Pretreatment with citrulline improves gut barrier after intestinal obstruction in mice

Background: Citrulline has been shown to be an important marker of gut function, regulator of protein metabolism, and precursor of arginine. The authors assessed the effects of citrulline on gut barrier integrity and bacterial translocation (BT) in mice undergoing intestinal obstruction. Methods: Mice were divided into 3 groups: sham, intestinal obstruction (IO), and citrulline (CIT). The CIT group received a diet containing 0.6% citrulline; the IO and sham groups were fed a standard chow diet. On the eighth day of treatment, all animals received a diethylenetriamine pentaacetic acid (DTPA) solution labeled with ^99mTechnetium (^99mTc‐DTPA) by gavage for the intestinal permeability study. Terminal ileum was ligated except the sham group, which only underwent laparotomy. After 4, 8, and 18 hours, blood was collected to determine radioactivity. Samples of ileum were removed 18 hours after intestinal obstruction for histological analysis. In another set of animals, BT was evaluated. Animals received 10⁸ CFU/mL of ^99mTc–Escherichia coli by gavage; 90 minutes later, they underwent ileum ligation. Intestinal fluid and serum were collected to measure sIgA and cytokines. Results: The CIT group presented decreased intestinal permeability and BT when compared with the IO group (P < .05). Histopathology showed that citrulline preserved the ileum mucosa. The sIgA concentration was higher in the CIT group (P < .05). The IO group presented the highest levels of interferon‐γ (P < .05). Conclusions: Pretreatment with citrulline was able to preserve barrier integrity and also modulated the immune response that might have affected BT decrease.     

The Role of L‐Arginine and Inducible Nitric Oxide Synthase in Intestinal Permeability and Bacterial Translocation

Background: Arginine has been shown to have several immunological and trophic properties in stressful diseases. Its metabolites, nitric oxide (NO) and polyamines, are related to arginine's effects. Thus, the aim of this study was to determine the effects of the NO donor L‐arginine and the role of inducible NO synthase (iNOS) on intestinal permeability and bacterial translocation in a model of intestinal obstruction (IO) induced by a simple knot in the terminal ileum. Material and Methods: Male C57BL6/J wild‐type (WT) and iNOS knockout (iNOS–/–) mice were randomized into 6 groups: Sham and Sham–/– (standard chow), IO and IO–/– (standard chow +IO), and Arg and Arg–/– (standard chow supplemented with arginine + IO). After 7 days of treatment with standard or supplemented chows, IO was induced and intestinal permeability and bacterial translocation were evaluated. The small intestine and its contents were harvested for histopathological and morphometric analysis and the determination of polyamine concentration. Results: Pretreatment with arginine maintained intestinal permeability (P > .05; Arg and Arg–/– groups vs Sham and Sham–/– groups), increased polyamine concentration in intestinal content (P < .05; Arg vs IO group), and decreased bacterial translocation in WT animals (Arg group vs IO and IO–/– groups). Absence of iNOS also presented a protective effect on permeability but not on bacterial translocation. Conclusion: Arginine supplementation and synthesis of NO by iNOS are important factors in decreasing bacterial translocation. However, when intestinal permeability was considered, NO had a detrimental role.     

Glutamine Supplementation Decreases Intestinal Permeability and Preserves Gut Mucosa Integrity in an Experimental Mouse Model

Background: Glutamine (GLN) is the preferred fuel for enterocytes, and GLN supplementation is critical during stressful conditions. The aim of this study was to evaluate the effect of GLN on intestinal barrier permeability and bacterial translocation in a murine experimental model. Methods: Swiss male mice (25–30 g) were randomized into 3 groups: (1) sham group; (2) intestinal obstruction (IO) group; (3) IO and GLN (500 mg/kg/d) group. Two different experiments were carried out to assess intestinal permeability and bacterial translocation. In the first experiment, the animals were divided into the 3 groups described above and received diethylenetriamine pentaacetate radiolabeled with technetium (^99mTc) on the eighth day. At different time points after intestinal obstruction, blood was collected to determine radioactivity. The animals were killed, and the small intestine was removed for histological analyses. In the bacterial translocation study, on the eighth day all groups received Escherichia coli labeled with ^99mTc. After 90 minutes, the animals underwent intestinal obstruction and were killed 18 hours later. Blood, mesenteric lymph nodes, liver, spleen, and lungs were removed to determine radioactivity. Statistical significance was considered when P ≤ .05. Results: The levels of intestinal permeability and bacterial translocation were higher in the IO group than in the sham and GLN groups (P < .05). GLN decreased intestinal permeability and bacterial translocation to physiologic levels in the treated animals and preserved intestinal barrier integrity. Conclusions: GLN had a positive impact on the intestinal barrier by reducing permeability and bacterial translocation to physiologic levels and preserving mucosal integrity.     

Pretreatment and Treatment With L‐Arginine Attenuate Weight Loss and Bacterial Translocation in Dextran Sulfate Sodium Colitis

Background: Imbalances in a variety of factors, including genetics, intestinal flora, and mucosal immunity, can contribute to the development of ulcerative colitis and its side effects. This study evaluated the effects of pretreatment or treatment with arginine by oral administration on intestinal permeability, bacterial translocation (BT), and mucosal intestinal damage due to colitis. Methods: C57BL/6 mice were distributed into 4 groups: standard diet and water (C: control group), standard diet and dextran sodium sulfate (DSS) solution (Col: colitis group), 2% L ‐arginine supplementation for 7 days prior to DSS administration and during disease induction (PT: pretreated group), and 2% L ‐arginine supplementation during disease induction (T: treated group). Colitis was induced by administration of 1.5% DSS for 7 days. After 14 days, intestinal permeability and BT were evaluated; colons were collected for histologic analysis and determination of cytokines; feces were collected for measurement of immunoglobulin A (IgA). Results: The Col group showed increased intestinal permeability (C vs Col: P < .05) and BT (C vs Col: P < .05). In the arginine‐supplemented groups (PT and T), this amino acid tended to decrease intestinal permeability. Arginine decreased BT to liver during PT (P < .05) and to blood, liver, spleen, and lung during T (P < .05). Histologic analysis showed that arginine preserved the intestinal mucosa and tended to decreased inflammation. Conclusions: Arginine attenuates weight loss and BT in mice with colitis.     

Arginine Supplementation Induces Arginase Activity and Inhibits TNF‐α Synthesis in Mice Spleen Macrophages After Intestinal Obstruction

Background: The purpose of this study was to assess the effect of arginine supplementation on arginase activity, tumor necrosis factor–α (TNF‐α) and interleukin‐10 (IL‐10) synthesis in cultured splenic macrophages from a murine model of intestinal obstruction (IO). The effects of nitric oxide synthase (iNOS) inhibition were also studied using iNOS knockout animals. Material and Methods: Male C57BL6/J wild‐type (WT) and iNOS knockout (iNOS–/–) mice were randomized into 6 groups: Sham and Sham–/– (standard chow), IO and IO–/– (standard chow + IO), and Arg and Arg–/– (standard chow supplemented with arginine + IO). After 7 days of treatment with standard or supplemented chow, IO was induced. Arginase activity as well as TNF‐α and IL‐10 levels were analyzed in splenic macrophage cultures. Results: Arginine supplementation and the absence of iNOS increased arginase activity in splenic macrophages (Arg, IO–/–, and Arg–/– groups vs the Sham group; P < .05). Arginine was also related to a decrease in TNF‐α levels (Arg vs IO group, P < .05) and maintenance of IL‐10 levels (Arg vs other groups, P > .05). The inhibition of iNOS did not result in effects on the concentration of cytokines (Sham–/–, IO–/–, and Arg–/– vs other, P < .05). Conclusions: Arginine supplementation and iNOS inhibition led to increased arginase activity. Arginine availability decreased plasma TNF‐α levels, which may be directly related to nitric oxide derived from arginine.     

The impact of arginine on bacterial translocation in an intestinal obstruction model in rats

BACKGROUND & AIMS: Arginine has been shown to have multiple beneficial metabolic and immunologic effects in stress situations. Supplementation of arginine has been shown to promote wound healing and intestinal mucosal recovery after trauma, ischemia or intestinal resection. Bacterial translocation has also been evaluated although with conflicting results and using different assessing techniques. Therefore, the aim of this study was to evaluate the effects of arginine on bacterial translocation in an intestinal obstruction model in rats using Escherichia coli labeled with 99mTechnetium. METHODS: Male Wistar rats (250-350 g) were randomized to receive conventional chow, diet supplemented with pure arginine or diet supplemented with an immunonutrition enteral formula, enriched with arginine, omega-3 fatty acid and RNA. After 7 days, the animals were anesthetized. Terminal ileum was isolated and a ligature was placed around it. E. coli labeled with 99mTechnetium (99mTc-E. coli) was inoculated into the intestinal lumen (terminal ileum). After 24 h, the animals were sacrificed. Blood, mesenteric lymph nodes (MLN), liver, spleen and lungs were removed for radioactivity determination. RESULTS: Arginine supplementation (300 mg/day, 600 mg/day or present in the enteral formula) reduced the level of bacterial translocation when compared with the control group (p<0.05). This was shown by significantly decrease uptake of 99mTc-E. coli in blood, MLN, liver, spleen and lungs of the animals in the experimental groups (p < 0.05). CONCLUSIONS: These results have shown that arginine was able to decrease bacteria translocation despite intestinal obstruction. There are several mechanisms which might explain the role of arginine and these will be the subject of future studies.     

Effect of arginine on gastrointestinal immunity during total parenteral nutrition

It has been well recognized that the prolonged use of total parenteral nutrition (TPN) leads to intestinal immunodeficiency and bacterial translocation (BT). Arginine (ARG) is known to have immunostimulatory effects. But its effects on gut immunity are unknown. This experiment was designed to evaluate the effects of arginine on gut immunity during TPN. Male Sprague Dowley rats were randomized to three groups: group I (chow) was fed rat chow and water ad libitum, group II (TPN) received a standard formula of TPN and group III (TPN-ARG) received the same formula of TPN as group II with the amino acid composition containing 0.5% arginine. With the duration of TPN, the rates of BT increased and interleukin 2 (IL-2) production decreased in TPN group. The results in TPN-ARG group were partly reversed. When TPN was administered for 2 weeks, the rate of BT decreased significantly (P < 0.05) and IL-2 production increased markedly (P < 0.01) in the TPN-ARG group compared with those in the TPN group. Our results suggest that arginine can decrease BT and increase IL-2 production in rats during prolonged TPN.     

Arginine-supplemented enteral nutrition in critically ill diabetic and obese rats: A dose-ranging study evaluating nutritional status and macrophage function

ObjectiveCritically ill diabetic and obese patients are at high risk of complications. Arginine availability is lowered in diabetes and in stress situations, yet arginine is necessary for immune response, mainly by its action through nitric oxide (NO). These facts argue for arginine-supplemented diets in critically ill patients. However, studies have raised concerns about possible adverse effects of such diets in intensive-care patients. We therefore analyzed the metabolic and immunologic effects of an arginine-enriched diet in stressed diabetic-obese rats.MethodsZucker Diabetic Fatty rats (fa/fa) were made endotoxemic by an intraperitoneal injection of lipopolysaccharide and then fed 4-d enteral nutrition enriched with arginine (ARG group) or a non-essential amino acid mix (NEAA group). The two groups each were subdivided into three subgroups: the ARG subgroups received 0.5 g (ARG0.5), 2 g (ARG2), and 5 g (ARG5) of arginine per kilogram daily, and the NEAA groups were made isonitrogenous with the corresponding ARG subgroups (NEAA0.5, NEAA2, and NEAA5). Plasma and urinary biomarkers were measured. Cytokine and NO production levels and inducible NO synthase and arginase protein levels were determined from peritoneal macrophages.ResultsThe survival rate was lower in the ARG5 and NEAA5 subgroups than in all the other subgroups. The nitrogen balance was higher in the ARG5 group than in the NEAA5 group. Plasma triacylglycerol levels were lower in the ARG2 group than in the NEAA2 group. Interleukin-6, tumor necrosis factor-α, and NO production in the macrophages decreased and arginase-1 was upregulated in the ARG-treated rats.ConclusionsIn this model, mortality was increased by the nitrogen burden rather than by arginine per se. Arginine improved nitrogen balance and had an anti-inflammatory action on macrophages by regulating NO production, probably through arginase-1 expression.     

Protection against increased intestinal permeability and bacterial translocation induced by intestinal obstruction in mice treated with viable and heat-killed <Emphasis Type="Italic">Saccharomyces boulardii</Emphasis>

Background  

There are substantial evidences suggesting that probiotics can protect the gastrointestinal tract against inflammatory or infectious episodes. The effects of oral treatment with viable or heat-killed cells of Saccharomyces boulardii (Sb) on bacterial translocation, intestinal permeability, histological aspect of the ileum, and some immunological parameters were evaluated in a murine intestinal obstruction (IO) model.     

Randomized,double-blind,placebo-controlled trial to evaluate efficacy of ketodiet in predialytic chronic renal failure

ObjectiveTo assess whether a ketodiet, a combination of ketoanalogs of essential amino acids (KAs) and a very low-protein diet, retards progression of chronic renal failure and maintains nutritional status.DesignA prospective, randomized, double-blind, placebo-controlled trial.SettingNephrology outpatient department in Northern Railways Central Hospital, New Delhi, India.PatientsThirty-four patients in predialytic stages of chronic renal failure (CRF), randomized to 2 comparable groups in terms of age, sex distribution, blood pressure control, etiology, use of angiotensin converting enzyme inhibitors, serum creatinine, glomerular filtration rate (GFR), and body mass index (BMI).InterventionSubjects randomly received either 0.6 g/kg/d protein plus placebo (n = 16) or 0.3 g/kg/d protein plus tablets of KAs (Ketosteril; Fresenius Kabi, Germany) (n = 18) for 9 months. A dietician administered the diet as well as the KAs or the placebo to the patients.Outcome measuresChanges in GFR and renal and nutritional parameters were measured.ResultsMean (± SD) GFR measured by the ^99mTc-DTPA (99 m technetium diethylenetri-aminepenta-aceticacid) plasma sample method was unchanged in the ketodiet group: 28.1 ± 8.8 (before) and 27.6 ± 10.1 mL/min/1.73 m² (after the study) (P = .72). However, it significantly decreased from 28.6 ± 17.6 to 22.5 ± 15.9 mL/min/1.73 m² in the placebo group (P = .015). Serum creatinine before and after the study in the ketodiet group was 2.26 ± 1.03 mg/dL and 2.07 ± 0.8 mg/dL (P = .90) and in the placebo group was 2.37 ± 0.85 and 3.52 ± 2.9 mg/dL (P = .066), respectively. In both groups the mean BMI did not change from 25.4 ± 4.2 to 24.5 ± 4.2 kg/m² (P = .46) for ketodiet and from 25.0 ± 6.8 to 23.9 ± 4.1 kg/m² (P = .39) for the placebo group. Serum total proteins decreased significantly (P = .038) in the placebo group, and serum albumin showed a trend (P = .061) toward reduction, whereas both of these parameters were maintained in the ketodiet group.ConclusionOver a 9-month period, very low-protein diet supplemented with ketoanalogs helped CRF patients to preserve GFR and maintain BMI. KAs were safe and efficacious in retarding the progression of renal failure and preserving the nutritional status of CRF patients.     

Differential effects of physical exercise and l-arginine on cortical spreading depression in developing rats

Abstract

Objective

We investigated the effect of early-in-life administration of l-arginine, combined with physical exercise, on cortical spreading depression (CSD) in young and adult rats.

Methods

l-arginine (300 mg/kg/day, n = 40) or distilled water (vehicle, n = 40) was given to the rats during postnatal days 7–35 by gavage. Physical exercise (treadmill) was carried out during postnatal days 15–35 in half of the animals in each gavage condition described above. The other half (non-exercised) was used for comparison. When the animals reached 35–45 days (young groups) or 90–120 days of age (adult) CSD was recorded on two cortical points during 4 hours and CSD propagation velocity was calculated.

Results

l-arginine-treated + exercised rats had increased body weight, but not brain weight, in adult age compared to l-arginine + non-exercised ones (P < 0.05). In both young and adult animals, l-arginine increased, whereas exercise decreased the CSD propagation velocity. Analysis of variance revealed a significant interaction between gavage treatment and age (P < 0.001), and also between gavage treatment and exercise (P = 0.004), but not between age and exercise. An additional control group of young rats, treated with 300 mg/kg of l-histidine, presented CSD velocities comparable to the corresponding water-treated controls, suggesting that the CSD acceleration seen in the l-arginine group was an l-arginine-specific effect, rather than an effect due to a non-specific amino acid imbalance.

Discussion

l-arginine and exercise affect CSD differentially (l-arginine accelerated, while exercise decelerated CSD), and both effects did interact. Probably, they depend on developmental plasticity changes associated with the treatments.     

Intravenous free and dipeptide-bound glutamine maintains intestinal microcirculation in experimental endotoxemia

ObjectiveThe administration of glutamine (Gln), which is depleted in critical illness, is associated with an improvement of gut metabolism, structure, and function. The aim of the present study was to evaluate the effects of intravenous Gln and its galenic formulation, l-alanyl-l-glutamine dipeptide (AlaGln), on the intestinal microcirculation during experimental endotoxemia using intravital fluorescence microscopy. Gln or AlaGln administration was performed as pretreatment or post-treatment, respectively. To identify further the underlying mechanisms, amino acid levels were studied.MethodsSixty male Lewis rats were randomly divided into six groups (n = 10/group): control, LPS (lipopolysaccharide 5 mg/kg intravenously), Gln/LPS (LPS animals pretreated with Gln 0.75 g/kg Gln intravenously), AlaGln/LPS (LPS animals pretreated with AlaGln intravenously, 0.75 g/kg Gln content), LPS/Gln (LPS animals post-treated with Gln 0.75 g/kg intravenously), and LPS/AlaGln (LPS animals post-treated with AlaGln intravenously, 0.75 g/kg Gln content). Two hours after the endotoxin challenge, the microcirculation of the terminal ileum was studied using intravital fluorescence microscopy. Blood samples were drawn at the beginning, during, and the end of the experiment to determine the amino acid levels.ResultsThe Gln and AlaGln pre- and post-treatment, respectively, prevented the LPS-induced decrease in the functional capillary density of the intestinal muscular and mucosal layers (P < 0.05). The number of adherent leukocytes in the submucosal venules was significantly attenuated after the Gln and AlaGln pre- and post-treatment (P < 0.05).ConclusionThe Gln and AlaGln administrations improved the intestinal microcirculation by increasing the functional capillary density of the intestinal wall and decreasing the submucosal leukocyte activation.     

Combined effects of bovine colostrum and glutamine in diclofenac-induced bacterial translocation in rat

BACKGROUND AND AIMS: The aim of this study was to examine whether the combined administration of bovine colostrum and glutamine was able to prevent the non-steroidal anti-inflammatory drug (NSAID)-induced gut damage and bacterial translocation (BT) in the rats. METHODS: The animal model population of the study consisted of six groups; control group, diclofenac group, diclofenac with milk group, diclofenac with colostrum group, diclofenac with glutamine group and diclofenac with colostrum and glutamine group. The animals with milk, colostrum or glutamine were fed with low fat milk, liquid colostrum or glutamine by orogastric gavage for 5 days before the diclofenac administration. Intestinal permeability, serum biochemical profiles and intestinal adhesion for assessment of the gut damage, and enteric bacterial overgrowth and BT at the mesenteric lymph nodes, liver, spleen and systemic blood were measured. RESULTS: Diclofenac caused the increase in gut damage, enteric bacterial numbers and BT. Supplements with colostrum or glutamine reduced these changes induced by diclofenac, but this result was not seen for supplementation with low fat milk. Combined administration of colostrum and glutamine reduced diclofenac-induced gut damage and BT as compared to the use of bovine colostrum alone or glutamine alone. CONCLUSIONS: This study suggested that the combined administration of bovine colostrum and glutamine might effectively reduce NSAID-induced gut damage and BT in the rat.     

Lactobacilli facilitate maintenance of intestinal membrane integrity during Shigella dysenteriae 1 infection in rats

ObjectiveLactobacilli are used in various dairy products and fermented foods for their potential health beneficial effects. Recently we reported the protective role of Lactobacillus rhamnosus and Lactobacillus acidophilus during Shigella dysenteriae 1 infection. Nevertheless, investigations on the membrane-stabilizing effect of L. rhamnosus and L. acidophilus have not been done. Hence, the present study evaluated the effect of L. rhamnosus and L. acidophilus on the maintenance of intestinal membrane integrity during S. dysenteriae 1–induced diarrhea in rats.MethodsRats were divided into eight groups (n = 6 in each group). Induced rats received single oral dose of S. dysenteriae (12 × 10⁸ colony-forming units [cfu]/mL). Treated rats received L. rhamnosus (1 × 10⁷cfu/mL) or L. acidophilus (1 × 10⁷cfu/mL) orally for 4 d, alone or in combination, followed by Shigella administration. At the end of the experimental period, animals were sacrificed and the assay of membrane-bound adenosine triphosphatases (Na⁺/K⁺-ATPase, Ca²⁺-ATPase, and total ATPase), immunoblot analysis of tight junctional proteins (claudin-1 and occludin), and transmission electron microscopic studies were performed.ResultsInduced rats showed a significant (P < 0.05) reduction in the membrane-bound ATPases and reduced expression of tight junction proteins in the membrane, coupled with their increased expression in the cytosol, indicating membrane damage. Transmission electron microscopic studies correlated with biochemical parameters. Pretreatment with combination of L. rhamnosus and L. acidophilus significantly prevented these changes.ConclusionLactobacillus rhamnosus and L. acidophilus synergistically offered better protection to the intestinal membrane when compared with individual treatments with these strains during S. dysenteriae 1 infection.     

Effects of Enteral Immunonutrition on the Maintenance of Gut Barrier Function and Immune Function in Pigs With Severe Acute Pancreatitis

Background: This study evaluated the effects of enteral immunonutrition (EIN) supplemented with glutamine, arginine, and probiotics on gut barrier function and immune function in pigs with severe acute pancreatitis (SAP). Methods: The model was induced by retrograde injection of 5% sodium taurocholate and trypsin via the pancreatic duct. After induction of SAP, 18 pigs were randomly divided into 3 groups, in which either parenteral nutrition (PN), control enteral nutrition (CEN), or EIN was applied for 8 days. Serum and pancreatic fluid amylase concentration was determined. Intestinal permeability (lactulose to mannitol ratio) was measured by high‐performance liquid chromatography, and plasma endotoxin was quantified by the chromogenic limulus amebocyte lysate technique. Samples of venous blood and organs were cultured using standard techniques. Pancreatitis severity and villi of ileum were scored according to histopathologic grading. Plasma T‐lymphocyte subsets were measured by flow cytometry, and immunoglobulins (Igs) were determined via enzyme‐linked immunosorbent assay. Results: There were no significant differences in serum and pancreatic fluid amylases concentrations or in pancreatitis severity between any 2 of the 3 groups. Compared with PN and CEN, EIN significantly decreased intestinal permeability, plasma endotoxin concentration, and the incidence and magnitudes of bacterial translocation, but increased ileal mucosal thickness, villous height, crypt depth, and percentage of normal intestinal villi. Significant differences were found in CD3⁺, CD4⁺ lymphocyte subsets, the ratio of CD4⁺: CD8⁺ lymphocyte subsets, and serum IgA and IgG, but not IgM, between any 2 of the 3 groups. Conclusions: EIN maintained gut barrier function and immune function in pigs with SAP.     

Quercetin bioavailability is associated with inadequate plasma vitamin C status and greater plasma endotoxin in adults

ObjectiveQuercetin bioavailability exhibits high interindividual variation for reasons that remain unclear. We conducted a 24-h pharmacokinetic study to investigate whether individual differences in circulating antioxidants, oxidative stress and inflammation, and intestinal permeability affect quercetin bioavailability.MethodsHealthy adults (n = 9 M/7 F; 34.3 ± 4.5 y; 27.0 ± 1.7 kg/m²) ingested 1095 mg quercetin aglycone with a standardized meal. Plasma antioxidants, biomarkers of oxidative stress and inflammation, and endotoxin were measured at baseline (0 h), and quercetin and its methylated metabolites isorhamnetin and tamarixetin were measured at timed intervals for 24 h.ResultsPlasma pharmacokinetics of quercetin, isorhamnetin and tamarixetin were highly variable between participants (CV_inter = 37–96%). Plasma vitamin C concentrations (34.6 ± 2.5 μmol/L), but no other antioxidants, were inversely correlated to the C_max and AUC_{0 to 24 h} of total quercetin (Q_total; sum of quercetin, isorhamnetin and tamarixetin; r = −0.52 to −0.53; P < 0.05). Plasma endotoxin (0.13 ± 0.01 EU/mL), a surrogate marker of intestinal permeability, was correlated to Q_total C_max (r = 0.45; P < 0.05) and tended to be correlated to Q_total AUC_{0 to 24 h} (r = 0.38; P = 0.07). Additionally, vitamin C was inversely related to C-reactive protein, myeloperoxidase, and endotoxin (r = −0.46 to −0.55; P < 0.05), whereas endotoxin was positively correlated to C-reactive protein (r = 0.73; P < 0.05).ConclusionsThese findings suggest that vitamin C status and plasma endotoxin may be associated with interindividual variations in quercetin bioavailability. Greater quercetin absorption and bioavailability may be associated with poor vitamin C status and increased intestinal permeability in healthy adults.     

Protective role of lactobacilli in Shigella dysenteriae 1-induced diarrhea in rats

ObjectiveStudies on lactic acid bacteria exemplify their use against various enteropathogens in vitro. Nevertheless, in vivo effects of Lactobacillus during Shigella infection have not been evaluated. The present study evaluated the effect of Lactobacillus rhamnosus and Lactobacillus acidophilus on neutrophil infiltration and lipid peroxidation during Shigella dysenteriae 1–induced diarrhea in rats.MethodsThe rats were divided into eight groups (n = 6 in each group). Induced rats received single oral dose of S. dysenteriae (12 × 10⁸ colony-forming units [cfu]/mL). Treated rats received L. rhamnosus (1 × 10⁷ cfu/mL) or L. acidophilus (1 × 10⁷ cfu/mL) orally for 4 d, alone or in combination, followed by Shigella administration. At the end of the experimental period, animals were sacrificed and the assay of the activity of alkaline phosphatase, myeloperoxidase, and antioxidants and the estimation of lipid peroxides were performed. Activity staining of superoxide dismutase and catalase was done in addition to gelatin zymography for matrix metalloproteinase (MMP; MMP-2 and MMP-9) activity. A portion of the intestinal tissue was fixed in 10% formalin for histologic studies.ResultsAdministration of S. dysenteriae 1 alone resulted in increased levels of myeloperoxidase, lipid peroxidation, alkaline phosphatase, and the expression of MMP-2 and MMP-9 with concomitant decrease in the antioxidant levels. Pretreatment with the combination of L. rhamnosus (1 × 10⁷ cfu/mL) and L. acidophilus (1 × 10⁷ cfu/mL) significantly attenuated these changes when compared with the diseased group. Histologic observations were in correlation with biochemical parameters.ConclusionLactobacillus rhamnosus plus L. acidophilus offered better protection when compared with individual treatment with these strains during Shigella infection.     

Association between intestinal tight junction permeability and whole-body electrical resistance in healthy individuals: A hypothesis

ObjectiveIntestinal permeability describes non-carrier–mediated modes of transport through the intestinal epithelium. Wrist–ankle bioimpedance analysis (BIA) is a standard method to determine body composition based on the measurements of whole-body electrical resistance and reactance values. The present report deals with the coincidentally observed associations between permeability results and electrical raw values of BIA and their subsequent reproduction in a larger group of individuals.MethodsTetrapolar wrist–ankle BIA was performed on day 1 in the initial sample (12 women, 36 ± 11 y of age) and the validation sample (36 healthy subjects, 26 women and 10 men, 35 ± 14 y of age). Intestinal permeability tests (lactulose and mannitol) were implemented within 1 wk thereafter. Wrist–ankle electrical resistance plus electrical resistance between current-conducting electrodes and voltage-sensing electrodes (Rtotal) was measured at 5 kHz and 100 kHz.ResultsPermeability and bioimpedance raw values were normal, indicating normal tight junction permeability and normal hydration. Lactulose correlated to R_50total in the initial sample (ρ = 0.639, P = 0.025) and in the validation sample (ρ = 0.673, P < 0.001). Weaker associations to R_50total were observed with mannitol (ρ = 0.381, P = 0.008) and lactulose/mannitol (ρ = 0.369, P = 0.010) in the total group of individuals. Regression analyses demonstrated that R_50total alone accounted for 41.3% of the variance in lactulose permeability.ConclusionThe nature of the observed positive association between intestinal tight junction permeability and whole-body electrical resistance is unclear. We hypothesize that regulation involving submolecular mechanisms based on the principles of quantum physics might have caused the observed association. Such coherent mechanisms might possibly play a role in basal physiologic regulation in humans.     

Carcinogenicity assays of wood dust and wood additives in rats exposed by long-term inhalation

Objective: This study evaluates whether wood dust and/or wood preservatives develop a carcinogenic potential against the tissues of the airways of rats. Methods: The formation of tumors of the respiratory tract after exposure to wood dust was studied in six groups of approximately 60 female Fischer 344 rats exposed by long-term inhalation to mean concentrations of (1) 18 mg/m³ of untreated oak wood dust, (2) wood preservatives containing ca. 1 μg/m³ lindane and 0.2 μg/m³ of pentachlorophenol (PCP) in the exposure air, or lindane and 18 μg/m3 of PCP (group lindane/PCP vapors, and group oak wood treated with lindane/PCP), (3) 21 or 39 μg/m³ of sodium dichromate (calculated as CrO₃, group chromate aerosol and group oak wood with chromate), and 72 μg/m³ of N-nitrosodimethylamine vapors as positive control. The negative control group consisted of 115 animals (sham-exposed). Results: Tumors of the nasal cavity developed in two rats exposed to chromate aerosol or in combination with wood dust (2/102, 2%). Malignant tumors of the lower respiratory tract were induced only in exposed groups of rats (three adenocarcinomas of the lung and four bronchiolar lung carcinomas, 7/254, 2.8%). More respiratory tract tumors were observed in rats exposed to chromate or wood with chromate (5/102, 5%), also in groups exposed to oak wood dust (oak untreated, oak + chromate, oak + lindane/PCP; together 5/155, 3.2%). Analysis of `unpreserved' oak wood dust revealed up to 5 μg/m³ of chromate. When this exposure was taken into account, eight of nine animals with respiratory tract tumors (including nasal cavity) had exposure to chromate, while only one tumor occurred in the group lindane/PCP. Otherwise the incidence of systemic tumors was increased in animals exposed to lindane/PCP, due in particular to a significantly increased incidence of liver tumors (OR=3.7; 1.24–11.3; P=0.019). Fatal (mucoepidermoid) tumors were induced by N-nitrosodimethylamine (NDMA) in the positive control (14/46, 30%). No such tumors of the respiratory tract were observed in the negative control. Conclusions: Tumors in the respiratory tract were found only in exposed animals, predominantly in the groups which inhaled oak wood dust and chromate stain. Chromate may play a decisive role for the etiology of tumors of the nasal cavity in wood workers. This assumption should be supported by further dose-response studies. Received: 23 May 2000 / Accepted: 13 September 2000     

Vaccination of pigs with attenuated Lawsonia intracellularis induced acute phase protein responses and primed cell-mediated immunity without reduction in bacterial shedding after challenge

BackgroundLawsonia intracellularis causes porcine proliferative enteropathy and is one of the most economically important diseases in modern pig production worldwide. The Enterisol^® Ileitis vaccine have been shown to reduce clinical disease and to increase weight gain, however, while the natural infection with L. intracellularis can provide complete protection against re-infection, this has not been achieved by this vaccine. We therefore undertook a detailed characterization of immune responses to L. intracellularis infection in vaccinated pigs (VAC) compared to previously infected pigs (RE) in order to pinpoint immunological determinants of protection.ResultsThe VAC pigs shed L. intracellularis to the same extent as non-vaccinated pigs after challenge, however less L. intracellularis in ileum and lymph nodes was seen post mortem. In the RE group, challenge did not lead to L. intracellularis shedding and no challenge bacteria were found post mortem. In both VAC and RE the acute phase haptoglobin response was diminished and L. intracellularis specific IgG responses were delayed and reduced compared to non-vaccinated pigs. On the other hand L. intracellularis specific IFN-γ responses tended to develop faster in the VAC group compared to controls.ConclusionAlthough vaccinated and non-vaccinated pigs shed L. intracellularis at similar levels after challenge, a lower number of intestinal L. intracellularis was observed in the vaccinated pigs at post mortem inspection. This might be due to the observed faster CMI responses upon challenge in vaccinated pigs. Complete protection against infection without L. intracellularis shedding, however, was only seen after a previous infection resulting in IFN-γ production predominantly by CD8⁺ and CD4⁺ CD8⁺ cells. Improved protective vaccines against L. intracellularis should therefore target stimulation of these T cell subsets.