Local and Nonlocal Electron Dynamics of Au/Fe/MgO(001) Heterostructures Analyzed by Time-Resolved Two-Photon Photoemission Spectroscopy.

Employing femtosecond laser pulses in front and back side pumping of Au/Fe/MgO(001) combined with detection in two-photon photoelectron emission spectroscopy, we analyze local relaxation dynamics of excited electrons in buried Fe, injection into Au across the Fe-Au interface, and electron transport across the Au layer at 0.6 to 2.0 eV above the Fermi energy. By analysis as a function of Au film thickness we obtain the electron lifetimes of bulk Au and Fe and distinguish the relaxation in the heterostructure's constituents. We also show that the excited electrons propagate through Au in a superdiffusive regime and conclude further that electron injection across the epitaxial interface proceeds ballistically by electron wave packet propagation.

Drug handling in a paediatric intensive care unit--can errors be prevented by a three-step intervention?

BACKGROUND: Drug handling in paediatric intensive care units (PICU) is prone to medication errors. We aimed to identify type and prevalence of those errors and to assess preventative interventions. METHODS: Prospective intervention study investigating a 3-step intervention for preventing errors in drug handling in a 10-bed PICU of a university hospital. Nurses' drug handling was monitored in daily routine to identify the number of patients affected by errors and overall prevalence and types of errors in drug handling. We implemented a comprehensive intervention consisting of an information handout, a training course, and a 76-page reference book tailored to reduce the prevalence. RESULTS: The prevalence of errors in drug handling decreased from 83 % (555 errors/668 processes)to 63 % (554/883; p < 0.001) after the intervention. The number of affected patients remained unchanged (95 % vs. 89 %, p = 0.370).Peroral (PO) drugs (1.33 errors/process) were more error-prone than intravenous (IV) drugs(0.64), despite being used less frequently (27 % vs.73 % of all processes, p < 0.001). The interventions decreased the prevalence to 0.77 errors/process(p < 0.001) in PO and to 0.52 in IV drugs (p = 0.025). CONCLUSION: Errors in drug handling were alarmingly frequent. PO drugs were frequently subject to errors, even though being used less frequently. The implementation of a comprehensive intervention succeeded in reducing the prevalence of errors. Yet further refinements are necessary to decrease also the number of affected patients.

Safety assessment of intraportal liver cell application in New Zealand white rabbits under GLP conditions.

Liver cell transplantation (LCT) is considered a new therapeutic strategy for the treatment of acute liver failure and inborn metabolic defects of the liver. Although minimally invasive, known safety risks of the method include portal vein thrombosis and pulmonary embolism. Since no systematic data on these potential side effects exist, we investigated the toxicological profile of repeated intraportal infusion of allogeneic liver cells in 30 rabbits under GLP conditions. Rabbit liver cells were administered once daily for 6 consecutive days at 3 different dose levels, followed by a 2-week recovery period. No test item-related mortality was observed. During cell infusion, clinical findings such as signs of apathy and hyperventilation, moderate elevations of liver enzymes ALT and AST and a slight decrease in AP were observed, all fully reversible. Cell therapy-related macroscopic and histological findings, especially in liver and lungs, were observed in animals of all dose groups. In conclusion, the liver and lungs were identified as potential toxicological target organs of intraportal allogeneic liver cell infusion. A NOAEL (no observed adverse effect level) was not defined because of findings observed also in the low-dose group. No unexpected reactions became apparent in this GLP study. Overall, LCT at total doses up to 12 % (2 % daily over 6 days) of the total liver cell count were tolerated in rabbits. Observed adverse effects are not considered critical for treatment in the intended patient populations provided that a thorough monitoring of safety relevant parameters is in place during the application procedure.

Regional transient portal ischemia and irradiation as preparative regimen for hepatocyte transplantation.

Hepatocyte transplantation is regarded as a promising option to correct hereditary metabolic liver disease. This study describes a novel method involving regional transient portal ischemia (RTPI) in combination with hepatic irradiation (IR) as a preparative regimen for hepatocyte transplantation. The right lobules of rat livers (45% of liver mass) were subjected to RTPI of 30-120 min. Liver specimens and serum samples were analyzed for transaminase levels, DNA damage, apoptosis, and proliferation. Repopulation experiments involved livers of dipeptidylpeptidase IV (DPPIV)-deficient rats preconditioned with RTPI (60-90 min) either with or without prior partial hepatic IR (25 Gy). After reperfusion intervals of 1 and 24 h, 12 million wild-type (DPPIV positive) hepatocytes were transplanted into recipient livers via the spleen. RTPI of 60-90 min caused limited hepatic injury through necrosis and induced a distinct regenerative response in the host liver. Twelve weeks following transplantation, small clusters of donor hepatocytes were detected within the portal areas. Quantitative analysis revealed limited engraftment of 0.79% to 2.95%, whereas control animals (sham OP) exhibited 4.16% (determined as relative activity of DPPIV when compared to wild-type liver). Repopulation was significantly enhanced (21.43%) when IR was performed prior to RTPI, optimum preconditioning settings being 90 min of ischemia and 1 h of reperfusion before transplantation. We demonstrate that RTPI alone is disadvantageous to donor cell engraftment, whereas the combination of IR with RTPI comprises an effective preparative regimen for liver repopulation. The method described clearly has potential for clinical application.

Recurrent acute liver failure and mitochondriopathy in a case of Wolcott-Rallison syndrome.

A 10-year-old Arabic boy of consanguineous parents has suffered eight episodes of acute liver failure with haemolysis triggered by intercurrent febrile illnesses. The first crisis occurred at 9 months of age, after which diabetes mellitus developed. By the age of 6 years, short stature, mild myopathy and later skeletal epiphyseal dysplasia also became evident. His psychosocial development and educational achievements have remained within normal limits. While there were no clear biochemical indicators of a mitochondrial disorder, an almost complete deficiency of complex I of the respiratory chain was demonstrated in liver but not in fibroblast or muscle samples. Molecular analysis of the eukaryotic translation initiation factor 2alpha kinase gene (EIF2AK3) demonstrated a homozygous mutation, compatible with a diagnosis of Wolcott-Rallison syndrome (WRS). This patient's course adds a new perspective to the presentation of WRS caused by mutations in the EIF2AK3 gene linking it to mitochondrial disorders: recoverable and recurrent acute liver failure. The findings also illustrate the diagnostic difficulty of mitochondrial disease as it cannot be excluded by muscle or skin biopsy in patients presenting with liver disease. The case also further complicates the decision-making process for liver transplantation in cases of acute liver failure in the context of a possible mitochondrial disorder. Such patients may be more likely to recover spontaneously if a mitochondrial disorder underlies the liver failure, yet without neurological features liver transplantation remains an option.

Use of the middle colic vein for liver cell transplantation in infants and small children.

INTRODUCTION: Because it is less invasive, intraportal liver cell transplantation (LCT) is an interesting alternative to whole organ transplantation. The inferior mesenteric vein is usually chosen for portal vein access. However, anatomical variations are common in children, so we investigated catheter insertion into the middle colic vein. PATIENTS AND METHODS: Three children (3 weeks to 3 years; 3 to 14 kg) underwent LCT in our center for acute liver failure or severe neonatal urea cycle disorders. Small 4.2-French Hickman lines were surgically introduced into the middle colic vein and advanced to the portal vein stem. The patients received repetitive infusions of liver cells over a period of 4-11 days. RESULTS: Catheter insertion was feasible and tolerated well despite the poor clinical condition of 1 patient and the metabolic instability in the other 2 patients. Blood could be drawn from all catheters, and measurement of portal vein pressure was possible in 2 children. The patient with acute liver failure died after 11 days from complications of the underlying disease. In the other 2 children, portal vein catheters stayed patent for several months. CONCLUSIONS: The middle colic vein can be recommended for placement of intraportal LCT catheters even in small and critically ill infants.

Liver cell transplantation for the treatment of inborn errors of metabolism.

Over the last 15 years, liver cell transplantation (LCT) has developed from an experimental laboratory technique to a potentially life-saving therapeutic option. Because of its minimally invasive nature, the method is especially attractive for (small) children. In children with liver-based inborn errors of metabolism, this transfer of enzyme activity can be regarded as a gene therapy, which can be installed independently and additionally to conservative treatment concepts. To date 14 children with inherited metabolic diseases have undergone LCT in various centres. Although individual results are encouraging, different treatment protocols, difficulties in the objective assessment of function of the transplant, and finally the lack of a controlled study make it difficult to judge the overall significance of LCT in the treatment of metabolic diseases and call for collaborative clinical research.

Indications for pediatric liver transplantation. Data from the Heidelberg pediatric liver transplantation program.

Nowadays liver transplantation is an established treatment for children with end-stage liver disease with very good 1- and 5-year survival. This has been achieved through constant improvement of surgical techniques, new immunosuppressive drugs and clinical management. Indications for liver transplantation in infants and children include acute liver failure (ALF), chronic liver failure with pruritus, complications of cholestasis and failure to thrive. In young children, the most common liver disease leading to transplantation is biliary atresia. Biliary atresia accounts for at least 50 percent of all liver transplants in children and is characterized by the failure of the bile ducts to develop normally and drain bile from the liver. Several models to assess prognosis of liver disease have been developed. In acute liver failure leukocyte count, bilirubin, International Normalized Ratio (INR) and age have a strong correlation with outcome. In chronic liver failure, PELD (Pediatric end-stage liver disease) Score and the occurrence of complications of liver disease are important prognostic tools. Since the start of our own paediatric liver transplantation program at the University of Heidelberg in 2003, already 15 Children between 5 months and 14 years have been transplanted. Indications and outcome of these patients are reviewed in this paper.

Postnatal changes in neonatal acylcarnitine profile.

++Electrospray-tandem mass spectrometry represents a powerful method for detection of inborn errors of fatty acid metabolism. In the present study, it was used to examine neonatal carnitine metabolism, which reflects fatty acid metabolism. In 70 healthy neonates, blood samples were taken from the umbilical cord and by heel-stick puncture in full-term neonates on postnatal d 5. Cord blood specimens were also obtained from 15 preterm and 10 small-for-gestational-age infants. Acylcarnitine concentrations were measured in dried blood spots by electrospray tandem mass spectrometry. Compared with cord blood, the levels of nearly all acylcarnitine species were significantly higher on the postnatal d 5, whereas free carnitine remained unchanged. Total acylcarnitine/free carnitine-ratio increased, whereas the free carnitine/total carnitine-ratio (0.54 +/- 0.05; p < 0.01) further decreased. A reduced availability of free carnitine in the early neonatal period may affect fatty acid oxidation and thus be of potential pathophysiological relevance under conditions with higher energy demands, e.g. in sepsis. Cord blood concentrations of free carnitine, total carnitine, and total acylcarnitines were strongly related to birth weight (p < 0.01). Lower umbilical artery pH, i.e. mild hypoxia, caused accumulation of mainly long-chain acylcarnitines. This implicates that long-chain acylcarnitines could serve as a parameter of perinatal asphyxia.

Decreased mechanical stability of neonatal red cell membrane quantified by measurement of the elastic area compressibility modulus.

Previous studies suggest that early loss of membrane might account for the shortened life-span of neonatal red blood cells (RBC). The elastic area compressibility modulus describes the force required to achieve a defined expansion of the membrane and is thus a suitable intrinsic material property to describe mechanical stability of the RBC membrane. We studied RBC in eight cord blood samples (representing fetal blood), ten 5-day old full-term neonates and seven healthy adults. The RBC were suspended in hypotonic buffer solution and investigated using a modification of the micropipet technique by Evans et al. Cord blood RBC (204+/-33 dyn/cm) and neonatal RBC (209+/-11 dyn/cm) showed a 25% lower elastic area compressibility modulus than adult cells (278+/-26 dyn/cm; p < 0.05). Thus, less force was necessary for expansion of neonatal RBC membrane. We conclude that neonatal RBC are more susceptible to mechanical damage of their membrane than adult cells.

Clinical symptoms, biochemical studies and therapeutic approaches in a sibship with a new congenital tubulopathy.

UNLABELLED: We report on two siblings suffering from a new congenital tubulopathy. Following normal pregnancies not complicated by polyhydramnios, severe renal losses of potassium, chloride, sodium and magnesium occurred in the first weeks after birth. Calcium metabolism was not affected. The distal tubular chloride reabsorption was considerably decreased in the two siblings (0.25 and 0.28, respectively). Secondary hyperaldosteronism, activation of the kallikrein-kinin system and elevated urinary prostaglandin excretion were observed. The effects of indomethacin, spironolactone and captopril on symptoms, electrolyte wasting, activation of renin-angiotensin-aldosterone and kallikrein-kinin system and prostaglandin synthesis were studied. In spite of persisting elevation of prostaglandin synthesis, captopril decreased electrolyte wasting, polyuria and hyperaldosteronism most effectively. CONCLUSION: We delineate an apparently new disorder characterized by a postnatal onset, an extremely decreased chloride reabsorption with extensive hyperchloriduria and hypermagnesiuria in the presence of normal calcium metabolism. The disorder can be distinguished from other tubulopathies with hypokalaemic alkalosis.

Severe hyperchloriduria-hyperkaliuria: a new congenital renal tubular abnormality?

A female infant, aged 5 weeks, had metabolic alkalosis associated with severe electrolyte disturbances. In addition to findings typically seen in patients with Bartter syndrome or hyperprostaglandin E syndrome, she had massive urinary excretion of prostaglandins E2 and E-M, normal calcium metabolism, hyperphosphaturia, and severe hyperchloriduria and hyperkaliuria with limited response to indomethacin. These findings may represent a new congenital renal tubular abnormality.