Impact of Many-Body Effects on Landau Levels in Graphene.

We present magneto-Raman spectroscopy measurements on suspended graphene to investigate the charge carrier density-dependent electron-electron interaction in the presence of Landau levels. Utilizing gate-tunable magnetophonon resonances, we extract the charge carrier density dependence of the Landau level transition energies and the associated effective Fermi velocity v_{F}. In contrast to the logarithmic divergence of v_{F} at zero magnetic field, we find a piecewise linear scaling of v_{F} as a function of the charge carrier density, due to a magnetic-field-induced suppression of the long-range Coulomb interaction. We quantitatively confirm our experimental findings by performing tight-binding calculations on the level of the Hartree-Fock approximation, which also allow us to estimate an excitonic binding energy of ≈6 meV contained in the experimentally extracted Landau level transitions energies.

Fabrication of comb-drive actuators for straining nanostructured suspended graphene.

We report on the fabrication and characterization of an optimized comb-drive actuator design for strain-dependent transport measurements on suspended graphene. We fabricate devices from highly p-doped silicon using deep reactive ion etching with a chromium mask. Crucially, we implement a gold layer to reduce the device resistance from ≈51.6 kΩ to ≈236 Ω at room temperature in order to allow for strain-dependent transport measurements. The graphene is integrated by mechanically transferring it directly onto the actuator using a polymethylmethacrylate membrane. Importantly, the integrated graphene can be nanostructured afterwards to optimize device functionality. The minimum feature size of the structured suspended graphene is 30 nm, which allows for interesting device concepts such as mechanically-tunable nanoconstrictions. Finally, we characterize the fabricated devices by measuring the Raman spectrum as well as the a mechanical resonance frequency of an integrated graphene sheet for different strain values.

Integrated impedance bridge for absolute capacitance measurements at cryogenic temperatures and finite magnetic fields.

We developed an impedance bridge that operates at cryogenic temperatures (down to 60 mK) and in perpendicular magnetic fields up to at least 12 T. This is achieved by mounting a GaAs HEMT amplifier perpendicular to a printed circuit board containing the device under test and thereby parallel to the magnetic field. The measured amplitude and phase of the output signal allows for the separation of the total impedance into an absolute capacitance and a resistance. Through a detailed noise characterization, we find that the best resolution is obtained when operating the HEMT amplifier at the highest gain. We obtained a resolution in the absolute capacitance of 6.4 aF/Hz at 77 K on a comb-drive actuator while maintaining a small excitation amplitude of 15 kBT/e. We show the magnetic field functionality of our impedance bridge by measuring the quantum Hall plateaus of a top-gated hBN/graphene/hBN heterostructure at 60 mK with a probe signal of 12.8 kBT/e.

Elimination of the musk fragrances galaxolide and tonalide from wastewater by ozonation and concomitant stripping.

Ozone reacts with the musk fragrances tonalide and galaxolide with rate constants of 8 M(-1)s(-1) and 140 M(-1)s(-1), respectively. In wastewater, ozone eliminates only the more reactive compound, galaxolide, in competition with its reaction with the wastewater matrix. As both compounds are also stripped in a bubble column, tonalide is also eliminated to some extent.

Effect of timolol therapy on outflow facility.

A 14-week course of timolol therapy in 38 eyes with open-angle glaucoma produced a statistically significant drop (6 mm Hg) in their mean intraocular pressure but had no effect on the mean coefficient of aqueous outflow. These data are compatible with those of Zimmerman et al. obtained after a single drop of treatment and suggest that timolol reduces intraocular pressure by inhibiting aqueous production.

Analysis of Cx43alpha1 promoter function in the developing zebrafish embryo.

The Cx43alpha1 gap junctions play an important role in cardiovascular development. Studies using transgenic mouse models have indicated that this involves an essential role for Cx43alpha1 in modulating neural crest cell motility. We previously showed that a 6.8 kb mouse genomic sequence containing the promoter and upstream regulatory sequences of the Cx43alpha1 gene can drive lacZ reporter gene expression in all neural crest cell lineages in the mouse embryo. To obtain further insights into the sequence motifs and regulatory pathways involved in targeting Cx43alpha1 gene expression in neural crest cells, we assayed the activity of the mouse Cx43alpha1 promoter in evolutionarily distantly related zebrafish embryos. For these studies, the 6.8kb Cx43alpha1 genomic sequence and various deletion derivatives were used to generate GFP or lacZ expression vectors. The transcriptional activities of these constructs were analyzed in vivo after microinjection into one- or two- cell stage zebrafish embryos. These studies indicated that the mouse Cx43alpha1 promoter can drive lacZ expression in neural crest cells in the zebrafish embryos. Analysis by whole mount in situ hybridization showed that the endogenous zebrafish Cx43alpha1 gene is expressed maternally and zygotically, and expression is observed in regions where neural crest cells are found. To further elucidate the developmental regulation of Cx43alpha1 gene expression, we screened a zebrafish BAC library and identified a clone containing the entire zebrafish Cx43alpha1 gene and flanking upstream and downstream sequences. The upstrean Cx43alpha1 promoter sequences from zebrafish, mouse, and human were analyzed for evolutionarily conserved DNA motifs. Overall these studies suggest that the sequence motifs and transcriptional regulation involved in the targeting Cx43alpha1 expression to neural crest cells are evolutionarily conserved in zebrafish and mouse embryos.

Unusual complex of ventral midline anomalies: a multiple congenital anomalies/mental retardation syndrome.

We report on an infant boy with facial anomalies, hypoplasia of corpus callosum, cerebral atrophy, cleft of lower sternum, absence of palpable medial abdominal muscles omphalocele, hypospadias, and other anomalies. This combination of congenital anomalies seems not to have been described before. A clear distinction from other syndromes and associations with midline defects seems possible, and thus a specific entity may be postulated.

Capillary leak syndrome in children who undergo cardiopulmonary bypass: clinical outcome in comparison with complement activation and C1 inhibitor.

OBJECTIVES: Capillary leak syndrome (CLS) is associated with significantly increased morbidity and occurs after cardiopulmonary bypass in children with congenital heart disease. We investigated the early clinical parameters that predict the development of CLS and examined the relationship between the presence of CLS and complement and contact activation and C1 esterase inhibitor (C1-INH) during and after bypass. DESIGN: In this prospective study we took serial serological measurements of the complement and contact system and C1-INH in a cohort of 27 infants before, during, and up to 96 h after open-heart surgery. RESULTS: Complement and contact activation and a decrease in C1-INH were measured in all infants during and after CPB. Ten infants developed CLS postoperatively. Younger age and longer bypass time were strongly correlated to the development of CLS. No relationship was found between the degree of hypothermia, weight, gender, or cross-clamp time. C1-INH concentration and activity were lower peri- and postoperatively in the CLS group. Infants with CLS had a more pronounced postoperative increase in the C5a and C3a levels, higher postoperative level of factor XIIa, and lower prekallikrein activity than those without CLS. CONCLUSION: Contact and complement activation occurs during cardiopulmonary bypass and contributes to CLS more frequently in infants of a younger age and with a prolonged bypass time. This activation and decrease in C1-INH was strongly expressed in the CLS group, and therefore early substitution of C1-INH may prevent CLS after open-heart surgery in high-risk infants.

Complement and contact activation during cardiovascular operations in infants.

BACKGROUND: By comparing the results of cardiac operations with or without cardiopulmonary bypass (CPB) in infants in a prospective study, we sought to determine which part of the postoperative systemic inflammatory response was caused by CPB. METHODS: Thirty-five patients were divided into two groups: 11 infants operated on without CPB and 24 infants operated on with CPB. Blood samples were drawn before, during, and after the operation. We assessed complement function and the concentrations or activities of C1q, C3, C4, C1 inhibitor, factor B, the activated split product C3a, and prekallikrein and factor XIIa of the contact system. RESULTS: All of the patients exhibited a decrease of complement proteins. This was greater in infants who underwent CPB. A increase in C3a and factor XIIa and changes in prekallikrein activity occurred only in infants during CPB. CONCLUSIONS: Complement activation occurs in all infants, but is significantly higher in the group with CPB. Contact activation only occurs in patients who undergo CPB. Thus, the inflammatory response is caused by the use of a CPB circuit and to a lesser degree by surgical procedures and anesthesia.

The D-1 dopamine receptor antagonist SCH 23390 also interacts potently with brain serotonin (5-HT2) receptors.

The interaction of SCH 23390 with central serotonin 5-HT2 receptors was studied in vivo on [3H]spiperone binding and in vitro on [3H]ketanserin binding. SCH 23390 inhibited [3H]spiperone binding in rat frontal cortex with an ID50 of 1.5 mg/kg i.p., thus being equipotent to the two 5-HT2 antagonists cinanserin and methysergide. In vitro, SCH 23390 competed with [3H]ketanserin with an IC50 of 30 nM. These data indicate that SCH 23390 also binds with high affinity to 5-HT2 receptors in rat brain.

Complement and contact activation in term neonates after fetal acidosis.

AIMS: To evaluate complement and contact activation after fetal acidosis. METHODS: Fifteen term neonates with hypoxic-ischaemic encephalopathy after umbilical arterial pH < 7.10 were compared with 15 healthy neonates with umbilical arterial pH > 7.20. Determinations of the complement function and C1-inhibitor activity were performed as kinetic tests 22-28 hours after birth. C1q, C1-inhibitor, and factor B concentrations were determined by radial immunodiffusion and those of C3a, C5a, and factor XIIa by enzyme immunoabsorbent assay. RESULTS: Median complement function (46 vs 73%), C1q (4.3 vs 9.1 mg/dl), and factor B (5.2 vs 7.7 mg/dl) decreased after fetal acidosis. The activated split products C3a (260 vs 185 micrograms/l), C5a (5.0 vs 0.6 micrograms/l), and factor XIIa (3.2 vs 1.3 micrograms/l) increased in the neonates after fetal acidosis. No differences were found in the concentration and activity of C1-inhibitor. CONCLUSIONS: Complement and contact activation occurred in the newborns with hypoxic-ischaemic encephalopathy. Activation of these systems generates mediators which can trigger inflammation and tissue injury.

Multisystem organ failure and capillary leak syndrome in severe necrotizing enterocolitis of very low birth weight infants.

BACKGROUND: Classification systems for necrotizing enterocolitis (NEC) in preterm infants have been developed to define severity grades relevant for treatment and prognosis. Multisystem organ failure (MSOF) and capillary leak syndrome (CLS) also have prognostic value in these patients. The aim of this retrospective study was to investigate the incidence and predictive value of MSOF and CLS according to the classification criteria. METHODS: The records of 1,022 very low birth weight infants admitted from 1982 to 1996 were reviewed for diagnosis of NEC stage IIA or higher (classification of Walsh and Kliegman). Among those patients (n = 50) the incidence of MSOF and CLS was determined, separately for surgical or conservative treatment. RESULTS: Twelve patients were assigned to stage II, 22 to stage IIIa, and 16 to stage IIIb; 31 infants underwent operation. Mortality rate was not influenced by the grade. In eight patients only gastrointestinal symptoms were found, whereas in 23 patients, up to three organ systems and in 19 patients, four or more organ systems were affected. Mortality depended on the number of involved organ systems. CLS occurred postoperatively in 10 of the 31 infants; eight of them died. CONCLUSION: The prognostic values of MSOF and CLS are higher than that of classification criteria in NEC of VLBW infants.

[Effect of dexamethasone and spironolactone therapy on diuresis and creatine clearance in premature infants with a birth weight below 1,500 g]. / Einfluss einer Dexamethason- und Spironolactontherapie auf die Diurese und Kreatininclearance bei Frühgeborenen mit einem Geburtsgewicht unter 1500 g.

BACKGROUND: The aim of the study was to examine the influence of dexamethasone and spironolactone on diuresis and creatinine clearance in 8-40 day old premature infants with a birth weight less than 1500 g. PATIENTS: 85 preterm infants were included in this study. Median birth weight was 1195 g (range 560-1495), mean gestational age was 28 (range 25-34) weeks. 31 infants were given dexamethasone if bronchopulmonary dysplasia was diagnosed and 32 infants received spironolactone. Indication for spironolactone was persistent ductus arteriosus or bronchopulmonary dysplasia. METHOD: The multivariate variance analysis (MANOVA) was performed to investigate the influence of spironolactone and dexamethasone on diuresis and creatinine clearance. Additional influence of gestational age, postnatal age and fluid intake wa eliminated by the multivariate variance analysis. RESULTS: Spironolactone therapy resulted in no differences for diuresis and creatinine clearance. Dexamethasone therapy increased creatinine clearance (p < 0.05) and diuresis (p < 0.005). CONCLUSIONS: Spironolactone is not very effective in the therapy of persistent ductus arteriosus and bronchopulmonary dysplasia. Diuresis and creatinine clearance are not increased. In conclusion spironolactone is more effective in clinical conditions associated with high circulating levels of aldosterone. Dexamethasone, on the other hand, has a high effect on diuresis and creatinine clearance. The pathomechanism for the increase of parameters studied is not completely understood.

The fine structure of the body wall of adult Paragonimus uterobilateralis.

The body wall of adult Paragonimus uterobilateralis was investigated by electron microscopy. The syncytial tegument contains prominent spines, mitochondria and disc-shaped granules. The apical surface forms ridges and pits, the basal membrane forms a conspicuous labyrinth. A layer of interstitial material with muscle fibres separates the syncytium from the parenchyme. The muscle fibres are organized in a transverse and a longitudinal layer and single radial fibres. Thick and thin myofilaments do not show any regular pattern. Tegumental and muscle cell bodies lie in clusters below the interstitial material. Tegumental cells are characterized by abundant ribosomes and granules, muscle cells are stacked with mitochondria. Cytoplasmic connections link both cell types to their functional portions.

Oxalate excretion during the first 7 weeks in very-low-birth-weight infants.

To determine reference values, we studied urinary excretion of oxalate prospectively and longitudinally in a cohort of 23 very-low-birth-weight (VLBW) infants. The urinary oxalate concentrations were evaluated in 24-hour urine samples by the oxalate oxidase method. Urine samples were obtained at 1, 2-3, 4-5 and 6-7 weeks of age. The median oxalate amount was 24 mumol/kg body weight/day with a 10th-90th percentile range of 16-45 in the 1st week. Oxalate excretion was highest in 2- to 3-week-old infants (median: 35; percentile range: 26-56 mumol/kg body weight/day). In the 4th-5th week, the median was 24 (percentile range: 15-47) mumol/kg body weight/day and in weeks 6-7 also 24 (percentile range: 10-36) mumol/ kg body weight/day. Also, the urinary oxalate concentration as well as the oxalate-creatinine ratio showed increased values in the first 3 weeks of life and decreased values afterwards. In a multivariate analysis, nutrition or gestational age did not affect the urinary oxalate concentration, the daily amount excreted or the oxalate-creatinine ratio. The investigated parameters (oxalate amount and oxalate-creatinine ratio in urine) were significantly age dependent). The data show that urinary oxalate excretion in VLBW infants approaches levels that are in the same range as those of patients with urolithiasis. Thus the risk of nephrocalcinosis in VLBW infants may be increased.

The identification of hyperoxaluria in very low-birthweight infants--which urine sampling method?

The present study was performed to determine the best method of urine collection for measurement of oxalate excretion in very low-birthweight (VLBW) infants and to verify the utility of the oxalate/creatinine ratio in VLBW infants. This has not been investigated in this group with developing renal function. In a prospective study of 30 VLBW infants, we compared oxalate excretion in urine collected over 24 h and in a spot urine sample. The urinary oxalate concentration was measured by the oxalate oxidase method. The correlation coefficient between the amount of oxalate per kilogram body weight excreted daily and the oxalate/creatinine ratio in spot urine sample was 0.80 (P < 0.0001) and with the oxalate/creatinine ratio in a 24-h urine collection 0.82 (P < 0.0001). The two highest levels of oxalate excretion (> 100 mumol/kg per day) were detected with both oxalate/creatinine ratios (> 1 mmol/ mmol). No circadian rhythm of oxalate excretion was found. The measurement of the oxalate/creatinine ratio in spot urine samples is suitable for screening VLBW infants for hyperoxaluria.