal anti-TxS serum and comparing turnover rates of TxS and its biological activity with those of other enzymes of arachidonic acid metabolism. Western-blot analysis, enzyme-linked immunosorbent assay, immunohistochemical staining and [35S]methionine-labeling experiments suggested a phorbol-ester-dependent early induction of synthesis of TxS. [35S]Methionine incorporation into TxS was stimulated within 4 h after initiation of differentiation and was associated with a major rise in the TxS catalytical activity. Pulse-chase experiments showed a half life for the TxS protein of 16.4 h in both control and phorbol-ester-treated cells. The biological half life of TxS was 10.5 h, as determined by PGH2 incorporation into TxB2 after cycloheximide treatment. In contrast, the biological half lives of PGH synthase, prostacyclin synthase and 5-lipoxygenase were significantly shorter and were 3, 2.5 and 2.5 h, respectively. These results reveal that Tx synthesis in macrophages is mediated by at least two distinct mechanisms; a protein-kinase-C-dependent induction of de novo synthesis of TxS and the selective resistance of the enzyme against the activity of protein kinase C.

The relative contribution of thromboxane (TX)A2/prostaglandin (PG)H2 and ADP to platelet shape change was determined using the specific TXA2/PGH2 antagonist, 13-azaprostanoic acid (13-APA) and the ADP antagonist, ATP. Shape change was induced in human platelet-rich plasma with doses of arachidonic acid (AA) or the PG endoperoxide analog U46619, which did not cause measurable ATP/ADP release. Pretreatment of platelet-rich plasma with 13-APA completely inhibited shape change to AA or U46619 but did not inhibit ADP-induced shape change. In contrast, ATP completely blocked shape change to ADP but not to AA or U46619. In addition, 13-APA and ATP also selectively reversed shape change. Thus, 13-APA added 1.5 min subsequent to AA or U46619 resulted in almost complete reversal of the shape change response. However, 13-APA did not reverse ADP-induced shape change. A similar selectivity was observed with ATP which reversed shape change to ADP but not to AA or U46619. These findings provide evidence that the interaction of TXA2/PGH2 with its receptor results in the direct stimulation of shape change independent of secreted ADP. Furthermore, maintenance of this shape change response appears to require continued occupation of the TXA2/PGH2 receptor.

Direct, in vivo microcirculatory experiments were undertaken with anesthetized rats to determine whether prostaglandin (PG)-like compounds and histamine may mediate post-occlusion hyperemia in single mesenteric arterioles. Superfusion of the mesenteric vasculature with two structurally different PG synthetase inhibitors, indomethacin and 5,8,11,14-eicosatetraynoic acid (ETA), was found to markedly inhibit postocclusion vasodilator responses in arterioles 20-22 micrometer i.d. Superfusion of mesentery with an H2-histamine receptor antagonist, metiamide, resulted in a 40% inhibition of the postocclusion vasodilator responses in arterioles. Superfusion of the mesenteric vasculature with a combination of indomethacin and metiamide resulted in a 95% suppression of the postocclusion dilator responses. Administration of either the PG synthetase inhibitors, metiamide, or a combination of both types of drugs did not, however, influence resting arteriolar tone or responsiveness to PGE1 or epinephrine. Although the results of these experiments implicate a role for PG-like substances and histamine in reactive or postocclusion hypermia, they do not provide evidence for a role of these humoral substances in the normal moment-to-moment regulation of arteriolar tone.

BACKGROUND

Devastating extremity injuries are prevalent but often survivable on the modern battlefield. These complex injuries require advanced methods of reconstruction, involving prolonged ischemic periods and reperfusion injury. Using our group's validated porcine model of gracilis myocutaneous flap transplantation, this study demonstrates that an interim perfusion of hydrogen sulfide (H2S) mitigates the effects of reperfusion injury in the setting of delayed restoration of blood flow.

METHODS

A gracilis myocutaneous flap (200-400 g; surface area, 250 cm²) was procured from the hind limb of a Yorkshire swine (70-90 kg, n=16). The right external carotid artery and the internal jugular vein are the recipient axis. Group 1 (control, n = 6) underwent delayed anastomosis with a 3-hour ischemic period. Group 2 (n=10) underwent a similar delayed anastomosis with an interim perfusion of H2S during the ischemic period. The animals survived for 14 days. Systemic biomarker assays for skeletal muscle tissue injury (creatine kinase, lactate dehydrogenase, and aspartate transaminase) and proinflammatory markers (tumor necrosis factor α and interleukin 6) provide assessment of reperfusion injury at the cellular level.

RESULTS

The control animals (3 hours of ischemia with an interim perfusion of heparinized saline) demonstrated increased levels of injury biomarkers and proinflammatory cytokines compared with the animals receiving H2S infusion and identical ischemic interval. The control flaps had a mean creatine kinase level of 280³×10 U/L (±80×10³), compared with the H2S group, which had a mean of 99×10³ U/L (±14×10³; P=0.0007 at postoperative day 2). lactate dehydrogenase levels (mean) were 26×10³ U/L (±8×10³) versus 9×10³ U/L (±3×10³; P=0.0004) and aspartate transaminase levels (mean) were 1651 U/L (±324) versus (873 U/L [±279]; P=0.0013) for the control and treatment groups, respectively. Similarly, an intergroup difference in IL-6 was found, although not statistically significant. Tumor necrosis factor α levels (mean) were 93 pg/mL (±14) versus 39 pg/mL (±4; P=0.0013) for the control and treatment groups, respectively.

CONCLUSIONS

This study demonstrated the mitigating properties of H2S on reperfusion injury. Interim perfusion with H2S resulted in diminution of ischemia-dependent biomarkers after 3 hours of ischemia. Follow-up studies will translate these findings as an evolving method for reconstructing previously unreconstructable injuries.

Studies of antisecretory compounds such as the H2-receptor antagonists have altered therapy and enhanced the understanding of peptic ulcer disease (PUD). While it is agreed that the dictum "no acid, no ulcer" is valid, acid hypersecretion does not appear to be the major determinant in a significant number of ulcer patients. More careful consideration of mucosal integrity in the pathogenesis of PUD is therefore necessary. A small but significant number of patients (5-15%) do not heal, despite the use of effective antiulcer drugs. Moreover, the posthealing recurrence rate may reach 75% after treatment is discontinued, and nearly one third of cigarette-smoking patients on maintenance therapy may suffer recurrences. Prostaglandins (PGs) are particularly important as potent antisecretory and effective antiulcer agents. In addition, recognition of their cytoprotective effects has stimulated research into the understanding and importance of mucosal protection and mucosal defense mechanisms. Animal studies show that PGs at nonantisecretory dosages prevent the development of gastric ulcers caused by virtually any insult. In humans, PGs prevent the mucosal damage caused by aspirin and ethanol. In some studies, the maintenance of normal mucosal integrity has been linked to normal mucosal production of PGs. Therefore, it is possible that exogenous PGs may be effective in patients whose ulcers do not heal with conventional therapy. They may reduce the recurrence of ulcers, particularly in those patients whose defect in mucosal integrity appears to be the major problem. Furthermore, in those patients subjected to the toxic effects of alcohol ingestion, nonsteroidal antiinflammatory drugs, antineoplastic drugs, and stress, exogenous PGs may prevent mucosal lesions. As such, PGs could be the ideal antiulcer drug.

Hemodialysis patients are frequently affected by peptic disease, and in many cases they have high serum levels of gastrin. The aim of this study was to evaluate the effects of omeprazole, an inhibitor of gastric parietal cells hydrogen pump, on peptic disease and gastric secretion of 16 selected dialysis patients. H2-receptors blocking drugs or gastric acidity buffers were withdrawn for 2 weeks, then omeprazole was administered for 4 weeks at a daily dosage of 20 mg. Before and after the omeprazole therapy, registration of subjective peptic symptoms, baseline serum gastrin dosage and endoscopy of upper digestive tract were performed. Before starting omeprazole, the serum gastrin value was 515 +/- 180 pg/l, all the patients complained of peptic symptoms, and endoscopy showed: 8 cases of duodenal ulcer, 3 cases of pyloric ulcer and 5 cases of antral erosive gastritis. At the end of the omeprazole treatment period, a slight but statistically not significant increase of serum gastrin level (537 +/- 198 pg/l) was observed. Twelve patients reported the total disappearance of symptoms of peptic disease, 3 patients a partial reduction, and 1 patient had no improvement. Control endoscopy showed the healing (white scar) of all the ulcers, and the disappearance of all the erosive lesions. In conclusion, our results show that a 20 mg/day omeprazole short-term therapy can be given safely to uremic patients undergoing hemodialysis and is effective for a quick healing of active peptic lesions.

Six percent hydrogen peroxide (H2O2) was used as a generator of the *OH free radical, and as an aggressor of gastric mucosa, in 100 Wistar rats. The mucosal cytoprotector effect of sucralfate, misoprostol, enprostil, cimetidine, ranitidine, famotidine and 10% aluminum sulphate yielded almost complete macroscopic and histological protection to the gastric mucosa. Misoprostol or enprostil gave partial protection whereas the H2 blockers aggravated the gastric necrotic lesions produced by the H2O2. We conclude that sucralfate is a true anti-oxidant that protects the gastric mucosa through its aluminum and sulphydril components, the increment of gastric mucins and endogenous PGs.

The neural histaminergic system is involved in a wide range of physiological processes, including anxiety. Histaminergic neurons are localized in the tuberomammillary nucleus of the posterior hypothalamus and share bidirectional connections with the lateral septum, an area well implicated in anxiety. The current study examined whether the histaminergic system of the lateral septum regulates rats' defensive behaviors in two animal models of anxiety, the elevated plus maze (EPM) and novelty-induced suppression of feeding paradigm (NISF). We found that bilateral infusions of histamine (1.0 μg and 5.0 μg) into the lateral septum selectively decreased rats' defensive behaviors in the EPM (both doses) and NISF (1.0 μg only). Follow-up studies found that pre-infusions of the H1 and H2 antagonists, pyrilamine (20 μg) and ranitidine (20 μg) respectively, reversed the anxiolytic-like effects of intra-LS histamine (1.0 μg) in the NISF but not in the EPM, while pre-infusions of the H3 antagonist ciproxifan (200 pg) attenuated the anxiolytic-like effects of intra-LS histamine in the EPM but not in the NISF. This double dissociation suggests that H1 and H2 receptors in the lateral septum, likely via a post-synaptic mechanism, mediate the anxiolytic-like effects of histamine in the NISF but not in the EPM. In contrast, lateral septal H3 receptors mediate, likely pre-synaptically, the anxiolytic-like effects of histamine in the EPM but not in the NISF. Our findings indicate that these receptors differentially contribute to rats' specific defensive behaviors in the EPM and NISF, that is, avoidance of open spaces and neophagia respectively.

Accumulating evidence shows that hydrogen sulfide (H2S) acts as a multifunctional signaling molecule in plants, whereas the interaction between H2S and ethylene is still unclear. In the present study we investigated the role of H2S in ethylene-promoted banana ripening and senescence by the application of ethylene released from 1.0 g·L-1 ethephon solution or H2S with 1 mM sodium hydrosulfide (NaHS) as the donor or in combination. Fumigation with ethylene was found to accelerate banana ripening and H2S treatment effectively alleviated ethylene-induced banana peel yellowing and fruit softening in parallel with decreased activity of polygalacturonase (PG). Ethylene+H2S treatment also delayed the decreases in chlorophyll and total phenolics, and increased the accumulation of flavonoid, whereas decreased the contents of carotenoid, soluble protein in banana peel and reducing sugar in pulp compared with ethylene treatment alone. Besides, ethylene+H2S treatment suppressed the accumulation of superoxide radicals (·O2-), hydrogen peroxide (H2O2) and malondialdehyde (MDA) which accumulated highly in ethylene-treated banana peels. Furthermore H2S enhanced total antioxidant capacity in ethylene-treated banana peels with the 2,2'-azobis(3-ethylbenz-thiazoline-6-sulfonic acid (ABTS) assay. The result of quantitative real-time PCR showed that the combined treatment of ethylene with H2S down-regulated the expression of ethylene synthesis genes MaACS1, MaACS2 and MaACO1 and pectate lyase MaPL compared with ethylene treatment, while the expression of ethylene receptor genes MaETR, MaERS1 and MaERS2 was enhanced in combination treatment compared with ethylene alone. In all, it can be concluded that H2S alleviates banana fruit ripening and senescence by antagonizing the effect of ethylene through reduction of oxidative stress and inhibition of ethylene signaling pathway.

Strain BCU110501T was the first isolate reported to fulfill Koch's postulates by inducing effective nodules on its host plant of origin Discaria trinervis (Rhalmnaceae). Based on 16S rRNA gene sequence similarities, the strain was found to be most closely related to the type strain of Frankia elaeagni DSM 46783T (98.6%) followed by F. alni DSM 45986T (98.2%), F. casuarinae DSM 45818T (97.8%) and F. inefficacies DSM 45817T (97.8%). Digital DNA:DNA hybridizations (dDDH) between strain BCU110501Tand the type strains of other Frankia species were clearly below the cutoff point of 70%. The G+C content of DNA is 72.36%. The cell wall of strain BCU110501T contained meso-diaminopimelic acid and the cell sugars were galactose, glucose, mannose, xylose and ribose. Polar lipids were phosphatidylinositol (PI), diphosphatidylglycerol (DPG), glycophospholipid (GPL1-3), phosphatidylglycerol (PG) and an unknown lipid (L). The major fatty acids of strain BCU110501T consisted of iso-C16:0, C17:1 w8c and C16:0. Major menaquinones were MK9 (H4), MK9 (H6) and MK9 (H2). Based on these analyses, strain BCU110501T (=DSM 46785T=CECT 9042T) should be classified as the type strain of a novel Frankia species, for which the name Frankia discariae sp. nov. is proposed.

Vascular prostanoids, isomerized from an intermediate prostaglandin (PG), H2, produced by cyclooxygenase (COX), exert various effects on the vascular system, both protective and destructive. During endothelial dysfunction, vascular protector prostacyclin/prostaglandin I2 (PGI2) is decreased, while inflammatory PGE2 and thrombotic TXA2 are increased. Therefore, our research aim was to reverse the event by controlling PGH2 metabolism by generating an in vivo model via enzymatic engineering of COX-1 and prostacyclin synthase (PGIS). The COX-1 and PGIS genes were linked to a 10-residue amino acid linker to form a Single-chain Enzyme Complex (SCHEC), COX-1-10aa-PGIS. Transgenic (CP-Tg) mice in a FVB/N background were generated using the pronuclear microinjection method. We first confirmed mRNA and protein expression of COX-1-10aa-PGIS in various CP-Tg mouse tissues, as well as upregulation of circulating PGI2. We then examined the cardiovascular function of these mice. Our CP-Tg mice exhibited marked resistance to vascular assault through induced carotid arterial blockage, acute thrombotic stroke and arterial arrest, angiotensin-induced peripheral vasoconstriction, and hepatic lipid accumulation after receiving a high-fat diet. They also had a longer lifespan compared with wild-type mice. This study raises the possibility of fighting cardiovascular diseases by regulating cellular arachidonic acid-derived PGH2 metabolites using enzymatic engineering.

To determine whether the serum pepsinogen I (PG I) level would be a suitable marker for selecting patients at risk for duodenal ulcer recurrence and, thus, would benefit from maintenance therapy, we treated duodenal ulcer patients with H2-receptor antagonists. After healing 140 ulcer patients we assessed the recurrence rate at 1 year with and without maintenance therapy. The annual recurrence rates in duodenal ulcer patients with hyper-PGI (95 ng/ml or more), with 66 ng/ml less than or equal to PGI less than 95 ng/ml, and with PGI less than 66 ng/ml were 87.0%, 27.3%, and 17.9%, respectively, when they did not receive maintenance therapy. In patients with hyper-PGI the recurrence rate was significantly lower in patients receiving maintenance therapy than in patients not receiving maintenance therapy, whereas in patients with PGI less than 66 ng/ml the recurrence rate was as low as 20% regardless of maintenance therapy. These results indicate that maintenance therapy with half the dose of H2-receptor antagonist is not required by patients with PGI less than 66 ng/ml, whereas those with hyper-PGI may be good candidates for long-term maintenance therapy.

A 82-year-old woman was admitted because of dehydration and chronic renal failure. Although her renal function was improved by hydration, granulocytopenia (granulocyte number 645/mm3) occurred. Treatment with a relatively high dose of H2 blocker for one month before admission may have caused the granulocytopenia. To prevent possible infection in the patient, we administered 75 g of granulocyte-colony stimulating factor (G-CSF) for 5 consecutive days but 4 days after commencement of administration of G-CSF, pain in both knee joints suddenly appeared. Synovial fluid aspiration revealed granulocytosis (10,400/mm3) and deposition of calcium pyrophosphate dihydrate in the knee joints. The level of G-CSF in the synovial fluid was increased in the joints (700 pg/ml), compared with the serum concentration (62 pg/ml). Furthermore, the concentrations of interleukin-6 and interleukin-8 were markedly increased in the synovial fluid. The results indicated that her pseudogout exacerbation by G-CSF was at least in part explained by the increased production of cytokines in the knee joints. Because the prevalence of pseudogout and gout is overwhelming in the elderly, the possibility of GCSF induced exacerbation of joint pain should be carefully considered in elderly patients.

BACKGROUND

Zollinger-Ellison syndrome is a very rare disease caused by tumor with gastrin producing cells accompanied by hypergastrinemia leading to gastric hypersecretion and peptic ulcers and their complications.

METHODS

Female case of gastrinoma (Zollinger-Ellison syndrome; Z-E) with a record of 38 yrs of survival. Acute gastro-duodenal ulcers started at 28 yr of age and Z-E was diagnosed by using gastrin assays. Basal and maximal acid outputs and ratio of basal/maximal outputs were away over normal limits. Because of ulcer recurrence and complications, patient was subjected to several gastric surgeries but refused total gastrectomy. She was also treated with many H2-receptor (R) antagonists and proton-pump inhibitors (PPI), each new drug being initially highly effective but then showing declining efficacy except when PPI, lansoprazole was used. The gastrin level rose in the course of disease from initial high value of 2000 pg/mL to the extreme 4500 ng/mL at present. During the last 2 yrs, metastasis mainly to liver developed and they were successfully treated by synthetic octapeptide derivative of somatostatin and, as a result, metastatis partly reduced and plasma gastrin drasticly decreased. Biopsy taken from liver metastasis showed the presence of typical gastrinoma cells with gastrin and chromogranin, while that from oxyntic mucosa revealed the ECL-cell hyperplasia with carcinoid tumors and unexpected gastric atrophy.

CONCLUSIONS

This phenomenal case described in this article might be the new proven evidence needed by gastroenterologists to overturn the traditional treatment using total gastrectomy as a treatment of choice to the partial gastrectomy combined with proton pump inhibitors.

The effects of 2-[(4-acetylphenyl)amino]-3-chloro-1,4-naphthalenedione (NQ-Y15), a synthetic 1,4-naphthoquinone derivative, on platelet activity and its mechanism of action were investigated. NQ-Y15 caused a concentration-dependent inhibition of the aggregation induced by thrombin, collagen, arachidonic acid (AA), and A23187. The IC50 values of NQ-Y15 on thrombin (0.1 U/mL)-, collagen (10 microg/mL)-, AA (50 microM)-, and A23187 (2 microM)-induced aggregation were 36.2 +/- 1.5, 6.7 +/- 0.7, 35.4 +/- 1.7, and 93.1 +/- 1.4 microM, respectively. NQ-Y15 also inhibited thrombin-, collagen-, AA-, and A23187-stimulated serotonin secretion in a concentration-dependent manner. However, a high concentration (100 microM) of NQ-Y15 showed no significant inhibitory effect on ADP-induced primary aggregation, which is independent of thromboxane A2 (TXA2) production in rat platelets. In fura-2-loaded platelets, the elevation of intracellular free calcium concentration stimulated by AA, thrombin, and 4-bromo-A23187 was inhibited by NQ-Y15 in a concentration-dependent manner. The formation of TXA2 caused by AA, thrombin, and collagen was inhibited significantly by NQ-Y15. NQ-Y15 inhibited TXA2 synthase in intact rat platelets, since this agent reduced the conversion of prostaglandin (PG) H2 to TXA2. Similarly, NQ-Y15 selectively inhibited the TXA2 synthase activity in human platelet microsomes, whereas it had no effect on activity of phospholipase A2, cyclooxygenase, and PGI2 synthase in vitro. NQ-Y15 inhibited platelet aggregation induced by the endoperoxide analogue U46619 in human platelets, indicating TXA2 receptor antagonism, possibly of a competitive nature. These results suggest that the antiplatelet effect of NQ-Y15 is due to a combination of TXA2 synthase inhibition with TXA2 receptor blockade, and that it may be useful as an antithrombotic agent.

The aim of the present study was twofold: 1) to assess whether inhibition of thromboxane A2 (TxA2) synthase exerts more potent antiplatelet effects when applied concomitantly with TxA2 and prostaglandin (PG)H2 receptor blockade and 2) whether these effects are mediated through redirection of PG endoperoxides toward the synthesis of antiplatelet PGs, such as PGI2 and PGE2. Thus, cyclic flow variations (CFVs), due to recurrent platelet aggregation, were initiated in the stenotic, endothelially injured carotid arteries of 39 rabbits. After 30 min of CFVs, the animals received: 1) SQ29548 (up to 0.6 mg/kg bolus + 0.2 mg kg-1 hr-1, n = 13), a TxA2/PGH2 receptor antagonist; 2) dazoxiben (up to 15 mg/kg bolus + 5 mg kg-1 hr-1, n = 13), a TxA2 synthase inhibitor and 3) picotamide (up to 20 mg/kg bolus + 20 mg kg-1 hr-1, n = 13), a drug with simultaneous TxA2 synthase and receptor blocking properties. CFVs were abolished in 6, 7, and 12 animals treated with SQ29548, dazoxiben, and picotamide, respectively (P < .01 for picotamide versus SQ29548 and dazoxiben). The animals in which CFVs were not abolished by SQ29548 or dazoxiben received the other drug at the same dose. CFVs were abolished by dazoxiben in five of seven rabbits that initially did not respond to SQ29548 and by SQ29548 in five of six animals that did not respond to dazoxiben. All animals that responded to the combination of SQ29548 and dazoxiben, as well as those that responded to picotamide, received increasing intravenous infusions of epinephrine to restore CFVs.(ABSTRACT TRUNCATED AT 250 WORDS)

OBJECTIVE

Histamine plays important physiological roles in upper gastrointestinal tract and acts via the H2 receptor. A polymorphism -1018 G>A (rs2067474) was identified in an enhancer element of the HRH2 promoter. We attempted to clarify the associations of this polymorphism with the progression of gastric mucosal atrophy.

METHODS

Gastric mucosa samples were obtained from 398 subjects with no malignancies. The rs2067474 genotype was determined by PCR-SSCP method. The degree of gastritis was assessed in 366 subjects and serum pepsinogen (PG) I/II levels were measured in 108 subjects. The subjects with atrophy score higher or equal to 2 and metaplasia score higher or equal to1 were classified into the severe atrophic gastritis group (SA group).

RESULTS

The -1018G>A minor allele frequencies in SA and non-SA groups were 8.02% and 13.3%, respectively (p=0.057). The -1018 GG homozygote had a significantly high risk for gastric mucosal atrophy (OR: 2.03, 95%CI: 1.03-4.01, p=0.042). In H. pylori positive subjects, GG homozygote was a more significant risk factor for gastric mucosal atrophy (OR: 2.32, 95%CI: 1.12-4.81, p=0.023). In addition, in the subjects older than 60 years, GG homozygote had also a significant risk for gastric mucosal atrophy (OR: 2.63, 95%CI: 1.15-6.00, p=0.022). In -1018 GG homozygote, PG I/II ratio was significantly lower in H. pylori positive than negative subjects and was significantly decreased with age (p=0.0032 by ANOVA), whereas it was not in the A carrier.

CONCLUSIONS

Our results suggest that HRH2 -1018 GG homozygote is a risk factor for the severity of gastric mucosal atrophy under the influence of H. pylori infection, especially in older subjects.

This study examined the changes in cerebral blood flow, water content, and lipoxygenase metabolites (leukotrienes) following bilateral carotid artery occlusion (BCO) and reperfusion in the gerbil. The effect of inhibiting lipoxygenase with nordihydroguaretic acid (NDGA) was also examined. BCO caused cerebral blood flow (measured using H2 clearance) to decline from 23.5 +/- 1.9 to 4.5 +/- 1.9 ml/min/100 gm. Reperfusion increased flow to 27.9 +/- 4 ml/min/100 gm at 10 min, which declined to 13.7 +/- 1.3 ml/min/100 gm at 50 min. Concomitant oedema measurement revealed brain specific gravity decreasing to 1.0402 +/- 0.0014 at 10 min and to 1.0325 +/- 0.0006 at 50 min reperfusion (nonoccluded controls). Leukotriene B4 (LTB4) increased from 26.8 +/- 4.6 to 33.5 +/- 2.1 pg/mg protein 10 min after reperfusion (p less than 0.05), but declined to 21.8 +/- pg/mg protein by 100 min (vs nonischaemic control = 21.3 +/- 2.9 pg/mg protein). Activation of arachidonate metabolism was confirmed by significantly increased 6 keto PGF1 alpha. Pretreatment of the animals with NDGA did not alter CBF, but increased specific gravity above saline-treated controls at 50 min of reperfusion (NDGA = 1.0370 +/- 0.002 vs control = 1.0325 +/- 0.0006, p less than 0.05). Similarly, NDGA blunted the increase in LTB4 formation 10 min after reperfusion (control = 26.8 +/- 4.6 pg/mg protein vs NDGA = 29.7 +/- 2.9 pg/mg protein, p = N.S.). These findings indicate that LTB4 production is stimulated by BCO and reperfusion in the gerbil, and that this stimulation occurs early on in the reperfusion. Further, we observe that the lipoxygenase inhibitor NDGA limits the formation of ischaemic cerebral oedema.(ABSTRACT TRUNCATED AT 250 WORDS)

Cells were isolated by use of collagenase, EDTA and pronase form human gastric mucosa obtained at peptic ulcer surgery (n = 61) or at Whipple's operations (n = 6). Enriched parietal cell fractions were prepared by isopycnic centrifugation with Percoll. H+ production, intracellular instrinsic factor and histamine content were maximal in the low density fraction containing 75% parietal cells and--among other nonparietal cell types--mast cells. H+ production, intrinsic factor secretion and adenylate cyclase-activity responded to histamine stimulation in a concentration dependent manner. Response was blocked by histamine H2 receptor antagonists (rantidine, famotidine). Dibutyryl cAMP and the phosphodiesterase inhibitor IMX were the most powerful stimuli whereas carbachol, hexoprenaline and pentagastrin were less effective. Prostaglandin E2 and 6-keto-PGF2 alpha occurred in the highest concentrations in the low density cell fraction. PG production increased linearly for 15 min and seemed to be influenced by the intracellular calcium level.

OBJECTIVE

We analyzed the involvement of thromboxane (TX) A2/prostaglandin (PG) H2 (TP) receptor in ischemia-induced neovascularization in mice.

RESULTS

Unilateral hindlimb ischemia was induced by right femoral artery ligature in male C57BL/6J mice (n=7 per group). Animals were then treated with or without TP receptor antagonist (S18886, 5 or 10 mg/kg per day; ramatroban, 10 mg/kg per day) or aspirin (30 mg/kg per day) in drinking water for 21 days. Hindlimb ischemia raised plasma level of TXB2, the stable metabolite of TXA2, by 4.7-fold. This increase was blocked by aspirin treatment whereas S18886 (5 or 10 mg/kg per day) had no effect. However, neither S 18886 nor aspirin affected postischemic neovascularization. We next assessed the putative involvement of TXA2 signaling in angiotensin II (Ang II) proangiogenic pathway. Ang II (0.3 mg/kg per day) enhanced TXB2 plasma levels by 2.6-fold over that of control (P<0.01). Ang II-induced TXB2 upregulation was reduced by cotreatment with Ang II type I receptor antagonist (candesartan, 20 mg/kg per day). Angiographic score, capillary number, and foot perfusion were improved by 1.7-, 1.7-, and 1.4-fold, respectively, in Ang II-treated mice compared with controls (P<0.05). Ang II proangiogenic effect was associated with a 1.6-fold increase in VEGF-A protein content (P<0.05) and a 1.4-fold increase in the number of Mac-3-positive cells (ie, macrophages) in ischemic areas (P<0.05). Interestingly, treatments with TP receptor antagonists or aspirin hampered the proangiogenic effects of Ang II.

CONCLUSIONS

Endogenous activation of TXA2 receptor by eicosanoids did not modulate spontaneous neovascularization in the setting of ischemia. Conversely, TXA2 signaling is involved in Ang II-induced AT1-dependent vessel growth.

The effects of nizatidine (N-[2-[[[2-[(dimethylamino)methyl]- 4-thiazolyl]methyl]thio]ethyl]-N'-methyl-2-nitro-1,1-ethenediamine , CAS 76963-41-2), a new histamine H2-receptor antagonist, on the content of prostaglandins (PGs) in the rat gastric mucosa at doses that inhibit basal gastric acid secretion were compared with those of two other histamine H2-receptor antagonists, cimetidine and ranitidine. Nizatidine did not inhibit basal gastric acid secretion at a dose of 0.4 mg/kg but showed dose-dependent inhibition at doses of 10, 30, and 100 mg/kg. This drug had no effects on the content of PG in the gastric mucosa when subcutaneously administered at doses of 0.4, 10, 30 and 100 mg/kg once daily for 5 days. Cimetidine and ranitidine administered at doses that markedly inhibit basal gastric acid secretion (250 and 100 mg/kg/d, respectively) had no effects on the content of PG in the gastric mucosa. On the other hand, nizatidine, cimetidine, or ranitidine at concentrations of 1-100 mumols/l did not inhibit in vitro PGE2 synthesis using sheep seminal vesicle microsomes. These results suggest that nizatidine did not affect in vitro PGE2 synthesis and even doses that markedly inhibit gastric acid secretion had no effects on the content of PGs in the gastric mucosa.

Acid secretion from isolated rabbit gastric parietal cells can be stimulated by gastric secretagogues, histamine (cyclic-AMP pathway) and carbachol (inositol phosphate pathway). Prostaglandins (PG) from E series are potent inhibitors of acid secretion. The intracellular mechanism of this inhibition was examined by using a stable PGE1-analogue, misoprostol. Aminopyrine (AP) accumulations due to histamine, IBMX and forskolin were dose-dependently inhibited by misoprostol, whereas a weak but significant biphasic effect on carbachol-induced AP accumulation was observed. The cyclic-AMP formation induced by histamine and IBMX were also inhibited by misoprostol in a non-competitive way. The potent effect of forskolin on cyclic-AMP levels was not modified by misoprostol in parietal cells, whereas it was potentiated in non-parietal cells. The inhibitory effect of misoprostol on AP accumulation was reduced by incubation of parietal cells with Bordetella pertussis toxin (IAP) but not with Cholera toxin (CT). Pretreatment of the cells with IAP did not alter cyclic-AMP levels of resting and histamine-stimulated parietal cells but abolished the inhibitory effect of misoprostol. Treatment with CT increased basal and histamine-stimulated cyclic-AMP levels and masked the inhibitory effect of misoprostol. The biphasic effect of misoprostol on carbachol-stimulated AP accumulation in parietal cells was confirmed on carbachol-stimulated phospholipase C activity and on [Ca2+]i stimulated by carbachol. These data confirm a direct and specific effect of the prostanoid on the Gi-subunit of the adenylate cyclase coupled to the histamine H2-receptor, and a biphasic effect on the phospholipase C pathway of the parietal cells.