Astragalus saponins modulate cell invasiveness and angiogenesis in human gastric adenocarcinoma cells

AIM OF THE STUDY

We had reported that Astragalus saponins (AST) exert promising anti-tumorigenic effects by suppressing the growth of HT-29 human colon cancer cells and tumor xenograft. In the present study, we further investigated the anti-angiogenic property of AST in human gastric adenocarcinoma cells (AGS) and attempted to elucidate the underlying mechanism.

MATERIALS AND METHODS

Viability of AGS cells was measured by using the MTT reduction method. Western blotting was performed to examine the effect of AST on apoptotic- and cell growth-related protein expression. Effect of AST on cell cycle progression was also evaluated using PI staining. A Matrigel invasion assay was then employed to demonstrate the effect of AST on the invasiveness of gastric cancer cells. The expression of invasion-associated proteins (VEGF and MMPs) was also investigated.

RESULTS

AST could induce apoptosis in AGS cells by activating caspase 3 with subsequent cleavage of poly(ADP-ribose) polymerase. Besides, cell cycle arrest at the G2/M phase had been observed in AST-treated cells, leading to substantial growth inhibition. The anti-proliferative effect of AST was associated with the regulation of cyclin B1, p21 and c-myc. Results indicate that the number of AGS cells invaded through the Matrigel membrane was significantly reduced upon AST treatment, with concomitant down-regulation of the pro-angiogenic protein vascular endothelial growth factor (VEGF) as well as the metastatic proteins metalloproteinase (MMP)-2 and MMP-9.

CONCLUSION

AST derived from the medicinal plant Astragalus membranaceus could modulate the invasiveness and angiogenesis of AGS cells besides its pro-apoptotic and anti-proliferative activities. These findings also suggest that AST has the potential to be further developed into an effective chemotherapeutic agent in treating advanced and metastatic gastric cancers.

Intrapulmonary shunt in the course of pediatric liver transplantation

The hepatopulmonary syndrome occurs when an intrapulmonary shunt (IPS) causes hypoxemia in patients with cirrhosis. Because IPS has not been clearly defined in children, we investigated the prevalence, clinical characteristics, and outcomes of IPS in children undergoing liver transplantation (OLT). Of the 107 pediatric OLT recipients between December 1994 and March 2005, 18 (16.8%) had IPS, as evaluated by contrast-enhanced echocardiography (CEE) at 9 months to 16 years of age. The degree of IPS was classified into five grades according to the extent of microbubbles in the left ventricle, with significant IPS defined as grade II or higher. Baseline characteristics, including serum total bilirubin, albumin, aminotransferase, and prothrombin time, did not differ in patients with or without IPS. The patients with IPS had significantly lower Pao2 and Sao2, longer duration of mechanical ventilation and hospital stay, and higher postoperative morbidity and mortality than patients without IPS (P < .05 each), but there were no other significant differences between the groups. The six patients with significant IPS (one grade II, three grade III, and two grade IV) showed a significantly greater morbidity and mortality than patients with grade I IPS (P < .05). Most of the positive CEE findings of IPS regressed within 6 months after OLT. These findings indicated that IPS is not uncommon among children undergoing OLT, but is reversible. Because severe IPS may increase patient morbidity and mortality, early assessment of IPS status using CEE is essential for pediatric OLT candidates.

The role of exercise training for patients with heart failure

Heart failure (HF) is characterized by dyspnea and fatigue leading to exercise intolerance. HF patients have been advised to avoid exercise because of concerns about detrimental cardiac effects. However, in many studies on the effects of exercise training HF patients have demonstrated beneficial outcomes. Furthermore, exercise training has been found to be safe. Recent studies have demonstrated that exercise training might reduce morbidity and mortality. Although these data are promising, confirmation is required from a large clinical trial powered to examine the effects of exercise training on mortality and morbidity. The "Heart Failure - A Controlled Trial Investigating Outcomes of Exercise TraiNing" (HF-ACTION) trial, a large randomized controlled clinical trial, will answer that question. Standardized guidelines for exercise training HF patients have not been established. Exercise training should be individualized according to the results of the exercise test. Ideally, the exercise program should be initiated in the setting of a supervised program followed by a home-based program. Each patient should have a tailored activity program based on a prescription for the frequency of each session, the intensity, duration of each session, and modalities to be used. Exercise training should involve aerobic exercise. Resistance exercise and interval training might be an acceptable method for HF patients; however, more studies are required for these types of exercise programs.

Long-term efficacy of atenolol for atrioventricular reciprocating tachycardia in children less than 5 years old

Atrioventricular reciprocating tachycardia (AVRT) using an accessory pathway is the most common supraventricular tachycardia observed in infancy and childhood. There is a general agreement to treat children older than 5 years who are on a potentially long-term antiarrhythmic agent with radiofrequency catheter ablation. Atenolol, a relatively long-acting and cardioselective beta-adrenoceptor blocker, has been used to control the various types of supraventricular tachycardia in children and adults. There are few reports on the use of atenolol in children <5 years old with AVRT. This retrospective study reports our experience in 22 children <5 years old (median age, 20 months) who received atenolol monotherapy between 1995 and 2001 for treatment of AVRT. AVRT was confirmed in 17 patients by transvenous or transesophageal electrophysiologic study and in 5 patients by documented preexcitation on electrocardiograms. In nine patients atenolol was the first antiarrhythmic drug given. In 15 of the 22 patients (68%) therapy with atenolol was considered successful. The average effective dose of atenolol in these 15 patients was 1.2 +/- 0.3 mg/kg/day. During a median follow-up of 41 months (8-74 months), atenolol had been discontinued in 10 patients and no further attacks of tachycardia occurred except in 1 patient. In no case did the drug have to be withdrawn for adverse effects. In conclusion, this retrospective study shows that atenolol as a monotherapy is efficient and relatively safe in the long-term treatment of AVRT in young children. Atenolol can be recommended as a first-line treatment option for the management of AVRT in infants and young children.

Aggravating effect of cigarette smoke exposure on experimental colitis is associated with leukotriene B(4) and reactive oxygen metabolites

BACKGROUND/AIMS

Cigarette smoking is closely related to the development and recurrence of inflammatory bowel disease (IBD). The present study aimed to investigate the underlying mechanisms of the adverse action of cigarette smoke (CS) exposure on trinitrobenzene sulfonic acid (TNBS)-induced IBD.

METHODS

Rats were preexposed to CS once daily for 4 days before receiving a TNBS enema, and they were killed 24 h afterwards. The colonic myeloperoxidase (MPO) and xanthine oxidase (XO) activities, leukotriene B(4) (LTB(4)) and glutathione (GSH) levels, as well as the production of reactive oxygen metabolites (ROMs) were measured.

RESULTS

CS preexposure significantly augmented the adverse effects of the TNBS enema on colonic damage and increase in MPO activity, while it did not significantly alter the XO activity. Meanwhile, the elevation of ROM production and LTB(4) concentration in colonic tissues after the TNBS enema was also markedly enhanced by CS exposure. In contrast, the depressive action of the TNBS enema on cellular antioxidant GSH levels was reduced further by CS exposure. Pretreatment with a specific LTB(4) antagonist, ONO-4057, protected against colonic damage, particularly in the CS group.

CONCLUSION

CS exposure aggravated experimental IBD. This adverse action could be due to the depletion of GSH together with overproduction of LTB(4), followed by the accumulation of neutrophils and ROMs in the colonic tissue.

Inducible RGS2 is a cross-talk regulator for parathyroid hormone signaling in rat osteoblast-like UMR106 cells

Parathyroid hormone (PTH) activates dual signal transduction systems via Galphas and Galphaq proteins. We now report a novel mechanism by which "cross-talk" may occur between the Galphas and Galphaq signaling pathways. RGS2 (Regulator of G protein Signaling 2) mRNA was rapidly and transiently increased only by PTH analogs (PTH1-84, 1-34, 1-31, and PTHrP) that activated the Galphas-mediated cAMP/PKA signaling pathway, whereas activation of the Galphaq-mediated Ca(2+)/PKC signaling pathway by PTH3-34 had no effect on RGS2 expression. Treatment of UMR106 cells with nonPTH activators of the cAMP/PKA signaling pathway such as cholera toxin, forskolin, 8-Br-cAMP, and dibutyryl-cAMP also significantly elevated RGS2 mRNA levels, while activator of the Galphaq pathway PMA did not. Pretreatment using the Galphas signaling pathway inhibitors SQ22536 and H89 significantly blocked PTH-induced RGS2 expression, but the Galphaq signaling pathway inhibitor bisindolylmaleimide I had no effect. Therefore, RGS2 expression is governed solely by the Galphas signaling pathway. Additionally, we demonstrate for the first time that RGS2 binds to both Galphas and Galphaq subunits in their transition state (GDP/AlF(-4)-bound) forms, suggesting that RGS2 has the potential to act as a bridge between the cAMP/PKA and Ca(2+)/PKC pathways, and that it may act as a cross-talk regulator for these two PTH signaling pathways.

Signal transduction of nitric oxide donor-induced protection in hydrogen peroxide-mediated apoptosis in H9C2 cardiomyoblasts

Nitric oxide (NO) attenuates hydrogen peroxide (H2O2)-mediated injury to H9C2 cardiomyoblasts. To examine the role of nitric oxide, cultured H9C2 cardiomyoblasts were treated with H2O2 for 2 h in the presence or absence of the NO donor, diethylamine nitric oxide (DEANO). DEANO (30 microM) attenuated H2O2-induced apoptosis in H9C2 cells. H2O2-exposed H9C2 cells resulted in apoptosis in a time-dependent manner estimated by DNA fragmentation assay, nuclear morphology stained with fluorescent dye, Hoechst 33258 and Annexin V staining. Pretreatment with z-VAD-FMK, a pancaspase inhibitor, or z-DEVD-CHO, a specific caspase-3 inhibitor, completely suppressed the DNA ladder in response to H2O2. An increase in caspase-3-like protease (DEVDase) activity was observed during apoptosis, but no caspase-1 activity (YVADase) was detected. Treatment of H9C2 cells with 100 microM H2O2, resulted in a strong activation of JNK/SAPK. However, the activation of JNK/ SAPK was clearly attenuated by 30 microM DEANO. Furthermore, the dominant negative JNK and SEK1-expressing cells displayed a marked decrease in a number of apoptotic cells. This inhibition of JNK1 in the system is involved in the protection of H2O2-induced apoptosis in H9C2 cardiomyoblasts.

Protective role of cyclooxygenase inhibitors in the adverse action of passive cigarette smoking on the initiation of experimental colitis in rats

Clinical and experimental findings had indicated that cigarette smoke exposure, and cyclooxygenase-2, are strongly associated with inflammatory bowel disease. The present study aimed to evaluate the role of cyclooxygenase-2 in the pathogenesis of experimental inflammatory bowel disease as well as in the adverse action of cigarette-smoke exposure. Rats were pretreated with different cyclooxygenase-2 inhibitors (indomethacin, nimesulide, or SC-236 (4-[5-(4-chlorophenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamide)) along with cigarette-smoke exposure before 2,4,6-trinitrobenzenesulfonic acid-enema. Results indicated that pretreatment with cyclooxygenase-2 inhibitors not only protected against 2,4,6-trinitrobenzenesulfonic acid-induced inflammatory bowel disease, but also attenuated the potentiating effect of cigarette-smoke exposure on colonic damage. Furthermore, the colonic cyclooxygenase-2 protein and mRNA expression was markedly induced by 2,4,6-trinitrobenzenesulfonic acid-enema, and it was potentiated further by cigarette-smoke exposure, while the cyclooxygenase-1 expression was not changed. The present study suggests that the highly induced cyclooxygenase-2 expression not only plays a pathogenic role in 2,4,6-trinitrobenzenesulfonic acid-induced inflammatory bowel disease, but also contributes to the adverse action of cigarette-smoke exposure on this disorder.

Beneficial intervention of experimental colitis by passive cigarette smoking through the modulation of cytokines in rats

BACKGROUND

Epidemiologic observations have indicated that cigarette smoking decreases the risk of ulcerative colitis, but the modes of action remain anonymous. The present study aimed to investigate the beneficial effects of passive cigarette smoking using an animal colitis model. We hypothesized that the underlying mechanisms may involve immunoregulation of cytokines.

METHODS

Experimental colitis was induced in rats by enema administration of 2,4-dinitrobenzene sulfonic acid (DNBS). Passive cigarette smoking by rats was performed for 1 hour once daily, from 3 days before DNBS enema until they were sacrificed on day 8. Other groups of DNBS-treated rats received therapeutic treatment of cyclosporin A or pentoxifylline, a tumor necrosis factor (TNF)-alpha inhibitor. Macroscopic and histologic damage were graded, and the colonic levels of different cytokines and the levels/activities of parameters related to neutrophil activation were also measured.

RESULTS

DNBS-induced colonic damage was improved in passive-cigarette-smoking rats. This was accompanied by attenuation of the elevated colonic myeloperoxidase and inducible nitric oxide synthase activities and leukotriene B4 level. Likewise, the augmentation in colonic levels of TNF-alpha, interleukin (IL)-1 beta, and IL-6 in colitis rats was also alleviated by passive cigarette smoking. In contrast, the deprivation of colonic IL-10 during colitis was preserved in cigarette-smoking rats. These effects were similarly accomplished by pentoxifylline and, to some degree, by cyclosporin A.

CONCLUSIONS

The results support the idea that the beneficial effects of passive cigarette smoking in experimental colitis involved immunoregulation of cytokines in colonic tissues.

Alcohol drinking and cigarette smoking: a "partner" for gastric ulceration

Alcohol consumption and cigarette smoking are two etiologic factors that have a close relationship with peptic ulcer diseases. Chronic active gastritis is reportedly associated with chronic alcohol ingestion. Nonetheless, the inflammatory changes are likely to be related to concurrent Helicobacter pylori infection that is common among alcoholics. Moreover, chronic alcoholism is also correlated with the presence of gastric metaplasia. Both clinically and experimentally, alcohol had been shown to affect the mucosal barrier and histology. These ulcerogenic effects play a crucial role in altering gastric mucosal defense mechanisms. Cigarette smoking is coupled with the initiation and prolongation of gastric ulcers. Epidemiologic data show that cigarette smoking increases both the incidence and relapse rate of peptic ulcer diseases and also delays ulcer healing in humans. Retrospective studies also indicate that cigarette smoking is a key factor in inducing ulcer diseases rather than a linked behavior. The general detrimental effects of cigarette smoking in the gastric mucosa include reduction of circulating epidermal growth factor, increase in tissue free radical production and the presence of free radicals in smoke, together with reduction of mucosal constitutive nitric oxide synthase activity. Furthermore, the alteration of normal gastric mucosal blood flow and angiogenesis and the suppression of cell proliferation contribute largely to the delay in ulcer healing in cigarette smokers. Concurrent consumption of alcohol and cigarette smoking significantly increases the risk of gastric ulcers. In animal experiments, cigarette smoking potentiated ethanol-induced gastric mucosal damage. The reduction of mucus secretion, increase in leukotriene B4 level, increased activities of inducible nitric oxide synthase, xanthine oxidase and myeloperoxidase, and the expression of adhesion molecules in the gastric mucosa accompanied such potentiating effects. Substances other than nicotine in cigarette smoke may also contribute to the above effects.

Coadministration of angiopoietin-1 and vascular endothelial growth factor enhances collateral vascularization

Using growth factors to induce vasculogenesis is a promising approach in the treatment of ischemic legs and myocardium. Because the vasculogenesis requires a cascade of growth factors, their receptors, and intracellular signals, such therapies may require the application of more than a single growth factor. We examined the effect of 2 endothelial cell-specific growth factors, angiopoietin-1 (Ang1) and vascular endothelial growth factor (VEGF), on primary cultured porcine coronary artery endothelial cells. VEGF, but not Ang1, increased DNA synthesis and cell number. Ang1 or VEGF induced migration and sprouting activity, increased plasmin and matrix metalloproteinase-2 secretion, and decreased tissue inhibitors of metalloproteinase type 2 secretion. A combination of the submaximal doses of Ang1 and VEGF enhanced these effects and was more potent than the maximal dose of either alone. In a rabbit ischemic hindlimb model, a combination of Ang1 and VEGF gene delivery produced an enhanced effect on resting and maximal blood flow and capillary formation that was greater than that of either factor alone. Angiographic analyses revealed that larger blood vessels were formed after gene delivery of Ang1 or Ang1 plus VEGF than after VEGF gene delivery. These results suggest that combined treatment of Ang1 and VEGF could be used to produce therapeutic vascularization.

Involvement of neutrophils and free radicals in the potentiating effects of passive cigarette smoking on inflammatory bowel disease in rats

BACKGROUND & AIMS

Cigarette smoking is associated with inflammatory bowel diseases (IBDs), particularly Crohn's disease, in humans. The aim of this study was to examine whether passive cigarette smoking aggravates experimental IBD in rats and to clarify the underlying mechanisms.

METHODS

Rats were exposed to cigarette smoke (CS) for 1 hour once daily for 4 days before induction of IBD by 2,4, 6-trinitrobenzene sulfonic acid (TNBS)-ethanol enema and were then killed at 2, 6, or 24 hours later.

RESULTS

Preexposure to CS significantly potentiated colonic damage induced by TNBS. TNBS-ethanol enema caused a pronounced increase in colonic myeloperoxidase activity, leukotriene B(4) level, and also inducible nitric oxide synthase activity, its protein, and messenger RNA expression. These parameters were all significantly increased further by exposure to CS. In contrast, increased colonic superoxide dismutase activity after TNBS-ethanol enema was attenuated by CS exposure. The potentiating effects of CS exposure on TNBS-induced IBD were significantly alleviated after pretreatment with cyclosporin A (an immunosuppressant), N (G)-nitro-L-arginine methylester (a nitric oxide synthase inhibitor), and dimethyl sulfoxide (a hydroxyl radical scavenger).

CONCLUSIONS

The results show that promotion of neutrophil infiltration and free radical production contributed significantly to the potentiating effect of passive cigarette smoking on experimental IBD.

Co-regulation of mucosal nitric oxide and prostaglandin in gastric adaptive cytoprotection

OBJECTIVE

The correlation between mucosal generation of nitric oxide (NO) and prostaglandin E2 (PGE2) in gastric adaptive cytoprotection was investigated.

MATERIALS AND TREATMENT

Male Sprague-Dawley rats were pretreated with either N(w)-nitro-L-arginine methyl ester (L-NAME, 12.5 mg/kg i.v.) or indomethacin (5 mg/kg s.c.). Following that, mild irritant 20% ethanol was administered, 15 min prior to 100% ethanol challenge.

METHODS

Macroscopic gastric mucosal damage, NO synthase activity, mucosal PGE2 and leukotriene C4 (LTC4) levels were measured.

RESULTS

Administration of L-NAME and indomethacin significantly reduced the protective action of 20% ethanol against 100% ethanol-induced gastric mucosal damage. Besides, mucosal activity of constitutive NO (cNO) synthase, but not of the inducible isozyme (iNO synthase), was elevated following 20% ethanol treatment. This was accompanied by a reduction in mucosal leukotriene C4 level. Indomethacin significantly inhibited mucosal PGE2 biosynthesis but increased cNO synthase activity. Nevertheless, L-NAME reduced both cNO and iNO formation and prevented the increase in cNO formation caused by 20% ethanol, while enhancing mucosal PGE2 production. Combined L-NAME and indomethacin treatment markedly potentiated ethanol-induced mucosal damage, and completely prevented the increase in cNO or PGE2 biosynthesis when either compound was given alone.

CONCLUSIONS

These findings suggest a co-regulatory relationship between mucosal NO and PG in the gastric defense system, which will be released after activation by the mild irritants to induce cytoprotection.

MR imaging of non-visualized pulmonary arteries at angiography in patients with congenital heart disease

The aim of this study was to evaluate whether MR could depict pulmonary arterial anatomy in more detail than routine angiography in patients with congenital interruption or acquired occlusion of the left pulmonary artery or pulmonary atresia. This study included 10 patients with tetralogy of Fallot (n=6) or pulmonary atresia with ventricular septal defect (n=3) or aorticopulmonary window (n=1) diagnosed by cardiac angiography and MR. Surgical confirmation was made in seven patients. Interruption of the proximal left pulmonary artery, diagnosed at the time of evaluation, was found in seven patients and acquired obstruction of the hilar pulmonary artery (PA) was found in two at cardiac angiography. In the remaining one patient with pulmonary atresia and an occluded palliative shunt, the central PA was not visualized at angiography. MR showed 3-6 mm-sized hilar PAs in five and a central PA in a patient with pulmonary atresia. In 4 of 6 (67%) surgically-proven patients with congenital or acquired left PA obstruction, the status of the PA distal to the obstruction was correctly diagnosed with MR. In conclusion, MR is an effective modality in depicting sizable PAs when routine angiography fails to visualize the PA anatomy.

Two cases of atrial flutter with fetal hydrops: successful fetal drug therapy

We describe two cases of fetal atrial flutter associated with severe fetal hydrops which were unresponsive to digoxin but were successfully treated with flecainide acetate. Two cases of fetal atrial flutter were identified in fetuses with severe fetal hydrops on 3rd trimester ultrasonogram(28 weeks' gestation and 30 weeks' gestation). Following failed digoxin monotherapy, flecainide acetate was added to digoxin. On the 7th day and 13th day after combined therapy, fetal heart rate converted to normal sinus rhythm without recurrence. Our cases showed that the combined therapy of digoxin and flecainide acetate can effectively treat fetal atrial flutter associated with fetal hydrops unresponsive to digoxin monotherapy.

Cell cycle regulators during human atrial development

OBJECTIVES

The molecular mechanisms that regulate cardiomyocyte cell cycle and terminal differentiation in humans remain largely unknown. To determine which cyclins, cyclin dependent kinases (CDKs) and cyclin kinase inhibitors (CKIs) are important for cardiomyocyte proliferation, we have examined protein levels of cyclins, CDKs and CKIs during normal atrial development in humans.

METHODS

Atrial tissues were obtained in the fetus from inevitable abortion and in the adult during surgery. Cyclin and CDK proteins were determined by Western blot analysis. CDK activities were determined by phosphorylation amount using specific substrate.

RESULTS

Most cyclins and CDKs were high during the fetal period and their levels decreased at different rates during the adult period. While the protein levels of cyclin D1, cyclin D3, CDK4, CDK6 and CDK2 were still detectable in adult atria, the protein levels of cyclin E, cyclin A, cyclin B, cdc2 and PCNA were not detectable. Interestingly, p27KIP1 protein increased markedly in the adult period, while p21CIP1 protein in atria was detectable only in the fetal period. While the activities of CDK6, CDK2 and cdc2 decreased markedly, the activity of CDK4 did not change from the fetal period to the adult period.

CONCLUSION

These findings indicate that marked reduction of protein levels and activities of cyclins and CDKs, and marked induction of p27KIP1 in atria, are associated with the withdrawal of cardiac cell cycle in adult humans.

Histological study of mechanisms of adaptive cytoprotection on ethanol-induced mucosal damage in rat stomachs

Adaptive cytoprotection in the gastric mucosa could be induced by exposure to low concentrations of noxious agents. However, experimental results reported so far were based on macroscopic studies. We aimed to investigate the phenomenon of gastric adaptive cytoprotection of mild irritants and its correlation with intramucosal mucus at the histological level. It was found that histological damage induced by ethanol had a negative correlation with the length of the mucus-secreting layer in the gastric mucosa. Mild irritants such as 20% ethanol and 5% NaCl preserved the 100% ethanol-induced intramucosal mucus depletion, but only the former agent demonstrated a cytoprotective effect against the histological damage, indicating that preservation of intramucosal mucus may not necessarily play a permissive role in adaptive cytoprotection. The capsaicin-sensitive sensory afferent neurons, sensory chemoreceptors, muscarinic receptors, alpha2-adrenoceptors and peripheral dopamine D2-receptors were found to be the components of the autonomic nervous system involved in the cytoprotective processes of 20% ethanol. Endogenous mediators including nitric oxide, prostaglandins, and possibly nonprotein sulfhydryl compounds also seemed to participate in such protection. Nevertheless, 0.3 M HCl did not show any effect either on mucosal damage or depletion of intramucosal mucus induced by absolute ethanol. These findings suggest that only 20% ethanol shows histological cytoprotection, which would involve various components of the autonomic nervous system and endogenous mediators. Furthermore, this investigation also implies a new perspective: that in order to study a true adaptive cytoprotection, histological examination of the gastric mucosa should be performed.

The correlation of the weakening effect on gastric mucosal integrity by 5-HT with neutrophil activation

The effects of 5-hydroxytryptamine (5-HT) on ethanol-induced gastric mucosal damage and on epithelial and vascular integrity were investigated. Male Sprague-Dawley rats were administered with 5-HT (5 or 10 mg/kg, IP) 30 min prior to the challenge with ethanol (40% v/v, 10 ml/kg, PO). 5-HT dose dependently aggravated ethanol-induced injury in the gastric mucosa. Both xanthine oxidase (XO) and myeloperoxidase (MPO) activities in the mucosa were significantly increased with the high dose of 5-HT, which also potentiated the elevation of these enzyme activities by ethanol. However, the mucosal superoxide dismutase activity was left unaltered. In neutropenic (antineutrophil serum-treated) animals, the ethanol-induced gastric mucosal injury was significantly ameliorated, with or without the pretreatment of 5-HT (10 mg/kg). In addition, the effect of 5-HT on the activity of MPO, but not of XO, was also attenuated in these animals. In the ex vivo gastric chamber study on pentobarbital-anesthetized animals, volume of gastric secretion was significantly decreased in the 5-HT-treated groups, with further reduction after ethanol incubation. Transmucosal potential difference (PD) was significantly reduced in 5-HT-treated rats, which also potentiated the ethanol-induced drop in PD. Nevertheless, 5-HT dose dependently increased mucosal vascular permeability and further enhanced during ethanol incubation. These findings suggest that 5-HT adversely affects the defense mechanisms of the gastric mucosa by reducing the secretory function of the mucosal cells and to weaken the epithelial and vascular integrity. Neutrophil activation appears to be responsible for the detrimental effects of 5-HT partly through the elevation in MPO activity. The increase in mucosal XO activity by 5-HT may induce free radical production and possibly modulate the ulcerogenic processes.

Rare variants of divided right ventricle with sequestered apical trabecular component

The right ventricle may be divided into two or more compartments by various structures in various ways. Rarely, the apical trabecular component may be sequestered from the rest of the right ventricle. We report 4 cases with different underlying lesions that share a common pathology of apical sequestration of the right ventricle resulting in diverse hemodynamic consequences. Case 1 had pulmonary valve stenosis. The apical sequestration of the right ventricle resulted in no significant hemodynamic consequence. Case 2 had multiple defects in the muscular ventricular septum. The volume of left-to-right shunt seemed to be reduced because of the commitment of some of the defects to the sequestered cavity. Case 3 had a large defect in the trabecular septum. As the defect involved the whole septum that was related to the sequestered right ventricular apex, the left ventricle together with the sequestered right ventricle formed a boot-shaped chamber. Hemodynamically, the muscular shelf was an interventricular septum. Case 4 had a coronary artery fistula to an isolated cavity that occupied the apical region of the right ventricle. The pathology was similar to the case that was reported as a five-chambered heart. The abnormal cavity was, in fact, the sequestered right ventricular apex.

The vascular and glandular organoprotective properties of metronidazole in the rodent stomach

BACKGROUND

The gastroprotective action of metronidazole, an antimicrobial used in the therapy against Helicobacter pylori infection, is unclear. Thus, the aim of the present investigation was to study the organoprotective action and antiulcer mechanisms of this drug in rodents.

METHODS AND RESULTS

Metronidazole (10 mg/kg), given either per os or intraperitoneally, 30 min beforehand, reduced ethanol (40%, 10 mL/kg, p.o.)-induced gastric mucosal damage in male rats. Likewise, oral administration of metronidazole dose-dependently attenuated the indomethacin (30 mg/kg, p.o.)-induced gastric lesion formation and the concurrent depletion of mucosal mucus. However, metronidazole did not affect the basal mucosal prostaglandin E2 content. In an ex vivo gastric chamber preparation, 40% ethanol incubation markedly lowered transmucosal potential difference and increased mucosal vascular permeability in rat stomachs. Incubation with all doses of metronidazole did not modulate gastric mucosal blood flow nor transmucosal potential difference, either before or after ethanol treatment. Nevertheless, the increase in vascular permeability by 40% ethanol was significantly alleviated by either p.o. or i.p. metronidazole pretreatment. In addition, exposure of the isolated rabbit gastric gland preparation to metronidazole (10(-5) and 10(-4) M) significantly attenuated the damaging action of 10% ethanol.

CONCLUSION

It is concluded that metronidazole possesses a direct vascular and glandular organoprotective property in the rodent stomach. However, the anti-ulcer action does not appear to involve prostaglandins nor act through the improvement of gastric mucosal blood flow. Preservation of intramucosal mucus may partly contribute to the prevention of indomethacin-induced ulceration in rats.

Bilateral patent ductus arteriosus and nonconfluent pulmonary arteries in neonates as shown by radial artery angiography

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Co-regulation of mucosal prostanoids and substance P by indomethacin in rat stomachs

The present investigation examined the correlation between the regulation of mucosal prostaglandin (PG) biosynthesis and the release of the neuropeptide substance P (SP) in rat stomachs by indomethacin, a cyclooxygenase inhibitor. When given subcutaneously at the dose of 5 mg/kg, indomethacin reduced mucosal biosynthesis of PGE2 and concurrently lowered mucosal SP level. The inter-relationship between mucosal generation of PG and SP was further demonstrated by using [D-Pro2, D-Trp7,9]-SP, which also inhibited PGE2 production besides its suppression on SP release. Co-administration of either arachidonic acid, the PGE2 precursor, or SP reversed the inhibitory actions of indomethacin and [D-Pro2, D-Trp7,9]-SP, respectively, on mucosal levels of PGE2 and SP. Our findings suggest that indomethacin, aside from its depletion of endogenous PG, also exerts a secondary action in regulating the release of SP, which is mediated indirectly through PG in the gastric mucosa. These actions may play a role in the modulation of gastric mucosal integrity.

The antilesion actions of anticholinergic agents on ethanol-induced injury in rat stomachs: the importance of gastric vascular integrity and tonicity

1. The antilesion actions of two antimuscarinic drugs on ethanol-induced gastric injury and mucosal integrity were examined in male rats. Histological examinations were made and gastric emptying rates determined after in vivo administration of the drugs to conscious rats. In anaesthetized rats, with an ex vivo gastric chamber, effects on gastric transmucosal potential difference, Evan's blue leakage and Na+ output were examined. 2. In conscious animals, atropine (1 mgkg-1, i.p.) and pirenzepine (1 mgkg-1, i.p.) both significantly reduced macroscopic lesion formation, but not microscopic damage and functional alterations, caused by orally administered absolute ethanol. Moreover, these drugs did not show any effect on the basal gastric adherent mucus level, nor the depleting action of ethanol on both adherent mucus and the mucosal mucus layer. Nevertheless, both atropine and pirenzepine significantly reduced gastric emptying rate. 3. In anaesthetized animals, pirenzepine but not atropine increased the basal transmucosal potential difference (PD); however, it could not prevent the ethanol-induced drop in PD. Furthermore, the inhibitory action of ethanol on sodium ion output from the gastric mucosa was not attenuated by these drugs. Pirenzepine, however, significantly lessened the increase in vascular permeability caused by 100% ethanol. This action was not shared by atropine. 4. These findings indicate that both atropine and pirenzepine exert their antilesion actions through the relaxation of the stomach. Pirenzepine also preserves the integrity of the gastric mucosal vasculature, which is distinct from the action of atropine. The protective action of these drugs occurs only at the macroscopic level.

Mucosal nitric oxide is not responsible for the hemodynamic changes induced by nicotine in rat stomachs

It has been shown that chronic nicotine treatment decreases gastric mucosal blood flow (GMBF). The mechanism for this action is still not defined. In this study, nicotine treatment (5, 25 or 50 μg/ml drinking water) for 10 days dose dependently reduced the GMBF and volume of hemoglobin but increased ethanol-induced gastric damage. These effects were potentiated by N(ω)-nitro-l-arginine methyl ester (l-NAME), a nitric oxide (NO) synthase inhibitor. l-arginine but not the d-analog restored the actions of l-NAME, indicating that the selective action of l-NAME. However, the potentiating actions of l-NAME were significantly attenuated in the nicotine-pretreated rats. When the basal mucosal NO synthase (both iNOS and cNOS) activity and its second messenger cyclic GMP levels were measured, no difference was found between the nicotine and the non-nicotine groups. Furthermore, high dose of l-arginine could not reverse the action of nicotine. These findings suggest that the adverse action of chronic nicotine treatment on GMBF and lesion formation is probably mediated through a NO independent mechanism.

Adaptive gastric mucosal cytoprotection in rats: different modes of action by three mild irritants

The mechanisms of adaptive mucosal cytoprotection by mild irritants were investigated in rats. In an ex vivo chamber preparation, application of 20% ethanol, 5% NaCl or 0.3 M HCl to the posterior side of the mucosa significantly protected that side of the stomach against mucosal damage caused by subsequent exposure to 100% ethanol, with contralateral transmission of protection to the anterior side by 20% ethanol and 0.3 M HCl. Atropine or lidocaine significantly reversed the cytoprotection of 20% ethanol. Bilateral vagotomy partially prevented the antilesion action of 20% ethanol, and completely prevented the action of 0.3 M HCl. However, the three mild irritants did not affect gastric mucosal blood flow, but restored the ion transport mechanism which was depressed by ethanol. It is therefore concluded that the three mild irritants have their own distinctive cytoprotective mechanisms against ethanol ulceration, which is predominantly not mediated by effects on the vascular system of the gastric mucosa.

Felodipine- and ethanol-induced gastric mucosal damage in rats

Calcium channel blockers like verapamil have been shown to potentiate ethanol-induced gastric mucosal damage. However, the exact mechanism for this adverse drug interaction is still unknown. We used felodipine to study the ulcerogenic mechanisms of calcium channel blockers and the pathogenesis of ethanol-induced ulceration. The experiment was conducted in an ex vivo gastric chamber prepared in anesthetized animals. Felodipine (0.25, 0.5, 1.0, or 2.0 mg/kg s.c.) dose-dependently reduced the systemic blood pressure which was accompanied by a decrease in gastric mucosal blood flow (GMBF), with an insignificant change in heart rate. Ethanol lowered the GMBF and produced gastric mucosal lesions, and these actions were potentiated by felodipine. Preincubation with calcium gluconate but not the sodium salt attenuated the adverse effects of ethanol on GMBF and lesion formation; it also significantly prevented the gastric effects of felodipine but not the decrease of the systemic blood pressure. It is concluded that felodipine aggravates ethanol ulceration through a depressive action on the GMBF. These actions were attenuated by the supplementation with calcium ions in the gastric mucosa. Therefore, maintenance of calcium homeostasis in the gastric wall could play a significant role in the prevention of ethanol ulceration in rats.

The importance of gastric emptying and mucosal folds in the adaptive cytoprotection of mild irritants in rats

This study examines the involvement of gastric emptying and mucosal folds in the adaptive cytoprotection of different mild irritants against 100% ethanol-induced gastric mucosal damage. Pre-exposure to either 20% ethanol, 5% NaCl or 0.3M HCl significantly reduced the gastric mucosal damage caused by 100% ethanol in rats. Administration of either one of the three mild irritants increased the basal gastric residual volume and decreased the area occupied by gastric mucosal folds, but only 20% ethanol reduced the gastric emptying rate. Indomethacin (5 mg/kg, s.c.) pretreatment did not affect ethanol ulceration and gastric emptying rate when given by itself, but reversed the flattening of mucosal folds produced by the three mild irritants, and abolished the protective effect of 20% ethanol. These results suggest that the gastric adaptive cytoprotection induced by the three mild irritants acts through luminal dilution of the noxious agent, possibly caused by gastric retention. The reduction of mucosal folds could also contribute to the anti-lesion action of 20% ethanol. It is therefore suggested that the protective actions of the three mild irritants act through different mechanisms.

Role of dorsal motor nucleus of vagus in gastric function and mucosal damage induced by ethanol in rats

Experimental evidence indicates that the autonomic nervous system, especially the cholinergic pathway modulates the mucosal defensive mechanism and affects mucosal damage in the stomach. The present study investigated the role of the dorsal motor nucleus of vagus (DMV) in gastric function and its influences on ethanol-induced mucosal damage in pentobarbitone-anesthetized rats. Electrolytic lesion of the DMV as compared with sham operation and lesions of other brain areas, eg, nucleus reticular gigantocellularis and cuneate nucleus, reduced the basal gastric mucosal blood flow (GMBF) and also the blood flow after ethanol administration. The same operation did not affect the acid secretion either in the basal state or during the ethanol treatment period. Lesions at the caudal half of the DMV produced a bigger depression of GMBF when compared with lesion at the rostral half. In the sham-operated rats, ethanol induced severe hemorrhagic lesions in the gastric glandular mucosa, and this was significantly potentiated by lesions at the DMV, especially in the caudal half. The present findings indicate that acute DMV damage at the caudal half markedly affects the GMBF but not the acid secretion. The action on GMBF may contribute to the aggravation of ethanol-induced gastric damage in rats. These data reinforce the idea that the central vagal pathway, especially the caudal half of the DMV, plays a significant role in the modulation of GMBF, which in turn affects the integrity of gastric mucosal barrier.

The role of non-protein sulfhydryl compounds in gastric adaptive cytoprotection against ethanol-induced mucosal damage in rats

The contribution of the endogenous nonprotein sulfhydryl compounds (SH) in gastric adaptive cytoprotection was investigated in rats. N-ethylmaleimide (NEM) treatment significantly reduced mucosal SH level, and aggravated the mucosal injury induced by absolute ethanol. Oral administration of the mild irritants, 20% ethanol, 5% NaCl or 0.3 M HCl, significantly increased the basal mucosal SH level. These agents also showed a cytoprotective action against the necrotizing effect of absolute ethanol. Administration of NEM did not alleviate this cytoprotective potential, although it abolished the increased SH level evoked by these mild irritants. Thus, it is concluded that modulation of endogenous SH by mild irritants perhaps only plays a minor role in the gastric adaptive cytoprotection.

The mechanistic pathway of gastric adaptive cytoprotection: a study on different components of the autonomic nervous system

1. The involvement of different components of the autonomic nervous system in the pathogenesis of ethanol-induced damage and the adaptive cytoprotection of mild irritants were studied in the gastric mucosa of male rats. 2. Capsaicin, yohimbine, and domperidone aggravated the 100% ethanol-induced gastric mucosal damage and attenuated the cytoprotective action of 20% ethanol, but not of 5% NaCl and 0.3 M HCl. Butoxamine and prazosin blocked the adverse actions of yohimbine and domperidone respectively. 3. Atropine, pirenzepine, and lidocaine lessened the severity of 100% ethanol-induced mucosal injury and further increased the cytoprotective action of 5% NaCl and 0.3 M HCl, but not of 20% ethanol. 4. Our results demonstrated that sensory afferent neurones, alpha 2-adrenoceptors and D2-dopaminergic receptors all play a significant role in the defensive mechanism of the gastric mucosa and the adaptive cytoprotection of 20% ethanol, while the M1- and M2-muscarinic receptors and sensory chemoreceptors on the gastric mucosa contribute only to the former action. The adverse effect of yohimbine and domperidone on lesion formation is probably mediated through the release of catecholamines, which subsequently act on the beta 2- and alpha 1-adrenoceptors respectively.

Contributions of physical and chemical properties of mild irritants to gastric cytoprotection in rats

The present study demonstrated the cytoprotective abilities of low concentrations of ethanol, NaCl and HCl, against the gastric mucosal damage caused by 100% ethanol, and the contributions of the physical and chemical properties of these mild irritants to their protective actions. The results have shown the differential protective effects of ethanol (10-40%), NaCl (2.5-12.5%) and HCl (0.15-0.45M), with the optimal cytoprotective concentrations being 20% ethanol, 5% NaCl and 0.3M HCl, respectively. Solutions of KCl and NaCl with similar osmolarity, and H2SO4 and HCl of similar acidity and osmolarity, all showed similar protective protective potentials as compared to the osmotic agent mannitol, which possessed a concentration- and tonicity-dependent protective action against 100% ethanol-induced mucosal damage. Some concentration of methanol, propan-2-ol and ethanol, having similar osmolarity with deionized water, exerted indifferent protective effects. It is therefore concluded that adaptive cytoprotection induced by low concentrations of NaCl and HCl could depend on their physical properties, while that of ethanol could act through its unique chemical property.

Anomalous origin of the right pulmonary artery from the ascending aorta: diagnosis by magnetic resonance imaging

Anomalous origin of the right pulmonary artery from the ascending aorta is a rare congenital anomaly. Magnetic resonance imaging (MRI) was performed on three patients with anomalous origin of the right pulmonary artery from the ascending aorta. ECG-gated, T1-weighted, spin-echo MRIs and cine MRIs were obtained. In one patient, postoperative MRI was also obtained. Echocardiography and cardiac catheterization were performed in three patients and angiocardiography was performed in two. MRI clearly showed anomalous origin of the right pulmonary artery from the posterior aspect of the ascending aorta, as well as combined anomalies including patent ductus arteriosus, aortopulmonary window, and interruption of the aortic arch in all three patients. Echocardiography missed this anomaly in all three. We suggest that MRI is an accurate imaging modality in diagnosing anomalous origin of the right pulmonary artery from the ascending aorta, obviating the need to perform angiocardiography.

Endogenous mediators in adaptive cytoprotection against ethanol-induced gastric gland damage in rabbits

The present study determined the participation of different endogenous mediators in adaptive cytoprotection against gastric gland damage caused by ethanol in rabbits. Using the isolated gland preparation, pretreatment with 10(-5)M of either indomethacin, Nw-nitro-L-arginine methyl ester (L-NAME) or N-ethylmaleimide (NEM), but not of substance P antagonist, intensified the 10% (v/v) ethanol-induced gastric gland damage and lessened the degree of cytoprotection evoked by 2% (v/v) ethanol to a significant level. Co-administration with 10(-4)M of prostaglandin E2, L-arginine or glutathione to the respective groups completely reversed the above adverse effects. These results demonstrate the involvement of endogenous prostaglandins, nitric oxide and glutathione in gastric adaptive cytoprotection against the damaging action of ethanol in the rabbit gastric glands.

A correlative study on the mechanism of adaptive cytoprotection against ethanol-induced gastric lesion formation in rats

The protective effect of mild irritants against the subsequent gastric injury induced by necrotizing agents has been termed 'adaptive cytoprotection'. In this study, the possible pathway and mechanisms of adaptive cytoprotection induced by 20% ethanol were investigated. An ex-vivo gastric chamber preparation was used. The gastric mucosa was exposed to 20% ethanol before subsequent administration of 100% ethanol 15 min later. Subdiaphragmatic vagotomy or drug pretreatment was carried out in order to elucidate the mechanisms of adaptive cytoprotection by 20% ethanol. The results showed that 20% ethanol pre-exposure significantly protected the gastric mucosa against damage caused by 100% ethanol. This protective action was completely abolished by atropine or lidocaine pretreatment, whereas vagotomy and hexamethonium failed to have a significant influence. The cytoprotective effect, however, was independent of the gastric secretory volume, titratable acid content, luminal soluble mucus level and gastric mucosal blood flow. Exposure of only half the gastric mucosa to the mild irritant resulted in the protection of both sides of the mucosa. All these findings indicate that the adaptive cytoprotection of 20% ethanol involves the participation of chemoreceptors and muscarinic receptors in the gastric mucosa. An internal enteric reflex arc, with transmission of signals within the gastric mucosa, may also contribute to the cytoprotective process of the mild irritant.

Modulatory role of 5-HT3 receptors in gastric function and ethanol-induced mucosal damage in rat stomachs

The involvement of 5-hydroxytryptamine (5-HT) in gastric function and mucosal damage has been defined. 5-HT also potentiates lesion formation in animals. The current study investigated further whether these actions are mediated through 5-HT3 receptors in rats. Ondansetron, a 5-HT3 receptor antagonist, was given subcutaneously, 2 or 4 mg/kg, 30 min before the gastric parameters were measured. The higher dose of ondansetron, 4 mg/kg, significantly increased gastric mucosal blood flow (GMBF) and also basal acid and Na+ secretion. However, it did not affect pepsin output. 5-HT time dependently reduced GMBF and pepsin secretion, but not that of acid and Na+. These actions were not altered by ondansetron pretreatment. The drug, however, dose dependently reduced ethanol-induced gastric mucosal lesions in the 5-HT-treated animals. These findings indicate that 5-HT3 receptors regulate not only basal GMBF, but also acid and Na+ secretion in stomachs. However, the depressive action of 5-HT on GMBF and pepsin secretion is most likely not mediated through 5-HT3 receptors. Ondansetron also modulates the toxicities of ethanol in the stomach and this action is likely to be mediated through the preservation of GMBF.

MRI of total anomalous pulmonary venous connections

OBJECTIVE

A prospective MR study was undertaken in 13 patients with total anomalous pulmonary venous connection (TAPVC) to determine the value of MR in its detection.

MATERIALS AND METHODS

Echocardiography was performed in all cases and cardiac angiography was performed in eight patients before MRI.

RESULTS

Magnetic resonance detected TAPVC in four cases without prior echocardiographic and angiographic diagnosis. In seven surgically proven cases, the diagnostic accuracy of preoperative MR, echocardiography, and cardiac angiography was 100 (7 of 7), 57 (4 of 7), and 25% (1 of 4), respectively. In the remaining cases including three cases for postoperative evaluation, MR findings correlated well with those of echocardiography or angiography. The combination of axial and coronal MRI visualized 96% of the individual anomalous pulmonary veins and 100% of the common pulmonary veins. Stenosis of a common pulmonary vein (three cases) or the superior vena cava (one case) was identified on MR in all cases.

CONCLUSION

Magnetic resonance is an effective modality in depicting TAPVCs.

The differential mechanisms of mild irritants on adaptive cytoprotection

The protective action of mild irritants has been established. However, the mechanisms as to how they antagonize the injurious action produced by the subsequent challenge with an ulcerogenic stimulus are still unclear. The present study examined the different protective mechanisms of an oral administration of the three mild irritants, 20% ethanol, 0.3 mol/L HCl or 5% NaCl against the gastric injurious actions of absolute ethanol in rats. In an attempt to clarify the pathways and mediators involved in the adaptive cytoprotection, [D-Pro2, D-Trp7,9]-substance P (substance P antagonist), Nw-nitro-L-arginine methyl ester (L-NAME), indomethacin, capsaicin, lidocaine, atropine or hexamethonium was given. The protective action of 20% ethanol but not the other two mild irritants, was antagonized by L-NAME, indomethacin and capsaicin, which are the inhibitors of nitric oxide (NO) and prostaglandins (PG) synthesis, and afferent sensory neuron blocker, respectively. Substance P antagonist, lidocaine or atropine given alone, prevented mucosal damage; however, only substance P antagonist enhanced the anti-lesion action of 20% ethanol, while atropine and lidocaine increased the protective effect of NaCl and HCl. The three mild irritants increased the residual gastric secretion. Only 20% ethanol and 5% NaCl but not 0.3% HCl significantly increased the basal adherent mucus and also attenuated the mucus depletion by absolute ethanol. It is concluded that the cytoprotective action of either ethanol or NaCl seems to be mediated through the increase of residual gastric secretion and adherent mucus. In the ethanol-treated group, these actions could act through the afferent sensory fibres, with NO and PG as the possible mediators.(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment of hemodynamic changes in rat stomachs by laser Doppler velocimetry and reflectance spectrophotometry. Effects of ethanol and prostaglandin E2 under ischemic and congestive conditions

One of the ulcerogenic mechanisms by which ethanol induces mucosal lesions in the stomach is the depression of gastric mucosal blood flow (GMBF). The goal of this study was to determine whether lesion formation is the result of vascular ischemia alone or ischemia combined with congestion. The aims of this study were to answer this question by evaluating the relationship between GMBF, oxygen saturation (ISO2) and hemoglobin volume (IHb) in the gastric mucosa under the influences of ethanol and prostaglandin E2 (PGE2) in the ischemic and congestive states, using a laser Doppler flowmeter and tissue spectrum analyzer. Ligation of the gastric celiac artery or vein markedly decreased the GMBF and the ISO2 level. The former procedure also reduced but the latter increased the IHb level. Ethanol administration produced effects similar to venous ligation, i.e. vascular stasis with ischemia. There was a negative correlation between GMBF and severity of lesion formation after ethanol administration. However, at the lesion site all the hemodynamic parameters were significantly reduced, indicating that a necrotic condition had occurred. PGE2 preincubation (25 micrograms) elevated GMBF, ISO2 and IHb levels. It also alleviated the reduction of blood flow induced by ethanol and increased the recovery rate of GMBF and ISO2 after the release of arterial or venous ligation. It is concluded that the decrease in blood flow due to ethanol is probably caused by constriction of venules rather than arterioles inside the mucosa, and this effect could lead to vascular congestion. PGE2 probably dilates both arterioles and venules in the gastric mucosa and thereby increases the blood flow in the gastric mucosa.(ABSTRACT TRUNCATED AT 250 WORDS)

The vagus nerve and its non-cholinergic mechanism in the modulation of ethanol-induced gastric mucosal damage in rats

The role of the cholinergic pathway in the vagus nerve in modulating gastric lesion formation by ethanol was examined, using an ex-vivo stomach chamber preparation. Subdiaphragmatic vagotomy significantly increased the lesion areas but lowered acid secretion and gastric mucosal blood flow (GMBF). Atropine had no effect, whereas pirenzepine antagonized ethanol-induced mucosal damage. All three procedures showed similar potencies in depressing acid secretion, but only pirenzepine reversed the fall in the GMBF produced by ethanol. These differential effects of vagotomy, atropine and pirenzepine on gastric function suggest that the cholinergic component in the vagus nerve may not be important in the formation of ethanol-induced gastric damage. The persistent protective action as well as the restoration of ethanol-induced GMBF drop by pirenzepine in vagotomized animals further support this hypothesis. The worsening effect of vagotomy is probably modulated by a non-cholinergic mechanism, the abolition of which makes the gastric mucosa more susceptible to damage by ethanol. The acid-independent protective action of pirenzepine and its influence on the GMBF, which were not exhibited by atropine, are indeed unique and perhaps may be attributed to this non-cholinergic pathway.

Supraventricular tachycardia mechanisms and their age distribution in pediatric patients

To better define the natural history of supraventricular tachycardia (SVT) in young patients, age distribution of SVT mechanisms was examined in 137 infants, children and adolescents. Patients with a history of cardiac surgery or neuromuscular diseases were excluded. An electrophysiologic study was performed in each patient: transesophageal (110 patients) or transvenous (14 patients) or both (13 patients). Mechanisms were classified as SVT using accessory atrioventricular (AV) connection (SVT using accessory connection, including orthodromic and antidromic reciprocating tachycardia), primary atrial tachycardia (including chaotic, automatic and reentrant atrial tachycardia), and tachycardia due to reentry within the AV node. SVT using accessory connection occurred in 100 of 137 patients (73%) and was the most prevalent mechanism. Primary atrial tachycardia and reentry within the AV node were present in 19 of 137 (14%) and 18 of 137 (13%) patients, respectively. Using a multinomial logit model, relative probabilities for tachycardia mechanisms for 5 age groups--prenatal, less than 1, 1 to 5, 6 to 10 and greater than 10 years--were determined. Primary atrial tachycardia (11 to 16%) and SVT using accessory connection (58 to 84%) appeared throughout infancy, childhood and adolescence. On the other hand, tachycardia due to reentry within the AV node (0 to 31%) rarely appeared before age 2 years. Mechanisms of SVT appear to have age-dependent distributions. SVT using accessory connection is the most common mechanism in young patients. We speculate that the propensity to tachycardia due to reentry within the AV node occurs during postnatal development.

Predictors of early mortality in patients with angiographically documented left main coronary artery disease

To determine predictors of early death after coronary angiography in patients with significant left main coronary artery disease (greater than or equal to 60% diameter narrowing, LMCAD), we reviewed the clinical records of patients with LMCAD who died after angiography. Of 1,288 patients with LMCAD studied between January 1978 and October 1989, 21 died within 2 days after angiography (group 1). As a control group, 85 patients were randomly sampled from 1,196 patients who survived at least 30 days after angiography (group 2). The predictors of early death after angiography in patients with LMCAD were older age (P less than 0.05), New York Heart Association Class III or IV (P less than 0.005), shorter duration of unstable angina (P less than 0.005), higher left ventricular end-diastolic pressure (P less than 0.006), lower ejection fraction (P less than 0.005), and significant left circumflex artery disease (P less than 0.006). The use of heparin infusion after angiography did not appear to be a significant factor. It is suggested that earlier operation or more aggressive management be undertaken in patients who, at cardiac catheterization, have significant LMCAD associated with the above-listed variables.