Intermittent hypoxia suppression of growth hormone and insulin-like growth factor-I in the neonatal rat liver.

OBJECTIVES: Extremely low gestational age neonates with chronic lung disease requiring oxygen therapy frequently experience fluctuations in arterial oxygen saturation or intermittent hypoxia (IH). These infants are at risk for multi-organ developmental delay, reduced growth, and short stature. The growth hormone (GH)/insulin-like growth factor-I (IGF-1) system, an important hormonal regulator of lipid and carbohydrate metabolism, promotes neonatal growth and development. We tested the hypothesis that increasing episodes of IH delay neonatal growth by influencing the GH/IGF-I axis. DESIGN: Newborn rats were exposed to 2, 4, 6, 8, 10, or 12 hypoxic episodes (12% O2) during hyperoxia (50% O2) from P0-P7, P0-P14 (IH), or allowed to recover from P7-P21 or P14-P21 (IHR) in room air (RA). RA littermates at P7, P14, and P21 served as RA controls; and groups exposed to hyperoxia only (50% O2) served as zero IH controls. Histopathology of the liver; hepatic levels of GH, GHBP, IGF-I, IGFBP-3, and leptin; and immunoreactivities of GH, GHR, IGF-I and IGF-IR were determined. RESULTS: Pathological findings of the liver, including cellular swelling, steatosis, necrosis and focal sinusoid congestion were seen in IH, and were particularly severe in the P7 animals. Hepatic GH levels were significantly suppressed in the IH groups exposed to 6-12 hypoxic episodes per day and were not normalized during IHR. Deficits in the GH levels were associated with reduced body length and increase body weight during IHR suggesting increased adiposity and catchup fat. Catchup fat was also associated with elevations in GHBP, IGF-I, leptin. CONCLUSIONS: IH significantly impairs hepatic GH/IGF-1 signaling during the first few weeks of life, which is likely responsible for hepatic GH resistance, increased body fat, and hepatic steatosis. These hormonal perturbations may contribute to long-term organ and body growth impairment, and metabolic dysfunction in preterm infants experiencing frequent IH and/or apneic episodes.

Chronic Intermittent Hypoxia Causes Lipid Peroxidation and Altered Phase 1 Drug Metabolizing Enzymes in the Neonatal Rat Liver.

Critically ill preterm neonates requiring oxygen therapy often experience frequent apneas with intermittent hypoxia (IH). IH-induced oxidative stress causes lipid peroxidation, which targets the liver and contributes to toxic drug reactions. We tested the hypothesis that incremental IH episodes induce oxidative damage in the neonatal liver and alter the expression of genes that regulate drug metabolism. Newborn rats were exposed to increasing IH episodes (12% O2) during hyperoxia (50% O2), or placed in room air (RA) until postnatal day 21 (P21) for recovery from IH (IHR). RA littermates served as controls, and pups exposed to 50% O2 served as hyperoxia controls. Hepatic histopathology, biomarkers of oxidative stress and oxidative DNA damage, antioxidants, and expression of genes that regulate drug metabolism were assessed. Oxidative stress and DNA damage, evidenced by 8-isoprostaglandin F2α (8-isoPGF2α) and 8-hydroxy-2'-deoxyguanosine (8-OH-dG), respectively, increased as a function of IH episodes, and was associated with decreased superoxide dismutase (SOD) and increased catalase activities. Pathological changes including cellular swelling, steatosis, necrosis, and focal sinusoid congestion were seen in IH, but not in IHR. Similarly, IH was associated with upregulation of several genes involved in DNA repair, which were downregulated during IHR. Of the genes involved in drug metabolism, aldehyde dehydrogenases (involved in lipid peroxidation) and cytochrome P450 (CYP) genes of the 2C family (involved in oxidative stress) were robustly upregulated both in IH and in IHR. Hepatic oxidative stress and lipid peroxidation occurring in response to chronic IH have implications for preterm infants, and may explain, in part, the pharmacokinetic variations and drug toxicities in this vulnerable population.

Lipogenesis in Huh7 cells is promoted by increasing the fructose: Glucose molar ratio.

AIM: To determine whether hepatocyte lipogenesis, in an in vitro cell culture model, is modulated by adjusting culture media monosaccharide content and concentration. METHODS: Hepatocytes (Huh7), demonstrating glucose and fructose uptake and lipid biosynthesis, were incubated in culture media containing either glucose alone (0.65-0.72 mmol/L) or isosmolar monosaccharide (0.72 mmol/L) comprising fructose:glucose (F:G) molar ratios ranging from 0.58-0.67. Following a 24-h incubation, cells were harvested and analyzed for total protein, triglyceride (TG) and cholesterol (C) content. Significant differences (P < 0.05) among groups were determined using analysis of variance followed by Dunnett's test for multiple comparisons. RESULTS: After a 24 h incubation period, Huh7 cell mass and viability among all experimental groups were not different. Hepatocytes cultured with increasing concentrations of glucose alone did not demonstrate a significant change either in C or in TG content. However, when the culture media contained increasing F:G molar ratios, at a constant total monosaccharide concentration, synthesis both of C and of TG increased significantly [F:G ratio = 0.58, C/protein (µg/µg) = 0.13; F:G = 0.67, C/protein = 0.18, P < 0.01; F:G ratio = 0.58, TG/protein (µg/µg) = 0.06; F:G ratio = 0.67, TG/protein = 0.11, P < 0.01]. CONCLUSION: In an in vitro hepatocyte model, glucose or fructose plus glucose support total cell mass and lipogenic activity. Increasing the fructose:glucose molar ratio (but not glucose alone) enhances triglyceride and cholesterol synthesis. These investigations demonstrate fructose promotes hepatocellular lipogenesis, and they provide evidence supporting future, in vivo studies of fructose's role in the development of hepatic steatosis and non-alcoholic fatty liver disease.

Inverse correlation between Helicobacter pylori colonization and obesity in a cohort of inner city children.

BACKGROUND: Recently, publications in adults and children have documented a potential role of Helicobacter pylori (H. pylori) in decreasing the likelihood of obesity. The present study compares the prevalence of H. pylori colonization between obese (body mass index [BMI] ≥ 95th percentile) and healthy weight (BMI ≥ 5th to <85th percentiles) children seen at an inner city medical center in the United States. METHODS: This retrospective study reviewed clinical features, BMI, and gastric histology of consecutive children aged 1-18 years undergoing an esophagogastroduodenoscopy. BMI percentile was calculated for age and gender. Helicobacter pylori colonization was determined by histopathologic identification of the organism. Multiple logistic regression was employed to measure the association between BMI and H. pylori colonization, controlling for baseline age, gender, and presenting symptoms. RESULTS: Among 340 patients (51.5% female, mean age of 10.5 ± 4.7 years), 98 (29%) were obese and 173 (51%) were healthy weight. The H. pylori colonization rate of the entire cohort was 18.5% (95% CI = 14.7-23.0%). Among obese children, 10% had H. pylori colonization compared to 21% of the healthy weight children (RR = 2.1, 95% CI = 1.1-4.0). Conversely, 39% of noncolonized children, but only 21% of the infected children, were obese (RR = 1.8, 95% CI = 1.1-3.3). Multivariate analysis revealed that being colonized with H. pylori is associated with a 50% reduction in the odds of being obese (adjusted OR = 0.5, 95% CI = 0.2-1.0). CONCLUSIONS: Our findings in a North American cohort are in agreement with studies from Asia and Europe suggesting that H. pylori infection decreases the prevalence of obesity in children. Further work to characterize the extent and nature of this relationship is warranted.

The liver in pediatric gastrointestinal disease.

Hepatic involvement is often encountered in gastrointestinal (GI) diseases, in part because of the close anatomic and physiologic relations between the liver and GI tract. Drainage of the mesenteric blood supply to the portal vein permits absorbed and/or translocated nutrients, toxins, bacterial elements, cytokines, and immunocytes to gain hepatic access. Liver problems in digestive disorders may range from nonspecific hepatocellular enzyme elevations to significant pathologic processes that may progress to end-stage liver disease. Hepatobiliary manifestations of primary GI diseases in childhood and adolescence are not uncommon and include several well-described associations, such as sclerosing cholangitis with inflammatory bowel disease. Liver damage may also result from the effects of drugs used to treat GI diseases, for example, the hepatotoxicity of immunomodulatory therapies. This review highlights the important features of the hepatic and biliary abnormalities associated with 3 common pediatric GI conditions: inflammatory bowel disease, celiac disease, and cystic fibrosis.

Ω-3 fatty acids prevent hepatic steatosis, independent of PPAR-α activity, in a murine model of parenteral nutrition-associated liver disease.

OBJECTIVES: ω-3 Fatty acids (FAs), natural ligands for the peroxisome proliferator-activated receptor-α (PPAR-α), attenuate parenteral nutrition-associated liver disease (PNALD). However, the mechanisms underlying the protective role of ω-3 FAs are still unknown. The aim of this study was to determine the effects of ω-3 FAs on hepatic triglyceride (TG) accumulation in a murine model of PNALD and to investigate the role of PPAR-α and microsomal triglyceride transfer protein (MTP) in this experimental setting. METHODS: 129S1/SvImJ wild-type or 129S4/SvJaePparatm/Gonz/J PPAR-α knockout mice were fed chow and water (controls); oral, fat-free PN solution only (PN-O); PN-O plus intraperitoneal (IP) ω-6 FA-predominant supplements (PN-ω-6); or PN-O plus IP ω-3 FA (PN-ω-3). Control and PN-O groups received sham IP injections of 0.9% NaCl. Hepatic histology, TG and cholesterol, MTP activity, and PPAR-α messenger RNA were assessed after 19 days. RESULTS: In all experimental groups, PN feeding increased hepatic TG and MTP activity compared with controls. Both PN-O and PN-ω-6 groups accumulated significantly greater amounts of TG when compared with PN-ω-3 mice. Studies in PPAR-α null animals showed that PN feeding increases hepatic TG as in wild-type mice. PPAR-α null mice in the PN-O and PN-ω-6 groups demonstrated variable degrees of hepatic steatosis, whereas no evidence of hepatic fat accumulation was found after 19 days of oral PN plus IP ω-3 FAs. CONCLUSIONS: PN induces TG accumulation (steatosis) in wild-type and PPAR-α null mice. In PN-fed wild-type and PPAR-α null mice given IP ω-3 FAs, reduced hepatic TG accumulation and absent steatosis are found. Prevention of steatosis by ω-3 FAs results from PPAR-α-independent pathways.

Dietary GD3 ganglioside reduces the incidence and severity of necrotizing enterocolitis by sustaining regulatory immune responses.

OBJECTIVES: Gangliosides are glycosphingolipids, rich in colostrum and in membrane microdomains, which promote enterocyte growth and differentiation, and modulate TH1/TH2 responses. In an in vitro intestinal explant model of necrotizing enterocolitis (NEC), gangliosides have been shown to ameliorate intestinal injury; however, possible immunomodulatory mechanisms associated with this observation, as well as potential in vivo protective effects of gangliosides, remain unknown. The present study evaluates the effects of dietary GD3, the predominant ganglioside in neonatal rat intestine, both on the clinicopathologic expression of disease and on ileal Foxp3+ T regulatory cell immune responses in an experimental NEC model. METHODS: Newborn rat pups were fed gavage formula (NEC) or formula supplemented with 15 µg/mL GD3 (GD3-NEC). Dam-fed (DF) littermates served as controls. NEC was induced by asphyxia and cold stress. At 96 hours, ileal gross and histologic changes were evaluated, and ileal cytokine profiles, Foxp3 expression, and Foxp3+ cell numbers were determined. RESULTS: GD3 decreased the incidence and gross and histopathologic severity of NEC. Ileal Foxp3 expression and Foxp3+ cell numbers were significantly decreased in the NEC group compared with DF. GD3 increased ileal Foxp3 expression and Foxp3+ cell numbers, in association with upregulation of anti-inflammatory cytokine interleukin (IL)-10 and chemokines, tissue inhibitor of metalloproteinases 1, IL-1 receptor antagonist (IL-1ra), and suppressed proinflammatory mediators. CONCLUSIONS: These data suggest that dietary GD3 protects newborn rats from NEC, in part, by augmenting mucosal Foxp3+ T regulatory immune responses.

Hirschsprung disease presenting as sigmoid volvulus: a case report and review of the literature.

While sigmoid volvulus is commonly seen in older patients, it is rarely encountered in children and younger adults. Consequently, heightened awareness of this entity is required to avoid a delay in diagnosis. Among the pediatric and adult cases of colonic volvulus previously reported in the English literature, 23 of the affected individuals have also been diagnosed with Hirschsprung disease (HD). This report describes a 12-year-old male with a history of chronic constipation who presented with vomiting and abdominal distension and was found to have sigmoid volvulus with previously unrecognized HD. The case presentation is followed by a review of the literature describing colonic volvulus secondary to HD in children.

Ileal immune dysregulation in necrotizing enterocolitis: role of CD40/CD40L in the pathogenesis of disease.

OBJECTIVES: CD40, a co-stimulatory molecule, plays a critical role in coordinating enteric inflammatory immune responses. In necrotizing enterocolitis (NEC), upregulation of IL-10, a CD40-modulated cytokine, has been described, but the role of the IL-10 receptor (IL-10Rß), CD40, and its ligand CD40L in disease pathogenesis is unknown. The study herein investigates ileal expression of CD40, CD40L, and IL-10R in a rat model of NEC. SUBJECTS AND METHODS: NEC was induced in newborn rats using established methods of formula feeding, asphyxia, and cold stress. Expression of CD40, CD40L, IL-10Rß, and other proinflammatory molecules, including Toll-like receptor-4 (TLR-4) and IL-18, was assessed by immunoblotting. Tissue infiltration by macrophages, monocytes, and T cells was examined by confocal immunohistochemistry. RESULTS: Ileum from rat pups with NEC showed increased expression of TLR-4, IL-18, and IL-10Rß. Sections from both NEC and control pups demonstrated preservation of ileal cells expressing CD40/CD40L. The distal ileum of controls expressed both CD40 and CD40L; conversely, neither molecule was detected in ileal tissue from NEC pups. Additional studies showed that treatment with epidermal growth factor (EGF), previously shown to ameliorate the severity of NEC in an animal model, did not restore CD40 expression. CONCLUSIONS: Ileal cytokine dysregulation, manifested by decreased CD40/CD40L and increased IL-10Rß expression, may be involved in the pathogenesis of NEC. Dampened CD40 signaling may be related to enhanced IL-10 expression and a suppressed T-cell response to injury. We speculate that augmenting CD40-CD40L interactions may achieve a protective effect in this NEC model.

Inhibitors of protein phosphatase-2A from human brain structures, immunocytological localization and activities towards dephosphorylation of the Alzheimer type hyperphosphorylated tau.

Protein phosphatase (PP)-2A, which regulates the phosphorylation of tau, is regulated by two endogenous inhibitor proteins, I(1)(PP2A) and I(2)(PP2A), in mammalian tissues. Here, we report the cloning of I(1)(PP2A) and I(2)(PP2A) from human brain, and show that in PC12 cells and in I(1)(PP2A)-GFP or I(2)(PP2A)-GFP transfected NIH3T3 and human neural progenitor cells, I(1)(PP2A) is localized mostly in the cell cytoplasm and I(2)(PP2A) mostly in the nucleus. The recombinant I(1)(PP-2A) and I(2)(PP-2A) inhibit PP-2A activity towards hyperphosphorylated tau in vitro; the dephosphorylation of the hyperphosphorylated tau at specific sites is selectively inhibited. Overexpression of I(1)(PP2A) as well as I(2)(PP2A) results in tau hyperphosphorylation and degeneration of PC 12 cells.

Simple and specific detection of abnormal prion protein by a magnetic bead-based immunoassay coupled with laser-induced fluorescence spectrofluorometry.

Transmissible spongiform encephalopathies (TSEs), also termed prion diseases, are fatal neurodegenerative conditions that affect both humans and animals. The transmissibility and fatal nature of TSEs necessitate their rapid and accurate diagnosis. Laser-induced fluorescence (LIF) spectrofluorometry is useful for obtaining measurements on fluorescence-labeled targets with a high degree of sensitivity. In the present study, we applied this technology to the immunological detection of abnormal prion protein, PrPSc, which is a universal diagnostic marker for TSEs. The assay format consists of a magnetic bead-based sandwich immunoassay utilizing a biotin-conjugated capture antibody and a fluorophore-labeled detector antibody. By using one pair of anti-PrP monoclonal antibodies (MAbs), PrPSc in brain homogenates from various experimental and natural TSEs can be easily detected with high specificity. Furthermore, the assay proved to be applicable for the detection of PrPSc in the lymph nodes from deer with TSE. The sensitivity of the assay was shown to be comparable to standard immunoblotting, but has several advantages over conventional tests, in terms of flexibility, simplicity, specificity, and run time. These results provide an important basis for the development of an early diagnostic test with potential for multi-sample analysis.

Cloning of murine cysteine sulfinic acid decarboxylase and its mRNA expression in murine tissues.

Cysteine sulfinic acid decarboxylase (CSD) is the rate-limiting enzyme for biosynthesis of taurine which is essential to biological processes such as development of the brain and eye, reproduction, osmoregulation as well as the anti-inflammatory activity of leukocytes. We report the cDNA sequence of murine CSD that predicts a polypeptide of 493 amino acids. This protein shares 98% and 90% of amino acids with rat and human CSD, respectively, indicating that it is a true ortholog of CSD. Northern blot analysis revealed that CSD mRNA is expressed in kidney and liver, and was not detected in lymphoid tissues and lung. The nucleotide sequence of murine CSD should be useful for genetic manipulation of the CSD gene.

Application of micro-ELISA technique for detection of specific IgM in Russian spring summer encephalitis patients

No abstract available.