The effects of cryoanalgesia combined with thoracic epidural analgesia in patients undergoing thoracotomy

This study was performed to evaluate the effects of cryoanalgesia combined with thoracic epidural analgesia on pain and respiratory complications in patients undergoing thoracotomy. Ninety patients were prospectively randomised to epidural analgesia alone (n = 45) or epidural analgesia and cryoanalgesia combined (n = 45). We monitored the use of rescue pain medication and changes in forced vital capacity and forced expired volume in 1 s, and recorded pain and opioid-related side-effects during the immediate postoperative period. The incidence of post-thoracotomy pain and numbness were also assessed up to the sixth month after surgery. Cryoanalgesia combined with thoracic epidural analgesia was associated with earlier recovery in pulmonary function, less pain during movement and a lower daily requirement for rescue analgesia one week after surgery. However, the combination of cryoanalgesia and epidural analgesia failed to decrease the incidence of long-term pain and numbness. In view of its associated long-term morbidity, cryoanalgesia combined with thoracic epidural analgesia is not recommended for patients undergoing thoracotomy.

Ultrastructural evaluation of the protective effect of nitroglycerin in preservation-reperfusion injury of rat lungs

AIM OF STUDY

Nitric oxide (NO) has been reported as a favorable protective supplement in donor lung preservation, but related ultrastructural studies are rare in the literature. This study was performed to assess the ultrastructural changes and to evaluate the protective effect of NO as donor nitroglycerin (NTG) treatment of ischemia-reperfusion injury in rat lungs.

MATERIALS AND METHODS

Fifteen Sprague-Dawley rats weighing 300 to 350 g were used in this study. The NTG group (n = 5) used intravenous administration followed by mixture in the University of Wisconsin (UW) solution. For the non-NTG group (n = 5), we injected the same amount of normal saline intravenously followed by admixture in the UW solution. The heart-lung blocks were removed, weighed, and kept in UW solution for 24 hours at 10 degrees C. Reperfusion using human blood diluted in Krebs-Hensleit solution was done for 60 minutes. For the control group (n = 5), we injected the same amount of normal saline intravenously, and removed the lungs with no preservation and reperfusion procedures.

RESULTS

The non-NTG group showed multiple patchy areas of alveolar collapse with marked swelling and destruction of type I epithelial cells, loss of type II cell surfactant granules, endothelial swelling and papillary projection, interstitial edema, and alveolar macrophages with active phagocytosis of the destroyed materials. The NTG group showed similar ultrastructural changes, but in a lesser severity compared with the non-NTG group.

CONCLUSION

Administration of the NTG reduced the ischemia-reperfusion injury in the rat donor lungs. Ultrastructural examination was an effective tool to evaluate the protective effect of NTG in ischemia-reperfusion procedures of donor lungs.

Over-expression of inducible heat shock protein 70 in the gastric mucosa of partially sleep-deprived rats

BACKGROUND

Previous findings have demonstrated increased expression of inducible heat shock protein 70 (iHSP70) in the gastric mucosa of rats exposed to partial sleep deprived (PSD). The purpose of this study was to investigate the functional role of iHSP70 and its relationship with acid secretion in the stomachs of PSD animals.

METHODS

A slowly rotating drum was used to induce PSD in male Sprague-Dawley rats with or without omeprazole treatment. Gastric mucosal samples were harvested for iHSP70 mRNA and protein analysis with RT-PCR and Western blotting, respectively. Enzyme immunoassay was used to determine plasma gastrin level and gastric acidity was measured by titration. The modulating effect of PSD on 0.6 M hydrochloric acid (HCl)-induced gastric damage was also evaluated.

RESULTS

PSD increased plasma gastrin, gastric acidity and expression of iHSP70, while significantly reducing HCl-induced gastric damage. Omeprazole administration decreased gastric acidity and reversed iHSP70 over-expression in PSD rats.

CONCLUSIONS

PSD increases gastric acidity which enhances expression of mucosal iHSP70. Over-expression of iHSP70 may be a protective homeostatic response of the stomach to stress induced by PSD and acid secretion.

Free radical-scavenging activity of Taiwanese native plants

The 70% aqueous acetone extracts of ten Taiwanese native plants were evaluated by various antioxidant assays, including 1, 1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl (.OH) radicals, and reducing power assay. In the present study, extracts of Acer buerferianum var. formosanum, Cleyera japonica var. morii, Cyclobalanopsis stenophylla var. stenophylloides, and Machilus zuihoensis exhibited stronger activity against DPPH radicals, and their IC50 values ranged from 5.4 to 8.3 microg/ml. The ten selected extracts effectively inhibited the formation of .OH generated in the Fenton reaction system. Among the extracts whose reducing power activities were determined, A. buerferianum var. formosanum, C. japonica var. morii, C. stenophylla var. stenophylloides, Eriobotrya deflex, and M. zuihoensis showed high activity. The results indicate the 70% aqueous acetone extracts of A. buerferianum var. formosanum, C. japonica var. morii, C. stenophylla var. stenophylloides, and M. zuihoensis with great potency in these assay systems and may be candidates for the development of natural antioxidants.

Effect of polysaccharides from Angelica sinensis on gastric ulcer healing

Our previous study showed that a crude extract from Angelica sinensis (ASCE), which mainly consisted of polysaccharides, significantly promoted migration and proliferation of normal gastric epithelial cells. These results strongly suggest that ASCE has a direct wound healing effect on gastric mucosa. However, there is no report concerning the effect of ASCE on gastric ulcer healing in animal models. In this study, we found that ASCE promoted ulcer healing. The area of the ulcer was reduced. This was accompanied with a significant increase in mucus synthesis when compared with the control. Angiogenesis was inhibited by the treatment of ASCE. Cell proliferation, ODC and EGFR protein expression was not affected in this process. Thus, the mechanism of how ASCE accelerates ulcer healing in addition to its effect on mucus synthesis remains to be investigated.

The production of D-xylose by enzymatic hydrolysis of agricultural wastes

Agricultural wastes, rich in D-xylose content, were hydrolyzed using the mixed crude enzymes produced by Penicillium sp. AHT-1 and Rhizomucor pusillus HHT-1. Shells of pistachio, peanut, walnut, chestnut, barley brans and sunflower seed peels, were used as raw or pretreated forms. Pretreatment was performed by milling or steam explosion. Enzymatic hydrolysis after steam explosion was more effective than milling processing. More than 13 g of D-xylose was produced from 100 g of milled pistachio shells, walnut shells, sunflower seed peels and peanut shells (less than 0.5 mm size) by the action of mixed enzyme solutions. A maximum of 36 g of D-xylose was produced from 100 g of milled pistachio shells when mixed enzyme solution, containing 3,000 U and 33 U per g of substrate with xylanase and beta-xyosidase activities, respectively, was applied. The ratio of the enzymatic hydrolysis as compared to acid hydrolysis in this finding was 100%.

Expression and immunolocalization of heat shock proteins in the healing of gastric ulcers in rats

BACKGROUND

Heat shock proteins are induced when cells are subjected to noxious stimuli. They afford cytoprotection and increase the resistance of the tissue to damage. However, their roles in the healing of gastric ulcers have not been well established. In this study, the expression and immunolocalization of three heat shock proteins (HSPs); namely inducible HSP70 (iHSP70), HSP47, and HSP32 during ulcer healing were investigated in rats with gastric ulcer.

METHODS

Gastric ulcers (kissing ulcers) were induced by luminal application of acetic acid solution. Gastric tissue samples were obtained from the ulcer base, ulcer margin, and non-ulcerated area around the ulcer margin at different time intervals after ulcer induction. The protein levels and distributions of HSPs were analyzed with Western blotting and immunohistochemical methods, respectively.

RESULTS

It was found that all HSPs were expressed in normal, non-ulcerated, and gastric ulcer tissues. HSP32 was elevated during inflammation (1-8 days after ulcer induction), while HSP47 expression was exacerbated at the ulcer base and margin during ulcer healing (3-12 days). Decreased expression of iHSP70 was observed at the ulcer base immediately after ulcer induction, but returned to normal level by the end of the healing stage (8-12 days). Inducible HSP70 was found distributed in the gastric glands and injured tissues in the inflamed areas. Wide distribution of HSP47 was detected in granulation tissues and collagen producing cells, while HSP32 was localized in the gastric glands and inflammatory cells.

CONCLUSIONS

The findings indicate that iHSP70, HSP47, and HSP32 play different roles during ulcer healing. HSP32 seems to act as an inflammatory defensive factor, and HSP47 as a collagen-specific molecular chaperon contributing significantly to gastric ulcer healing. However, the role of iHSP70 in the ulcer healing process is still undefined.

A 3.0-kDa low molecular weight heparin promotes gastric ulcer healing in rats

BACKGROUND

Previous studies have shown that intragastric administration of unfractionated heparin enhances gastric ulcer healing in rats. As the large molecule of heparin may be partially degraded in the upper gastrointestinal tract, it is likely that fragments of heparin, derived from the unfractionated parent compound, are involved in the anti-ulcer action in the stomach. Therefore, it is possible that low molecular weight heparin may have a similar ulcer healing effect.

METHODS

Male Sprague-Dawley rats with acetic acid-induced gastric ulcers were given a 3.0-kDa low molecular weight heparin (0.6-6.0 mg/kg) intravenously or intragastrically once daily for 4 days. Ulcer healing, mucosal histological changes, angiogenesis and gastric mucus production both in vivo and in vitro were determined. The bleeding time was measured to indicate the anticoagulation activity.

RESULTS

Both intravenous and intragastric low molecular weight heparin dose dependently accelerated gastric ulcer healing, which was accompanied by a significant increase in mucosal regeneration and proliferation, angiogenesis and mucus content in the stomach. The drug also stimulated the mucus production in MKN-28 cells. Drug administration by either route did not alter the bleeding time in rats.

CONCLUSIONS

A 3.0-kDa low molecular weight heparin possesses an ulcer healing effect similar to that of unfractionated heparin in the stomach of the rat. This smaller molecular drug is superior to the unfractionated form, does not affect the coagulation activity and may show better absorption in the gastrointestinal tract.

Modulation of heme oxygenase in tissue injury and its implication in protection against gastrointestinal diseases

Heme oxygenase (HO) is the rate-limiting enzyme in the catabolism of heme, followed by production of biliverdin, free iron and carbon monoxide (CO). There are three isoforms of HO: HO-1 is highly inducible, whereas HO-2 and HO-3 are constitutively expressed. In addition to heme, a variety of nonheme compounds, including heavy metals, cytokines, endotoxins and heat shock stress are strong inducers of HO-1 expression. Many studies indicated that induction of HO-1 is associated with a protective response due to the removal of free heme, which is shown to be toxic. However, recent studies demonstrated that the expression of HO-1 in response to different inflammatory mediators could contribute in part to the resolution of inflammation and have protective effects on brain, liver, kidney and lung against injuries. These beneficial effects seem to be due to the production of bile pigment biliverdin and bilirubin that is a potent antioxidant, as well as the release of iron and CO. However, there are few studies concerning the relationship between HO-1 and inflammation as well as injury in the gut. Interestingly, a preliminary study implicated that induction of HO-1 expression in a colonic damage model induced by trinitrobenzene sulfonic acid played a critical protective role, indicating that activation of HO-1 could act as a natural defensive mechanism to alleviate inflammation and tissue injury in the gastrointestinal tract.

Hepatotoxicity of prenatal and postnatal exposure to nicotine in rat pups

Prenatal and postnatal exposure to nicotine have been shown to affect developing tissues in growing animals. Rat pups were exposed to nicotine prenatally and/or postnatally for 10 days by feeding pregnant and lactating rat dams water containing 0, 54, or 108 microM of nicotine. Nicotine exposure did not affect either litter sizes or body weights at birth and at 10 days of age. Exposure to 108 microM of nicotine prenatally increased significantly the incidence of focal necrosis at birth, and the liver damage was still evident at 10 days of age even after the pups were allowed to suckle dams not exposed to any nicotine during the study period. Continuation of nicotine exposure postnatally increased the incidence and severity of focal and confluent necrosis. Postnatal exposure to 108 microM of nicotine to pups not previously exposed also increased the incidence of mild focal and confluent necrosis, although not significantly. Exposure to nicotine prenatally did not affect liver malondialdehyde (MDA) levels at birth. However, liver MDA was significantly lower in rat pups exposed to nicotine prenatally when they were 10 days of age irrespective of whether there were further exposure to nicotine postnatally. Reasons for the late onset of the low MDA levels need further investigation. Postnatal nicotine exposure to either 54 or 108 microM of nicotine to pups not previously exposed fails to affect liver MDA at 10 days of age. The significant decrease in hepatic superoxide dismutase (SOD) levels reflects those of hepatic injury, indicating the possibility of a nicotine-induced downregulation of SOD enzyme production.

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.

Low incidence of genetic alterations of the p16CDKN2a in clear cell chondrosarcoma

Mutational inactivation of the cyclin-dependent kinase inhibitors (CDKIs) (p16CDKN2a) tumor suppressor gene has been found in a variety of human tumor types. To investigate the involvement of CDKI abnormality in clear cell chondrosarcoma, alterations of CDKIs were examined in clear cell chondrosarcoma tissues using a quantitative DNA/PCR, PCR-SSCP. Two of 38 specimens (5.2%) we analyzed showed abnormally low levels of p16CDKN2a amplification, suggesting that the allelic deletion of the gene might be low frequent event in progression of this tumor. For detection of subtle sequence alterations such as point mutations, we performed SSCP analysis of the entire coding region of the p16CDKN2a gene. No altered SSCP patterns were found in 38 clear cell chondrosarcoma specimens. This study reflects the very low incidence of genetic alterations of the p16CDKN2a gene in clear cell chondrosarcoma. Therefore, we conclude that the alteration of the p16CDKN2a gene is not involved significantly in the development of clear cell chondrosarcoma.

Interleukin-1beta induces cyclo-oxygenase-2 expression in gastric cancer cells by the p38 and p44/42 mitogen-activated protein kinase signaling pathways

BACKGROUND AND AIMS

Cyclo-oxygenase-2 (COX-2) is the inducible enzyme in the gastric mucosa responsible for prostaglandin production during inflammation and ulcer healing. The regulation of COX-2 gene expression in gastric epithelial cells is not well understood. In this study, we investigated the effect of interleukin (IL)-1beta on COX-2 expression in the human gastric cancer cell, and explored the signaling pathways involved.

METHODS

Gastric cancer cell line AGS was treated with IL-1beta or the inhibitors of mitogen-activated protein-Erk kinase (MEK) and p38 mitogen-activated protein (MAP) kinase prior to the addition of IL-1beta. The COX-2 mRNA or protein levels were measured by using RT-PCR or western blot analysis, respectively. Prostaglandin E2 (PGE2) production/secretion was determined by using the prostaglandin E2 EIA assay. The phosphorylation/activation of p44/42 and p38 MAP kinases were determined by using western blot analysis and using phospho-specific antibodies.

RESULTS

Interleukin-1beta treatment dose- and time-dependently increased COX-2 mRNA and protein expression levels, and enhanced PGE2 production/secretion in AGS cells. In contrast, IL-1beta had no effect on the level of the constitutively expressed COX-1. In parallel to the increase of COX-2, we showed that p44/42 and p38 MAP kinase activities were also upregulated by IL-1beta treatment. To demonstrate the cause-effect relationship, we showed that inhibition of MEK and p38 MAP kinase with specific inhibitors suppressed IL-1beta-mediated increases in COX-2 mRNA and protein levels, and the PGE2 production.

CONCLUSIONS

Our results demonstrated that in human gastric cancer cells, IL-1beta upregulates the COX-2 gene expression through the activation of MEK/p44/42 and p38 MAP kinases pathway.

12-Lipoxygenase inhibition induced apoptosis in human gastric cancer cells

Arachidonic acid release from membrane phospholipids is essential for tumour cell proliferation. Lipoxygenases constitute a pathway for arachidonate metabolism. The present study investigated the expression of 12-lipoxygenase and its effect on cell proliferation as well as survival in two human gastric cancer cell lines (AGS and MKN-28). RT-PCR and western blots, respectively, showed 12-LOX mRNA and protein expression in both AGS and MKN-28 cell lines. Treatment with a 12-LOX inhibitor, baicalein, significantly inhibited cancer cell proliferation, but a metabolite of 12-LOX activity, 12 hydroxyeicosatetraenoic acid (12-HETE) reversed baicalein-induced growth inhibition. Furthermore, the blockade of the 12-LOX pathway through a 12-LOX inhibitor and antisense induced apoptosis of gastric cancer cell lines. The biochemical characteristics of apoptosis were p53-independent combined with a decrease in bcl-2 expression. Caspase-7 was proteolytically activated and responsible for the apoptosis execution.

Macrophage migration inhibitory factor is an important mediator in the pathogenesis of gastric inflammation in rats

BACKGROUND & AIMS

Macrophage migration inhibitory factor (MIF) has been shown to play a pivotal role in inflammatory and immune-mediated diseases. This study investigates the role of MIF in gastric inflammation.

METHODS

Expression of MIF was examined in a rat gastric ulcer model induced by acetic acid, and the functional role of MIF in acute gastric ulcer was investigated by administration of a neutralizing anti-MIF antibody.

RESULTS

MIF messenger RNA and protein were markedly up-regulated in acute gastric ulcer, which correlated with the accumulation of macrophages (P < 0.001) and neutrophils (P < 0.05) at the site of inflammation. Macrophages, like neutrophils, were the major inflammatory cells infiltrating the ulcer base and they strongly expressed inducible nitric oxide synthase. However, macrophages, not neutrophils, were a rich source of MIF production in acute gastric ulcer. In vivo and in vitro blockade of MIF with the neutralizing anti-MIF antibody significantly inhibited the marked up-regulation of MIF, tumor necrosis factor alpha, inducible nitric oxide synthase, and intercellular adhesion molecule-1. This was associated with the marked inhibition of macrophage (70% reduced) and neutrophil (60% reduced) accumulation and activation, thus reducing ulcer sizes and attenuating ulceration.

CONCLUSIONS

This study has shown that MIF was markedly up-regulated during acute gastric ulcer. Inhibition of acute gastric ulcer by blockade of MIF indicates that MIF is a key inflammatory mediator and plays a pathogenic role in gastric inflammation.

Epidermal growth factor and its receptor in chronic active gastritis and gastroduodenal ulcer before and after Helicobacter pylori eradication

BACKGROUND

Helicobacteria pylori infection of gastroduodenal mucosa is strongly associated with gastritis and peptic ulcer disease. The aims of the present study were to compare the gastroduodenal mucosal levels of epidermal growth factor (EGF) and its receptor (EGFR) among H. pylori-negative controls and H. pylori infected patients with chronic active gastritis or gastroduodenal ulcer before and after H. pylori eradication.

METHODS

The protein levels of EGF in mucosal tissues and saliva were determined by a solid-phase enzyme-linked immunosorbent assay (ELISA). Repeat transcription-polymerase chain reaction and the following polymerase chain reaction ELISA were employed to examine the mucosal EGFR mRNA expression.

RESULTS

Mucosal injury and H. pylori infection increased EGF protein levels and EGFR mRNA expression in the antral mucosa. The concentration of EGF in saliva was not affected by mucosal damage or H. pylori infection. Successful H. pylori eradication normalized the EGFR mRNA back to its basal level 6 weeks after treatment. However, after unsuccessful eradication their high levels in the antrum persisted. All patients experienced ulcer healing after drug treatment, regardless of H. pylori eradication.

CONCLUSIONS

Mucosal damage increased the expression of EGF protein and EGFR mRNA in the gastric mucosa. H. pylori could induce the expression of EGFR but not the EGF in the antral mucosa. The expression of EGFR could be a contributing factor for ulcer healing in patients with H. pylori infection.

Inhibition of proteasome function induced apoptosis in gastric cancer

The ubiquitin-proteasome pathway plays a critical role in the degradation of cellular proteins and cell cycle control. Dysregulating the degradation of such proteins should have profound effects on tumor growth and causes cells to undergo apoptosis. The aims of this study are to evaluate the ubiquitin-proteasome pathway in gastric cancer and the potential role of pharmacological inhibition of proteasome on induction of apoptosis in gastric cancer cells. Gastric cancer cell lines AGS (p53 wild-type) and MKN-28 (p53 mutant) were treated with proteasome inhibitor MG132. The results showed that MG132 inhibited cell proliferation in AGS and MKN-28 cells in a time- and dose-dependent manner. The inhibition of cell proliferation was caused by apoptosis which was also time- and dose-dependent. AGS cells were more responsive to MG132 than MKN-28 cells. Induction of apoptosis was preceded by the activation of caspase-3, as measured by a colorimetric caspase-3 cellular activity and Western blotting of the cleavage of caspase-3 and its substrate PARP. Activation of caspase-7 was also exhibited. In addition, z-VAD-fmk, a broad spectrum caspase inhibitor, reversed apoptosis induced by MG132 in AGS and MKN28 cells. Although z-DEVD-fmk, a specific caspase-3 inhibitor, suppressed MG132-induced apoptosis in MKN28 cells, it only partially rescued the apoptotic effect in AGS cells. Caspase-3 activation was the result of release of cytochrome c from mitochondria into the cytosol, as a consequence of upregulation of bax. There were overexpressions of all the proteasome-related proteins p53, p21(waf1) and p27(kip1) at 4 hr after proteasome inhibition which was identified by the accumulation of ubiquitin-tagged proteins. This was accompanied by accumulation of cells at G(1) phase. Our present study suggests that inhibition of proteasome function in gastric cancer cells induces apoptosis and proteasomal inhibitors have potential use as novel anticancer drugs in gastric cancer.

Sleep deprivation increase the expression of inducible heat shock protein 70 in rat gastric mucosa

AIM: To investigate if sleep deprivation is able to increase the expression of inducible heat shock protein 70 in gastric mucosa and its possible role in mucosal defense.

METHODS: Rats for sleep disruption were placed inside a computerized rotating drum, gastric mucosa was taken from rats with 1, 3 and 7 d sleep deprivation. RT-PCR, immunohistochemistry and Western blotting were used to determine the expression of heat shock protein 70. Ethanol (500 mL·L^-1, i.g.) was used to induce gastric mucosa damage.

RESULTS: RT-PCR, Western blotting and immunostaining confirmed that the sleep deprivation as a stress resulted in significantly greater expression of inducible heat shock protein 70 in gastric mucosa of rats. After the 500 mL·L^-1 ethanol challenge, the ulcer area found in the rats with 7 d sleep deprivation (19.15 ± 4.2) mm² was significantly lower (P < 0.01) than the corresponding control (53.7 ± 8.1) mm².

CONCLUSION: Sleep deprivation as a stress, in addition to lowering the gastric mucosal barrier, is able to stimulate the expression of inducible heat shock protein 70 in gastric mucosa of rats, the heat shock protein 70 may play an important role in gastric mucosal protection.

Delivery of glucocorticoid conjugate in rat gastrointestinal tract and its treatment for ulcerative colitis

AIM

To evaluate colonic delivery and therapeutic effect of the newly synthesized dexamethasone (DX)-dextran (500 000) conjugate (DXD50) in the rat.

METHODS

The amount of dexamethasone was measured in the contents from different parts of rat gastrointestinal tract and in plasma after ig conjugate. Therapeutic effect of conjugate and DX was tested in trinitrobenzenesulfonic acid-induced colitis in rat. Repair of colitis was assessed by measuring colonic ulceration area, colon weight, and colonic myeloperoxidase (MPO) activity. Systemic immunosuppression of DX was evaluated with weight of thymus and spleen and lymphocyte count in peripheral blood from rat with ulcerative colitis.

RESULTS

Dexamethasone released from conjugate was mainly distributed in contents of cecum and colon. When DXD50 and DX 0.25 micromol . kg-1 . d-1 were used ig to treat ulcerative colitis in rat, the ulcerative area of colon was reduced by 55.6 % and 33.3 %, respectively whereas colon weight was reduced by 17.9 % and 2.6 %, respectively. The conjugate had no effect on lymphocyte count in peripheral blood, spleen weight, and thymus weight of rat which could be reduced markedly by the same dose of DX (P < 0.05 vs control).

CONCLUSION

DXD50, which could specifically deliver DX to large intestine, is a promising agent in the treatment of human inflammatory bowel disease.

Protective role of heme oxygenase-1 on trinitrobenzene sulfonic acid-induced colitis in rats

Preliminary studies showed that the inducible form of heme oxygenase (HO-1) was induced and played a protective role in the process of inflammation. The present study investigated the possible role of HO-1 in 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis in rats. We measured HO-1 activity in TNBS-induced colitis in rats and analyzed the severity of colitis along with altered HO activity by assessing lesion area and myeloperoxidase activity. HO-1 mRNA and protein expressions were determined at different time points after TNBS induction. Free radical production and inducible nitric oxide synthase (iNOS), which participate in oxidative injury, were also assayed. HO activity and HO-1 gene expression increased markedly after TNBS induction. Administration with tin mesoporphyrin (SnMP), a HO inhibitor, potentiated the colonic damage along with a reduction in HO-1 activity. Furthermore, the reduction of HO-1 expression by SnMP also enhanced reactive oxygen species and iNOS expression, both of which were dramatically increased after the TNBS enema. L-Arginine pretreatment further aggravated the injurious action of SnMP. Our results indicate that HO-1 plays a protective role in the colonic damage induced by the TNBS enema, and the preventive effects probably result from decreased free radical production and inhibition of iNOS expression in colonic tissues.

Protein denaturation described by a two-state structural model of liquid water

Our laboratory has been involved in expounding an outer neighbor molecular-level structural theory for liquid water in the supercooled and ordinary thermodynamic regimes. This theory, which depends on transformations with increasing temperature or pressure, is consistent with all the properties of this substance, including the ten or so "anomalies", and has been recently used to explain the effect that surrounding water has on proteins. For example, the sharp decrease in the hydration entropies of polar groups can be explained through a consideration of the promotion of ice-Ih-type bonding structure at the expense of the less stable ice-II-type bonding structure. These structural transformations occur in the local neighborhood of the polar group. In this paper we discuss this outer neighbor two-state structural theory for liquid water, the role it plays in explaining water's anomalous properties and its description of protein denaturation both as a function of temperature and pressure.

Influence of gender difference and gastritis on gastric ulcer formation in rats

BACKGROUND

Male patients with gastritis are found to have a high risk of developing peptic ulcer diseases. However, how gastritis or gender difference affects gastric ulcer formation is unclear. The present study aimed to investigate the relationship between ethanol-induced acute gastritis and gastric ulcer formation in rats.

METHODS

Acute gastritis or gastric ulcer was induced in the rat stomach by 80% ethanol or 60% acetic acid, respectively. Rats were killed either with gastritis alone or thereafter at day 1, 3 or 6 after ulcer induction. The number of proliferating and apoptotic cells, the mucosal mucus and prostaglandin E(2) (PGE(2)) level were also determined.

RESULTS

Male rats with acute gastritis potentiated gastric ulcer formation, while gastritis in female rats prevented ulceration. Female rats with gastritis had a significantly faster ulcer-healing rate. More apoptotic cells were found in the gastritis groups, but only the female gastritis group produced more proliferating cells and had a decrease in the apoptosis-over-proliferation ratio. The mucus level was higher in female rats after ulcer induction. Mucosal PGE(2) level was higher in female rats with acute gastritis. Both mucus and PGE(2) were increased during ulcer healing in both genders.

CONCLUSIONS

This study shows that gender difference plays a role in the pathogenesis of ulcer formation. The number of cells with apoptosis or proliferation determines, in part, the gender difference on gastric ulcer formation in rats. Gastric PGE(2) not only contributes to this process, but also together with gastric mucus participates in the ulcer-healing process in the stomach.

Inducible HSP70 mediates delayed cardioprotection via U-50488H pretreatment in rat ventricular myocytes

To test the hypothesis that heat-shock proteins (HSPs) mediate delayed cardioprotection of prior kappa-opioid receptor (kappa-OR) stimulation, we first correlated cellular injury and viability with the expression of HSP70s in isolated rat ventricular myocytes subjected to prior kappa-OR stimulation with the selective agonist trans-(+/-)-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)cyclohexyl]benzeneacetamide (U-50488H) and delayed lethal simulated ischemia (LSI). Cell injury and viability were indicated by lactate dehydrogenase release and trypan blue exclusion, respectively. The reduced injury and increased viability after pretreatment with U-50488H were concentration dependent and correlated directly with the expression of both stress-inducible (HSP70) and constitutive (HSC70) proteins. The effects mimic those with metabolic inhibition preconditioning (MIP). The cardioprotection against LSI by pretreatment with U-50488H and MIP was abolished and antagonized, respectively, via blockade of the kappa-OR by its selective antagonist, nor-binaltorphimine. We also found that blockade of the production of HSP70 but not HSC70 blocked the inhibitory effect of pretreatment with U-50488H on injury and viability. These observations provide evidence that stress-inducible HSP70 mediates delayed cardioprotection of prior kappa-OR stimulation.

Protective effect of polysaccharides-enriched fraction from Angelica sinensis on hepatic injury

A polysaccharides-enriched fraction from the root of Angelica sinensis, which is known for its antiulcer action on the gastrointestinal tract, was isolated and studied for its hepato-protective effect in rodents. Intra-gastric administration of Angelica sinensis polysaccharides-enriched fraction (AP) at the doses of 50 or 75 mg/kg dose-dependently prevented liver toxicity induced by acetaminophen in mice but did not affect the serum acetaminophen concentration. It normalized the rises of serum alanine transferase (ALT) and hepatic nitric oxide synthase (NOS) activities and the decrease of glutathione level in the liver. It also reduced the hepatic malondialdehyde (MDA) concentration. The protective effect was less evident in the carbon tetrachloride (CCl4)-treated animals including mice and rats. In the rat the elevated serum ALT level was unaffected though the MDA level was similarly reduced by the higher dose of AP. In these animals, CCl4 increased the hepatic glutathione level instead while the NOS activity remained unchanged. These findings suggest that the pathogenic mechanisms of both acetaminophen and CCl4 are different. AP is more effective in the protection against liver damage induced by acetaminophen, which is associated with the glutathione depletion and nitric oxide synthase activation in the liver.

A mechanistic study of proliferation induced by Angelica sinensis in a normal gastric epithelial cell line

It has been reported that an extract from Angelica sinensis mainly consisting of polysaccharides (95%) prevented ethanol- or indomethacin-induced gastric mucosal damage (Cho CH et al. Planta Med 2000;66:348-51). However, it is not known whether Angelica sinensis has a direct stimulatory effect on the healing of gastric mucosal lesions. To study the hypothesis that Angelica sinensis has a direct mucosal healing effect in rats and in isolated gastric epithelial cells, we assessed the wound repair in both animals and normal cell culture (RGM-1), as well as [3H]thymidine incorporation, ornithine decarboxylase (ODC) activity, and ODC protein and c-Myc protein expression after different treatments in RGM-1 cells. We found that Angelica sinensis crude extract (ASCE) dose-dependently enhanced gastric ulcer healing in rats and promoted wound repair in RGM-1 cells. It also significantly stimulated [3H]thymidine incorporation and ODC activity in RGM-1 cells in a concentration-dependent manner. ODC and c-Myc protein expression was also increased as a result of this process. DL-alpha-difluoromethyl-ornithine repressed the [3H]thymidine incorporation and ODC activity induced by ASCE. Pretreatment with c-Myc antisense oligodeoxynucleotides blocked the stimulatory action of ASCE on [3H]thymidine incorporation and ODC protein expression. These data suggest that ASCE has a direct mucosal healing effect on gastric epithelial cells, while ODC and c-Myc are closely associated with this effect.

Extreme-ultraviolet lensless Fourier-transform holography

We demonstrate 100-nm-resolution holographic aerial image monitoring based on lensless Fourier-transform holography at extreme-UV (EUV) wavelengths, using synchrotron-based illumination. This method can be used to monitor the coherent imaging performance of EUV lithographic optical systems. The system has been implemented in the EUV phase-shifting point-diffraction interferometer recently developed at Lawrence Berkeley National Laboratory. Here we introduce the idea of the holographic aerial image-recording technique and present imaging performance characterization results for a 10x Schwarzschild objective, a prototype EUV lithographic optic. The results are compared with simulations, and good agreement is obtained. Various object patterns, including phase-shift-enhanced patterns, have been studied. Finally, the application of the holographic aerial image-recording technique to EUV multilayer mask-blank defect characterization is discussed.

Increased erythritol production in fed-batch cultures of Torula sp. by controlling glucose concentration

The effect of glucose concentration on erythritol production by Torula sp. was investigated. The maximum volumetric productivity of erythritol was obtained at an initial glucose concentration of 300 g l(-1) in batch culture. The volumetric productivity was maximal at a controlled glucose concentration of 225 g l(-1), reducing the lag time of the erythritol production. A fed-batch culture was established with an initial glucose concentration of 300 g l(-1) and with a controlled glucose concentration of 225 g l(-1) in medium containing phytic acid as a phosphate source. In this fed-batch culture, a final erythritol production of 192 g l(-1) was obtained from 400 g l(-1) glucose in 88 h. This corresponded to a volumetric productivity of 2.26 g l(-1) h(-1) and a 48% yield.

High prevalence of mixed infections by Helicobacter pylori in Hong Kong: metronidazole sensitivity and overall genotype

BACKGROUND

Diversity in metronidazole susceptibility and genotypes of Helicobacter pylori have been reported with varying results in different areas.

AIMS

To investigate the prevalence of multiple strain infection in a symptomatic Chinese population and to determine the metronidazole susceptibility pattern and genotypic characteristics of these infecting strains.

METHODS

Gastric biopsies from antrum, body and cardia were taken during upper endoscopy in symptomatic patients referred to our department. Pooled cultures and single colony isolates were obtained and tested for metronidazole susceptibility and random amplified polymorphic DNA (RAPD) fingerprint patterns.

RESULTS

A total of 461 isolates were successfully cultured from 46 patients. Fifty-seven per cent of subjects had metronidazole-resistant strains. Among them, 77% carried a mixture of sensitive and resistant strains, non-uniformly distributed in the gastric mucosa. Mixed genotypes were found by RAPD typing in 24% of subjects. These did not correlate with the metronidazole susceptibility/resistance pattern.

CONCLUSION

H. pylori infections with mixed metronidazole sensitive/resistant strains and mixed genotypes are common in Hong Kong. This makes it prudent to use bacterial strains from several biopsy sites when testing for traits such as drug resistance or virulence in relation to disease.

The role of nitric oxide on cigarette smoke-induced programmed cell death in the gastric mucosa

BACKGROUND

This study was designed to investigate the effect of cigarette smoking on apoptosis in the gastric mucosa and the role of nitric oxide (NO) in the gas phase and extracts in the tar phase in this pathological process.

METHODS

Male Sprague-Dawley rats and human gastric epithelial cell line AGS were used in the study.

RESULTS

Cigarette smoking significantly increased apoptotic bodies in the rat gastric mucosa. However, neither filtered cigarette smoke, in which most of the substances in the tar phase were removed, nor oral administration of the two cigarette smoke extracts produced any effect on apoptosis. Interestingly, in this experiment pretreatment with a NO donor, the chloroform extract (CE) could significantly increase apoptosis. In in vitro study, only the CE induced DNA fragmentation, which could be elevated further by preincubation with a NO donor. The same extract also elevated inducible nitric oxide synthase (iNOS) activity. Inhibition of iNOS by N(G)-nitro-L-arginine methylester hydrochloride (L-NAME) partially abolished CE-induced apoptosis.

CONCLUSIONS

These findings suggested that exogenous and endogenous NO had a synergistic effect with substances in the tar phase to induce programmed cell death in gastric epithelial cells both in vivo and in vitro.

Suppression of collagen-induced arthritis with histone H1

Besides roles in nucleus mediating the condensation of DNA into chromatin, the involvement of histones in autoimmune diseases, hormone regulation, and killing leukemia cells has been reported. In order to investigate the functions of histones on an autoimmune disease, histone H1 was injected into collagen-induced arthritis (CIA) mice. A dramatic suppression of CIA by histone H1 was observed at a dose of 1 mg/kg bodyweight of mouse. In addition, the increased level of anti-inflammatory cytokine IL-10 was detected in cultured splenocytes from the mouse treated with histone H1. These findings suggest that histone H1 suppresses the collagen-induced arthritis, possibly by increasing the level of IL-10 production.

Relationship between ethanol-induced gastritis and gastric ulcer formation in rats

BACKGROUND/AIMS

Patients with peptic ulcer diseases have a high prevalence of coexisting chronic gastritis. The mechanism of how gastritis leads to gastric ulcer formation is yet to be determined. The purpose of this study was to clarify the relationship between gastritis and gastric ulcer in rats.

METHODS

Ethanol (80% v/v, p.o.) was given repeatedly in rats to induce subchronic gastritis. Gastric ulcer was then induced by 60% acetic acid.

RESULTS

Findings showed that subchronic gastritis potentiated gastric ulcer formation. It also produced more apoptotic cells, together with an overexpression of tumor necrosis factor-alpha (TNF alpha) in the gastric mucosa. Inhibition of the production/release of TNF alpha by pentoxifylline prevented the increase in apoptosis and the enhancement of susceptibility to ulcerative damage by subchronic gastritis. However, such subchronic gastritis did not further affect the rate of ulcer healing in these animals.

CONCLUSION

The induction of gastritis resulted in an activation of TNF alpha expression followed by apoptosis in the gastric mucosa. This could lead to an increase in the severity of ulcerative damage in the stomach.

Arsenic trioxide induces apoptosis in human gastric cancer cells through up-regulation of p53 and activation of caspase-3

Arsenic trioxide (As(2)O(3)) can induce clinical remission in patients suffering from acute promyelocytic leukemia, through induction of apoptosis and activation of caspases. We investigated the potential use of As(2)O(3) in human gastric cancer and its possible mechanisms. Human gastric cancer cell lines AGS and MKN-28 were treated with various concentrations (0.1 to 100 microM) of As(2)O(3) for 24 to 72 hr. Apoptosis was determined by acridine orange staining, flow cytometry and DNA fragmentation. Protein levels of p53, p21(waf1/cip1), c-myc, bcl-2 and bax were detected by Western blotting. Effects of As(2)O(3) on caspase-3 protease activity, its protein concentration and cleavage of poly(ADP)-ribose polymerase (PARP) were also studied. As(2)O(3) inhibited cell growth and induced apoptosis in both cell lines, though AGS cells were more sensitive. As(2)O(3) induced apoptosis in AGS cells in a concentration- and time-dependent manner. Treatment resulted in a marked increase in p53 protein levels as early as 4 hr. Co-incubation with p53 anti-sense oligo-nucleotide suppressed As(2)O(3)-induced intracellular p53 over-expression and apoptosis. As(2)O(3) increased the activity of caspase-3, with appearance of its 17 kDa peptide fragment, and cleavage of PARP, with appearance of the 85 kDa cleavage product, both in parallel with the induction of apoptosis. Both the tripeptide caspase inhibitor zVAD-fmk and the specific caspase-3 inhibitor DEVD-fmk partially suppressed As(2)O(3)-induced caspase-3 activation and apoptosis. As(2)O(3) inhibits cell growth and induces apoptosis in gastric cancer cells, involving p53 over-expression and activation of caspase-3. The potential use of this compound in the treatment of gastric cancer is worth further investigation.

Arsenic trioxide induces apoptosis in human gastric cancer cells through up-regulation of p53 and activation of caspase-3

Arsenic trioxide (As(2)O(3)) can induce clinical remission in patients suffering from acute promyelocytic leukemia, through induction of apoptosis and activation of caspases. We investigated the potential use of As(2)O(3) in human gastric cancer and its possible mechanisms. Human gastric cancer cell lines AGS and MKN-28 were treated with various concentrations (0.1 to 100 microM) of As(2)O(3) for 24 to 72 hr. Apoptosis was determined by acridine orange staining, flow cytometry and DNA fragmentation. Protein levels of p53, p21(waf1/cip1), c-myc, bcl-2 and bax were detected by Western blotting. Effects of As(2)O(3) on caspase-3 protease activity, its protein concentration and cleavage of poly(ADP)-ribose polymerase (PARP) were also studied. As(2)O(3) inhibited cell growth and induced apoptosis in both cell lines, though AGS cells were more sensitive. As(2)O(3) induced apoptosis in AGS cells in a concentration- and time-dependent manner. Treatment resulted in a marked increase in p53 protein levels as early as 4 hr. Co-incubation with p53 anti-sense oligo-nucleotide suppressed As(2)O(3)-induced intracellular p53 over-expression and apoptosis. As(2)O(3) increased the activity of caspase-3, with appearance of its 17 kDa peptide fragment, and cleavage of PARP, with appearance of the 85 kDa cleavage product, both in parallel with the induction of apoptosis. Both the tripeptide caspase inhibitor zVAD-fmk and the specific caspase-3 inhibitor DEVD-fmk partially suppressed As(2)O(3)-induced caspase-3 activation and apoptosis. As(2)O(3) inhibits cell growth and induces apoptosis in gastric cancer cells, involving p53 over-expression and activation of caspase-3. The potential use of this compound in the treatment of gastric cancer is worth further investigation.

Arsenic trioxide induces apoptosis in human gastric cancer cells through up-regulation of p53 and activation of caspase-3

Arsenic trioxide (As(2)O(3)) can induce clinical remission in patients suffering from acute promyelocytic leukemia, through induction of apoptosis and activation of caspases. We investigated the potential use of As(2)O(3) in human gastric cancer and its possible mechanisms. Human gastric cancer cell lines AGS and MKN-28 were treated with various concentrations (0.1 to 100 microM) of As(2)O(3) for 24 to 72 hr. Apoptosis was determined by acridine orange staining, flow cytometry and DNA fragmentation. Protein levels of p53, p21(waf1/cip1), c-myc, bcl-2 and bax were detected by Western blotting. Effects of As(2)O(3) on caspase-3 protease activity, its protein concentration and cleavage of poly(ADP)-ribose polymerase (PARP) were also studied. As(2)O(3) inhibited cell growth and induced apoptosis in both cell lines, though AGS cells were more sensitive. As(2)O(3) induced apoptosis in AGS cells in a concentration- and time-dependent manner. Treatment resulted in a marked increase in p53 protein levels as early as 4 hr. Co-incubation with p53 anti-sense oligo-nucleotide suppressed As(2)O(3)-induced intracellular p53 over-expression and apoptosis. As(2)O(3) increased the activity of caspase-3, with appearance of its 17 kDa peptide fragment, and cleavage of PARP, with appearance of the 85 kDa cleavage product, both in parallel with the induction of apoptosis. Both the tripeptide caspase inhibitor zVAD-fmk and the specific caspase-3 inhibitor DEVD-fmk partially suppressed As(2)O(3)-induced caspase-3 activation and apoptosis. As(2)O(3) inhibits cell growth and induces apoptosis in gastric cancer cells, involving p53 over-expression and activation of caspase-3. The potential use of this compound in the treatment of gastric cancer is worth further investigation.

Angelica sinensis modulates migration and proliferation of gastric epithelial cells

A crude extract from Angelica sinensis (ASCE), which mainly consists of polysaccharides, prevents ethanol- or indomethacin-induced gastric mucosal damage and promotes ulcer healing. The aim of this study was to test the hypothesis that ASCE has a direct stimulating effect on gastric epithelial cells for wound healing. We found that ASCE significantly promoted the migration of epithelial cells over an artificial wound on the surface of an RGM-1 monolayer. The extract also stimulated DNA synthesis in a dose-dependent manner and concomitantly increased EGF mRNA expression. Co-incubation of ASCE with anti-EGF antibody reduced the speed of migration and the DNA synthesis, which however were still higher than the control without ASCE. These results strongly suggest that ASCE has a direct wound healing effect on gastric mucosa, and this is acting partially through an EGF-mediated pathway.

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.

Current roles of nitric oxide in gastrointestinal disorders

It has been confusing as to what roles nitric oxide (NO) has in different physiological and pathological mechanisms in various diseases. In the gastrointestinal tract, NO can be either protective or deleterious in different disorders. This depends on what type of nitric oxide synthase (NOS) is involved in these pathological conditions. Constitutive NOS (cNOS) is responsible for production of NO in physiological context. In contrast, inducible NOS (iNOS) produces NO in pathophysiological circumstances. NO is implicated in mechanisms maintaining the integrity of the gastric epithelium. In this connection, it regulates gastric blood flow and directly stimulates gastric mucus secretion by activating soluble guanylate cyclase. A blockade of NO production resulted in an impairment of the vascular response and the subsequent alkaline flux in the lumen. This would impair the restitution process. Endogenous NO also contributes to the inhibition of acid secretion in the stomach. Indeed the adverse action of cigarette smoking on ulcer healing is largely dependent on the deficiency of cNOS and a subsequent depression of gastric blood flow and angiogenesis. To this end, NO may act as a crucial signal to promote endothelial cell differentiation into vascular tubes. In experimental colitis, NO derived from iNOS, together with other free radicals contribute significantly to the inflammatory response in the colon. It is also involved in the ulcerogenic effect of passive smoking on colitis. The mechanism is likely mediated through the interaction with superoxide to produce peroxynitrite, a strong oxidizing agent that initiates lipid peroxidation. In conclusion, NO in low concentration derived from cNOS is cytoprotective by directly acting as an inducer of defense responses in the gastrointestinal tract. However, higher concentrations of NO from iNOS exhibit toxic effects through nitrosative and oxidative stress.

The Na+ -Ca2+ exchanger is essential for embryonic heart development in mice

The cardiac Na+ -Ca2+ exchanger 1 (NCX1) is thought to be the major calcium extrusion mechanism and to play an important role in the regulation of intracellular calcium in the heart. The Na+ -Ca2+ exchanger is particularly abundant in the heart, although it is found in a variety of other tissues. To investigate the role of NCX1, we have generated NCX1-deficient mice. Mice heterozygous for the NCX1 mutation showed no discernable phenotype, grew normally, and were fertile; however, no viable homozygote was observed among 175 offspring obtained from intercrosses of heterozygotes. All the homozygous mutant mice died in utero before E10.5. Morphological analysis indicated that homozygotes of NCX1 mutation at E9.5 died with an underdeveloped heart with a dilated pericardium. Microscopic analysis of these embryos showed myocardial cell loss due to apoptosis. The apoptosis was first observed in E8.5 mutant heart. Areas outside the heart appeared normal in the mutant embryos at E8.5. In contrast, at E9.0, various regions of mutant embryos showed extensive cell loss. These results suggest that mutant embryos die owing to cardiac abnormalities caused by apoptotic cell loss, indicating that NCX1 is essential for normal development of the heart.

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.

Transmission phase gratings for EUV interferometry

The performance of the recently developed EUV phase-shifting point diffraction interferometer (PS/PDI) depends heavily on the characteristics of the grating beamsplitter used in the implementation. Ideally, such a grating should provide throughput of better than 25% and diffraction efficiency, defined as the ratio of the first-diffracted-order power to the zero-order power, variable in the range from approximately 10 to 500. The optimal method for achieving these goals is by way of a phase grating. Also, PS/PDI system implementation issues favor the use of transmission gratings over reflection gratings. Here, the design, fabrication, and characterization of a recently developed transmission phase grating developed for use in EUV interferometry is described.

Role of protein kinase C in alpha(1)-adrenergic regulation of a(Na)(i) in guinea pig ventricular myocytes

We investigated the role of protein kinase C (PKC) in alpha(1)-adrenergic regulation of intracellular Na(+) activity (a(Na)(i)) in single guinea pig ventricular myocytes. a(Na)(i) and membrane potentials were measured with the Na(+)-sensitive indicator sodium-binding benzofuran isophthalate and conventional microelectrodes, respectively, at room temperature (24-26 degrees C) while myocytes were stimulated at a rate of 0.25-0.3 Hz. The PKC activator 4beta-phorbol 12-myristate 13-acetate (PMA) decreased a(Na)(i) in a concentration-dependent manner. PMA (100 nM) produced a maximal decrease in a(Na)(i) of 1.5 mM from 6.5 +/- 0.4 to 5.0 +/- 0.4 mM (means +/- SE, n = 12, P < 0.01). The PMA concentration required for a half-maximal decrease in a(Na)(i) was 0.46 +/- 0.13 nM (n = 3, P < 0.01). An inactive phorbol, 4alpha-phorbol 12-myristate 13-acetate, did not decrease a(Na)(i). The decrease caused by PMA could be blocked by the PKC inhibitors staurosporine and bisindolylmaleimide I (GF-109203X). Stimulation of the alpha(1)-adrenoceptor with 50 microM phenylephrine decreased a(Na)(i) from 6.1 +/- 0.3 to 4.6 +/- 0.3 mM (n = 11, P < 0.01). The decrease in a(Na)(i) produced by phenylephrine was blocked by pretreatment with staurosporine, GF-109203X, or PMA. The decrease in a(Na)(i) produced by PMA was not prevented by pretreatment with tetrodotoxin but was blocked by pretreatment with strophanthidin or high extracellular K(+) concentration. The results suggest that alpha(1)-adrenergic receptor activation results in a decrease in a(Na)(i) via PKC-induced stimulation of the Na(+)-K(+) pump in cardiac myocytes.

Differential changes in the expression of cyclic nucleotide phosphodiesterase isoforms in rat brains by chronic treatment with electroconvulsive shock

Electroconvulsive shock (ECS) has been suggested to affect cAMP signaling pathways to exert therapeutic effects. ECS was recently reported to increase the expression of PDE4 isoforms in rat brain, however, these studies were limited to PDE4 family in the cerebral cortex and hippocampus. Thus, for comprehensive understanding of how ECS regulates PDE activity, the present study was performed to determine whether chronic ECS treatment induces differential changes in the expression of all the PDE isoforms in rat brains. We analyzed the mRNA expression of PDE isoforms in the rat hippocampus and striatum using reverse transcription polymerase chain reaction. We found chronic ECS treatment induced differential changes in the expression of PDE isoform 1, 2, 3, 4, 5 and 7 at the rat hippocampus and striatum. In the hippocampus, the expression of PDE1A/B (694%), PDE4A (158%), PDE4B (323 %), and PDE4D (181%) isoforms was increased from the controls, but the expression of PDE2 (62.8%) and PDE7 (37.8%) decreased by chronic ECS treatment. In the striatum, the expression of PDE1A/B (179%), PDE4A (223%), PDE4B (171%), and PDE4D (327%) was increased by chronic ECS treatment with the concomitant decrease in the expression of PDE2 (78.4%) and PDE3A (67.1%). In conclusion, chronic ECS treatment induces differential changes in the expression of most PDE isoforms including PDE1, PDE2, PDE3, PDE4, PDE5, and PDE7 in the rat hippocampus and striatum in an isoform- and brain region-specific manner. Such differential change is suggested to play an important role in regulation of the activity of PDE and cAMP system by ECS.

The role of polyamines in gastric mucus synthesis inhibited by cigarette smoke or its extract

BACKGROUND

Cigarette smoking was shown to delay gastric ulcer healing and reduce synthesis of mucus, which is important for gastric ulcer protection and healing. Polyamines are important in these processes.

AIMS

To study the effects of cigarette smoking on the synthesis of mucus and to investigate if such an effect is acting by interference with the polyamine pathway.

METHODS

Gastric mucosal ornithine decarboxylase activity, mucous secreting layer thickness, and ulcer size were determined after different concentrations of cigarette smoke exposure (0, 2, or 4%) in intact animals and animals with ulcers. Synthesis of mucus and ornithine decarboxylase activity and mRNA expression were also assessed in cigarette smoke extract treated MKN-28 cells.

RESULTS

Exposure to cigarette smoke significantly reduced the thickness of the mucous secreting layer and gastric mucosal ornithine decarboxylase activity in animals with or without ulcers. Spermidine not only reversed inhibition of mucus synthesis in both intact and ulcer bearing animals but also reversed the delay in ulcer healing. Cigarette smoke extract significantly reduced mucus synthesis and ornithine decarboxylase activity but not its mRNA expression in MKN-28 cells. The reduction in mucus synthesis was restored by spermidine.

CONCLUSIONS

Cigarette smoke and its extract repress mucus synthesis in vivo and in vitro, respectively. Reduction of ornithine decarboxylase activity in gastric mucosa is closely associated with this effect.

Intragastric administration of heparin enhances gastric ulcer healing through a nitric oxide-dependent mechanism in rats

Our preliminary finding indicated that intravenous (i.v.) injection of heparin increased gastric ulcer healing in rats. However, the anticoagulant action of i.v. heparin could produce complications in ulcer patients if the drug was used as an anti-ulcer agent. The present study aimed to investigate whether intragastric (i.g.) administration of heparin, known to have no anticoagulant activity, would have the similar ulcer healing effect and the relationship of this effect, if any, with nitric oxide (NO), a substance suggested to be important for ulcer healing. Heparin (100, 500, 1000 U/kg, i.g. ) administered once daily for 4 days accelerated the healing of gastric ulcer induced by acetic acid in Sprague-Dawley rats, which was accompanied by an increase in mucosal proliferation and regeneration at the ulcer margin, microvessel number both at the ulcer margin and base, and the thickness of mucus layer. Both activity and content, but not the mRNA of constitutive nitric oxide synthase (cNOS) in the gastric mucosa were enhanced. L-N(G)-nitroarginine methyl ester (L-NAME), an inhibitor of NOS activity blocked the cNOS activity activated by heparin and reversed the beneficial effects of heparin on ulcer healing. The bleeding time was not altered by i.g. heparin. These findings demonstrate that i.g. heparin promotes the healing processes of gastric ulcer. Such effect is suggested to act through the stimulation of mucosal cNOS activity. In addition, i.g. heparin is better than i.v. heparin without the potential anticoagulation effect.

High prevalence of Helicobacter pylori infection with dual resistance to metronidazole and clarithromycin in Hong Kong

BACKGROUND

Metronidazole resistance is a common problem in most Asian countries, and clarithromycin has been widely used in Hong Kong.

AIM

To determine the prevalence of Helicobacter pylori strains resistant to metronidazole and clarithromycin in Hong Kong and to assess the effect on eradication rates. Also to determine the genetic mutation in relation to phenotypic divergence in clarithromycin-resistant strains.

METHODS

H. pylori were cultured from gastric biopsies obtained from 87 patients during upper endoscopy. Minimal inhibitory concentrations of metronidazole and clarithromycin were determined by Etest and agar dilution methods. Mutations in clarithromycin-resistant strains were identified by polymerase chain reaction and restriction analysis. Random amplified polymorphic DNA fingerprinting was performed on clarithromycin-resistant and susceptible isolates.

RESULTS

The prevalences of H. pylori strains resistant to metronidazole and clarithromycin were 49.4% and 10.8%, respectively, in Hong Kong. Dual resistance to metronidazole and clarithromycin were found in 7. 2% of patients. The agreement between E-test and agar dilution methods was determined by error-rate bound analysis as 95.4% for metronidazole and 100% for clarithromycin. Dual resistant strains reduced the eradication rate to 66.7%. Among clarithromycin-resistant strains tested, all were due to A2144G point mutation in 23S rRNA gene. Random amplified polymorphic DNA fingerprinting suggested various phenotypically mixed populations.

CONCLUSIONS

The prevalence of metronidazole-resistant H. pylori strains remained static whilst the prevalence of clarithromycin-resistant strains was not rare in Hong Kong. An alarming 7.2% of patients were resistant to both the antimicrobials, which had a definite impact on treatment success. All cases of resistance to clarithromycin were due to A2144G mutation in 23S rRNA of H. pylori.