Minimal enteral feeding reduces the risk of sepsis in feed-intolerant very low birth weight newborns

AIMS

To evaluate the efficacy and safety of minimal enteral feeding (MEF) nutritional practice in feed-intolerant very low birth weight (VLBW) infants.

METHODS

A retrospective design using data reported in the clinical charts of VLBW newborns consecutively observed in neonatal intensive care units (NICU) that presents feed intolerance. During the study period, two feeding strategies were adopted: total parenteral nutrition (PN) (group 1) or PN plus MEF (group 2), for at least 24 h. Primary outcome was the time to reach full enteral feeding; secondary outcomes were the occurrence of sepsis, the time to regain birth weight, the length of hospitalization, the occurrence of necrotizing enterocolitis (NEC) Bell stage >II and death.

RESULTS

In total, 102 newborns were evaluated: 51 in group 1, and 51 in group 2. Neonates in group 2 achieved full enteral nutrition earlier (8 days, interquartile range [IQR] 5) compared with subjects receiving total PN (11 days, IQR 5, p < 0.001). A reduction of sepsis episodes was observed in group 2 (15.7%) compared with group 1 (33.3%, p = 0.038). Additionally, subjects in group 2 regained their birth weight and were discharged earlier. The occurrence of NEC and death were similar in the two groups.

CONCLUSION

Minimal enteral feeding in very low birth weight infants presenting feed intolerance reduces the time to reach full enteral feeding and the risk of sepsis. This feeding practice does not increase the risk of necrotizing enterocolitis and death.

Comparative therapeutic effects of metformin and vitamin E in a model of non-alcoholic steatohepatitis in the young rat

Only in the last few years has non-alcoholic steatohepatitis been recognized as an important and relatively common liver disease. To date, the therapeutic options are limited, vitamin E and metformin have been proposed for the treatment of this condition, although their mechanisms are not completely clarified as yet. The aim of this study was to investigate the anti-inflammatory and anti-oxidative mechanisms of these drugs in an experimental model of non-alcoholic steatohepatitis in the young rat. Male rats, just after weaning, were divided into four groups: a control group that received a standard diet; a high fat diet group; two high fat diet fed groups treated with vitamin E or metformin, respectively. After 4 weeks, we evaluated in the liver the modification of lipid peroxidation, assessed by malondialdehyde, TNF-alpha levels, S-nitrosylated protein, inducible nitric oxide sinthase (iNOS), and peroxisome proliferators-activated receptors (PPAR) expression and metalloproteinase activity. High fat diet increased malondialdehyde, nitrotyrosilated proteins, and TNF-alpha tissue content. Moreover, a decrease of PPAR-alpha and an increase of PPAR-gamma expression were observed. An increase of metalloproteinase activity was also shown. Among drug treatments, metformin reduced body weight gain and fat mass, metalloproteinase activity, and TNF-alpha tissue content, while it restored PPAR-alpha expression and downregulated PPAR-gamma expression. Vitamin E reduced the oxidative damage, protein nitrotyrosilation, and tissue TNF-alpha levels. Moreover a decrease of PPAR-gamma expression was also shown. These findings confirm the efficacy of both drugs as therapeutic tools in preventing the early onset of liver damage and non-alcoholic fatty liver disease progression.

Clinical variability of cardio-facio-cutaneous syndrome: report of two additional cases

We describe two new cases of cardio-facio-cutaneous (CFC) syndrome, and underline the clinical variability of the CFC phenotype in our two patients presenting with border-line psychomotor development. The first patient showed some additional clinical manifestations, such as cryptorchidism and scoliosis, and the second one had atypical skin lesions.

Probiotics for treatment of acute diarrhoea in children: randomised clinical trial of five different preparations

OBJECTIVE

To compare the efficacy of five probiotic preparations recommended to parents in the treatment of acute diarrhoea in children. Design Randomised controlled clinical trial in collaboration with family paediatricians over 12 months.

SETTING

Primary care.

PARTICIPANTS

Children aged 3-36 months visiting a family paediatrician for acute diarrhoea.

INTERVENTION

Children's parents were randomly assigned to receive written instructions to purchase a specific probiotic product: oral rehydration solution (control group); Lactobacillus rhamnosus strain GG; Saccharomyces boulardii; Bacillus clausii; mix of L delbrueckii var bulgaricus, Streptococcus thermophilus, L acidophilus, and Bifidobacterium bifidum; or Enterococcus faecium SF68.

MAIN OUTCOME MEASURES

Primary outcomes were duration of diarrhoea and daily number and consistency of stools. Secondary outcomes were duration of vomiting and fever and rate of admission to hospital. Safety and tolerance were also recorded.

RESULTS

571 children were allocated to intervention. Median duration of diarrhoea was significantly shorter (P<0.001) in children who received L rhamnosus strain GG (78.5 hours) and the mix of four bacterial strains (70.0 hours) than in children who received oral rehydration solution alone (115.0 hours). One day after the first probiotic administration, the daily number of stools was significantly lower (P<0.001) in children who received L rhamnosus strain GG and in those who received the probiotic mix than in the other groups. The remaining preparations did not affect primary outcomes. Secondary outcomes were similar in all groups.

CONCLUSIONS

Not all commercially available probiotic preparations are effective in children with acute diarrhoea. Paediatricians should choose bacterial preparations based on effectiveness data.

TRIAL REGISTRATION NUMBER

Current Controlled Trials ISRCTN56067537 [controlled-trials.com].

Results from the pediatric European register for treatment of Helicobacter pylori (PERTH)

BACKGROUND AND AIM

Data on the eradication treatment for childhood Helicobacter pylori are scanty. A register was established on the European Society for Pediatric Gastroenterology Hepatology and Nutrition (ESPGHAN) website to collect data on treatment performed by European pediatricians to ascertain what is practiced in the field.

SUBJECTS

From January 2001 to December 2002, information on 597 children were entered by 23 European Centers, but only data of 518 treated children were completed and analyzed (86.7%, 262 male subjects, median age 9 years, range 1-14). According to their nationality, 226 children were from Southern Europe, 132 from Eastern Europe, 68 from Western Europe, and 4 from northern Europe, 68 from North Africa, and 20 from Asia. At endoscopy, 454 children had gastritis and 64 had ulcer (12.3%). Antibiotic sensitivity, tested in 361 cases, revealed 18% clarithromycin-resistant and 19% metronidazole-resistant H. pylori strains.

RESULTS

Treatment was performed for 1 week in 388 and for 2 weeks in 130 children. Antibiotics were associated with proton pump inhibitors (PPI) in 345 and with bismuth in 121 children. Triple therapy was given to 485 children, dual therapy to 26, quadruple to 7. Follow-up data, by (13)C-Urea-Breath Test or histology or both, were available for 480 children. Overall eradication rate was 65.6%, significantly higher in children with ulcer (79.7%) than without (63.9%, p = .001). When given as first treatment, bismuth-containing triple therapies were more efficacious than PPI-containing ones (77% versus 64%, p = .02, OR 1.88, 95% CI 1.1-3.3). Twenty-seven different treatment regimens were used, but only six were administered to at least 18 children (range 18-157). There was no difference between treatments given for 1 or 2 weeks, or given as first or second therapies.

CONCLUSION

European pediatricians entering data in the register used 27 different regimens. Bismuth-containing therapies resulted in higher eradication rate. Omeprazole-containing triple therapies were the most used although their efficacy was low. Therapies recommended for adults do not appear to be suitable for children.

Polymorphisms of tumor necrosis factor-alpha but not MDR1 influence response to medical therapy in pediatric-onset inflammatory bowel disease

AIM

We investigated the contribution of variants of tumour necrosis factor (TNF)-alpha and MDR1 genes in the predisposition and response to medical therapy in a large pediatric cohort of patients with Crohn disease (CD) and ulcerative colitis (UC).

PATIENTS AND METHODS

In this study, 200 patients with CD, 186 patients with UC, 434 parents (217 trios), and 347 healthy unrelated controls were investigated. Single-nucleotide polymorphisms -G308A and -C857T of the TNF-alpha gene and C3435T of the MDR1 gene were investigated and correlated with clinical subphenotypes and efficacy of medical therapy.

RESULTS

The frequency of the -308A allele of the TNF-alpha gene was significantly increased in both patients with CD (15%; odds ratio [OR] = 2.79; P < 0.01) and patients with UC (11%; OR = 1.96; P < 0.003) compared with controls (6%). Carriers of this allele were 27% in CD (OR = 2.94; P < 0.01) and 19% in UC (OR = 1.86; P = 0.015) compared with 11% in healthy controls. No significant difference was found for both the -C857T and C3435T single-nucleotide polymorphisms. With the genotype/phenotype analysis, no correlation in patients with UC with the MDR1 gene was found. CD carriers of the -308A allele had a higher frequency of surgical resection (35% vs 20%; OR = 2.1; P = 0.035) and more frequent resistance to steroids (22% vs 8%; OR = 0.29; P = 0.032) compared with noncarriers. These findings were confirmed by stepwise logistic regression.

CONCLUSIONS

In our pediatric cohort, the promoter -308A polymorphism of TNF-alpha but not the MDR1 gene is significantly involved in the predisposition to both CD and UC. This polymorphism carries a significant reduction in response to steroid therapy, probably leading to a more frequent need for surgical resection.

Zinc fights diarrhoea in HIV-1-infected children: in-vitro evidence to link clinical data and pathophysiological mechanism

Diarrhoea-related morbidity is reduced by zinc supplementation in HIV-1-infected children. The mechanisms of this effect are largely undefined. We provide evidence for role for Tat (transactivating peptide produced by HIV-1) in the pathogenesis of diarrhoea in AIDS patients. In this study we showed that zinc, preventing Tat-induced fluid secretion, directly limits a specific mechanism of HIV-1-related diarrhoea. Our data support a 'zinc approach' in adjunct to specific antiretroviral therapy in HIV-1-infected children.

Growth hormone regulates intestinal ion transport through a modulation of the constitutive nitric oxide synthase-nitric oxide-cAMP pathway

AIM: Growth hormone (GH) directly interacts with the enterocyte stimulating ion absorption and reducing ion secretion induced by agonists of cAMP. Since nitric oxide (NO) is involved in the regulation of transepithelial ion transport and acts as a second messenger for GH hemodynamic effects, we tested the hypothesis that NO may be involved in the resulting effects of GH on intestinal ion transport.

METHODS: Electrical parameters reflecting trans-epithelial ion transport were measured in Caco-2 cell monolayers mounted in Ussing chambers and exposed to GH and cholera toxin (CT) alone or in combination, in the presence or absence of the NO synthase (NOS) inhibitor, Nω-nitro-L-arginine methyl ester (L-NAME). Similar experiments were conducted to determine cAMP and nitrite/nitrate concentrations. NOS expression was assayed by Western blot analysis.

RESULTS: L-NAME causes total abrogation of absorptive and anti-secretory effects by GH on intestinal ion transport. In addition, L-NAME was able to inhibit the GH-effects on intracellular cAMP concentration under basal conditions and in response to CT. GH induced a Ca²⁺-dependent increase of nitrites/nitrates production, indicating the involvement of the constitutive rather than the inducible NOS isoform, which was directly confirmed by Western blot analysis.

CONCLUSION: These results suggest that the GH effects on intestinal ion transport, either under basal conditions or in the presence of cAMP-stimulated ion secretion, are mediated at an intracellular level by the activity of cNOS.

Therapy with gastric acidity inhibitors increases the risk of acute gastroenteritis and community-acquired pneumonia in children

OBJECTIVE

Gastric acidity (GA) inhibitors, including histamine-2 receptor antagonists (H2 blockers) and proton pump inhibitors (PPIs), are the mainstay of gastroesophageal reflux disease (GERD) treatment. A prolonged GA inhibitor-induced hypochlorhydria has been suggested as a risk factor for severe gastrointestinal infections. In addition, a number of papers and a meta-analysis have shown an increased risk of pneumonia in H2-blocker-treated intensive care patients. More recently, an increased risk of community-acquired pneumonia associated with GA inhibitor treatment has been reported in a large cohort of adult patients. These findings are particularly relevant to pediatricians today because so many children receive some sort of GA-blocking agent to treat GERD. To test the hypothesis that GA suppression could be associated with an increased risk of acute gastroenteritis and pneumonia in children treated with GA inhibitors, we conducted a multicenter, prospective study.

METHODS

The study was performed by expert pediatric gastroenterologists from 4 pediatric gastroenterology centers. Children (aged 4-36 months) consecutively referred for common GERD-related symptoms (for example, regurgitation and vomiting, feeding problems, effortless vomiting, choking), from December 2003 to March 2004, were considered eligible for the study. Exclusion criteria were a history of GA inhibitors therapy in the previous 4 months, Helicobacter pylori infection, diabetes, chronic lung or heart diseases, cystic fibrosis, immunodeficiency, food allergy, congenital motility gastrointestinal disorders, neuromuscular diseases, or malnutrition. Control subjects were recruited from healthy children visiting the centers for routine examinations. The diagnosis of GERD was confirmed in all patients by standard criteria. GA inhibitors (10 mg/kg ranitidine per day in 50 children or 1 mg/kg omeprazole per day in 50 children) were prescribed by the physicians for 2 months. All enrolled children were evaluated during a 4-month follow-up. The end point was the number of patients presenting with acute gastroenteritis or community-acquired pneumonia during a 4-month follow-up study period.

RESULTS

We obtained data in 186 subjects: 95 healthy controls and 91 GA-inhibitor users (47 on ranitidine and 44 on omeprazole). The 2 groups were comparable for age, gender, weight, length, and incidence of acute gastroenteritis and pneumonia in the 4 months before enrollment. Rate of subjects presenting with acute gastroenteritis and community-acquired pneumonia was significantly increased in patients treated with GA inhibitors compared with healthy controls during the 4-month follow-up period. In the GA inhibitor-treated group, the rate of subjects presenting with acute gastroenteritis and community-acquired pneumonia was increased when comparing the 4 months before and after enrollment. No differences were observed between H2 blocker and PPI users in acute gastroenteritis and pneumonia incidence in the previous 4 months and during the follow-up period. On the contrary, in healthy controls, the incidence of acute gastroenteritis and pneumonia remained stable.

CONCLUSIONS

This is the first prospective study performed in pediatric patients showing that the use of GA inhibitors was associated with an increased risk of acute gastroenteritis and community-acquired pneumonia in GERD-affected children. It could be interesting to underline that we observed an increased incidence of intestinal and respiratory infection in otherwise healthy children taking GA inhibitors for GERD treatment. On the contrary, the majority of the previous data showed that the patients most at risk for pneumonia were those with significant comorbid illnesses such as diabetes or immunodeficiency, and this points to the importance of GA suppression as a major risk factor for infections. In addition, this effect seems to be sustained even after the end of therapy. The results of our study are attributable to many factors, including direct inhibitory effect of GA inhibitors on leukocyte functions and qualitative and quantitative gastrointestinal microflora modification. Additional studies are necessary to investigate the mechanisms of the increased risk of infections in children treated with GA inhibitors, and prophylactic measures could be considered in preventing them.

Inhibitory effect of HIV-1 Tat protein on the sodium-D-glucose symporter of human intestinal epithelial cells

OBJECTIVE

The pathophysiology of HIV-1-related intestinal dysfunction is largely unknown. We previously found that the transactivator factor peptide (Tat) produced by HIV-1 induces ion secretion and inhibits cell proliferation in human enterocytes. Because sugar malabsorption is a frequent feature in AIDS patients, we evaluated whether Tat inhibits intestinal glucose absorption.

DESIGN AND METHODS

We measured Na-D-glucose symporter (SGLT-1) activity and determined its phenotypic expression in Caco-2 cells, in the presence and absence of Tat, in uptake experiments using a non-metabolized radiolabelled glucose analogue, and by western blot analysis, respectively. alpha-Tubulin staining was used to study the effects exerted by Tat on cell structure.

RESULTS

Tat dose dependently inhibited glucose uptake by human enterocytes. This effect was prevented by anti-Tat polyclonal antibodies and by L-type Ca channels agonist Bay K8644. Western blot analysis of cellular lysates and brush-border membrane preparations showed that Tat induced SGLT-1 missorting. Tat also caused a dramatic decrease in alpha-tubulin staining, which indicates dysruption of the cytoskeleton organization.

CONCLUSIONS

Tat acutely impairs intestinal glucose absorption through SGLT-1 missorting. This result indicates that Tat is directly involved in AIDS-associated intestinal dysfunction.

Combined use of noninvasive tests is useful in the initial diagnostic approach to a child with suspected inflammatory bowel disease

OBJECTIVE

To assess the effectiveness of the combined use of fecal calprotectin (FC), anti-Saccharomyces cerevisiae antibody (ASCA), perinuclear staining antineutrophil antibody (pANCA), small intestinal permeability test (IP), and bowel wall ultrasonography measurement (BWUS) in the diagnostic work-up of children with suspected inflammatory bowel disease (IBD).

METHODS

All children referred for initial assessment of possible IBD were eligible. Patients with symptoms or signs (right-lower quadrant mass, perianal disease, or hematochezia) mandating a complete work-up for IBD were excluded. All enrolled patients underwent a clinical, laboratory, radiographic, and endoscopic evaluation including biopsy examinations. The immunoglobulin (Ig)G and IgA ASCA, IgG pANCA, FC, IP, and BWUS were tested in all patients at the initial assessment.

RESULTS

A final diagnosis of IBD was made in 27 patients: 17 Crohn disease and 10 ulcerative colitis. Eighteen children had other gastrointestinal diagnoses (8 functional bowel disorders, 5 food allergy-mediated diseases, 4 infectious enterocolitis, 1 familial Mediterranean fever). In patients with simultaneous abnormal values of FC, BWUS, and ASCA/pANCA, the estimated probability of having IBD was 99.47%. Patients with negative results on all tests had a 0.69% of probability of IBD.

CONCLUSIONS

The incorporation of noninvasive diagnostic tests into the initial diagnostic approach may avoid unnecessary invasive procedures and facilitate clinical decision-making when the diagnosis of IBD in children is initially uncertain.

Guanylin and E. coli heat-stable enterotoxin induce chloride secretion through direct interaction with basolateral compartment of rat and human colonic cells

We previously detected specific binding activity of Escherichia coli heat-stable enterotoxin (ST), the guanylin exogenous ligand, in rat colonic basolateral membranes. Because guanylin circulates in the bloodstream, we tested the hypothesis that it modulates intestinal ion transport by acting on the serosal side of intestinal cells. The effects of the mucosal and serosal addition of ST and guanylin on ion transport were investigated in the rat proximal colon and in Caco-2 cells in Ussing chambers, by monitoring short-circuit current (Isc). cGMP concentration was measured in Caco-2 cells by RIA. Mucosal ST addition induced an increase in Isc in rat proximal colon consistent with anion secretion. Serosal addition induced the same effects but to a lesser extent. The electrical effects observed in Caco-2 cells paralleled those observed in rat proximal colon. A pattern similar to the electrical response was observed with cGMP concentration. Guanylin addition to either side of Caco-2 cells induced the same effects as ST, although to a lesser extent. In all conditions, the electrical effect disappeared in the absence of chloride. ST directly interacts with basolateral receptors in the large intestine inducing chloride secretion through an increase of cGMP. However, the serosal effects are less pronounced compared with those observed with mucosal addition. Guanylin shows the same pattern, suggesting that it plays a role in the regulation of ion transport in the colon, but the relative importance of serosally mediated secretion remains to be determined.

Zinc Inhibits Cholera Toxin–Induced, but NotEscherichia coliHeat‐Stable Enterotoxin–Induced, Ion Secretion in Human Enterocytes

BACKGROUND

Because zinc deficiency in malnourished children is associated with severe diarrhea, use of zinc supplementation has been proposed as an adjunct to oral rehydration. However, the effects of zinc on enterocyte ion transport are largely unknown. The objective of the present study was to investigate the effects of zinc on transepithelial ion transport under basal conditions and under conditions of enterotoxin-induced ion secretion.

METHODS

Ion transport was investigated by monitoring electrical parameters in human intestinal Caco-2 cells that were mounted in Ussing chambers and exposed to increasing concentrations of zinc, both in the absence and presence of either cholera toxin (CT) or Escherichia coli heat-stable enterotoxin (ST). Intracellular cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) concentrations were also determined.

RESULTS

The addition of zinc to the luminal or basolateral side of enterocytes induced a chloride-dependent, dose-related decrease in short-circuit current, indicating ion absorption. It also resulted in a substantial reduction in CT-induced ion secretion and in cAMP concentration. E. coli ST-induced ion secretion and cGMP concentration were not affected. Ion absorption peaked at 35 mu mol/L zinc, whereas excess zinc load induced active ion secretion.

CONCLUSIONS

By causing a decrease in cAMP concentration, zinc directly promotes ion absorption and substantially reduces CT-induced, but not E. coli ST-induced, ion secretion.

Butyrate as an effective treatment of congenital chloride diarrhea

BACKGROUND & AIMS

Many therapeutic attempts have demonstrated to be ineffective in reducing the severity of congenital chloride diarrhea and its long-term complications. The short-chain fatty acid butyrate stimulates intestinal water and ion absorption through a variety of mechanisms, including the activation of a parallel Cl-/butyrate and Na+/H+ exchanger. In this case report, we report the therapeutic efficacy of butyrate on an 11-year-old patient affected by congenital chloride diarrhea.

METHODS

The efficacy of increasing doses of oral butyrate (from 50 to 100 mg/kg/day) was investigated through the daily evaluation of stool volume, bowel movements, fecal incontinence, serum, and stool electrolytes concentrations. The modifications in transepithelial intestinal ion transport elicited by butyrate were examined by rectal dialysis study.

RESULTS

A butyrate dose of 100 mg/kg/day induced a normalization of stool pattern and of serum and fecal electrolytes concentration. The rectal dialysis study demonstrated a proabsorptive effect induced by butyrate on Na+, Cl-, and K+ intestinal transport. Butyrate therapy was well tolerated during the entire 12-month observation period, and the stool pattern and fecal and serum ion concentrations remained stable within the normal ranges. No clinical adverse events or episodes of dehydration requiring hospital care were observed.

CONCLUSIONS

Butyrate could be effective in treating congenital chloride diarrhea. It is easily administered, useful in preventing severe dehydration episodes, and may be a promising therapeutic approach for a long-term treatment in this rare and severe condition.

Microflora in inflammatory bowel diseases: a pediatric perspective

Several lines of evidence link inflammatory bowel diseases to modifications of intestinal microflora. Epidemiologic and clinical data suggest a triggering role for select agents in ulcerative colitis and in Crohn disease. Experimental evidence indicates that intestinal microorganisms are needed for developing intestinal inflammation in IL-10 knockout mice, and this is associated with an increased number of adherent clostridia and a decrease of lactobacilli and bifidobacteria. It may be hypothesized that a host-agent-specific relationship leads to an abnormal immune response, which may be genetically driven in select inflammatory bowel diseases. However, different from adults, the pattern of intestinal microflora undergoes profound changes during the early stage of life, contributing to the development of the immune system. A close relationship exists between microbiologic and immunologic imprinting. The microbiologic imprinting in neonates may be modified using bacterial probiotics that colonize the intestine, modify the immune response, and decrease the risk for atopy. Probiotics may decrease the recurrences of inflammatory bowel diseases. Preliminary evidence of intestinal antiinflammatory effects has been detected in children with cystic fibrosis. Overall these data provide the rationale to investigate the interaction between intestinal microflora and the local and general immune response in children with, or at risk for, inflammatory bowel diseases. This approach may be a key for understanding the pathophysiology of intestinal inflammation and may disclose novel strategies to educate better the immune system, particularly during its developmental stage.

Effects of disease activity on anti-Saccharomyces cerevisiae antibodies: implications for diagnosis and follow-up of children with Crohn's disease

BACKGROUND

To determine diagnostic accuracy of anti-Saccharomyces cerevisiae antibodies (ASCA) in identifying children with inflammatory bowel disease (IBD) and to differentiate Crohn's disease (CD) from other IBD forms; and to determine the effect of medical or surgical treatment and of disease location and activity on ASCA titers.

METHODS

Serum samples were obtained from 196 IBD children and 142 controls. ASCA IgA and IgG titers were measured by ELISA. Measurements were repeated during the follow up of CD children.

RESULTS

ASCA titers were significantly higher in CD than in other IBD and in control patients. Combination of IgA and IgG ASCA positivity was highly specific for CD. Medical treatment and disease location did not influence assay results. Significantly lower ASCA titers were obtained in CD children with intestinal resection compared to CD-affected children who did not undergo surgical resection. ASCA titers correlated significantly with disease activity, and children with severe active disease showed higher ASCA values compared to those in remission. A significant reduction of ASCA was observed during the follow-up of CD children when clinical remission was achieved.

CONCLUSIONS

The diagnostic accuracy of ASCA is influenced by disease activity and this suggests an additional use for the follow-up of CD children of this assay.

Nitric oxide produced by the enterocyte is involved in the cellular regulation of ion transport

The role of nitric oxide (NO) in the intestinal basal ion transport and under conditions of enterotoxin-induced ion secretion is controversial. Namely it is not clear whether NO enhances or counteracts intestinal ion secretion and whether the effects on transport result from a direct interaction with the enterocyte. The cell origin of NO is also unclear. We have tested the hypothesis that NO produced by the enterocyte directly regulates ion transport processes either in basal condition or in response to cholera toxin-induced secretion. Electrical variables reflecting transepithelial ion transport were measured in Caco-2 cell monolayers mounted in Ussing chambers exposed to the NO synthase inhibitor Nomega-nitro-l-arginine methyl ester, in the presence or absence of cholera toxin. cAMP concentrations were also measured. NO release was determined by nitrite-nitrate concentration. NO synthase activities were assayed by Western blot analysis. Nomega-nitro-l-arginine methyl ester had a secretory effect, as judged by increased basal short-circuit current and cAMP concentration. It also increased cholera toxin-induced electrical response and cAMP production. Either cholera toxin or the cAMP analog 8-bromo-cAMP induced a rapidly progressive and Ca2+-dependent increase in NO concentration, suggesting a homeostatic up-regulation of the constitutive form of NO synthase. Western blot analysis showed an increase in constitutive NO synthase enzyme isoform. These results indicate that the enterocyte regulates its own ion transport processes, either in basal condition or in the presence of active secretion, through the activation of a constitutive NO synthase-NO pathway, functioning as a braking force of cAMP-induced ion secretion.

Effects of HIV-1 Tat protein on ion secretion and on cell proliferation in human intestinal epithelial cells

BACKGROUND & AIMS

Severe diarrhea and enteropathy of unknown origin are frequent in patients infected with human immunodeficiency type 1 virus (HIV-1). The HIV-1 transactivating factor protein (Tat) is a key factor in the pathogenesis of acquired immunodeficiency syndrome. We investigated whether Tat could directly induce ion secretion and cell damage in enterocytes.

METHODS

Electrical parameters (ion transport studies) were measured in Caco-2 cell monolayers and in human colonic mucosa specimens mounted in Ussing chambers. The effect of Tat on intestinal mucosa integrity was determined by monitoring the transepithelial electrical resistance of Caco-2 cell monolayers. (3)H-thymidine incorporation and cell count were used to evaluate the effect of Tat on cell growth. Intracellular calcium concentrations were measured at the single-cell level using microfluorometry technique.

RESULTS

Tat protein induced ion secretion in Caco-2 cells and in human colonic mucosa similar to that induced by bacterial enterotoxins. It also significantly prevented enterocyte proliferation. In both instances, the effect of Tat was maximum at concentrations within the range detected in the sera of HIV-1-infected patients. Anti-Tat antibodies inhibited both effects. Ion secretion and the antiproliferative effects were mediated by L-type Ca(2+) channels. An increase in intracellular calcium concentration in Caco-2 cells was found after addition of Tat.

CONCLUSIONS

These results indicate that Tat may be involved in HIV-1-related intestinal disease through direct interaction with enterocytes.

Effects of nutritional rehabilitation on intestinal function and on CD4 cell number in children with HIV

BACKGROUND

A complex interplay of malnutrition, intestinal dysfunction, and immune impairment increases the progression of human immunodeficiency virus (HIV) disease in children. The authors tested the hypothesis that nutritional support improves intestinal and immune functions in children infected with human immunodeficiency virus (HIV).

METHODS

A questionnaire was circulated through reference centers for pediatric HIV infection to evaluate the effects of nutritional rehabilitation, total parenteral nutrition (TPN) and enteral nutrition (EN), in children. Information included changes in body weight, CD4 cell numbers, and intestinal absorption-as judged by the xylose load-before and after clinical nutritional support and the outcome of children.

RESULTS

Sixty-two children underwent nutritional support: 46 received TPN and 16 received EN. All but three had full-blown acquired immunodeficiency syndrome, and all were severely malnourished. Baseline clinical conditions were worse in children receiving TPN than in those receiving EN. Intestinal dysfunction was detected in all children who received xylose oral load. A significant increase in CD4 cell count, xylose levels, and body weight followed EN. A similar pattern was observed after TPN, but none of the parameters significantly changed. Twenty-seven children who received TPN and three who received EN eventually died. Fourteen who received TPN and eight who received EN were shifted to oral feeding, and five who received TPN and five who received EN continued with clinical nutritional support at the end of the observation period.

CONCLUSIONS

Nutritional intervention may restore intestinal absorption and increase CD4 cell numbers. The efficacy of nutritional intervention is enhanced if provided before a terminal stage of HIV infection. These data provide evidence of a close association among nutritional condition, intestinal absorption, and immune impairment.

Ritonavir combination therapy restores intestinal function in children with advanced HIV disease

OBJECTIVES

To investigate the intestinal absorptive processes in children with HIV infection before and after treatment with combination therapy that includes ritonavir. To test the hypothesis that combination therapy improves intestinal function.

DESIGN

Intestinal function tests were performed in 10 children with advanced HIV disease at the enrollment and after 3 and 6 months of therapy with ritonavir combined with two HIV reverse transcriptase inhibitors. HIV viral load and CD4 cell counts were also determined; body weight was monitored.

METHODS

The D-xylose absorption test, the steatocrit and the determination of fecal alpha1-antitrypsin concentration were used to evaluate carbohydrate and fat absorption, as well as fecal protein loss. Serum iron levels were measured to indirectly evaluate iron absorption. HIV-1 RNA-polymerase chain reaction (PCR) and immunofluorescence imaging were used to evaluate virologic and immunologic responses.

RESULTS

In all, 9 children had carbohydrate malabsorption, 3 steatorrhea, 2 protein loss, and 7 iron deficiency. Most tests produced normal results after 3 months of therapy, and all abnormalities were abolished 6 months after institution of combination therapy. Mean results of each of four absorption tests were significantly changed on combination therapy. Viral load was progressively reduced and CD4 count was increased, with an inverse relationship. An evident shift of body weight pattern toward catch-up growth was observed in all children.

CONCLUSIONS

Ritonavir combination therapy results in prompt and sustained restoration of intestinal function, which is associated with reduction in viral load, increase in CD4 counts, and gain in body weight.