5 research outputs found
Adequate feeding and the usefulness of the respiratory quotient in critically ill children
Objective: We determined incidences of underfeeding and overfeeding in children who were admitted to a multidisciplinary tertiary pediatric intensive care and evaluated the usefulness of the respiratory quotient (RQ) obtained from indirect calorimetry to assess feeding adequacy. Methods: Children 18 y and younger who fulfilled the criteria for indirect calorimetry entered our prospective, observational study and were studied until day 14. Actual energy intake was recorded, compared with required energy intake (measured energy expenditure plus 10%), and classified as underfeeding (<90% of required), adequate feeding (90% to 110% of required), o
Selective sparing of goblet cells and paneth cells in the intestine of methotrexate-treated rats
Proliferation, differentiation, and cell death were studied in small
intestinal and colonic epithelia of rats after treatment with
methotrexate. Days 1-2 after treatment were characterized by decreased
proliferation, increased apoptosis, and decreased numbers and depths of
small intestinal crypts in a proximal-to-distal decreasing gradient along
the small intestine. The remaining crypt epithelium appeared flattened,
except for Paneth cells, in which lysozyme protein and mRNA expression was
increased. Regeneration through increased proliferation during days 3-4
coincided with villus atrophy, showing decreased numbers of villus
enterocytes and decreased expression of the enterocyte-specific genes
sucrase-isomaltase and carbamoyl phosphate synthase I. Remarkably, goblet
cells were spared at villus tips and remained functional, displaying Muc2
and trefoil factor 3 expression. On days 8-10, all parameters had returned
to normal in the whole small intestine. No methotrexate-induced changes
were seen in epithelial morphology, proliferation, apoptosis, Muc2, and
TFF3 immunostaining in the colon. The observed small intestinal sparing of
Paneth cells and goblet cells following exposure to methotrexate is likely
to contribute to epithelial defense during increased vulnerability of the
intestinal epithelium
Specific responses in rat small intestinal epithelial mRNA expression and protein levels during chemotherapeutic damage and regeneration
The rapidly dividing small intestinal epithelium is very sensitive to the
cytostatic drug methotrexate. We investigated the regulation of epithelial
gene expression in rat jejunum during methotrexate-induced damage and
regeneration. Ten differentiation markers were localized on tissue
sections and quantified at mRNA and protein levels relative to control
levels. We analyzed correlations in temporal expression patterns between
markers. mRNA expression of enterocyte and goblet cell markers decreased
significantly during damage for a specific period. Of these,
sucrase-isomaltase (-62%) and CPS (-82%) were correlated. Correlations
were also found between lactase (-76%) and SGLT1 (-77%) and between I-FABP
(-52%) and L-FABP (-45%). Decreases in GLUT5 (-53%), MUC2 (-43%), and TFF3
(-54%) mRNAs occurred independently of any of the other markers. In
contrast, lysozyme mRNA present in Paneth cells increased (+76%). At the
protein level, qualitative and quantitative changes were in agreement with
mRNA expression, except for Muc2 (+115%) and TFF3 (+81%), which increased
significantly during damage, following independent patterns. During
regeneration, expression of each marker returned to control levels. The
enhanced expression of cytoprotective molecules (Muc2, TFF3, lysozyme)
during damage represents maintenance of goblet cell and Paneth cell
functions, most likely to protect the epithelium. Decreased expression of
enterocyte-specific markers represents decreased enterocyte function, of
which fatty acid transporters were least affected
Changes in small intestinal homeostasis, morphology, and gene expression during rotavirus infection of infant mice
Rotavirus is the most important cause of infantile gastroenteritis. Since
in vivo mucosal responses to a rotavirus infection thus far have not been
extensively studied, we related viral replication in the murine small
intestine to alterations in mucosal structure, epithelial cell
homeostasis, cellular kinetics, and differentiation. Seven-day-old
suckling BALB/c mice were inoculated with 2 x 10(4) focus-forming units of
murine rotavirus and were compared to mock-infected controls. Diarrheal
illness and viral shedding were recorded, and small intestinal tissue was
evaluated for rotavirus (NSP4 and structural proteins)- and
enterocyte-specific (lactase, SGLT1, and L-FABP) mRNA and protein
expression. Morphology, apoptosis, proliferation, and migration were
evaluated (immuno)histochemically. Diarrhea was observed from days 1 to 5
postinfection, and viral shedding was observed from days 1 to 10. Two
peaks of rotavirus replication were observed at 1 and 4 days
postinfection. Histological changes were characterized by the accumulation
of vacuolated enterocytes. Strikingly, the number of vacuolated cells
exceeded the number of cells in which viral replication was detectable.
Apoptosis and proliferation were increased from days 1 to 7, resulting in
villous atrophy. Epithelial cell turnover was significantly higher (<4
days) than that observed in controls (7 days). Since epithelial renewal
occurred within 4 days, the second peak of viral replication was most
likely caused by infection of newly synthesized cells. Expression of
enterocyte-specific genes was downregulated in infected cells at mRNA and
protein levels starting as early as 6 h after infection. In conclusion, we
show for the first time that rotavirus infection induces apoptosis in
vivo, an increase in epithelial cell turnover, and a shutoff of gene
expression in enterocytes showing viral replication. The shutoff of
enterocyte-specific gene expression, together with the loss of mature
enterocytes through apoptosis and the replacement of these cells by less
differentiated dividing cells, likely leads to a defective absorptive
function of the intestinal epithelium, which contributes to rotavirus
pathogenesis
Inhibition of cyclooxygenase activity reduces rotavirus infection at a postbinding step.
Elevated levels of prostaglandins (PGs), products of cyclooxygenases
(COXs), are found in the plasma and stool of rotavirus-infected children.
We sought to determine the role of COXs, PGs, and the signal transduction
pathways involved in rotavirus infection to elucidate possible new targets
for antiviral therapy. Human intestinal Caco-2 cells were infected with
human rotavirus Wa or simian rotavirus SA-11. COX-2 mRNA expression and
secreted PGE2 levels were determined at different time points
postinfection, and the effect of COX inhibitors on rotavirus infection was
studied by an immunofluorescence assay (IFA). To reveal the signal
transduction pathways involved, the effect of MEK, protein kinase A (PKA),
p38 mitogen-activated protein kinase (MAPK), and NF-kappaB inhibitors on
rotavirus infection was analyzed. In infected Caco-2 cells, increased
COX-2 mRNA expression and secreted PGE2 levels were detected. Indomethacin
(inhibiting both COX-1 and COX-2) and specific COX-1 and COX-2 inhibitors
reduced rotavirus infection by 85 and 50%, respectively, as measured by an
IFA. Indomethacin reduced virus infection at a postbinding step early in
the infection cycle, inhibiting virus protein synthesis. Indomethacin did
not seem to affect viral RNA synthesis. Inhibitors of MEK, PKA, p38 MAPK,
and NF-kappaB decreased rotavirus infection by at least 40%. PGE2
counteracted the effect of the COX and PKA inhibitors but not of the MEK,
p38 MAPK, and NF-kappaB inhibitors. Conclusively, COXs and PGE2 are
important mediators of rotavirus infection at a postbinding step. The
ERK1/2 pathway mediated by PKA is involved in COX induction by rotavirus
infection. MAPK and NF-kappaB pathways are involved in rotavirus infection
but in a PGE2-independent manner. This report offers new perspectives in
the search for therapeutic agents in treatment of severe
rotavirus-mediated diarrhea in children