Effects of n-3 fatty acid, fructose-1, 6-diphosphate and glutamine on mucosal cell proliferation and apoptosis of small bowel graft after transplantation in rats

Deep hypothermia protects against acute hypoxia in vivo in rats: a mechanism related to the attenuation of oxidative stress

There is growing interest in using hypothermia to prevent hypoxic damage in clinical and experimental models, although the mechanisms regulated by hypothermia are still unclear. As reactive oxygen and nitrogen species are the main factors causing cellular damage, our objective was to study the scope of hypothermia in preventing hypoxia-induced oxidative damage. We analysed systemic and hepatic indicators of oxidative stress after an acute hypoxic insult (10% oxygen in breathing air) in normothermic (37°C body temperature) and hypothermic conditions (22°C) in rats. Exposure to hypoxia resulted in tissue damage (aspartate aminotransferase increased from 54.6 ± 6.9 U l(-1) in control animals to 116 ± 1.9 U l(-1) in hypoxia, and alanine aminotransferase increased from 19 ± 0.8 to 34 ± 2.9 U l(-1)), oxidative stress (nitric oxide metabolites increased from 10.8 ± 0.4 μM in control rats to 23 ± 2.7 μM in hypoxia, and thiobarbituric reactive substances increased from 3.3 ± 0.2 to 5.9 ± 0.4 nm) and antioxidant consumption (reduced/oxidized glutathione ratio changed from 9.8 ± 0.3 to 6.8 ± 0.3). In contrast, when hypothermia was applied prior to hypoxia, the situation was reversed, with a reduction in aspartate aminotransferase (from 116 ± 1.9 in hypoxic animals to 63 ± 7.8 U l(-1) in animals exposed to hypothermia followed by hypoxia), alanine aminotransferase (from 34 ± 2.9 to 19 ± 0.9 U l(-1)), oxidative stress (nitric oxide metabolites decreased from 23 ± 2.7 to 17.8 ± 1.9 μM and thiobarbituric acid-reactive substances decreased from 5.9 ± 0.4 to 4.3 ± 0.2 nm) and antioxidant preservation (reduced/oxidized glutathione ratio changed from 6.8 ± 0.3 to 11.1 ± 0.1). Hypoxia induced a decrease in liver enzymatic antioxidant activities even during hypothermia. Both treatments, hypoxia and hypothermia, produced a similar increase in hepatic caspase-3 activity. In conclusion, hypothermia prevented the tissue damage and oxidative stress elicited by hypoxia. Our results provide new evidence concerning the protective mechanism of hypothermia in vivo.

Is there a link between soft drinks and erectile dysfunction?

This review focuses on the potential role of soft drinks, particularly the sugar component, in the pathogenesis of erectile dysfunction (ED). We analyzed the hypothetical link between metabolic disorders, induced by sweetened soft drinks overconsumption, and ED. High caloric intake, high refined-carbohydrates, and high fructose corn syrup (HFCS) content and less satiety are main factors responsible for metabolic disorders contributing to ED development. Regular diet mistakes among human males, such as soft drink consumption, may lead to slow and asymptomatic progression of ED, finally resulting in full claimed manifestation of ED.

Intestinal protective effect of a commercial fish protein hydrolysate preparation

OBJECTIVES

A partially hydrolysed, dried, product of pacific whiting fish is marketed as a health food supplement supporting 'intestinal health'. Scientific data supporting these claims are severely limited. We, therefore, examined if it influenced intestinal injury caused by the NSAID, indomethacin.

METHODS

Effects of fish hydrolysate on proliferation ([3H]-thymidine) and indomethacin-induced apoptosis (active caspase-3-immunostaining) utilised HT29 cells. In vivo studies used mice (n=8/group). 4/6 groups had fish hydrolysate (25 or 50 mg/ml) supplemented to their drinking water for 7 days. All mice received indomethacin (85 mg/kg subcutaneously) or placebo, 12 h before killing. Small intestinal injury was assessed using morphometry and morphology, proliferation (crypt BrdU labelling ) and apoptosis (active caspase-3 immunostaining).

RESULTS

Fish hydrolysate stimulated proliferation of HT29 cells. Apoptosis increased 3-fold following incubation with indomethacin but co-presence of fish hydrolysate truncated this effect by 40% (p<0.01). In mice, fish hydrolysate reduced the villus damaging effects of indomethacin by 60% (p<0.05). Indomethacin increased intestinal proliferation by 65%, irrespective of presence of hydrolysate. In contrast, intestinal caspase-3 activity increased by 83% in animals given indomethacin but this rise was truncated by 70% by co-presence of hydrolysate (p<0.01).

CONCLUSION

This natural bioactive product reduced apoptosis and the gut damaging effects of indomethacin.

Clinical trial: protective effect of a commercial fish protein hydrolysate against indomethacin (NSAID)-induced small intestinal injury

BACKGROUND

A partially hydrolysed and dried product of pacific whiting fish is marketed as a health food supplement supporting 'intestinal health'.

AIM

To examine whether the partially hydrolysed and dried product of pacific whiting fish influenced the small intestinal damaging side effects of the nonsteroidal anti-inflammatory drug, indomethacin.

METHODS

Eight human volunteers completed a double-blind, placebo-controlled, crossover protocol of clinically relevant dose of indomethacin (50 mg t.d.s. p.o. for 5 days) with 7 days of fish hydrolysate or placebo starting 2 days prior to indomethacin. Changes in gut permeability were assessed using 5 h urinary lactulose:rhamnose (L/R) ratios.

RESULTS

Fish hydrolysate given alone did not affect permeability. In the main study (n = 8), baseline values were similar for both arms (0.28 +/- 0.05 and 0.35 +/- 0.07). Administration of indomethacin (+placebo) caused a fivefold rise in L/R ratios (increasing to 1.54 +/- 0.35), whereas L/R ratios in the same subjects ingesting indomethacin + fish hydrolysate was only 0.59 +/- 0.14 (P < 0.01 vs. indomethacin alone). Dyspeptic symptoms occurred in four of eight subjects taking indomethacin alone, but zero of eight when hydrolysate was co-administered.

CONCLUSION

Natural bioactive products (nutriceuticals), such as fish hydrolysates, may provide a novel approach to the prevention and treatment of NSAID-induced and other gastrointestinal injurious conditions.

Long-chain n-3 fatty acids in lipid rafts: implications for anti-inflammatory effects

Emerging evidence indicates that dietary intake of long-chain n-3 fatty acids changes the lipid composition of lipid rafts and caveolae, which are cholesterol- and sphingolipid-rich microdomains of the plasma membrane. Membrane proteins that are involved in signal transduction events relevant to inflammation are specifically localised to these microdomains. By altering the lipid composition of the membrane microdomains, n-3 fatty acids have the potential to modulate these signalling events and exert anti-inflammatory actions.

Influence of adding fish oil to parenteral nutrition on gut-associated lymphoid tissue

BACKGROUND

Lack of enteral nutrition reduces gut-associated lymphoid tissue (GALT) mass and function, a mechanism underlying the increased morbidity of infectious complications in severely injured or critically ill patients. Strategies to restore parenteral nutrition (PN)-induced changes of GALT mass and function have been pursued. However, the influences of adding fish oil to PN on gut immunity remain to be clarified.

METHODS

Male Institute of Cancer Research (ICR) mice (n = 50) were randomized to 4 groups: ad libitum chow (chow), fat free PN (fat (-)-PN), PN + fish oil (FO-PN), and PN + safflower oil (SO-PN). The PN groups were given isocaloric and isonitrogenous PN solutions. The FO- and SO-PN groups received 20% of total calories from fat emulsions. After 5 days of feeding, lymphocytes from Peyer's patches (PPs), the intraepithelial space (IE), and the lamina propria (LP) of the entire small intestine were isolated. GALT lymphocyte numbers and phenotypes (CD4+, CD8+, alphabetaTCR+, gammadeltaTCR+, B220+ cells) were determined. Immunoglobulin A (IgA) levels of small intestinal washings were also measured by enzyme-linked immunosorbent assay. Another set of mice (n = 24) was used to determine plasma fatty acid compositions after feeding.

RESULTS

Lymphocyte numbers from PPs and the LP and intestinal IgA levels were significantly lower in the PN groups than in the chow group, with no significant differences between any 2 PN groups. The FO- and SO-PN groups showed moderate recovery of IE cell numbers compared with the fat (-)-PN group. Omega-3 and omega-6 fatty acid levels were increased with fish and safflower oil additions, respectively, compared with the fat (-)-PN group.

CONCLUSIONS

Adding fish oil to PN does not exacerbate PN-induced GALT changes but rather partially reverses these changes, with increased plasma omega-3 fatty acid levels.

Glutamine inhibits cytokine-induced apoptosis in human colonic epithelial cells via the pyrimidine pathway

Glutamine (Gln) prevents apoptosis in intestinal epithelial cells, but the mechanism(s) remain unknown. Gln-derived metabolites include ammonia, glutamate (Glu), glutathione (GSH), and nucleotides. We previously showed that Gln potently inhibited apoptosis in cytokine-treated human colonic HT-29 cells; this effect was specific to Gln, unaffected by Glu, and unrelated to intracellular GSH. The current research examines mechanism(s) for Gln-induced antiapoptotic effects in HT-29 cells treated with TNF-alpha-related apoptosis-inducing ligand (TRAIL). Proliferating cells were treated with Gln or selected Gln metabolites for 24 h. Cells were then treated with TRAIL and Gln or its downstream metabolites, and apoptosis was assessed at 8 h after treatment. The purine and pyrimidine precursors inosine and orotate inhibited TRAIL-induced apoptosis. However, inhibition of purine synthesis with azaserine did not alter the potent antiapoptotic effect of Gln. In contrast, the pyrimidine synthesis inhibitor, acivicin, completely prevented this response. Supplementation with the pyrimidine uracil or the pyrimidine precursor orotate rescued the acivicin-induced blockade of Gln antiapoptotic action. Removal of bicarbonate, a substrate for pyrimidine synthesis, also inhibited the antiapoptotic effects of Gln. Uracil and thymine alone also significantly decreased TRAIL-induced apoptosis. The antiapoptotic effects of Gln were independent of DNA/RNA synthesis as measured by flow cytometry and bromodeoxyuridine incorporation. In conclusion, Gln prevents TRAIL-induced apoptosis in HT-29 cells through a mechanism involving the pyrimidine pathway. Our data also demonstrate the novel antiapoptotic effects of pyrimidine bases and their precursor orotate in these human intestinal cells.

Apoptosis inhibition during preservation by fructose-1,6-diphosphate and theophylline in rat intestinal transplantation

OBJECTIVE

This study evaluated the effect of fructose-1,6-diphosphate (FDP), theophylline, or the addition of both together to the preservation solution (University of Wisconsin [UW]) on apoptosis during preservation and the effect of apoptosis minimization on the early reperfusion period after transplantation.

DESIGN

Prospective, randomized, and controlled animal study.

SETTING

Laboratory of a research institute.

SUBJECT

Male Wistar rats.

INTERVENTIONS

The jejunum was isolated and preserved for 6 hrs in UW solution. FDP and theophylline were added to the UW solution to evaluate their effects on apoptosis both alone and together. The role of adenosine with respect to FDP was examined by increasing endogenous adenosine. In addition, rats were subjected to intestinal transplantation for the evaluation of the effect of apoptosis on bacterial translocation, histology, and neutrophil infiltration after reperfusion.

MEASUREMENTS AND MAIN RESULTS

Caspase-3 activity, assayed both in vitro or by cleaved caspase-3 levels in Western blots or immunohistochemically, and the number of terminal deoxynucleotidyl transferase-mediated biotin-dUTP nick-end labeling (TUNEL)-positive cells decreased with FDP and with theophylline addition to UW solution. Increase of endogenous adenosine reversed the antiapoptotic effect of FDP. FDP and theophylline together demonstrated a more pronounced antiapoptotic effect and prevented bacterial translocation after transplantation.

CONCLUSION

Supplementary FDP to UW solution decreased apoptosis through an adenosine-independent mechanism. Addition of theophylline to UW solution decreased both apoptosis and bacterial translocation. Concomitant theophylline and FDP addition to preservation solution is recommended to maintain low levels of apoptosis during intestinal hypothermic preservation and to decrease bacterial translocation.

Antisense glutaminase inhibition decreases glutathione antioxidant capacity and increases apoptosis in Ehrlich ascitic tumour cells

Glutamine is an essential amino acid in cancer cells and is required for the growth of many other cell types. Glutaminase activity is positively correlated with malignancy in tumours and with growth rate in normal cells. In the present work, Ehrlich ascites tumour cells, and their derivative, 0.28AS-2 cells, expressing antisense glutaminase mRNA, were assayed for apoptosis induced by methotrexate and hydrogen peroxide. It is shown that Ehrlich ascites tumour cells, expressing antisense mRNA for glutaminase, contain lower levels of glutathione than normal ascites cells. In addition, 0.28AS-2 cells contain a higher number of apoptotic cells and are more sensitive to both methotrexate and hydrogen peroxide toxicity than normal cells. Taken together, these results provide insights into the role of glutaminase in apoptosis by demonstrating that the expression of antisense mRNA for glutaminase alters apoptosis and glutathione antioxidant capacity.

Effect of local CTLA4Ig gene transfection on acute rejection of small bowel allografts in rats

AIM: To evaluate the local expression of CTLA4Ig gene in small bowels and its action on preventing acute rejection of the small bowel allografts.

METHODS: Wistar rats underwent heterotopic small bowel transplantation from SD rats. The recipients were divided into experimental group (allografts were transfected with CTLA4Ig gene) and control group (CTLA4Ig gene not transfected) randomly. In the experimental group, the donor small bowels were perfused in vitro with CTLA4Ig cDNA packaged with lipofectin vector via intra-superior mesenteric artery before transplantation, and the CTLA4Ig expression in the small bowel grafts post-transplantation was assessed by immunohistology. On d 3, 7 and 10 post-transplantation, the allografts in each group were harvested for the examination of histology and assay of apoptosis.

RESULTS: Small bowel allografts treated with CTLA4Ig cDNA showed abundant CTLA4Ig expression after transplantation. Acute rejection grade Ⅰ on day 7 and grade Ⅱ on day 10 after transplantation was noticed in the control allografts, and a dramatically increased number of apoptotic enterocytes in parallel to the progressive rejection could be recognized. In contrast, the allografts treated with CTLA4Ig cDNA showed nonspecific histological changes and only a few of apoptotic enterocytes were found after transplantation.

CONCLUSION: Local CTLA4Ig gene transfection of small bowel allograft is feasible, and the local CTLA4Ig expression in the allograft can prevent acute rejection after transplantation.