Glutamine Analogues As Adjunctive Therapy for Infectious Diarrhea

Treatment of cryptosporidiosis: nitazoxanide yes, but we can do better

INTRODUCTION

Cryptosporidiosis was initially recognized as an important cause of diarrhea in AIDS patients. It has been underdiagnosed in other populations. Recent studies have highlighted the importance of Cryptosporidium as a cause of diarrhea and malnutrition in young children in resource-poor countries and an emerging pathogen in organ-transplant recipients.

AREAS COVERED

Nitazoxanide is FDA approved for treatment of cryptosporidiosis in immunocompetent people. However, it is less effective in HIV and transplant patients and malnourished children. In transplant recipients, there is emerging data on antiparasitic combinations for cryptosporidiosis, including combinations of nitazoxanide, azithromycin, and in one case rifaximin. High-throughput phenotypic screens have identified some potential treatments. Among them, clofazimine was no better than placebo in a trial in AIDS patients. There have also been efforts to develop drug versus specific parasite targets. However, in part due to safety issues, none of these compounds have advanced into clinical trials.

EXPERT OPINION

Development of new and more efficacious therapies for cryptosporidium is imperative. Current approve therapy is far from optimal and lacks efficacy in high-risk populations, such as, patients living with HIV. Additionally, there is limited data on patients with other types of immunosuppression (Transplanted, autoimmune conditions, etc).

Differences in Metabolic Profiles of Healthy Dogs Fed a High-Fat vs. a High-Starch Diet

Obesity is a common problem in dogs and overconsumption of energy-rich foods is a key factor. This study compared the inflammatory response and fecal metabolome of dogs fed a high-fat vs. a high-starch diet. Ten healthy lean adult beagles were equally allocated into two groups in a cross-over design. Each group received two diets in which fat (horse fat) and starch (pregelatinized corn starch) were exchanged in an isocaloric way to compare high fat vs. high starch. There was a tendency to increase the glucose and glycine concentrations and the glucose/insulin ratio in the blood in dogs fed with the high-fat diet, whereas there was a decrease in the level of Non-esterified fatty acids and a tendency to decrease the alanine level in dogs fed with the high-starch diet. Untargeted analysis of the fecal metabolome revealed 10 annotated metabolites of interest, including L-methionine, which showed a higher abundance in dogs fed the high-starch diet. Five other metabolites were upregulated in dogs fed the high-fat diet, but could not be annotated. The obtained results indicate that a high-starch diet, compared to a high-fat diet, may promote lipid metabolism, anti-oxidative effects, protein biosynthesis and catabolism, mucosal barrier function, and immunomodulation in healthy lean dogs.

Fecal Microbiota Functional Gene Effects Related to Single-Dose Antibiotic Treatment of Travelers' Diarrhea

Background

Travelers' diarrhea (TD) is common among military personnel deployed to tropical and subtropical regions. It remains unclear how TD and subsequent antibiotic treatment impact the resident microflora within the gut, especially given increased prevalence of antibiotic resistance among enteric pathogens and acquisition of multidrug-resistant organisms. We examined functional properties of the fecal microflora in response to TD, along with subsequent antibiotic treatment.

Methods

Fecal samples from US and UK military service members deployed to Djibouti, Kenya, and Honduras who presented with acute watery diarrhea were collected. A sample was collected at acute presentation to the clinic (day 0, before antibiotics), as well as 7 and/or 21 days following a single dose of antibiotics (azithromycin [500 mg], levofloxacin [500 mg], or rifaximin [1650 mg], all with loperamide). Each stool sample underwent culture and TaqMan reverse transcription polymerase chain reaction analyses for pathogen and antibiotic resistance gene detection. Purified DNA from each sample was analyzed using the HumiChip3.1 functional gene array.

Results

In total, 108 day 1 samples, 50 day 7 samples, and 94 day 21 samples were available for analysis from 119 subjects. Geographic location and disease severity were associated with distinct functional compositions of fecal samples. There were no overt functional differences between pre- and postantibiotic treatment samples, nor was there increased acquisition of antibiotic resistance determinants for any of the antibiotic regimens.

Conclusions

These results indicate that single-dose antibiotic regimens may not drastically alter the functional or antibiotic resistance composition of fecal microflora, which should inform clinical practice guidelines and antimicrobial stewardship.

Clinical Trials Registration Number

NCT01618591.

Dietary alanyl-glutamine improves growth performance of weaned piglets through maintaining intestinal morphology and digestion-absorption function

Alanyl-glutamine (Ala-Gln), a highly soluble and stable glutamine dipeptide, is known to improve gut integrity and function. The aim of this study was to evaluate whether dietary Ala-Gln supplementation could improve growth performance, intestinal development and digestive-absorption function in weaned piglets. A total of 100 purebred Yorkshire piglets weaned at 21 days of age were assigned randomly to four dietary treatment groups and fed a basal diet (control group) or a basal diet containing 0.15%, 0.30% and 0.45% Ala-Gln, respectively. Compared with the control group, piglets fed the Ala-Gln diets had higher average daily gain and lower feed : gain and diarrhea rate (P < 0.05). Moreover, dietary Ala-Gln supplementation increased villous height and villous height : crypt depth ratio in duodenum and jejunum (P < 0.05), as well as the activities of maltase and lysozyme in jejunum mucosa (P < 0.05). In addition, a decrease in serum diamine oxidase activity and crypt depth in duodenum and jejunum was observed in piglets fed the Ala-Gln diets (P < 0.05). Serum cytosolic phospholipase A2 (cPLA2) concentration and gene expression of cPLA2, Na+-dependent glucose transporter 1, glucose transporter 2 and peptide transporter 1 in jejunum were increased by feeding Ala-Gln diets relative to control diet (P < 0.05). These results indicated that feeding Ala-Gln diet has beneficial effects on the growth performance of weaned piglets, which associated with maintaining intestinal morphology and digestive-absorption function.

Phenylalanine isotope pulse method to measure effect of sepsis on protein breakdown and membrane transport in the pig

The primed-continuous (PC) phenylalanine (Phe) stable isotope infusion methodology is often used as a proxy for measuring whole body protein breakdown (WbPB) in sepsis. It is unclear if WbPB data obtained by an easy-to-use single IV Phe isotope pulse administration (PULSE) are comparable to those by PC. Compartmental modeling with PULSE could provide us more insight in WbPB in sepsis. Therefore, in the present study, we compared PULSE with PC as proxy for WbPB in an instrumented pig model with Pseudomonas aeruginosa-induced severe sepsis (Healthy: n = 9; Sepsis: n = 13). Seventeen hours after sepsis induction, we compared the Wb rate of appearance (WbR_a) of Phe obtained by PC (L-[ring-¹³C₆]Phe) and PULSE (L-[¹⁵N]Phe) in arterial plasma using LC-MS/MS and (non)compartmental modeling. PULSE-WbR_a was highly correlated with PC-WbR_a (r = 0.732, P < 0.0001) and WbPB (r = 0.897, P < 0.0001) independent of the septic state. PULSE-WbR_a was 1.6 times higher than PC-WbR_a (P < 0.001). Compartmental and noncompartmental PULSE modeling provide comparable WbR_a values, although compartmental modeling was more sensitive. WbPB was elevated in sepsis (Healthy: 3,378 ± 103; Sepsis: 4,333 ± 160 nmol·kg BW^-1·min^-1, P = 0.0002). With PULSE, sepsis was characterized by an increase of the metabolic shunting (Healthy: 3,021 ± 347; Sepsis: 4,233 ± 344 nmol·kg BW^-1·min^-1, P = 0.026). Membrane transport capacity was the same. Both PC and PULSE methods are able to assess changes in WbR_a of plasma Phe reflecting WbPB changes with high sensitivity, independent of the (patho)physiological state. The easy-to-use (non)compartmental PULSE reflects better the real WbPB than PC. With PULSE compartmental analysis, we conclude that the membrane transport capacity for amino acids is not compromised in severe sepsis.

Alanyl-glutamine attenuates 5-fluorouracil-induced intestinal mucositis in apolipoprotein E-deficient mice

Apolipoprotein E (APOE=gene, apoE=protein) is a known factor regulating the inflammatory response that may have regenerative effects during tissue recovery from injury. We investigated whether apoE deficiency reduces the healing effect of alanyl-glutamine (Ala-Gln) treatment, a recognized gut-trophic nutrient, during tissue recovery after 5-FU-induced intestinal mucositis. APOE-knockout (APOE-/-) and wild-type (APOE+/+) C57BL6J male and female mice (N=86) were given either Ala-Gln (100 mM) or phosphate buffered saline (PBS) by gavage 3 days before and 5 days after a 5-fluorouracil (5-FU) challenge (450 mg/kg, via intraperitoneal injection). Mouse body weight was monitored daily. The 5-FU cytotoxic effect was evaluated by leukometry. Intestinal villus height, villus/crypt ratio, and villin expression were monitored to assess recovery of the intestinal absorptive surface area. Crypt length, mitotic, apoptotic, and necrotic crypt indexes, and quantitative real-time PCR for insulin-like growth factor-1 (IGF-1) and B-cell lymphoma 2 (Bcl-2) intestinal mRNA transcripts were used to evaluate intestinal epithelial cell turnover. 5-FU challenge caused significant weight loss and leukopenia (P<0.001) in both mouse strains, which was not improved by Ala-Gln. Villus blunting, crypt hyperplasia, and reduced villus/crypt ratio (P<0.05) were found in all 5-FU-challenged mice but not in PBS controls. Ala-Gln improved villus/crypt ratio, crypt length and mitotic index in all challenged mice, compared with PBS controls. Ala-Gln improved villus height only in APOE-/- mice. Crypt cell apoptosis and necrotic scores were increased in all mice challenged by 5-FU, compared with untreated controls. Those scores were significantly lower in Ala-Gln-treated APOE+/+ mice than in controls. Bcl-2 and IGF-1 mRNA transcripts were reduced only in the APOE-/- -challenged mice. Altogether our findings suggest APOE-independent Ala-Gln regenerative effects after 5-FU challenge.

Diagnosis and treatment of severely malnourished children with diarrhoea

Children with severe acute malnutrition complicated by diarrhoea require special care due to their unique physiological vulnerability and increased mortality risks. A systematic literature review (1950-2013) was conducted to identify the most effective diagnostic and therapeutic measures for the community-based management of severely malnourished children with diarrhoea. No studies directly addressed this question, so the search was broadened to include inpatient care. Of the 129 studies identified, 32 were selected for full review and found to contain varying degrees of indirectness, inconsistency and bias. Evidence from diagnostic studies point to the use of both prolonged and persistent diarrhoea as morbidity markers, rapid hypoglycaemia diagnosis and the frequent aetiological role of Cryptosporidium. Therapeutic studies suggest benefits from routine antiparasitic medication and feeding regimens with ready-to-use-therapeutic foods, lactose-free diets and zinc supplementation. Existing rehydration treatment guidelines were affirmed, but the utility of glutamine and low osmolarity feeds were inconclusive.

A review of the global burden, novel diagnostics, therapeutics, and vaccine targets for cryptosporidium

Cryptosporidium spp are well recognised as causes of diarrhoeal disease during waterborne epidemics and in immunocompromised hosts. Studies have also drawn attention to an underestimated global burden and suggest major gaps in optimum diagnosis, treatment, and immunisation. Cryptosporidiosis is increasingly identified as an important cause of morbidity and mortality worldwide. Studies in low-resource settings and high-income countries have confirmed the importance of cryptosporidium as a cause of diarrhoea and childhood malnutrition. Diagnostic tests for cryptosporidium infection are suboptimum, necessitating specialised tests that are often insensitive. Antigen-detection and PCR improve sensitivity, and multiplexed antigen detection and molecular assays are underused. Therapy has some effect in healthy hosts and no proven efficacy in patients with AIDS. Use of cryptosporidium genomes has helped to identify promising therapeutic targets, and drugs are in development, but methods to assess the efficacy in vitro and in animals are not well standardised. Partial immunity after exposure suggests the potential for successful vaccines, and several are in development; however, surrogates of protection are not well defined. Improved methods for propagation and genetic manipulation of the organism would be significant advances.

Intestinal epithelial restitution after TcdB challenge and recovery from Clostridium difficile infection in mice with alanyl-glutamine treatment

BACKGROUND

Clostridium difficile is an anaerobic bacterium that causes antibiotic-associated diarrhea. It produces toxin A and toxin B (TcdB), which cause injury to the gut epithelium. Glutamine is a fundamental fuel for enterocytes, maintaining intestinal mucosal health. Alanyl-glutamine (AQ) is a highly soluble dipeptide derivative of glutamine. We studied whether administration of AQ ameliorates the effects of TcdB in the intestinal cells and improves the outcome of C. difficile infection in mice.

METHODS

WST-1 proliferation and cell-wounding-migration assays were assessed in IEC-6 cells exposed to TcdB, with or without AQ. Apoptosis and necrosis were assessed using Annexin V and flow cytometry. C57BL/6 mice were infected with VPI 10463 and treated with either vancomycin, AQ, or vancomycin with AQ. Intestinal tissues were collected for histopathologic analysis, apoptosis staining, and determination of myeloperoxidase activity.

RESULTS

AQ increased proliferation in intestinal cells exposed to TcdB, improved migration at 24 and 48 hours, and reduced apoptosis in intestinal cells challenged with TcdB. Infected mice treated with vancomycin and AQ had better survival and histopathologic findings than mice treated with vancomycin alone.

CONCLUSIONS

AQ may reduce intestinal mucosal injury in C. difficile-infected mice by partially reversing the effects of TcdB on enterocyte proliferation, migration, and apoptosis, thereby improving survival from C. difficile infection.

Zinc, vitamin A, and glutamine supplementation in Brazilian shantytown children at risk for diarrhea results in sex-specific improvements in verbal learning

OBJECTIVE

To identify the impact of supplemental zinc, vitamin A, and glutamine, alone or in combination, on long-term cognitive outcomes among Brazilian shantytown children with low median height-for-age z-scores.

METHODS

A randomized, double-blind, placebo-controlled trial was conducted in children aged three months to nine years old from the urban shanty compound community of Fortaleza, Brazil. Demographic and anthropometric information was assessed. The random treatment groups available for cognitive testing (total of 167 children) were: (1) placebo, n = 25; (2) glutamine, n = 23; (3) zinc, n = 18; (4) vitamin A, n = 19; (5) glutamine+zinc, n = 20; (6) glutamine+vitamin A, n = 21; (7) zinc+vitamin A, n = 23; and (8) glutamine+zinc+vitamin A, n = 18. Neuropsychological tests were administered for the cognitive domains of non-verbal intelligence and abstraction, psychomotor speed, verbal memory and recall ability, and semantic and phonetic verbal fluency. Statistical analyses were performed using SPSS, version 16.0. ClinicalTrials.gov: NCT00133406.

RESULTS

Girls receiving a combination of glutamine, zinc, and vitamin A had higher mean age-adjusted verbal learning scores than girls receiving only placebo (9.5 versus 6.4, p = 0.007) and girls receiving zinc+vitamin A (9.5 versus 6.5, p = 0.006). Similar group differences were not found between male study children.

CONCLUSIONS

The findings suggest that combination therapy offers a sex-specific advantage on tests of verbal learning, similar to that seen among female patients following traumatic brain injury.

Novel in vitro and in vivo models and potential new therapeutics to break the vicious cycle of Cryptosporidium infection and malnutrition

BACKGROUND

Although several animal models of cryptosporidiosis have been reported, most involve genetically or pharmacologically immune-suppressed hosts.

METHODS

We report challenge with excysted (in vitro and in vivo) and unexcysted (in vivo) Cryptosporidium parvum oocysts in human colonic adenocarcinoma (HCT-8) cells and weaned nourished and malnourished C57BL/6 mice, following outcomes of growth rate, stool shedding, and tissue burden. We tested treatment with an oligodeoxynucleotide containing unmethylated CpG motif (CpG-ODN) and alanyl-glutamine in vivo and in vitro.

RESULTS

C. parvum-challenged mice showed prolonged weight loss (>10% over 4 days), robust stool shedding (>3 logs/d over 7 days), and epithelial infection in the ileum, cecum, and colon. Of 2 potential therapeutic compounds evaluated in the model, CpG-ODN reduced body weight loss (to <6% on days 3-7 after challenge), reduced shedding of organisms (by 25% on days 1 and 3 after challenge), and decreased the burden of parasites in the ileum. Alanyl-glutamine showed similar benefits. In vitro findings suggested that effects on the epithelial component of the mucosa probably likely responsible for beneficial effects seen in vivo.

CONCLUSIONS

Weaned mice provide a convenient and reproducible model of cryptosporidial disease, including its vicious cycle with body weight loss and heavier infection with malnutrition, and this model may be useful in exploring innovative therapeutic solutions for this challenging infectious disease.

Effects of adenosine A₂A receptor activation and alanyl-glutamine in Clostridium difficile toxin-induced ileitis in rabbits and cecitis in mice

Background

Severe Clostridium difficile toxin-induced enteritis is characterized by exuberant intestinal tissue inflammation, epithelial disruption and diarrhea. Adenosine, through its action on the adenosine A_2A receptor, prevents neutrophillic adhesion and oxidative burst and inhibits inflammatory cytokine production. Alanyl-glutamine enhances intestinal mucosal repair and decreases apoptosis of enterocytes. This study investigates the protection from enteritis by combination therapy with ATL 370, an adenosine A_2A receptor agonist, and alanyl-glutamine in a rabbit and murine intestinal loop models of C. difficile toxin A-induced epithelial injury.

Methods

Toxin A with or without alanyl-glutamine was administered intraluminally to rabbit ileal or murine cecal loops. Animals were also given either PBS or ATL 370 parenterally. Ileal tissues were examined for secretion, histopathology, apoptosis, Cxcl1/KC and IL-10.

Results

ATL 370 decreased ileal secretion and histopathologic changes in loops treated with Toxin A. These effects were reversed by the A_2A receptor antagonist, SCH 58261, in a dose-dependent manner. The combination of ATL 370 and alanyl-glutamine significantly further decreased ileal secretion, mucosal injury and apoptosis more than loops treated with either drug alone. ATL 370 and alanyl-glutamine also decreased intestinal tissue KC and IL-10.

Conclusions

Combination therapy with an adenosine A_2A receptor agonist and alanyl-glutamine is effective in reversing C. difficile toxin A-induced epithelial injury, inflammation, secretion and apoptosis in animals and has therapeutic potential for the management of C. difficile infection.

Evaluation of HIV protease and nucleoside reverse transcriptase inhibitors on proliferation, necrosis, apoptosis in intestinal epithelial cells and electrolyte and water transport and epithelial barrier function in mice

Background

Protease inhibitors (PI's) and reverse transcriptase drugs are important components of highly active antiretroviral therapy (HAART) for treating human acquired immunodeficiency syndrome (AIDS). Long-term clinical therapeutic efficacy and treatment compliance of these agents have been limited by undesirable side-effects, such as diarrhea. This study aims to investigate the effects of selected antiretroviral agents on intestinal histopathology and function in vivo and on cell proliferation and death in vitro.

Methods

Selected antiretroviral drugs were given orally over 7 days, to Swiss mice, as follows: 100 mg/kg of nelfinavir (NFV), indinavir (IDV), didanosine (DDI) or 50 mg/kg of zidovudine (AZT). Intestinal permeability measured by lactulose and mannitol assays; net water and electrolyte transport, in perfused intestinal segments; and small intestinal morphology and cell apoptosis were assessed in treated and control mice. In vitro cell proliferation was evaluated using the WST-1 reagent and apoptosis and necrosis by flow cytometry analysis.

Results

NFV, IDV, AZT and DDI caused significant reductions in duodenal and in jejunal villus length (p < 0.05). IDV and AZT increased crypt depth in the duodenum and AZT increased crypt depth in the jejunum. NFV, AZT and DDI significantly decreased ileal crypt depth. All selected antiretroviral drugs significantly increased net water secretion and electrolyte secretion, except for DDI, which did not alter water or chloride secretion. Additionally, only NFV significantly increased mannitol and lactulose absorption. NFV and IDV caused a significant reduction in cell proliferation in vitro at both 24 h and 48 h. DDI and AZT did not alter cell proliferation. There was a significant increase in apoptosis rates in IEC-6 cells after 24 h with 70 ug/mL of NFV (control: 4.7% vs NFV: 22%) while IDV, AZT and DDI did not show any significant changes in apoptosis compared to the control group. In jejunal sections, IDV and NFV significantly increased the number of TUNEL positive cells.

Conclusion

The PI's, NFV and IDV, increased cell apoptosis in vivo, water and electrolyte secretion and intestinal permeability and decreased villus length and cell proliferation. NFV was the only drug tested that increased cell apoptosis in vitro. The nucleoside reverse transcriptase inhibitors, AZT and DDI, did not affect cell apoptosis or proliferation. These findings may partly explain the intestinal side-effects associated with PI's.

The globalization of health research: harnessing the scientific diaspora

The scientific diaspora is a unique resource for U.S. universities. By drawing on the expertise, experience, and catalytic potential of diaspora scientists, universities can capitalize more fully on their diverse intellectual resources to make lasting contributions to global health. This article examines the unique contributions of the diaspora in international research collaborations, advantages of harnessing the diaspora and benefits to U.S. universities of fostering these collaborations, challenges faced by scientists who want to work with their home countries, examples of scientists engaging with their home countries, and specific strategies U.S. universities and donors can implement to catalyze these collaborations. The contributions of the diaspora to the United States are immense: International students enrolled in academic year 2007-2008 contributed an estimated $15 billion to the U.S. economy. As scientific research becomes increasingly global, the percentage of scientific publications with authors from foreign countries has grown from 8% in 1988 to 20% in 2005. Diaspora scientists can help build trusting relationships with scientists abroad, and international collaborations may improve the health of underserved populations at home. Although opportunities for diaspora networks are increasing, most home countries often lack enabling policies, infrastructure, and resources to effectively utilize their diaspora communities abroad. This article examines how some governments have successfully mobilized their scientific diaspora to become increasingly engaged in their national research agendas. Recommendations include specific strategies, including those that encourage U.S. universities to promote mini-sabbaticals and provide seed funding and flexible time frames.

Malnutrition as an enteric infectious disease with long-term effects on child development

Malnutrition is a major contributor to mortality and is increasingly recognized as a cause of potentially lifelong functional disability. Yet, a rate-limiting step in achieving normal nutrition may be impaired absorptive function due to multiple repeated enteric infections. This is especially problematic in children whose diets are marginal. In malnourished individuals, the infections are even more devastating. This review documents the evidence that intestinal infections lead to malnutrition and that malnutrition worsens intestinal infections. The clinical data presented here derive largely from long-term cohort studies that are supported by controlled animal studies. Also reviewed are the mechanisms by which enteric infections lead to undernutrition and by which malnutrition worsens enteric infections, with implications for potential novel interventions. Further intervention studies are needed to document the relevance of these mechanisms and, most importantly, to interrupt the vicious diarrhea-malnutrition cycle so children may develop their full potential.

Alanyl-glutamine and glutamine supplementation improves 5-fluorouracil-induced intestinal epithelium damage in vitro

In this study, we have examined the role of glutamine derivatives in reducing 5-fluorouracil (5-FU)-induced epithelial damage in an undifferentiated crypt intestinal cell line, IEC-6. In this model, we have investigated proliferation indirectly by detecting the enzyme-derived formazan dye from the tetrazolium salt WST-1 in viable cells at 24 and 48 h after 5-FU treatment. Migration was measured at 12 and 24 h after razor scraping of the cell monolayer. Cell death was measured by quantifying the percentage of apoptotic and necrotic figures by flow cytometry at 12 and 24 h following 5-FU challenge. Neither glutamine nor alanyl-glutamine prevented 5-FU-induced apoptosis and necrosis in IEC-6 cells at 12 and 24 h after 5-FU challenge. However, glutamine and alanyl-glutamine enhanced migration and proliferation when compared with 5-FU-treated controls (P < 0.05). These new findings support our earlier study on the benefit of oral glutamine in enhancing epithelial recovery after 5-FU challenge.

Enteric infections, diarrhea, and their impact on function and development

Enteric infections, with or without overt diarrhea, have profound effects on intestinal absorption, nutrition, and childhood development as well as on global mortality. Oral rehydration therapy has reduced the number of deaths from dehydration caused by infection with an enteric pathogen, but it has not changed the morbidity caused by such infections. This Review focuses on the interactions between enteric pathogens and human genetic determinants that alter intestinal function and inflammation and profoundly impair human health and development. We also discuss specific implications for novel approaches to interventions that are now opened by our rapidly growing molecular understanding.

Wasting and intestinal barrier function in children taking alanyl-glutamine-supplemented enteral formula

OBJECTIVE

We examined the effect of a diet supplemented with alanyl-glutamine (AG) or placebo glycine (G) on intestinal barrier function and growth in children in northeastern Brazil.

PATIENTS AND METHODS

One hundred seven children ages 7.9 to 82.2 months with a weight-for-age (WAZ), height-for-age (HAZ), or weight-for-height (WHZ) z-score less than -1 were studied. From July 2003 to November 2004, 51 study patients received AG (24 g/d) and 56 received G (25 g/d; isonitrogenic concentration) control for 10 days. Lactulose/mannitol excretion ratio was used as a measure of intestinal permeability and was performed on days 1 and 10 of nutritional supplementation. Weight and height were measured on days 1, 10, 30, and 120 of the protocol.

RESULTS

The patients were similar on admission with regard to age, sex, birth weight, nutritional status, lactulose/mannitol ratio, and serum concentrations of glutamine and arginine. The percentage of lactulose urinary excretion significantly improved (decreased) in children receiving AG for 10 days but not in those receiving glycine controls. AG significantly increased cumulative change over 120 days in WHZ and WAZ scores but not HAZ scores after adjustment for age and season in comparison with the placebo glycine group.

CONCLUSIONS

Children tolerated AG-supplemented enteral formula well, and it significantly improved cumulative WHZ and WAZ over 120 days in comparison with children in the placebo glycine group. The data also suggested a beneficial effect of AG in the barrier function paracellular pathway, albeit with reduced mannitol excretion. Thus, although the effect of AG on reduced mannitol concentration requires clarification, AG appears to improve nutrition and barrier function.

An updated review on Cryptosporidium and Giardia

Cryptosporidium and Giardia are two of the most commonly occurring enteric protozoans. They are responsible for diarrheal diseases that may lead to nutritional deficiencies and significant morbidity and mortality, especially among children in developing countries and patients who have immune defects. Both are difficult to diagnose with microscopic techniques. This article provides an updated review of the epidemiology, pathogenesis, clinical manifestations, and treatment of Cryptosporidium and Giardia.

Caspase and bid involvement in Clostridium difficile toxin A-induced apoptosis and modulation of toxin A effects by glutamine and alanyl-glutamine in vivo and in vitro

Clostridium difficile is the leading cause of nosocomial bacterial diarrhea. Glutamine and its stable and highly soluble derivative alanyl-glutamine, have been beneficial in models of intestinal injury. In this study, we extend our work on the mechanisms of Clostridium difficile toxin A (TxA)-induced apoptosis in human intestinal epithelial T84 cells and evaluate the effects of glutamine and alanyl-glutamine on TxA-induced apoptosis in vitro and disruption of ileal mucosa in vivo. T84 cells were incubated with TxA (100 ng/ml) in medium with or without glutamine or alanyl-glutamine (3 to 100 mM). Apoptosis was evaluated by DNA fragmentation in vitro and the terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end-labeling method in vivo. Caspase and Bid involvement were investigated by Western blotting. Ligated rabbit ileal loops were used for the evaluation of intestinal secretion, mucosal disruption, and apoptosis. TxA induced caspases 6, 8, and 9 prior to caspase 3 activation in T84 cells and induced Bid cleavage by a caspase-independent mechanism. Glutamine or alanyl-glutamine significantly reduced TxA-induced apoptosis of T84 cells by 47% and inhibited activation of caspase 8. Both glutamine and alanyl-glutamine reduced TxA-induced ileal mucosal disruption and secretion. Altogether, we further delineated the apoptosis-signaling cascade induced by TxA in T84 cells and demonstrated the protective effects of glutamine and alanyl-glutamine. Glutamine and alanyl-glutamine inhibited the apoptosis of T84 cells by preventing caspase 8 activation and reduced TxA-induced intestinal secretion and disruption.

Infectious diarrhea in developed and developing countries

Diarrhea from gastrointestinal infection remains a common problem. In industrialized countries, management is aimed at reducing morbidity and defining groups that may benefit from further investigation. Most infectious diarrhea is self-limiting and only requires supportive management. Viral agents are increasingly recognized as causative agents of epidemic and sporadic diarrhea. In developing countries, diarrhea is a major cause of mortality in children. Oral rehydration therapy, guided by a clinical assessment of the degree of dehydration, is cheap, simple, and effective and remains the mainstay of management of infant diarrhea. Controversies focus on the optimal formulation of oral rehydration solution. A vaccine against rotavirus has the potential to save millions of lives worldwide.

Pathophysiology and impact of enteric bacterial and protozoal infections: new approaches to therapy

Despite numerous scientific advances in the past few years regarding the pathogenesis, diagnostic tools and treatment of infectious enteritis, enteric infections remain a serious threat to health worldwide. With globalization of the food supply, the increase in travel, mass food processing and antibiotic resistance, infectious diarrhea has become a critical concern for both developing and developed countries. Oral rehydration therapy has been cited as the most important medical discovery of the century due to the millions of lives that have been saved. However, statistics concerning diarrhea-induced mortality and the highly underestimated morbidity continue to demonstrate the severity of the problem. A more complete understanding of the pathogenesis of infectious diarrhea and potential new vaccines and effective treatments are badly needed. In addition, public health preventive actions, such as early detection of outbreaks, care with food, water and sanitation and, where relevant, immunization, should be considered a priority. This article provides an overview of the epidemiological impact, pathogenesis and new approaches to the management of enteric infections.

Effect of glutamine on water and sodium absorption in human jejunum at baseline and during PGE1-induced secretion

Glutamine, a major fuel for enterocytes, stimulates water and sodium absorption in animal models of secretory diarrhea, but data in humans are still limited. The aim of this study was to investigate the effect of glutamine on jejunal absorption during hypersecretion in humans. In six healthy adults, the effects of glutamine on jejunal absorption were assessed with a triple-lumen tube on two occasions, at baseline and during PGE1-induced hypersecretion (0.1 μg·kg−1·min−1) in a random order. Isoosmolar solutions containing polyethylene glycol 4000 as nonabsorbable marker were infused in the jejunum at 10 ml/min over 1-h periods: saline (sodium chloride 308 mmol/l), glucose-mannitol 45:45 mM, glucose 90 mM, alanine-glucose 45:45 mM, glutamine-glucose 45:45 mM, and glutamine 90 mM. Net absorptive and secretory fluxes were measured at steady state. At baseline, glutamine- and alanine-containing solutions induced a threefold increase of water and sodium absorption ( P < 0.05); 90 mM glutamine stimulated water absorption more than 90 mM glucose (3.6 ± 0.6 vs. 1.9 ± 0.3 ml·min−1·30 cm−1, P < 0.05). PGE1-induced hypersecretion was reduced ( P < 0.05) by solutions of alanine-glucose, glutamine-glucose, and glutamine 90 mM ( P < 0.05) and reversed to absorption by alanine-glucose and glutamine-glucose. Glutamine and alanine absorption was nearly complete and was not influenced by PGE1. In conclusion, glutamine stimulates water and electrolyte absorption in human jejunum, even during experimental hypersecretion. In addition to the metabolic effects of glutamine, these results support the evaluation of glutamine-containing solutions for the rehydration and the nutritional support of patients with secretory diarrhea.

Alanyl-glutamine hastens morphologic recovery from 5-fluorouracil-induced mucositis in mice

OBJECTIVE

In this study, we postulated the beneficial role of oral alanyl-glutamine, a more stable glutamine derivative to decrease 5-fluorouracil (5-FU)-induced mucositis in mice.

METHODS

We measured different morphologic parameters to assess structural changes over time in the small bowel, including crypt depth, villus height, villus area, mitotic and apoptotic indices at the crypt level using terminal deoxyuridine triphosphate nick end labeling, and hematoxylin-eosin staining of ileal tissue. In addition, we analyzed the effect of different alanyl-glutamine concentrations on animal weight curves after 5-FU treatment.

RESULTS

Neither glutamine nor alanyl- glutamine prevented the 5-FU intestinal structural damage or apoptosis in crypt enterocytes at 24 h after 5-FU challenge. However, we found that alanyl-glutamine, but not glutamine, speeds intestinal recovery when compared with 5-FU-treated controls (P < 0.05), predominantly by enhancing mitotic activity and crypt length.

CONCLUSION

Our findings provide important data to support clinical studies of oral alanyl-glutamine in 5-FU-induced mucositis.

Diarrhea and reduced levels of antiretroviral drugs: improvement with glutamine or alanyl-glutamine in a randomized controlled trial in northeast Brazil

The effects of therapy with glutamine and alanyl-glutamine on diarrhea and antiretroviral drug levels in patients with acquired immune deficiency syndrome (AIDS) were examined in a randomized, double-blinded, placebo-controlled study in northeast Brazil. Patients with AIDS and with diarrhea and/or wasting were randomized into 4 groups to determine the efficacy of glutamine or high- or low-dose alanyl-glutamine given for 7 days, compared with isonitrogenous glycine given to control subjects. All patients in whom baseline antiretroviral drug levels were determined had low levels 2 h after dosing. Gastrointestinal symptom scores improved with receipt of high-dose alanyl-glutamine (P<.05) or glutamine (P<.01). Antiretroviral drug levels increased in patients given alanyl-glutamine (P=.02) or glutamine (P=.03) by 113% (P=.02) and 14% (P=.01), respectively. Antiretroviral drug resistance mutations were common in all groups. The dose-related efficacy of alanyl-glutamine and glutamine in treating diarrhea and in increasing antiretroviral drug levels shows that these supplements may help to improve therapy for patients with AIDS who have diarrhea and/or wasting in developing, tropical areas.

Cholera, diarrhea, and oral rehydration therapy: triumph and indictment

Cholera drove the sanitary revolution in the industrialized world in the 19th century and now is driving the development of oral rehydration therapy (ORT) in the developing world. Despite the long history of cholera, only in the 1960s and 1970s was ORT fully developed. Scientists described this treatment after the discovery of the intact sodium-glucose intestinal cotransport in patients with cholera. This new understanding sparked clinical studies that revealed the ability of ORT to reduce the mortality associated with acute diarrheal disease. Despite the steady reductions in mortality due to acute dehydrating diarrheal diseases achieved by ORT, the costly morbidity due to these diseases remains, the result of a failure to globalize sanitation and to control the developmental impact of diarrheal diseases and their associated malnutrition. New advances in oral rehydration and nutrition therapy and new methods to recognize its costs are discussed in this review.