Enhancement of in vivo endothelialization of tissue-engineered vascular grafts by granulocyte colony-stimulating factor

Successful reconstruction of large-diameter blood vessel in humans has been demonstrated using the tissue engineering technique, but improvement in patency of small-diameter bioartificial vascular graft remains a great challenge. This study reports that granulocyte colony-stimulating factor (G-CSF) can enhance in vivo endothelialization of tissue-engineered vascular grafts, which could be used to improve patency of small-diameter vascular graft. Vascular grafts were tissue engineered with decellularized canine abdominal aortas and canine autologous bone marrow-derived cells. Prior to cell seeding onto decellularized graft matrices, bone marrow-derived cells were induced to differentiate into endothelial cells and smooth muscle cells. The cell-seeded vascular grafts were implanted into the abdominal aortas of bone marrow donor dogs. Before and after graft implantation, G-CSF was administered subcutaneously to the dogs (n = 3). The grafts implanted into the dogs not receiving G-CSF were used as controls (n = 3). Eight weeks after implantation, grafts in both groups showed regeneration of vascular tissues including endothelium and smooth muscle. Importantly, endothelium formation was more extensive in the G-CSF-treated grafts than in the control grafts, as assessed with reverse transcription polymerase chain reaction, western blot, and immunohistochemistry. In addition, intimal hyperplasia was significantly reduced in the G-CSF-treated grafts compared to the control grafts. This study suggests that G-CSF administration could be applied to improve patency of small-diameter tissue-engineered vascular grafts.

Angiogenesis Facilitated by Autologous Whole Bone Marrow Stem Cell Transplantation for Buerger's Disease

We hypothesized that angiogenesis can be triggered by autologous whole bone marrow stem cell transplantation. Twenty-seven patients (34 lower limbs) with Buerger's disease, who were not candidates for surgical revascularization or radiologic intervention, were enrolled in this study. Six sites of the tibia bone were fenestrated using a 2.5-mm-diameter screw under fluoroscopic guidance. Clinical status and outcome were determined using the "Recommended Standards for Reports." To mobilize endothelial progenitor cells (EPCs) from bone marrow, recombinant human granulocyte colony-stimulating factor (r-HuG-CSF) was injected subcutaneously as a dose of 75 microg, preoperatively. During the follow-up period (19.1 +/- 3.5 months), one limb showed a markedly improved outcome (+3), and 26 limbs showed a moderately improved outcome (+2). Thirteen limbs among 17 limbs with nonhealing ulcers healed. Postoperative angiograms were obtained for 22 limbs. Two limbs showed marked (+3), five limbs moderate (+2), and nine limbs slight (+1) collateral development. However, six limbs showed no collateral development (0). Peripheral blood and bone marrow samples were analyzed for CD34 and CD133 molecules to enumerate potential EPCs, and EPC numbers were found to be increased in peripheral blood and in bone marrow after r-HuG-CSF injection. In conclusion, the transplantation of autologous whole BMCs by fenestration of the tibia bone represents a simple, safe, and effective means of inducing therapeutic angiogenesis in patients with Buerger's disease.

Enhancement of adipose tissue formation by implantation of adipogenic-differentiated preadipocytes

Engineered adipose tissue could be used for the reconstruction or augmentation of soft tissues lost due to mastectomy or lumpectomy in plastic and reconstructive surgery. Preadipocytes are a feasible cell source for adipose tissue regeneration. However, the enhancement of the in vivo adipogenic conversion of preadipocytes remains a major task. In vitro, the adipogenic differentiation of preadipocytes prior to implantation might enhance the adipose tissue regeneration. In the present study, we investigated whether implantation of adipogenic-differentiated preadipocytes enhances the adipose tissue formation compared with implantation of undifferentiated preadipocytes. We also investigated whether basic fibroblast growth factor (bFGF) further enhances the adipose tissue formation mediated by the implantation of adipogenic-differentiated preadipocytes. A fibrin matrix containing human preadipocytes cultured in adipogenic differentiation-inducing conditions with (group 1) or without (group 2) bFGF was injected into the subcutaneous spaces of athymic mice. Fibrin matrices containing undifferentiated human preadipocytes with (group 3) or without (group 4) bFGF were also implanted. Six weeks after implantation, the implanted cells formed new tissues in all groups. Importantly, the implantation of adipogenic-differentiated preadipocytes resulted in more extensive adipogenesis than the implantation of undifferentiated preadipocytes, as evaluated by adipose tissue area and human adipocyte-specific gene expression in the newly formed tissues. In addition, bFGF enhanced neovascularization in the newly formed tissues and further enhanced the adipogenesis mediated by the adipogenic-differentiated preadipocytes. The present study demonstrates that the implantation of adipogenic-differentiated preadipocytes enhances adipose tissue regeneration, as compared with the implantation of undifferentiated preadipocytes, and that cell transplantation-mediated adipogenesis can be further enhanced by the delivery of bFGF.

Granulocyte colony-stimulating factor treatment enhances the efficacy of cellular cardiomyoplasty with transplantation of embryonic stem cell-derived cardiomyocytes in infarcted myocardium

We tested the hypothesis that granulocyte colony-stimulating factor (G-CSF) administration would enhance the efficacy of cellular cardiomyoplasty with embryonic stem (ES) cell-derived cardiomyocytes in infarcted myocardium. Three weeks after myocardial infarction by cryoinjury, Sprague-Dawley rats were randomized to receive either an injection of medium, ES cell-derived cardiomyocyte transplantation, G-CSF administration, or a combination of G-CSF administration and ES cell-derived cardiomyocyte transplantation. Eight weeks after treatment, the cardiac tissue formation, neovascularization, and apoptotic activity in the infarct regions were evaluated by histology and immunohistochemistry. The left ventricular (LV) dimensions and function of the treated heart were evaluated by echocardiography. Transplanted ES cell-derived cardiomyocytes survived and participated in the myocardial regeneration in the infarcted heart. A combination of G-CSF treatment and ES cell-derived cardiomyocyte transplantation significantly promoted angiogenesis and reduced the infarct area and cell apoptosis in the infarcted myocardium compared with ES cell-derived cardiomyocyte transplantation alone. The combination therapy also attenuated LV dilation, as compared with ES cell-derived cardiomyocyte transplantation alone. G-CSF treatment can enhance the efficacy of cellular cardiomyoplasty by ES cell-derived cardiomyocyte transplantation to treat myocardial infarction.

Novel action of gastric proton pump inhibitor on suppression of Helicobacter pylori induced angiogenesis

BACKGROUND

Although activation of mitogen activated protein kinases (MAPKs) by Helicobacter pylori infection is associated with induction of host angiogenesis, which may contribute to H pylori associated gastric carcinogenesis, the strategy for its prevention has not been identified. As we previously reported a strong inhibitory action of gastric proton pump inhibitors (PPIs) on MAPK extracellular signal regulated kinase (ERK)1/2 phosphorylation, we investigated whether PPIs could suppress the H pylori induced angiogenesis via inhibition of MAPK ERK1/2.

METHODS

To address the relationship between H pylori infection and angiogenesis, comparative analysis of density of CD34(+) blood vessel was performed in tissues obtained from 20 H pylori positive gastritis and 18 H pylori negative gastritis patients. Expression of hypoxia inducible factor 1 (HIF-1alpha) and vascular endothelial growth factor (VEGF) was tested by reverse transcription-polymerase chain reaction and secretion of interleukin 8, and VEGF was measured by ELISA. To evaluate the direct effect of H pylori infection on the tubular formation of human umbilical vein endothelial cells (HUVEC), an in vitro angiogenesis assay was employed. Activation of MAPK and nuclear factor kappaB (NFkappaB) was detected by immunoblotting.

RESULTS

H pylori positive gastritis patients showed a higher density of CD34(+) blood vessels (mean 40.9 (SEM 4.4)) than H pylori negative gastritis patients (7.2+/-0.8), which was well correlated with expression of HIF-1alpha. Conditioned media from H pylori infected gastric epithelial cells directly induced tubular formation of HUVEC and the increase of in vitro angiogenesis was suppressed by PPI treatment. Infection of H pylori significantly upregulated expression of HIF-1alpha and VEGF in gastric epithelial cells and expression of proangiogenic factors was mediated by MAPK activation and partially responsible for NFkappaB activation. PPIs effectively inhibited the phosphorylation of MAPK ERK1/2 that is a principal signal for H pylori induced angiogenesis.

CONCLUSIONS

The fact that PPIs could downregulate H pylori induced angiogenesis indicates that antiangiogenic treatment using a PPI could be a promising protective therapeutic approach for H pylori associated carcinogenesis.

Gabapentin reduces rectal mechanosensitivity and increases rectal compliance in patients with diarrhoea-predominant irritable bowel syndrome

BACKGROUND

Gabapentin has been shown to reduce elements of central sensitization in human experimental hyperalgesia. It remains uninvestigated whether gabapentin has beneficial effects for irritable bowel syndrome associated with visceral hypersensitivity.

AIMS

To evaluate the effects of gabapentin on sensory and motor function of the rectum in patients with diarrhoea-predominant irritable bowel syndrome.

METHODS

Forty patients with diarrhoea-predominant irritable bowel syndrome completed this randomized, double-blind, placebo-controlled, parallel-grouped study. All patients received a barostat study and were subsequently randomized for 5-day treatment with gabapentin 300 mg/day and then 600 mg/day or placebo. On day 6, after subjects had their morning dose, the barostat experiment was repeated.

RESULTS

The threshold pressures for bloating, discomfort and pain significantly increased after gabapentin, but not after placebo. Significant increase in the pressure and corresponding wall tension inducing discomfort or pain were observed in the gabapentin group, but not in the placebo group. Rectal compliance significantly increased after gabapentin, but not after placebo. The postprandial increase of rectal tone was not affected by gabapentin.

CONCLUSION

Our results show that gabapentin reduces rectal sensory thresholds through attenuating rectal sensitivity to distension and enhancing rectal compliance in diarrhoea-predominant irritable bowel syndrome patients. The clinical efficacy of this drug in irritable bowel syndrome patients warrants investigation.

Engineering of volume-stable adipose tissues

Autologous adipose tissues have been clinically used for augmentation of soft tissues lost due to mastectomy or lumpectomy in plastic and reconstructive surgery. However, this therapy has problems of absorption and subsequent volume loss of the implanted adipose tissues. In this study, volume-stable adipose tissues were engineered in vivo using mechanical support structures fabricated from biodegradable synthetic polymers. Dome-shaped mechanical support structures were fabricated by reinforcing poly(glycolic acid) fiber-based matrices with poly(L-lactic acid). The support structures were placed into subcutaneous pockets of athymic mice, and human preadipocytes suspended in fibrin matrix were injected into the space under the support structures (group I). Injection of either fibrin matrix without preadipocytes under the support structures (group II) or fibrin matrix containing preadipocytes into subcutaneous spaces with no support structures (group III) served as controls. Six weeks after implantation, the original implant volume was maintained approximately in groups I and II, whereas, group III showed significant implant shrinkage. The compressive modulus of the mechanical support structures did not change significantly over 6-week incubation in phosphate-buffered saline at 37 degrees C. Histological analyses of the implants showed regeneration of adipose tissues in group I. In contrast, groups II and III did not show extensive adipose tissue formation. This study demonstrates that volume-stable adipose tissues can be engineered in vivo using mechanical support structures. This technique offers the potential for augmentation of adipose tissues with volume conservation.

Vascular patches tissue-engineered with autologous bone marrow-derived cells and decellularized tissue matrices

Synthetic polymer vascular patches used in cardiovascular surgery have shortcomings such as thrombosis, intimal hyperplasia, calcification, infection, and no growth potential. Tissue-engineered vascular patches using autologous vascular cells may solve these problems. In this study, we developed a tissue-engineered vascular patch using autologous bone marrow-derived cells (BMCs) and decellularized tissue matrices. Vascular smooth muscle cells and endothelial cells were differentiated from bone marrow mononuclear cells in vitro. Tissue-engineered vascular patches were fabricated by seeding these cells onto decellularized canine inferior vena cava matrices and implanted into the inferior vena cava of dogs. Three weeks after implantation, the tissue-engineered vascular patches were patent with no sign of thrombus formation. Histological, immunohistochemical, and electron microscopic analyses of the vascular patches retrieved 3 weeks after implantation revealed regeneration of endothelium and smooth muscle and the presence of collagen and elastin. BMCs labeled with a fluorescent dye prior to implantation were detected in the retrieved vascular patches, indicating that the BMCs survived after implantation and contributed to the vascular tissue regeneration. This study demonstrates that vascular patches can be tissue-engineered with autologous BMCs and decellularized tissue matrices.

Mechano-active tissue engineering of vascular smooth muscle using pulsatile perfusion bioreactors and elastic PLCL scaffolds

Blood vessels are subjected in vivo to mechanical forces in a form of radial distention, encompassing cyclic mechanical strain due to the pulsatile nature of blood flow. Vascular smooth muscle (VSM) tissues engineered in vitro with a conventional tissue engineering technique may not be functional, because vascular smooth muscle cells (VSMCs) cultured in vitro typically revert from a contractile phenotype to a synthetic phenotype. In this study, we hypothesized that pulsatile strain and shear stress stimulate VSM tissue development and induce VSMCs to retain the differentiated phenotype in VSM engineering in vitro. To test the hypothesis, rabbit aortic smooth muscle cells (SMCs) were seeded onto rubber-like elastic, three-dimensional PLCL [poly(lactide-co-caprolactone), 50:50] scaffolds and subjected to pulsatile strain and shear stress by culturing them in pulsatile perfusion bioreactors for up to 8 weeks. As control experiments, VSMCs were cultured on PLCL scaffolds statically. The pulsatile strain and shear stress enhanced the VSMCs proliferation and collagen production. In addition, a significant cell alignment in a direction radial to the distending direction was observed in VSM tissues exposed to radial distention, which is similar to that of native VSM tissues in vivo, whereas VSMs in VSM tissues engineered in the static condition randomly aligned. Importantly, the expression of SM alpha-actin, a differentiated phenotype of SMCs, was upregulated by 2.5-fold in VSM tissues engineered under the mechano-active condition, compared to VSM tissues engineered in the static condition. This study demonstrates that tissue engineering of VSM tissues in vitro by using pulsatile perfusion bioreactors and elastic PLCL scaffolds leads to the enhancement of tissue development and the retention of differentiated cell phenotype.

Immunochemical and Biological Analysis of Allergenicity with Excretory-Secretory Products of Anisakis simplex Third Stage Larva

BACKGROUND

Anisakis simplex third stage larvae (L3) are parasites that frequently give rise to allergic responses. The larvae molt into fourth stage larvae (L4), and at each stage they produce L3-excretory-secretory products (L3-ESP) and L4-ESP, respectively, which are different in their main protein constituents. Although the allergenicity of L4-ESP has been investigated by several research groups, research on the allergenicity of L3-ESP has not been carried out by any researcher. In this investigation, the allergenicity and antigenicity of L3-ESP were investigated in comparison with L4-ESP, using rat sera.

METHODS

Rat sera were produced by L3 oral infection two times with a 9-week interval. Larvae ESP prepared by culture were concentrated and fractioned using lyophilizer and a centrifugal filter device, respectively. Immunochemical analysis was performed using both indirect ELISA and immunoblot. Biological allergenicity was analyzed by RBL-2H3 exocytosis.

RESULTS

With the indirect ELISA, the optical density (OD) value of the nonfractioned (NF)-L3ESP was only one third of that of the NF-L4ESP in both specific IgM and IgG. On measuring specific IgE, the OD of NF-L3ESP was less than one tenth of that of NF-L4ESP. In addition, neither antigen nor allergen was shown in NF-L3ESP, but it was shown in NF-L4ESP with immunoblot. However, the biological allergenicity of NF-L3ESP was comparable to that of NF-L4ESP. To demonstrate the presence of any allergen, L3-ESP was fractioned and found to carry twelve visualized allergen bands from 10 to 186 kDa by immunoblot.

CONCLUSIONS

These results indicate that L3-ESP may include the important allergens necessary to induce the allergy by L3 oral infection, as compared to L4-ESP.

Small-diameter blood vessels engineered with bone marrow-derived cells

OBJECTIVE

The objective of this study is to investigate if bone marrow-derived cells (BMCs) regenerate vascular tissues and improve patency in tissue-engineered small-diameter (internal diameter = 3 mm) vascular grafts.

SUMMARY BACKGROUND DATA

BMCs have demonstrated the ability to differentiate into endothelial-like cells and vascular smooth muscle-like cells and may offer an alternative cell source for vascular tissue engineering. Thus, we tissue-engineered small-diameter vascular grafts with BMCs and decellularized arteries.

METHODS

Canine BMCs were differentiated in vitro into smooth muscle alpha-actin/smooth muscle myosin heavy-chain-positive cells and von Willebrand factor/CD31-positive cells and seeded onto decellularized canine carotid arteries (internal diameter = 3 mm). The seeded grafts were implanted in cell donor dogs. The vascular-tissue regeneration and graft patency were investigated with immunohistochemistry and angiography, respectively.

RESULTS

The vascular grafts seeded with BMCs remained patent for up to 8 weeks in the canine carotid artery interposition model, whereas nonseeded grafts occluded within 2 weeks. Within 8 weeks after implantation, the vascular grafts showed regeneration of the 3 elements of artery (endothelium, media, and adventitia). BMCs labeled with a fluorescent dye prior to implantation were detected in the retrieved vascular grafts, indicating that the BMCs participated in the vascular tissue regeneration.

CONCLUSIONS

Here we show that BMCs have the potential to regenerate vascular tissues and improve patency in tissue-engineered small-diameter vascular grafts. This is the first report of a small-diameter neovessel engineered with BMCs as a cell source.

Implantation of bone marrow mononuclear cells using injectable fibrin matrix enhances neovascularization in infarcted myocardium

Neovascularization may improve cardiac function and prevent further scar tissue formation in infarcted myocardium. A number of studies have demonstrated that bone marrow-derived cells have the potential to induce neovascularization in ischemic tissues. In this study, we hypothesized that implantation of bone marrow mononuclear cells (BMMNCs) using injectable fibrin matrix further enhances neovascularization in infarcted myocardium compared to BMMNC implantation without matrix. To test this hypothesis, infarction was induced in rat myocardium by cryoinjury. Three weeks later, rat BMMNCs were mixed with fibrin matrix and injected into the infarcted myocardium. Injection of either BMMNCs or medium alone into infarcted myocardium served as controls. Eight weeks after the treatments, histological analyses indicated that implantation of BMMNCs using fibrin matrix resulted in more extensive tissue regeneration in the infarcted myocardium compared to BMMNC implantation without matrix. Examination with fluorescence microscopy revealed that cells labeled with a fluorescent dye prior to implantation survived in the infarcted myocardium at 8 weeks of implantation. Importantly, implantation of BMMNCs using fibrin matrix resulted in much more extensive neovascularization in infarcted myocardium than BMMNC implantation without matrix. The microvessel density in infarcted myocardium was significantly higher (p < 0.05) when BMMNCs were implanted using fibrin matrix (350 +/- 22 microvessels/mm2) compared to BMMNC implantation without matrix (262 +/- 13 microvessels/mm2) and medium injection (76 +/- 9 microvessels/mm2). In addition, average internal diameter of microvessels was significantly larger (p < 0.05) in BMMNC implantation with fibrin matrix group (14.6 +/- 1.2 microm) than BMMNC implantation without matrix group (10.2 +/- 0.7 microm) and medium injection group (7.3 +/- 0.5 microm). These results suggest that fibrin matrix could serve as a cell implantation matrix that enhances neovascularization efficacy for myocardial infarction treatment.

Agmatine reduces infarct area in a mouse model of transient focal cerebral ischemia and protects cultured neurons from ischemia-like injury

Agmatine is a primary amine formed by the decarboxylation of L-arginine synthesized in mammalian brain. In this study, we investigated the neuroprotective effect of agmatine on ischemic and ischemia-like insults. Primary cortical neuronal cultures were subjected to oxygen-glucose deprivation (OGD), a model of ischemia-like injury, and treated with agmatine before or at the start of OGD, or upon reperfusion. Neuronal death was reduced when agmatine was present during OGD, and this protection was associated with a reduction of nitric oxide (NO) and neuronal nitric oxide synthase (nNOS), but not inducible NOS (iNOS). Protection by agmatine was also studied at the in vivo level using a model of middle cerebral artery occlusion (MCAO) in mice. Mice were subjected to 2 h MCAO. Agmatine was administered either 30 min before ischemia, at the start of MCAO, at the start of reperfusion, or 2 or 5 h into reperfusion. Agmatine markedly reduced infarct area in all treatment groups except when treatment was delayed 5 h. The number of nNOS immunopositive cells was correlated with neuroprotection. Interestingly, immunoreactivity for iNOS was reduced only when agmatine was administered before and at the onset of MCAO. Our study suggests that agmatine may be a novel therapeutic strategy to reduce cerebral ischemic injury, and may act by inhibiting the detrimental effects of nNOS.

Smooth muscle-like tissues engineered with bone marrow stromal cells

Bone marrow-derived cells have demonstrated the ability to differentiate into multiple mesenchymal cell lineages. Here we tested whether smooth muscle (SM)-like tissues can be created in vivo with bone marrow stromal cells (BMSCs). Cultured canine BMSCs, which expressed SM cell-specific markers including SM alpha-actin and SM myosin heavy chain, were seeded on three-dimensional, biodegradable polymer scaffolds and implanted into peritoneal cavity of athymic mice. The cell-scaffold constructs retrieved 4 weeks after implantation formed three-dimensional tissues. Immunohistochemical analyses showed that the tissue reconstructs expressed SM alpha-actin and SM myosin heavy chain. Masson's trichrome staining showed the presence of significant amounts of collagen in the tissue reconstructs. Cells labeled with a fluorescent tracer prior to implantation were still present in the tissue reconstructs 4 weeks after implantation. Non-seeded scaffolds (control groups) retrieved 4 weeks after implantation did not exhibit extensive tissue formation. This study demonstrates the potential of BMSCs as an alternative cell source for tissue engineering of SM.

HEK 293 cell suspension culture using fibronectin-adsorbed polymer nanospheres in serum-free medium

Previously, we reported on suspension culture of anchorage-dependent animal cells using plain polymer nanospheres in serum-containing medium. For commercial cell culture, it is more advantageous to use serum-free medium than serum-containing medium. To culture anchorage-dependent animal cells using polymer nanospheres in serum-free medium, the nanospheres need to be coated with cell adhesion proteins. In this study, we utilized fibronectin-adsorbed polymer nanospheres for suspension culture of anchorage-dependent animal cells in serum-free medium. Fibronectin was adsorbed onto poly(lactic-co-glycolic acid) nanospheres (433 nm in average diameter) by immersing the nanospheres in fetal bovine serum. The nanospheres were used to culture human embryonic kidney (HEK) 293 cells in serum-free medium in stirred suspension bioreactors. Nanospheres attached between HEK 293 cells and promoted cell aggregate formation compared with culture without nanospheres. Most cells in the aggregates were viable over a 10-day culture period. Importantly, the use of poly(lactic-co-glycolic acid) nanospheres promoted the cell growth significantly, compared with culture without nanospheres (3.8- vs 1.8-fold growth). The nanosphere culture method developed in this study removes the time-consuming and costly process of adaptation of anchorage-dependent animal cells to suspension culture in serum-free medium. This culture method may be useful for the large-scale suspension culture of various types of anchorage-dependent animal cells in serum-free medium.

Long-term evaluation of mice model infected with Helicobacter pylori: focus on gastric pathology including gastric cancer

BACKGROUND

Long-term evaluation of gastric pathology after H. pylori infection is very important in order to reveal its clinical implications, since debate still exists on the gastric carcinogenesis provoked by H. pylori infection in animal models.

AIM

Either to evaluate the long-term outcome of H. pylori infection or to determine how H. pylori could provoke gastric cancer in the mice model.

METHODS

Four-week-old specific pathogen free C57BL/6 mice (n = 115) were infected with SS1, the mouse-adapted H. pylori strain. After 4, 8, 16, 24, 36, 50 and 80 weeks of bacterial infection, the H. pylori-infected mice were sacrificed.

RESULTS

After 80 weeks of infection, almost all the H. pylori-infected mice developed hyperplastic gastritis, but did not show any evidence of gastric adenoma, dysplasia or carcinoma. PCNA positive cells were most abundant after 50 weeks and tended to decrease thereafter up to 80 weeks, whereas apoptosis began to be noted 8 weeks after H. pylori infection, showing 7-8 apoptotic cells/high power field, and tending to increase as time passed. Normally observed neutral mucin decreased during the experiment, showing the most marked decrease 50 weeks after H. pylori infection. In contrast, acidic mucin was noted from 50 weeks after infection.

CONCLUSION

The SS1-infected mouse seems to be a suitable animal model for H. pylori-related research, and H. pylori itself does not induce gastric cancer in normal wild-type mouse model following long-term exposure, which could be explained by the balance that exists between cell proliferation and apoptosis.

Effect of long-term administration of rebamipide on Helicobacter pylori infection in mice

BACKGROUND

It has been suggested that chronic, persistent, uncontrolled inflammations in the stomach could provide the basic step for the beginning of carcinogenesis. One of the potential clinical applications of rebamipide is the inhibition of the immunoinflammatory response in gastric mucosa imposed by Helicobacter pylori.

AIM

To determine the implications of long-term rebamipide treatment in H. pylori infection, we studied the underlying moleculo-pathological changes in gastric lesions in mice infected with H. pylori (SS1 strain), following this treatment.

METHODS

C57BL/6 mice were sacrificed 24 and 50 weeks after H. pylori infection, respectively. Colonization rates of H. pylori, degree of gastric inflammation and other pathological changes including atrophic gastritis and metaplasia, serum levels of IL-1beta, TNF-alpha, IFN-gamma and IL-10, mRNA transcripts of various mouse cytokines and chemokines, and NF-kappaB binding activities, and finally the presence of gastric adenocarcinoma were compared between an H. pylori infected group (HP), and an H. pylori infected group administered with long-term rebamipide-containing pellet diets (HPR).

RESULTS

Serum levels of IL-1beta, IFN-gamma and TNF-alpha, the gastric mucosal expression of ICAM-1, HCAM and MMP, and transcriptional regulation of NF-kappaB-DNA binding were all significantly decreased in the HPR group compared with the HP group. An RNase protection assay showed, in the rebamipide administered group, significantly decreased mRNA levels of apoptosis-related genes such as caspase-8, FasL, Fas, TRAIL and various cytokines genes such as IFN-gamma, RANTES, TNF-alpha, TNFR p75, IL-1beta. In the experiment designed to provoke gastric cancer through MNU treatment with H. pylori infection, the incidence of gastric carcinoma was not different in either group. However, long-term administration of rebamipide showed the advantage of decreasing precancerous lesions like chronic atrophic gastritis and showed molecular evidence of attenuation of proliferation.

CONCLUSION

The long-term administration of rebamipide should be considered in the treatment of H. pylori since it demonstrated molecular and biological advantages like a lessening of gastric inflammation and a possible chemopreventive effect.

Portal vein aneurysm of the umbilical portion: imaging features and the relationship with portal vein anomalies

BACKGROUND

We evaluated the imaging features of portal vein aneurysm occurring at the umbilical portion and the relation between portal vein aneurysm of the umbilical portion and portal vein anomaly.

METHODS

Retrograde analysis was performed in 18 patients with portal vein aneurysm of the umbilical portion of the portal vein. We analyzed the size, shape, and imaging findings of portal vein aneurysm. In addition, we evaluated associated portal vein anomalies, specifically, the branching pattern of the intrahepatic portal vein and the position of the umbilical portion of the left portal vein.

RESULTS

The diameter of the portal vein aneurysm ranged from 1.5 to 2.2 cm and the shape of the portal vein aneurysm was saccular (n = 14) or fusiform (n = 4). Imaging findings of the portal vein aneurysm of the umbilical portion were typical for its vascular nature. Portal vein anomalies were seen in eight of 18 patients (44%): the right anterior segmental portal vein (n = 7) or the right anterior and posterior segmental portal veins (n = 1) originating from the umbilical portion of the left portal vein and a rightward deviation of the umbilical portion of the left portal vein (n = 4).

CONCLUSION

Due to its vascular nature, noninvasive diagnostic modalities can enable the detection of portal vein aneurysm of the umbilical portion, and there is a close relation between portal vein aneurysm of the umbilical portion and portal vein anomaly.

Pictorial review: various causes of hepatic capsular retraction: CT and MR findings

Hepatic capsular retraction adjacent to hepatic tumour is rare, although this finding has been described in a variety of malignant tumours and haemangioma. The authors have seen various causes of hepatic capsular retraction associated with hepatic tumours, including a variety of malignant tumours, haemangioma and post-treatment of malignant tumours, as well as cases not associated with a hepatic tumour, including confluent hepatic fibrosis, oriental cholangiohepatitis and bile duct necrosis. Furthermore, causes of pseudoretraction of the hepatic capsule, including accessory fissure and normal liver parenchyma between the protruded masses, are described.

Identification of the GTP binding site of human glutamate dehydrogenase by cassette mutagenesis and photoaffinity labeling

It has been reported that the hyperinsulinism-hyperammonemia syndrome is caused by mutations in glutamate dehydrogenase (GDH) gene that affects enzyme sensitivity to GTP-induced inhibition. To identify the GTP binding site(s) within human GDH, mutant GDHs at Tyr-266 or Lys-450 position were constructed by cassette mutagenesis. More than 90% of the initial activities were remained at the concentration of GTP up to 300 microm for the Lys-450 mutant GDHs regardless of their size, hydrophobicity, and ionization of the side chains, whereas the wild type GDH and the Tyr-266 mutant GDHs were completely inhibited by 30 microm GTP. The binding of GTP to the wild type GDH or the mutant GDHs was further examined by photoaffinity labeling with 8-[gamma-(32)P]azidoguanosine 5'-triphosphate (8-N(3)-GTP). Saturation of photoinsertion with 8-N(3)-GTP occurred apparent K(d) values near 20 microm for the wild type GDH or the Tyr-266 mutant GDH, and the photoinsertion of 8-N(3)-[gamma-(32)P]GTP was significantly decreased in the presence of 300 microm GTP. Unlike the wild type GDH or the Tyr-266 mutant GDH, less than 10% of photoinsertion was detected in the Lys-450 mutant GDH, and the photoinsertion was not affected by the presence of 300 microm GTP. The results with cassette mutagenesis and photoaffinity labeling demonstrate selectivity of the photoprobe for the GTP binding site and suggest that Lys-450, but not Tyr-266, is required for efficient binding of GTP to GDH. Interestingly, studies of the steady-state velocity showed that both the wild type GDH and the Tyr-266 mutant GDHs were inhibited by ATP at concentrations between 10 and 100 microm, whereas less than 10% of the initial activities of the Lys-450 mutant GDHs were diminished by ATP. These results indicate that Lys-450, but not Tyr-266, may be also responsible for the ATP inhibition; therefore, ATP bound to the GTP site.

Transduction of human catalase mediated by an HIV-1 TAT protein basic domain and arginine-rich peptides into mammalian cells

Antioxidant enzymes such as superoxide dismutase (SOD) and catalase (CAT) have been considered to have a beneficial effect against various diseases mediated by reactive oxygen species (ROS). Although a variety of modified recombinant antioxidant enzymes have been generated to protect against the oxidative stresses, the lack of their transduction ability into cells resulted in limited ability to detoxify intracellular ROS. To render the catalase enzyme capable of detoxifying intracellular ROS when added extracellularly, cell-permeable recombinant catalase proteins were generated. A human liver catalase gene was cloned and fused with a gene fragment encoding the HIV-1 Tat protein transduction domain (RKKRRQRRR) and arginine-rich peptides (RRRRRRRRR) in a bacterial expression vector to produce genetic in-frame Tat-CAT and 9Arg-CAT fusion proteins, respectively. The expressed and purified fusion proteins can be transduced into mammalian cells (HeLa and PC12 cells) in a time- and dose-dependent manner when added exogenously in culture medium, and transduced fusion proteins were enzymatically active and stable for 60 h. When exposed to H(2)O(2), the viability of HeLa cells transduced with Tat-CAT or 9Arg-CAT fusion proteins was significantly increased. In combination with transduced SOD, transduced catalase also resulted in a cooperative increase in cell viability when the cells were treated with paraquat, an intracellular antioxide anion generator. We then evaluated the ability of the catalase fusion proteins to transduce into animal skin. This analysis showed that Tat-CAT and 9Arg-CAT fusion proteins efficiently penetrated the epidermis as well as the dermis of the subcutaneous layer when sprayed on animal skin, as judged by immunohistochemistry and specific enzyme activities. These results suggest that Tat-CAT and 9Arg-CAT fusion proteins can be used in protein therapy for various disorders related to this antioxidant enzyme.

Self-expanding coil stent with a long delivery system for palliation of unresectable malignant gastric outlet obstruction: a prospective study

BACKGROUND AND STUDY AIMS

Peroral intubation of a self-expanding metal stent is usually difficult in patients with unresectable malignant gastric outlet obstruction, because the delivery systems currently available are not long enough and cannot easily pass the angulated gastroduodenal structure. We carried out a prospective study to assess the efficacy of a coil stent with a newly developed long delivery system, for palliation of unresectable malignant gastric outlet obstruction.

PATIENTS AND METHODS

In 29 patients with unresectable malignant gastric outlet obstruction, caused by gastric cancer (26 patients), pancreatic head cancer (two patients), or duodenal cancer (one patient), peroral intubation of a self-expanding nickel-titanium coil stent was attempted, using a lengthened delivery system of 150 cm, under endoscopic and fluoroscopic guidance.

RESULTS

Management was successful in 26 of 29 patients (89.7 %) without immediate major complications. In one patient in whom peroral intubation failed, percutaneous intubation of the coil stent via percutaneous endoscopic gastrostomy was done. After insertion of the coil stent, food ingestion with symptomatic improvement with regard to vomiting was achieved in 26 of 27 patients (96.3 %), including the patient with percutaneous stent insertion. During the follow-up period, dysphagia and Karnofsky scores improved significantly. Stent migration occurred in two patients, and tumor ingrowth in another two; re-intervention was done successfully performed in two instances. The mean survival time was 124 days (range 34 - 310 days) in the 22 patients who had no need for re-intervention during follow-up; among these was a patient who experienced stent occlusion by food material, which was easily corrected with endoscopic flushing.

CONCLUSIONS

Peroral intubation of a self-expanding coil stent using a long delivery system is a safe and effective palliative technique for unresectable malignant gastric outlet obstruction, and significantly improves the quality of life of patients.

Effects of ADP on different inhibitory properties of brain glutamate dehydrogenase isoproteins by perphenazine

Incubation of glutamate dehydrogenase isoproteins (GDH I and GDH II) from bovine brains with perphenazine resulted in a time-dependent loss of enzyme activity. 2-Oxoglutarate and NADH, separately or together, gave partial but not complete protection against the inhibition. Although there were no detectable differences between GDH I and GDH II in inhibition by perphenazine in the absence of ADP, the sensitivities to the inhibition by the drug were significantly distinct for the two isoproteins in the presence of ADP. Low concentrations of ADP (0.05-0.20 mM) did not interfere with the inhibition of GDH I and GDH II by perphenazine. However, in the presence of high concentrations of ADP (0.5-1.0 mM), inhibitory effects of perphenazine on GDH isoproteins were significantly diminished as determined by enzyme kinetics and quantitative affinity chromatography on perphenazine-Sepharose. GDH I was more sensitively reacted with ADP than GDH II on the inhibition by perphenazine. Since physiological ADP levels can vary from 0.05 to > 1.0 mM depending on the rate of oxidative phosphorylation, our results suggest a possibility that two types of GDHs are differently regulated by the antipsychotic actions of perphenazine depending on the physiological concentrations of ADP. GTP and L-leucine, other well-known allosteric regulators, did not affect the inhibitory actions of perphenazine on bovine brain GDH isoproteins.

Oxidative stress is more important than acid in the pathogenesis of reflux oesophagitis in rats

BACKGROUND

Although antisecretory medications such as histamine type II receptor antagonists or proton pump inhibitors have been used to treat reflux oesophagitis, a considerable number of patients do not achieve complete mucosal healing or suffer from either sustained symptoms or ensuing complications, suggesting other damaging factors or impaired mucosal resistance are also involved in the pathogenesis of reflux oesophagitis.

AIMS

The present study was designed to evaluate oxidative stress as the major pathogenic factor of reflux oesophagitis and to determine the usefulness of antioxidants in the treatment of reflux oesophagitis.

MATERIALS AND METHODS

Reflux oesophagitis was induced by insertion of a 3 mm calibre ring into the duodenum, 1 cm distal to the ligament of Treitz, in Sprague-Dawley rats.

RESULTS

DA-9601, a novel antioxidant substance, significantly attenuated the gross and histopathological scores of reflux oesophagitis compared with those treated with ranitidine alone or reflux oesophagitis controls in a dose dependent manner. Only scattered erosions were observed in the antioxidant pretreated group but acid suppression by ranitidine was not effective in decreasing the severity of reflux oesophagitis. Significantly increased amounts of malondialdehyde (MDA), increased nuclear factor kappaB (NFkappaB) activation, and depletion of reduced glutathione (GSH) were observed in experimentally induced reflux oesophagitis. DA-9601 pretreatment attenuated the decrement in mucosal GSH levels and decreased MDA formation significantly. DA-9601 treatment caused significant reductions in activation of NFkappaB transcription factor, especially the p50 subunit, in accordance with the significantly higher levels of inhibitory protein of NFkappaB expression.

CONCLUSION

Reflux oesophagitis caused considerable levels of oxidative stress in the oesophageal mucosa and antioxidant treatment should be considered as supplementary therapy in the prevention or treatment of reflux oesophagitis with acid suppression.

Molecular cloning and functional expression of bovine brain GABA transaminase

We isolated a cDNA that encodes the bovine brain gamma-aminobutyrate transaminase (GABA-T; EC 2.6.1.19) from the lambda gt 11 cDNA library, which showed a high degree of sequence similarity to the corresponding enzymes from various sources. Northern blot analysis revealed two differentially expressed GABA-T transcripts of approximately 2.0 and 6.0 kb in the bovine tissues. Southern blot analysis indicates that the two GABA-T transcripts are encoded in a greater-than 10-kb, single-copy gene. Bovine GABA-T cDNA was expressed in E. coli using the pGEX bacterial- expression vector system. The overexpressed GABA-T was enzymatically active after purification, and it had very similar kinetic parameters when compared with those of other mammalian GABA-Ts.