High-Temperature Syngas Desulfurization and Particulate Filtration by ZnO/Ceramic Filters.

Combustible gas (e.g., gasification syngas) cleaning at high temperatures can obtain further gains in energy efficiency for power generation and importantly leads to a simplified process and lower cost as a commercially viable source of clean energy. Thus, a feasibility study for high-temperature desulfurization (HTDS) and additional high-temperature particulate filtration (HTPF) of a raw syngas using ZnO sorbent-dispersed Raney CuO (ZnO/R-CuO) and ceramic filter (ZnO/CF) has been carried out. By synchrotron X-ray absorption near-edge structure (XANES) spectroscopy, mainly Zn(II) and Cu(II) are found in the ZnO/R-CuO sorbents. Both ZnO and R-CuO in the sorbents are involved in HTDS (1% H2S) at 873 K to form ZnS, Cu2S, and a small amount of CuS and reach relatively high HTDS efficiencies (82-90%). In addition, regeneration of the sulfurized sorbent by oxidation with O2 at 873 K (HTRG) for 1 h can restore ZnO and CuO for continuous and repetitive HTDS-HTRG cycles. To facilitate the HTDS engineering applications by the ZnO/R-CuO sorbents, their reaction rate constant (8.35 × 104 cm3/g/min) and activation energy (114.8 kJ/mol) at 873 K have also been determined. Furthermore, the ZnO/CF sorbent/filter can perform HTDS and additional HTPF at 873 K with very high particulate removal efficiencies (>98%). This demonstrates the feasibility for hot-syngas cleaning with a much better energy efficiency and lesser cost for cleaner power generation.

Functionalised cyclodextrin-based metal-organic frameworks.

CD-MOF, an extended framework incorporating the C8 symmetric cyclic oligosaccharide, γ-cyclodextrin (γ-CD), is based on the coordination of alkali metal cations to alternating α-1,4-linked d-glucopyranosyl units on the primary and secondary faces of the γ-CD tori. Here, we report the synthesis and characterisation of an amino-functionalised CD-MOF that is isostructural with pristine CD-MOF and adsorbs CO2 permanently.

Room-temperature CO Thermoelectric Gas Sensor based on Au/Co3O4 Catalyst Tablet.

A carbon monoxide (CO) thermoelectric (TE) gas sensor was fabricated by affixing a Au/Co3O4 catalyst tablet on a TE film layer. The Au/Co3O4 catalyst tablet was prepared by a co-precipitation and tablet compression method and its possible catalytic mechanism was discussed by means of x-ray diffraction, field emission scanning electron microscopy, high resolution transmission electron microscopy, x-ray photoelectron spectroscopy, temperature-programmed reduction of hydrogen, Fourier transform infrared spectroscopy and Brunauer-Emmett-Teller analysis. The optimal catalyst, with a Au content of 10 wt%, was obtained at a calcination temperature between 200 and 300 °C. The small size of the Au nanoparticles, high specific surface, the existence of Co3+ and water-derived species contributed to  high catalytic activity. Based on the optimal Au/Co3O4 catalyst tablet, the CO TE gas sensor worked at room temperature and showed a response voltage signal (ΔV) of 23 mV, high selectivity among hydrogen and methane, high stability, and a fast response time of 106 s for 30 000 ppm CO/air. In addition, a CO concentration in the range of 5000-30 000 ppm could obviously be detected and exhibited a linear relationship with ΔV. The CO TE gas sensor provides a promising option for the detection of CO gas at room temperature.

Increased risk of hepatocellular carcinoma in chronic hepatitis C patients with new onset diabetes: a nation-wide cohort study.

BACKGROUND: The impact of diabetes for hepatocellular carcinoma (HCC) development in chronic hepatitis C (CHC) patients remains controversial. AIM: To investigate the risk of HCC in CHC patients who develop new onset diabetes. METHODS: We conducted a nation-wide cohort study by using Taiwanese National Health Insurance Research Database, which comprised of data from >99% of entire population. Among randomly sampled one million enrollees, 6251 adult CHC patients were identified from 1997 to 2009. Diabetes was defined as new onset in the patient who was given the diagnosis in the years 1999-2009 but not in 1997-1998. The cohorts of CHC with new onset diabetes (n = 1100) and 1:1 ratio age-, gender-, and inception point (onset date of diabetes) matched nondiabetes (n = 1087) were followed up from the inception point until the development of HCC, withdrawal from insurance, or December 2009. RESULTS: After adjustment for competing mortality, patients with new onset diabetes had a significantly higher cumulative incidence of HCC (Relative Risk = 1.544, 95% CI = 1.000-2.387, modified log-rank test, P = 0.047) as compared to those without. After adjustment for age, gender, cirrhosis, hyperlipidaemia, CHC treatment, diabetes treatment, comorbidity index, obesity and statins therapy by Cox proportional hazard model, diabetes was still an independent predictor for HCC (hazard ratio (HR) = 1.906, 95% CI = 1.102-3.295, P = 0.021). The risk for HCC was increased in those who were 40-59 years old, independent of other variables (HR = 3.086, 95% CI = 1.045-9.112, P = 0.041), and after adjustment for competing mortality (modified log-rank test, P = 0.009). CONCLUSION: Chronic hepatitis C patients who develop diabetes are at an increased risk of hepatocellular carcinoma over time.

Increased risk of hepatocellular carcinoma in chronic hepatitis B patients with new onset diabetes: a nationwide cohort study.

BACKGROUND: Diabetes increases the risk of hepatocellular carcinoma (HCC), however, the time-relationship between hepatitis B virus and diabetes for the development of HCC remains unclear. AIM: To explore the risk of HCC in chronic hepatitis B patients with newly diagnosed diabetes. METHODS: We conducted a nationwide cohort study by using Taiwanese National Health Insurance Research Database, which covers over 99% of entire population. Among randomly sampled one million enrollees, 14 523 chronic hepatitis B patients were diagnosed in years 1997-2009. We defined new onset diabetes as patients who were given the diagnosis in the years 1999-2009, but not in 1997-1998. The cohorts of chronic hepatitis B with new onset diabetes (n = 2099) and 1:1 ratio age-, gender- and inception point (onset date of diabetes)- matched nondiabetes (n = 2080) were followed up from the inception point until development of HCC, withdrawal from insurance or December 2009. RESULTS: After adjustment for competing mortality, patients with new onset diabetes had a significantly higher cumulative incidence of HCC [relative risk = 1.628, 95% confidence interval (CI) = 1.114-2.378, modified log-rank test, P = 0.012] as compared to nondiabetes patients. After adjustment for age, gender, hyperlipidaemia, chronic hepatitis B treatment, statins therapy, cirrhosis, comorbidity index and obesity, diabetes was still an independent predictor for HCC (hazard ratio = 1.798, 95% CI = 1.194-2.707, P = 0.005). CONCLUSION: Chronic hepatitis B patients with newly diagnosed diabetes have an increased risk of hepatocellular carcinoma over time.

The effects of an injury to the brain on bone healing and callus formation in young adults with fractures of the femoral shaft.

In patients with traumatic brain injury and fractures of long bones, it is often clinically observed that the rate of bone healing and extent of callus formation are increased. However, the evidence has been unconvincing and an association between such an injury and enhanced fracture healing remains unclear. We performed a retrospective cohort study of 74 young adult patients with a mean age of 24.2 years (16 to 40) who sustained a femoral shaft fracture (AO/OTA type 32A or 32B) with or without a brain injury. All the fractures were treated with closed intramedullary nailing. The main outcome measures included the time required for bridging callus formation (BCF) and the mean callus thickness (MCT) at the final follow-up. Comparative analyses were made between the 20 patients with a brain injury and the 54 without brain injury. Subgroup comparisons were performed among the patients with a brain injury in terms of the severity of head injury, the types of intracranial haemorrhage and gender. Patients with a brain injury had an earlier appearance of BCF (p < 0.001) and a greater final MCT value (p < 0.001) than those without. There were no significant differences with respect to the time required for BCF and final MCT values in terms of the severity of head injury (p = 0.521 and p = 0.153, respectively), the types of intracranial haemorrhage (p = 0.308 and p = 0.189, respectively) and gender (p = 0.383 and p = 0.662, respectively). These results confirm that an injury to the brain may be associated with accelerated fracture healing and enhanced callus formation. However, the severity of the injury to the brain, the type of intracranial haemorrhage and gender were not statistically significant factors in predicting the rate of bone healing and extent of final callus formation.

Embolization of a ruptured lenticulostriate artery aneurysm.

Aneurysms arising from the lenticulostriate artery (LSA) are rare. So far, only 23 cases have been reported in the literature (Ahn et al. 2007 [1], Gandhi et al. 2008 [2], Harreld et al. 2010 [3]). Early detection and treatment of these aneurysms is difficult because of their small size, deep location and complex surrounding vasculature. The majority of reported cases were treated surgically, and only two were treated with endovascular embolization (Harreld et al. 2010 [3], Larrazabal et al. 2001 [4]). We present here a case of an LSA aneurysm that was successfully embolized with n-butyl cyanoacrylate (n-BCA) with no recurrence after 1 year of follow-up.

Cytotoxicity of arsenic trioxide is enhanced by (-)-epigallocatechin-3-gallate via suppression of ferritin in cancer cells.

Arsenic trioxide (ATO) treatment is a useful therapy against human acute promyelocytic leukemia (APL), however, it concomitantly brings potential adverse consequences including serious side effect, human carcinogenicity and possible development of resistance. This investigation revealed that those problems might be relaxed by simultaneous application with (-)-epigallocatechin-3-gallate (EGCG), one of the major components from green tea. EGCG significantly lowered down the ATO concentration required for an effective control of APL cells, HL-60. The simultaneous treatment of ATO with EGCG induced a mitochondria-dependent apoptosis in HL-60 cells significantly, which accounted for more than 70% of the cell death in the treatment. The mechanism of apoptosis induction was elucidated. EGCG in HL-60 cells acted as a pro-oxidant enhancing intracellular hydrogen peroxide significantly. ATO, on the other hand, induced heme oxygenase-1 (HO-1) to catalyze heme degradation, thereby provided ferrous iron for EGCG-induced hydrogen peroxide to precede Fenton reaction, which in turn generated deleterious reactive oxygen species to damage cell. In addition, EGCG inhibited expression of ferritin, which supposedly to sequester harmful ferrous iron, thereby augmented the occurrence of Fenton reaction. This investigation also provided evidence that ATO, since mainly acted to induce HO-1 in simultaneous treatment with EGCG, could be replaced by other HO-1 inducer with much less human toxicity. Furthermore, several of our preliminary investigations revealed that the enhanced cytotoxicity induced by combining heme degradation and Fenton reaction is selectively toxic to malignant but not non-malignant cells.

Pulmonary toxicity in mice exposed to low and medium doses of water-soluble multi-walled carbon nanotubes.

Carbon nanotubes (CNTs) are a class of new allotrope of carbon. Different functionalized CNTs may vary from their physical and chemical properties to the biological property. In this study, the toxicity of water-soluble taurine multi-walled CNTs (tau-MWNTs), raw MWNTs and positive control crystalline silicon dioxide particles on mouse lungs via intratracheal instillation (i.t.) was investigated. The dosages we used were 0.125, 0.25, 0.5 or 1 mg/kg of tau-MWNTs and raw MWNTs, and 1 mg/kg of silicon dioxide particles; Serum and lungs were collected at 1, 7, 14 or 28 days postexposure. The biochemical and cellular parameters were assessed, which include the ratio of the lung weight and body weight (lung indices), lactate dehydrogenase (LDH), alkaline phosphatase (ALP) and angiotensin converting enzyme (ACE) in serum, and malondialdehyde (MDA), reduced glutathione (GSH), total sulfhydryl group (TSH) in lung tissue homogenates as well as the hydroxyproline in lungs. The characteristic recovery of the lung injury at 28 days postexposure was examined by the assessment of LDH, ALP, lung indices, and histopathology. ACE, MDA, GSH, TSH and histopathological changes showed that tau-MWNTs were less toxic than the raw MWNTs. Histopathological and ultrastructural investigation indicated that the acute pulmonary inflammation in lungs alleviated after 7d postexposure, and were greatly recovered within 28d. Meanwhile, the entrapment of tau-MWNTs reduced greatly by the 28d postexposure. Whereas the heavier pathologic changes induced by raw MWNTs lasted 7 days more than that of tau-MWNTs. Notably, no occurrence of granulomas and fibrosis were found in this study both in the two CNTs samples through 28d postexposure. Silicon dioxide particles, on the contrary, produced more severe damage to lungs than CNTs did in lung index, as well as other biochemical and cellular parameters. These findings indicate that water-soluble tau-MWNTs in low and medium doses induce slight and recoverable pulmonary inflammation in mice, and are less toxic than the insoluble raw MWNTs.

Multiple factors conferring high radioresistance in insect Sf9 cells.

Sf9, a lepidopteran cell line isolated from the fall armyworm, Spodoptera frugiperda, was shown to be significantly more resistant to growth inhibition and apoptosis induction effects of x-ray irradiation than several human cell lines of different origins. The single-cell electrophoresis technique revealed that Sf9 cells showed lower x-ray irradiation-induced DNA damage as well as better efficiency at repairing these damages. In addition, Sf9 cells were lower in both background and x-ray irradiation-induced intracellular oxidative stress, in which the higher intracellular level of reduced glutathione seemed to play a major role. The significance of oxidative stress in determining the radioresistance of Sf9 cells was confirmed by their being more resistant to hydrogen peroxide while equally susceptible to other non-reactive oxygen species of N-nitroso alkylating agents when compared with a human cell line. Although the Sf9 and human cell lines were equally susceptible to the lethal effects of N-nitroso alkylating agents, the components of DNA damage-induced and the repair enzymes involved significantly differ. This phenomenon is also discussed in this report.

First Report of Soybean Pod and Stem Blight Caused by Diaporthe phaseolorum var. sojae in Taiwan.

Genera, Diaporthe and Phomopsis, from an important pathogenic complex of soybean (Glycine max) throughout the world, cause reductions in plant stands, yield, and seed health and quality (1). In a study of the Diaporthe/Phomopsis complex in Taiwan in March 2008, four stem samples with black fruiting structures in linear rows on senescent soybean were collected from the research fields at AVRDC, Shanhua, Tainan, Taiwan. Unidentified fungal isolates were obtained by surface disinfection of infected stems and plating excised tissues on potato dextrose agar (PDA). Colonies of the isolates showed ropelike white mycelia with yellowish tonalities. Small and scattered black stromata were observed frequently in the medium. Mutic pycnidia were found solitarily or aggregated in conidiomata on PDA plates after 10 days of incubation at 24°C with a 12-h photoperiod with near-UV light. All isolates produced α-conidia that measured 8.78 × 3.32 (7.00 to11.00 × 3.00 to 4.00) µm, and sporadically, ß-conidia of 30.58 × 0.85 (26.00 to 33.00 × 0.60 to 1.20) µm. Perithecia were not observed in the collected stem samples or the fungal cultures on PDA. Restriction fragment length polymorphism patterns of the PCR products amplified by ITS4 and ITS5 primers for all isolates were identical to the patterns reported for Diaporthe phaseolorum var. sojae (3). Thus, all isolates were identified as D. phaseolorum var. sojae on the basis of morphologic and genetic characteristics (2,3). Pathogenicity was confirmed through inoculations during the V2 growth stage of soybean seedlings by atomizing conidial suspensions (1 × 107 α-conidia/ml) of each isolate on soybean seedlings as well as by injecting the inoculum into soybean stems separately. Four plants in each of three replications were inoculated for each method and six noninoculated plants served as controls. Plants were incubated in a growth chamber at 25°C and maintaining relative humidity at 100% by a humidifier for 48 h in darkness; thereafter, plants were maintained in the greenhouse at temperatures ranging from 23 to 34°C. Seven days after inoculation, red-brown leaf spots and coalescent lesions were observed on seedlings atomized by inoculum suspensions, as well as brown lesions and black pycnida in linear rows observed on plants inoculated by stem injection. No symptoms were observed on noninoculated plants. The fungal isolates obtained from inoculated soybeans were morphologically identical to those used as inoculum. The pathogenicity test was repeated twice. To our knowledge, this is the first explicit report identifying the causal agent of soybean pod and stem blight in Taiwan. The vouchers of infected specimens are available at AVRDC-The World Vegetable Center. Reference: (1) R. P. Mulrooney. Plant Dis. 70:600, 1988. (2) R. N. Pioli et al. Phytopathology 93:136, 2003. (3) A. W. Zhang et al. Phytopathology 88:1306, 1998.

First Report of the A2 Mating Type of Phytophthora capsici Infecting Peppers (Capsicum annuum) in Taiwan.

Phytophthora capsici Leonion was first identified on pepper (Capsicum annuum L) in Taiwan in 1976. At that time, only the A1 mating type was present (2). In 2007, the A2 mating type of P. capsici was identified on tomato and eggplant in the central part of the country (1). During an excessively rainy period in mid-2008, many chili and sweet pepper fields in Taiwan suffered severe losses due to P. capsici. Symptoms included a foliar blight and stem, root, and fruit rot. Plants eventually wilted and died. Symptomatic plants were collected from chili- and sweet pepper-production areas in central, southern, and eastern Taiwan. Fifty-three isolates from single zoospores were identified by PCR using species-specific primers CAPFW/CAPRV2 (4). Mating type was determined by co-inoculating rape seed agar plates (3) with mycelial plugs of the tester and a known isolate. Pc134, maintained by the mycology unit at The World Vegetable Center, and 27220, provided by P. J. Ann at the Taiwan Agricultural Research Institute, were used as reference isolates of A1 and A2 mating types, respectively. Plates were examined microscopically for oospores after 5 to 7 days of incubation at 24°C in the dark. Of the 53 isolates, 15 were identified as the A2 mating type and the remaining 38 isolates were identified as A1. The A2 mating type was found in the central and southern regions while the A1 mating type was widely distributed across all three regions. The sporangia of the A2 mating type were 60.4 to 73.4 × 40.9 to 51.8 µm (average 69.2 × 44.7 µm), whereas sporangia of the A1 mating type were 50.1 to 73.9 × 37.9 to 48.1 µm (average 61.4 × 44.1 µm). In general, the A2 mating type produced longer sporangia and only a few isolates produced chlamydospores in V8 broth and on agar. To our knowledge, this is the first report of the A2 mating type of P. capsici infecting peppers in Taiwan. The presence of both mating types in the same field has been observed. References: (1) P. J. Ann et al. Plant Pathol. Bull. 17:69, 2008. (2) L. S. Leu and C. W. Kao. Plant Prot. Bull. (Taiwan) 23:59, 1981. (3) M. M. Sautor. Mycologia 59:161, 1967. (4) C. Silvar et al. Eur. J. Plant Pathol. 112:43, 2005.

Optically modulated internal strain in InGaN quantum dots grown on SiN(x) nano masks.

Optically modulated internal strain has been observed in InGaN quantum dots (QDs) deposited on SiN(x) nano masks. The modulated internal strain can induce a number of intriguing effects, including the change of refractive index and the redshift of InGaN A(1)(LO) phonon. The underlying mechanism can be well accounted for in terms of the variation of internal strain through the converse piezoelectric effect arising from the screening of the internal electric field due to spatial separation of photoexcited electrons and holes. Our results point out a convenient way for the fine tuning of physical properties in nitride-based semiconductor nanostructures, which is very important for high quality optoelectronic devices.

Role of bone marrow-derived cells in experimental chronic pancreatitis.

BACKGROUND: Chronic pancreatitis is a known risk factor for pancreatic adenocarcinoma. Recent work has pointed to a role for bone marrow-derived progenitor cells (BMDCs) in chronic inflammation-based carcinogenesis. Consequently, the role of BMDCs in chronic pancreatitis was investigated. METHODS: The fate of BMDCs was followed using green fluorescent protein and the Y chromosome as bone marrow markers in gender-mismatched transplanted mice treated with repeated injections of cerulein for up to 45 weeks. The phenotype of engrafted BMDCs was assessed based on the co-expression of bone marrow and pancreatic markers. RESULTS: After 45 weeks of cerulein treatment, mice developed severe chronic pancreatitis but no preneoplastic lesions. BMDCs did engraft in the pancreas. Most of the BMDCs were desmin positive and contributed to 5.12% (1.12%) (mean (SEM)) of the pancreatic stellate cell population. Pancreatic stellate cells derived from the bone marrow could be activated, as demonstrated by alpha-smooth muscle actin expression, suggesting a role in tissue repair. BMDCs could also be found in pancreatic ducts, based on dolichos biflorus agglutinin and cytokeratin 19 stainings, but at a much lower frequency (0.62% (0.11%)). CONCLUSION: BMDCs contribute to the pancreatic stellate cell population, suggesting a role in pancreatic tissue repair. In the absence of preneoplastic lesions, BMDCs contribute at a very low level to the ductal epithelium of the chronically inflamed pancreas. The role of BMDCs in pancreatic carcinogenesis remains to be defined.

Genotoxicity of low dose N-nitroso propoxur to human gastric cells.

Propoxur is among the most popular insect control agents in subtropical countries such as Taiwan. As a member of the N-methylcarbamate insecticide group, propoxur is notorious for its potential for conversion into highly genotoxic N-nitroso derivatives. Due to the fact that the stomach has been identified as the major target for N-nitroso N-methylcarbamates, this investigation used a human gastric cell line, SC-M1, in order to obtain results pertinent to the authentic adverse effects of this compound on human health. This report reveals that at dose levels inhibiting < or = 10% cell growth, a 2-h pulsed treatment of N-nitroso propoxur induced significant amounts of DNA damage. Most of the damaged DNA was repaired within 24 h after treatment removal, such that an outcome with a significant induction of chromosomal aberrations was not observed. Gene mutations and anchorage independence, on the other hand, were significantly induced by this same treatment. In conclusion, exposure to low doses of N-nitroso propoxur is not cytotoxic nor clastogenic, nevertheless, has the potential to increase genetic instability and, possibly as a result, to enhance the malignant potential of treated cells. We suggest that although the damaged DNA was repaired during the transient G2/M arrest period, it was probably not done in an appropriate way which would preserve the original genetic stability.

First Report of the A2 Mating Type of Phytophthora infestans on Tomato Crops in Taiwan, Republic of China.

In a study of the Phytophthora infestans population in Taiwan, samples with symptoms typical of late blight were collected from field crops in an important potato- (Solanum tuberosum) and tomato-(Lycopersicon esculentum) production area in the central highlands region. Isolates were obtained by surface disinfecting leaf sections and plating them onto antibiotic-amended rye A agar (1). After subculturing, the pathogen was confirmed as P. infestans on the basis of morphological characters (2). Mating type was determined by co-inoculating unamended rye agar plates with mycelial plugs of the test isolate and a reference P. infestans isolate of either the A1 or A2 mating type (four plates per test isolate, two with different A1, and two with different A2 reference isolates). After incubation (15°C darkness, 7 to 14 days), plates were examined microscopically for the presence of oospores where the colonies interacted. In 2004, one isolate of 200 tested, and in 2006, one isolate of 102 tested, produced oospores only with A1 reference isolates and were concluded to be A2 mating type. In vitro testing showed the two A2 isolates were metalaxyl-resistant (ED50 values >100 mg of metalaxyl per liter on rye grain agar), which is typical of recent P. infestans isolates from potato and tomato in this area (2). Twenty-one single-sporangial isolates from each of the two A2 strains were tested for mating type against two different A1 isolates of P. infestans and confirmed as A2. These isolates were characterized using the techniques described by Deahl et al. (1) and had the allozyme genotype 100/100/111, 100/100 at the loci coding for glucose-6-phosphate isomerase and peptidase, respectively, and were mitochondrial haplotype IIb. This multi-locus genotype is characteristic of recent P. infestans isolates from tomato and potato in Taiwan, but all previous such isolates were A1 mating type and attributed to the US-11 clonal lineage (1). When evaluated on differential hosts, both A2 isolates were tomato race PH-1 and complex potato race R 0,1,2,3,4,7,9,11. RG57 fingerprinting showed that the A2 isolates had fingerprints identical to each other and to A1 P. infestans isolates of the US-11 clonal lineage from tomato in Taiwan (101 011 100 100 110 101 011 001 1). Koch's postulates were completed and the two A2 isolates were found to be highly aggressive on cultivars of potato and tomato. To our knowledge, this is the first report of A2 mating type strains of P. infestans in the field in Taiwan, but currently, their incidence is very low (<1%). One crop from which an A2 isolate was obtained also yielded an A1 isolate, while A1 isolates were obtained from crops in the vicinity of the other. The concurrent presence of the two mating types of P. infestans poses a risk of sexual reproduction and oospore formation in tomato or potato in Taiwan. References: (1) K. L. Deahl et al. Pest Manag. Sci. 58:951, 2002. (2). D. C. Erwin and O. K. Ribeiro, Page 346 in: Phytophthora Diseases Worldwide. The American Phytopathological Society. St. Paul, MN, 1996.

Hypergastrinemia increases gastric epithelial susceptibility to apoptosis.

Plasma concentrations of the hormone gastrin are elevated by Helicobacter pylori infection and by gastric atrophy. It has previously been proposed that gastrin acts as a cofactor during gastric carcinogenesis and hypergastrinemic transgenic INS-GAS mice are prone to developing gastric adenocarcinoma, particularly following H. pylori infection. We hypothesised that the increased risk of carcinogenesis in these animals may partly result from altered susceptibility of gastric epithelial cells to undergo apoptosis. Gastric corpus apoptosis was significantly increased 48 h after 12Gy gamma-radiation in mice rendered hypergastrinemic by transgenic (INS-GAS) or pharmacological (omeprazole treatment of FVB/N mice) methods and in both cases the effects were inhibited by the CCK-2 receptor antagonist YM022. However, no alteration in susceptibility to gamma-radiation-induced gastric epithelial apoptosis was observed in mice overexpressing progastrin or glycine-extended gastrin. Apoptosis was also significantly increased in gastric corpus biopsies obtained from H. pylori-infected humans with moderate degrees of hypergastrinemia. We conclude that hypergastrinemia specifically renders cells within the gastric corpus epithelium more susceptible to induction of apoptosis by radiation or H. pylori. Altered susceptibility to apoptosis may therefore be one factor predisposing to gastric carcinogenesis in INS-GAS mice and similar mechanisms may also be involved in humans.

Human gastric cells resistant to (-)-epigallocatechin gallate show cross-resistance to several environmental pollutants.

After a long-term culture in (-)-epigallocatechin gallate (EGCG, 20 microM), a major constituent of green tea, human gastric AGS cells developed 2.2-fold resistance to EGCG. The resistant AGS (AGS-R) cells were cross-resistant to several N-methylcarbamate insecticides, which are among the major control agents for pest insects in Taiwan. The AGS-R cells also showed protective effects against both the cytotoxicity and DNA damage induced by one of the mutagenic derivatives of N-methylcarbamate insecticide, N-nitroso methomyl, which is known to target the mammalian gastric tract. Therefore, acquisition of resistance by AGS cells through chronic exposure to EGCG implies that the tea-drinking habit of the Taiwanese is probably beneficial for the health of the gastric tract. In addition, AGS-R cells were cross-resistant to sodium arsenite and hydrogen peroxide, indicating that tolerance to oxidative stress might play a role in the development of resistance described in this investigation.

28-day oral toxicity study of the aqueous extract from spider brake (Pteris multifida Poiret) in rats.

Spider brake (Pteris multifida Poiret) is a very important folk herb and a constituent in most of the traditional herbal beverage formulas in Taiwan; however, little toxicological information is available regarding the safety following repeated exposure. The present study was conducted to evaluate the toxicity of aqueous extract from spider brake (SB) in Sprague-Dawley rats on dietary oral gavage at concentrations of 100, 500, and 1000 mg/kg b.w. day for 28 days. There were no adverse effects on general condition, growth, feed and water consumption, feed conversion efficiency, red blood cell and clotting potential parameters, clinical chemistry values, and organ weights except for neutrophils and lymphocytes being slightly diminished in male and female rats at the highest dose, respectively. Necropsy and histopathology findings revealed no treatment-related changes in any of the organs. The results obtained in this study allowed us to conclude that the SB properly utilized in the traditional oral administration could be devoid of any toxic risk.

Free radical-scavenging activity of aqueous extract of Pteris multifida Poiret.

Aqueous extract of Pteris multifida showed scavenging activities on DPPH, hydroxyl radicals and reducing power.