Case report: Rhabdomyolysis in children in acute and chronic disease-a challenging condition in pediatric emergency medicine

Rhabdomyolysis is a challenging condition in pediatric emergency departments (PED): It ranges from asymptomatic illness with isolated elevation of creatine kinase (CK) levels to a life-threatening condition associated with extreme elevations in CK, electrolyte imbalances, circulatory failure (CF), acute kidney injury (AKI), and multi-organ disease. Most common causes of rhabdomyolysis are viral myositis and trauma, hereditary metabolic myopathies must be considered when facing rhabdomyolysis in early childhood. We report two cases of severe rhabdomyolysis with CF in our PED, thereby summarizing first-line management of rhabdomyolysis.

Elevated concentrations of sedoheptulose in bloodspots of patients with cystinosis caused by the 57-kb deletion: implications for diagnostics and neonatal screening

Cystinosis is an autosomal recessive lysosomal storage disease caused by mutations in CTNS. The most prevalent CTNS mutation is a homozygous 57-kb deletion that also includes an adjacent gene named SHPK (CARKL), encoding sedoheptulokinase. Patients with this deletion have elevated urinary concentrations of sedoheptulose. Using derivatisation with pentafluorobenzyl hydroxylamine and liquid chromatography-tandem mass spectrometry (LC-MS/MS), we developed a new sensitive method for the quantification of sedoheptulose in dried blood spots. This method can be utilized as a quick screening test to detect cystinosis patients homozygous for the 57-kb deletion in CTNS; which is the most common mutation of cystinosis. Sedoheptulose concentrations in the deleted patients were 6 to 23 times above the upper limit for controls. The assessment of sedoheptulose in a bloodspot from a known cystinosis patient homozygous for the 57-kb deletion retrieved from the Dutch neonatal screening program showed that sedoheptulose was already elevated in the neonatal period. There was no overlap in sedoheptulose levels between cystinosis patients homozygous for the 57-kb deletion and cystinosis patients not homozygous for this deletion. Our presented method can be used prior to mutation analysis to detect cystinosis patients homozygous for the 57-kb deletion. We feel that the presented method enables fast (pre)-symptomatic detection of cystinosis patients homozygous for the 57-kb deletion, allowing early treatment.

Differenzialdiagnose des Polyhydramnions beim Hyperprostaglandin-E-Syndrom: Case-Report

INTRODUCTION

A polyhydramnion is diagnosed in 0.4 to 3.3 % of all pregnancies. The most common causes of increased amniotic fluid include maternal diabetes mellitus, fetal malformations and chromosomal aberrations, twin-to-twin transfusion syndrome, rhesus incompatibility syndrome, and congenital infections. After exclusion of other etiologies for polyhydramnion, the very rare, autosomal-recessive transferred hyperprostaglandin E syndrome (HPS) has to be considered.

PATIENTS AND METHODS

We report on a 31-year-old women who visited our obstetrical outpatient clinics at 22 + 4 weeks of gestation for prenatal ultrasound scanning and amniocentesis. This, the patient's third pregnancy had been without complications so far. She had delivered two children before, one of them bearing the HPS. The women herself suffered from epilepsy. At 26 + 0 weeks of gestation the pregnancy was complicated by a polyhydramnion requiring serial amniocentesis for reducing amniotic fluid load. Among others, her amniotic fluid was analyzed for chloride concentration and for genetic aberrations regarding HPS. Serological investigations and an oral glucose tolerance test (oGTT) were performed.

RESULTS

Amniocentesis revealed a normal chromosomal pattern. The oGTT demonstrated values in the normal range. Serological investigations regarding TORCH infections were without pathological findings. The chloride concentration was highly increased in the amniotic fluid, which is suspicious for HPS. Finally, molecular analysis proved an NKCC2-mutation responsible for HPS. A cesarean section was performed at 33 + 3 weeks of gestation.

CONCLUSION

If HPS is suspected to be the cause of polyhydramnions, the chloride concentrations in the amniotic fluid and molecular analysis for HPS should be performed. Interdisciplinary care, diagnostics and therapy in an experienced perinatal center are essential for an optimal outcome of the pregnancy and the newborn infant.

Urogenital distribution of a mouse membrane-associated prostaglandin E(2) synthase

PGE(2) plays a critical role in regulating renal function and facilitating reproduction. One of the rate-limiting biosynthetic enzymes in PGE(2) synthesis is the terminal PGE(2) synthase (PGES). In the present studies, we report the functional expression of a membrane-associated murine PGES (mPGES) and its expression in urogenital tissues. Two independent cDNA clones sharing an identical open reading frame of 459 bp and encoding a peptide of 153 amino acids, but differing in the 3'-untranslated region, were identified. Assays for enzymatic activity, using microsomes prepared from cells transfected with mPGES cDNA, showed that these cDNA sequences encode a functional protein that catalyzes the conversion of PGH(2) to PGE(2). Constitutive expression of mPGES was highest in the mouse kidney, ovary, and urinary bladder but was also expressed at lower levels in uterus and testis. Renal mPGES expression was predominantly localized to epithelia of distal tubules and medullary collecting ducts. High expression was also seen in transitional epithelial cells of bladder and ureter and in the primary and secondary follicles in the ovary. In conclusion, mPGES is constitutively expressed along the urogenital tract, where it may have important roles in normal physiology and disease.

Pathogenetic role of cyclooxygenase-2 in hyperprostaglandin E syndrome/antenatal Bartter syndrome: therapeutic use of the cyclooxygenase-2 inhibitor nimesulide

Patients with hyperprostaglandin E syndrome/antenatal Bartter syndrome typically have renal salt wasting, hypercalciuria with nephrocalcinosis, and secondary hyperaldosteronism. Antenatally, these patients have fetal polyuria, leading to polyhydramnios and premature birth. Hyperprostaglandin E syndrome/antenatal Bartter syndrome is accompanied by a pathologically elevated synthesis of prostaglandin E(2), thought to be responsible for aggravation of clinical symptoms such as salt and water loss, vomiting, diarrhea, and failure to thrive. In this study administration of the cyclooxygenase-2 (COX-2) specific inhibitor nimesulide to patients with hyperprostaglandin E syndrome/antenatal Bartter syndrome blocked renal prostaglandin E(2) formation and relieved the key parameters hyperprostaglandinuria, secondary hyperaldosteronism, and hypercalciuria. Partial suppression of serum thromboxane B(2) synthesis resulting from platelet COX-1 activity and complete inhibition of urinary 6-keto-prostaglandin F(1alpha), reflecting endothelial COX-2 activity, indicate preferential inhibition of COX-2 by nimesulide. Amelioration of the clinical symptoms by use of nimesulide indicates that COX-2 may play an important pathogenetic role in hyperprostaglandin E syndrome/antenatal Bartter syndrome. Moreover, on the basis of our data we postulate that COX-2-derived prostaglandin E(2) is an important mediator for stimulation of the renin-angiotensin-aldosterone system in the kidney.

Cyclooxygenase-2 expression is associated with the renal macula densa of patients with Bartter-like syndrome

BACKGROUND

Bartter-like syndrome (BLS) is a heterogeneous set of congenital tubular disorders that is associated with significant renal salt and water loss. The syndrome is also marked by increased urinary prostaglandin E2 (PGE2) excretion. In rodents, salt and volume depletion are associated with increased renal macula densa cyclooxygenase-2 (COX-2) expression. The expression of COX-2 in human macula densa has not been demonstrated. The present studies examined whether COX-2 can be detected in macula densa from children with salt-wasting BLS versus control tissues.

METHODS

The intrarenal distribution of COX-2 protein and mRNA was analyzed by immunohistochemistry and in situ hybridization in 12 patients with clinically and/or genetically confirmed BLS. Renal tissue rejected for transplantation, from six adult patients not affected by BLS, was also examined.

RESULTS

The expression of COX-2 immunoreactive protein was observed in cells of the macula densa in 8 out 11 patients with BLS. In situ hybridization confirmed the expression of COX-2 mRNA in the macula densa in 6 out of 10 cases. COX-2 protein was also detected in the macula densa in a patient with congestive heart failure. The expression of COX-2 immunoreactive protein was not observed in cells associated with the macula densa in kidneys from patients without disorders associated with hyper-reninemia.

CONCLUSION

These studies demonstrate that COX-2 may be detected in the macula densa of humans. Since macula densa COX-2 was detected in cases of BLS, renal COX-2 expression may be linked to volume and renin status in humans, as well as in animals.

Dehydration activates an NF-kappaB-driven, COX2-dependent survival mechanism in renal medullary interstitial cells

Renal prostaglandin (PG) synthesis is mediated by cyclooxygenase-1 and -2 (COX1 and COX2). After dehydration, the maintenance of normal renal function becomes particularly dependent upon PG synthesis. The present studies were designed to examine the potential link between medullary COX1 and COX2 expression in hypertonic stress. In response to water deprivation, COX2, but not COX1, mRNA levels increase significantly in the renal medulla, specifically in renal medullary interstitial cells (RMICs). Water deprivation also increases renal NF-kappaB-driven reporter expression in transgenic mice. NF-kappaB activity and COX2 expression could be induced in cultured RMICs with hypertonic sodium chloride and mannitol, but not urea. RMIC COX2 expression was also induced by driving NF-kappaB activation with a constitutively active IkappaB kinase alpha (IKKalpha). Conversely, introduction of a dominant-negative IkappaB mutant reduced COX2 expression after hypertonicity or IKKalpha induction. RMICs failed to survive hypertonicity when COX2 was downregulated using a COX2-selective antisense or blocked with the selective nonsteroidal anti-inflammatory drug (NSAID) SC58236, reagents that did not affect cell survival in isotonic media. In rabbits treated with SC58236, water deprivation induced apoptosis of medullary interstitial cells in the renal papilla. These results demonstrate that water deprivation and hypertonicity activate NF-kappaB. The consequent increase in COX2 expression favors RMIC survival in hypertonic conditions. Inhibition of RMIC COX2 could contribute to NSAID-induced papillary injury.

Distribution and cellular localization of prostacyclin synthase in human brain

Prostacyclin (PGI(2)) is a labile, lipid-derived metabolite of arachidonic acid synthesized through the sequential action of cyclo-oxygenase (COX) and prostacyclin synthase (PGIS). In addition to its well-characterized vasodilatory and thrombolytic effects, an increasing number of studies report an important role of PGI(2) in nociception in various animal species. In this study we investigated the regional distribution of PGIS in human brain by immunohistochemistry and in situ hybridization. PGIS-immunoreactive (ir) protein was localized to blood vessels throughout the brain. Neuronal cells and glial cells, such as microglia and oligodendrocytes, also showed intense labeling. The strongest expression of PGIS was seen in large principal neurons, such as pyramidal cells of the cortex, pyramidal cells of the hippocampus, and Purkinje cells of the cerebellum. Abundance of PGIS mRNA was observed in blood vessels and large neurons and correlated well with the immunohistochemical findings. The expression of PGIS in human brain was further demonstrated by immunoblotting and detection of 6-keto-PGF (1alpha), the stable degradation product of prostacyclin in human brain homogenate. These results demonstrate a widespread expression of PGIS in the central nervous system and suggest a potentially important role of prostacylin in modulating neuronal activity in human brain.

Cyclooxygenase-2-selective inhibitors impair glomerulogenesis and renal cortical development

BACKGROUND

Antenatal exposure to nonsteroidal anti-inflammatory drugs (NSAIDs) has been associated with renal dysgenesis in humans.

METHODS

These studies characterized cyclooxygenase-2 (COX-2) versus COX-1-selective inhibition on nephrogenesis in the rodent using histomorphometry, immunohistology, and in situ hybridization.

RESULTS

Administration of a COX-2-selective inhibitor (SC58236), started during pregnancy until weaning, significantly impaired development of the renal cortex and reduced glomerular diameter in both mice and rats. An identical phenotype was demonstrated in COX-2 -/- mice. In contrast to its effects on the developing kidney, a COX-2 inhibitor had no effect on glomerular volume in adult mice. This effect was specific for COX-2 because maternal administration of a COX-1-selective inhibitor (SC58560) did not affect renal development despite significantly inhibiting gastric mucosal prostaglandin E2 (PGE2) synthesis in pups. The expression of COX-2 immunoreactivity peaked in the first postnatal week and was localized to S-shaped bodies and the macula densa in the cortex. Treatment with a COX-2 inhibitor during this period (from postnatal day 0 to day 21) severely reduced glomerular diameter, whereas treatment limited to pregnancy did not affect glomerular size.

CONCLUSION

These data demonstrate an important role for COX-2 activity in nephrogenesis in the rodent, and define a specific time period of susceptibility to these effects.

Selective targeting of cyclooxygenase-2 reveals its role in renal medullary interstitial cell survival

Renal medullary interstitial cells (MICs) are a major site of cyclooxygenase (COX)-mediated PG synthesis. These studies examined the role of COX in MIC survival. Immunoblot and nuclease protection demonstrate that cultured MICs constitutively express COX2, with little constitutive COX1 expression. SC-58236, a COX2-selective inhibitor, but not SC-58560, a COX1 inhibitor, preferentially blocks PGE2 synthesis in MICs. Transduction with a COX2 antisense adenovirus reduced MIC COX2 protein expression and also decreased PGE2 production. Antisense downregulation of COX2 was associated with MIC death, whereas a control adenovirus was without effect. Similarly, the COX2-selective inhibitor SC-58236 (30 microM) and several nonselective COX-inhibiting nonsteroidal anti-inflammatory drugs (NSAIDs), including sulindac, ibuprofen, and indomethacin, all caused MIC death. In contrast, SC-58560, a COX1-selective inhibitor, was 100-fold less potent for inducing MIC death than its structural congener SC-58236. NSAID-induced MIC death was associated with DNA laddering and nuclear fragmentation, consistent with apoptosis. These results suggest that COX2 plays an important role in MIC survival. COX2 inhibition may contribute to NSAID-associated injury of the renal medulla.

Localization of the prostacyclin receptor in human kidney

BACKGROUND

Prostacyclin is an important mediator of renal hemodynamics. Furthermore, recent studies argue for a role of this arachidonic acid metabolite in the regulation of salt and water handling in the distal nephron. To gain insight into the network of prostacyclin signal transduction, we analyzed the intrarenal distribution of the prostacyclin receptor (IP receptor) in adult human kidney.

METHODS

Specific polyclonal antibodies against a synthetic peptide of the human IP receptor were generated. By means of immunohistology the localization of IP receptor protein was studied. The mRNA expression for IP receptor was analyzed by in situ hybridization using specific cRNA probes.

RESULTS

In human kidney sections both IP receptor-immunoreactive protein and mRNA were expressed in smooth muscle cells and endothelial cells. Expression of the IP receptor was observed in glomerular cells, namely mesangial cells, endothelial cells, and podocytes. Both mRNA and protein expression for IP receptor was observable in Tamm-Horsfall-negative distal tubules and collecting ducts.

CONCLUSIONS

The vascular expression of the IP receptor is consistent with the known vasodilatory effect of prostacyclin in vascular beds. Glomerular expression argues for a role of this autacoid in the regulation of glomerular hemodynamics. The tubular distribution might point towards the involvement of prostacyclin in renal salt and water handling.

Localization of cyclooxygenase-1 and -2 in adult and fetal human kidney: implication for renal function

To gain insight into the roles of cyclooxygenase (COX)-1 and -2 in human kidney, we analyzed their expressions and localization in adult and fetal normal kidney. Immunohistology showed expression of COX-1 in collecting duct cells, interstitial cells, endothelial cells, and smooth muscle cells of pre- and postglomerular vessels. Expression of COX-2 immunoreactive protein could be localized to endothelial and smooth muscle cells of arteries and veins and intraglomerularly in podocytes. In contrast to the rat, COX isoforms were not detected in the macula densa. These data were confirmed by in situ mRNA analysis using digoxigenin-labeled riboprobes. In fetal kidney, COX-1 was primarily expressed in podocytes and collecting duct cells. Expression levels of COX-1 in both cell types increased markedly from subcapsular to juxtamedullary cortex. Glomerular staining of COX-2 was detectable in podocytes only at the endstage of renal development. In summary, the localization of COX-2 suggests that this enzyme may be primarily involved in the regulation of renal perfusion and glomerular hemodynamics. The expression of COX-1 in podocytes of the fetal kidney and its absence in adult glomeruli suggests that this isoform might be involved in glomerulogenesis.

Brefeldin A induced dose-dependent changes to Golgi structure and function in the rat exocrine pancreas

We have studied the effect of increasing concentrations of Brefeldin A (BfA) on the rate of secretion in vitro of pulse-labeled proteins and individual enzymes and on the fine structure of the Golgi apparatus in pancreatic acinar cells derived from control rats and from animals stimulated in vivo by feeding a synthetic proteinase inhibitor (FOY 305). A half-maximal inhibition of intracellular transport of newly synthesized proteins was observed at 0.125 microgram/ml BfA which in FOY-stimulated pancreatic lobules was more pronounced. The Golgi apparatus at this low dose of BfA was still preserved and consisted of stacks of narrow cisternae devoid of secretory material. Granule formation from the trans-Golgi network (TGN) was greatly reduced. A nearly complete inhibition of both total protein and individual enzyme transport was observed at 0.5 microgram/ml BfA. This inhibitory effect was more pronounced with enzyme proteins which are transported slowly through the cellular compartments (e.g. lipase) as compared to faster moving proteins (e.g. chymotrypsinogen). The Golgi apparatus at 0.5 microgram/ml BfA was fragmented into clouds of small uniform vesicles which were stained with an antibody directed against TGN 38 and which were surrounded by a network of tubular membranes reacting with an antibody against p58, a marker protein of the intermediate compartment between rough endoplasmic reticulum (RER) and Golgi. Incubation of pancreatic lobules in 10 micrograms/ml BfA led to a disappearance of the small vesicles and a relocation of TGN 38 into the RER, while the tubuloreticular membranes of the intermediate compartment remained unaffected. Aggregates of clathrin cages devoid of membranes accumulated in the area of the previous Golgi vesicles. The inhibitory effect of 0.5 microgram/ml BfA on both intracellular transport and Golgi fine structure was readily reversible within 15 to 30 min upon removal of the drug, but took 1 h or longer after incubation in 5 or 10 micrograms/ml BfA.