Kinetically limited CO adsorption: spill-over as a highly effective adsorption pathway on bimetallic surfaces

We demonstrate that the (local) adsorbed carbon monoxide, COad , coverage on the Pt-free areas of bimetallic Pt/Ru(0001) surfaces (a Ru(0001) substrate partly covered by Pt monolayer islands) can be increased to ∼0.80 monolayers (ML), well above the established saturation COad coverage of 0.68 ML, even under ultrahigh vacuum conditions by using spill-over of CO adsorbed on the Pt islands to the Ru areas as an highly effective adsorption channel. The apparent COad saturation coverage of 0.68 ML on pure Ru(0001) is identified as due to kinetic limitations, hindering further uptake from the gas phase, rather than being caused by thermodynamic reasons. This spill-over mechanism is proposed to be a general phenomenon for adsorption on bimetallic surfaces.

[Determination of radioactivity by smartphones]

The interest in the detection of radioactive materials has strongly increased after the accident in the nuclear power plant Fukushima and has led to a bottleneck of suitable measuring instruments. Smartphones equipped with a commercially available software tool could be used for dose rate measurements following a calibration according to the specific camera module.

AIM

We examined whether such measurements provide reliable data for typical activities and radionuclides in nuclear medicine.

METHODS

For the nuclides 99mTc (10 - 1000 MBq), 131I (3.7 - 1800 MBq, therapy capsule) and 68Ga (50 - 600 MBq) radioactivity with defined geometry in different distances was measured. The smartphones Milestone Droid 1 (Motorola) and HTC Desire (HTC Corporation) were compared with the standard instruments AD6 (automess) and DoseGUARD (AEA Technology).

RESULTS

Measurements with the smartphones and the other devices show a good agreement: linear signal increase with rising activity and dose rate. The long time measurement (131I, 729 MBq, 0.5 m, 60 min) demonstrates a considerably higher variation (by 20%) of the measured smartphone data values compared with the AD6. For low dose rates (< 1 µGy/h), the sensitivity decreases so that measurements of e. g. the natural radiation exposure do not lead to valid results. The calibration of the camera responsivity for the smartphone has a big influence on the results caused by the small detector surface of the camera semiconductor.

CONCLUSIONS

With commercial software the camera module of a smartphone can be used for the measurement of radioactivity. Dose rates resulting from typical nuclear medicine procedures can be measured reliably (e. g., dismissal dose after radioiodine therapy). The signal shows a high correlation to measured values of conventional dose measurement devices.

Efficacy, safety and tolerability of vidofludimus in patients with inflammatory bowel disease: the ENTRANCE study

BACKGROUND

Vidofludimus (SC12267) is a novel oral immunomodulator inhibiting dihydroorotate dehydrogenase (DHODH) and the expression of proinflammatory cytokines including interleukin-17 (IL17A and IL17F) and interferon-gamma. The objective of the study was to explore the efficacy, safety and tolerability of vidofludimus in steroid-dependent inflammatory bowel disease (IBD).

METHODS

The open label uncontrolled ENTRANCE study (ClinicalTrials.gov NCT00820365) has been conducted at 13 study centers in Germany, Bulgaria and Romania. Thirty-four steroid-dependent patients with a confirmed diagnosis of Crohn's disease (CD) or ulcerative colitis (UC) were treated with a once daily 35mg oral dose of vidofludimus over 12weeks. Steroids were tapered during the first 8weeks followed by a steroid-free treatment period of 4weeks. Complete response was defined as steroid-free clinical remission at week 12; partial response was defined as being in remission at steroid dose equal or lower than the individual patient's threshold dose for relapse.

RESULTS

Of the thirty-four patients enrolled in this trial 26 were evaluable for primary efficacy assessment. After completion of the 12weeks treatment phase 8 out of 14 (57.1%) patients with CD and 6 out of 12 (50.0%) patients with UC were in steroid-free remission (complete responders). Another 4 (28.6%) patients in CD and 5 (41.7%) patients in UC were partial responders. Vidofludimus was well tolerated, no drug-related serious adverse events were observed.

CONCLUSIONS

This trial provides first evidence of clinical efficacy of vidofludimus in IBD. Although the safety and tolerability profile seems favorable, long-term controlled studies are needed to further investigate its potential as novel IBD therapy.

Alkalinizing effect of NaHCO₃ with and without glucose when administered orally to euhydrated neonatal dairy calves

The use of oral rehydration solutions (ORS) is well established as an effective treatment to correct water-, electrolyte-, and acid-base balance in diarrheic calves. The main ingredients of a commercial ORS are Na, glucose, and alkalinizing agents, such as NaHCO3. Particular importance is attributed to the combination of glucose and Na at a specific ratio to optimize intestinal sodium, and thereby water uptake, through the sodium-glucose co-transport. Enhancing intestinal Na absorption by combining glucose and Na in an ORS has the potential to improve the alkalinizing effect of an ORS according the strong ion theory. The objective of this study was to investigate the effect of glucose on the alkalinizing effect of NaHCO3 when administered orally. Nine healthy neonatal Holstein-Friesian calves underwent 3 oral treatments with 2-L solutions of NaHCO3 (150 mmol/L), glucose (300 mmol/L), and glucose + NaHCO3 (300 mmol/L + 150 mmol/L, respectively) in randomized order. Arterial and venous blood was obtained before treatment and in 30-min intervals thereafter for blood gas analysis and determination of plasma protein and electrolyte concentrations. Urine was collected volumetrically to determine urine volume, osmolality, pH, net acid excretion, and renal Na excretion after treatment. Plasma volume changes were extrapolated from plasma protein concentration changes. Treatment and time effects were tested with repeated measures ANOVA. Only subtle differences between oral administration of NaHCO3, with and without glucose, were observed for the change of the standard HCO3 concentration relative to baseline. No differences in plasma Na, plasma volume expansion, renal Na, net base excretion, urine volume, or pH could be identified between animals treated orally with NaHCO3 with and without glucose. Similarly, no differences in blood glucose concentration, plasma volume expansion, urine volume, or renal glucose excretion were observed in the 8h after treatment when comparing oral glucose treatment with and without NaHCO3. Our results indicate that combination of NaHCO3 with glucose in a hypertonic ORS only had a minor effect on the alkalinizing effect of NaHCO3, which is unlikely to be of clinical relevance. The combination of NaHCO3 and glucose neither improved Na, glucose, nor water absorption in euhydrated neonatal dairy calves, questioning the relevance of a specific ratio between Na and glucose in ORS for calves.

Long-term outcome of children with acute cerebellitis

BACKGROUND

Acute cerebellitis (AC) is characterized by cerebellar symptoms and magnetic resonance imaging (MRI) changes primarily confined to the cerebellum.

OBJECTIVE

To analyze the neurological and cognitive long-term outcome of children with AC.

METHODS

Children with AC diagnosed by typical clinical features and MRI findings were included in this retrospective study. Medical charts were reviewed and neurological deficits were assessed by neurological examination or by the expanded disability status scale telephone interview. Cognitive outcome was evaluated with a parental questionnaire (Kognitive Probleme bei Kindern und Jugendlichen).

RESULTS

A total of 11 children (6 boys, 5 girls; age range: 3 years to 14 years and 10 months) were included. Of them, six children had a severe disease manifestation including mental status changes and neurological symptoms. Of the rest, two children had a moderate and three children had a mild form of AC. MRI of the cerebellum was obtained in the acute phase revealing signal alterations with different patterns. The average follow-up period was 4 years and 4 months. A complete recovery was observed in five children. Neurological sequelae were reported in five children ranging from ataxia to mild tremor. Cognitive deficits were found in six patients. The affected areas of cognition did include spatial visualization ability, language skills, and concentration.

CONCLUSION

Neurological and cognitive sequelae are common in children with AC and underline the role of the cerebellum in cognition.

Blood parameters and corneal-reflex of finishing pigs with and without lung affections observed post mortem in two abattoirs stunning with CO₂

In two pig abattoirs of different slaughter capacities, the stunning efficacy of CO2 on finishing pigs with and without pneumonic lesions (observed post mortem) was reflected against the corneal-reflex and blood parameters (blood pH, pCO2 and pO2) from individual finishers. Stunning duration was 120 s (abattoir A) and 90 s (abattoir B), respectively. Pneumonia in finisher pigs is frequently observed during post mortem inspection, which may raise concerns about a delay of unconsciousness because of hampered gas exchange in the lungs. The aim of this study was to examine possible pneumonia consequences for stunning efficacy under commercial conditions. For that, corneal reflex, O2 and CO2 partial pressure in the blood as well as blood pH were measured in 2650 finishers from abattoir A and 2100 from abattoir B. The partial pressure of O2 after stunning accounted to about 3 kPa, the partial pressure of CO2 was found at levels of about 24 kPa in abattoir A (after 120 s CO2 exposure) and 17.5 kPa in abattoir B (after 90 s CO2 exposure). In abattoir A, the blood pH was at 6.9, and at 7.0 in abattoir B. The corneal reflex was observed in 6.2% of pigs in abattoir A and 17.1% of pigs in abattoir B. A correlation between pneumonic lesions and blood status was not observed. However, for some individual farms, a significant correlation between pneumonia and corneal reflex was observed.

Interaction of CO and deuterium with bimetallic, monolayer Pt-island/film covered Ru(0001) surfaces

The adsorption properties of structurally well defined bimetallic Pt/Ru(0001) surfaces, consisting of a Ru(0001) substrate partly or fully covered by monolayer Pt islands or a monolayer Pt film, were studied by temperature programmed desorption (TPD) using CO and deuterium as probe molecules. Additionally, the adsorption of CO was investigated by infrared reflection absorption spectroscopy (IRAS). The presence of the pseudomorphic platinum islands or monolayer film leads to considerable modifications of the adsorption properties for both adsorbates, both on the Pt covered and, to a smaller extent, on the bare Ru part of the surfaces. In addition to distinct weakly bound adspecies, which are adsorbed on the monolayer Pt islands, we find unique contributions from island edge desorption, from spill-over processes during the desorption run, and a general down-shift of the peak related to desorption from Pt-free Ru(0001) areas with increasing Pt coverage. These effects, which we consider as characteristic for adsorption on bimetallic surfaces with large contiguous areas of the respective types, are discussed in detail.

Design and capabilities of an experimental setup based on magnetron sputtering for formation and deposition of size-selected metal clusters on ultra-clean surfaces

The design and performance of an experimental setup utilizing a magnetron sputtering source for production of beams of ionized size-selected clusters for deposition in ultra-high vacuum is described. For the case of copper cluster formation the influence of different source parameters is studied and analyzed. Size-selected clusters are deposited on substrates and the efficiency of an electrostatic quadrupole mass selector is tested. Height analysis using atomic force microscopy (AFM) demonstrates relative standard size deviations of 7%-10% for the particles of various sizes between 6 nm and 19 nm. Combined analysis by AFM and transmission electron microscopy reveals that the clusters preserve almost spherical shape after the deposition on amorphous carbon substrates. Supported nanoparticles of a few nanometres in diameter have crystalline structure with a face-centered cubic (fcc) lattice.

Inosine, not adenosine, initiates endothelial glycocalyx degradation in cardiac ischemia and hypoxia

Ischemia/reperfusion and hypoxia/reoxygenation of the heart both induce shedding of the coronary endothelial glycocalyx. The processes leading from an oxygen deficit to shedding are unknown. An involvement of resident perivascular cardiac mast cells has been proposed. We hypothesized that either adenosine or inosine or both, generated by nucleotide catabolism, attain the concentrations in the interstitial space sufficient to stimulate A3 receptors of mast cells during both myocardial ischemia/reperfusion and hypoxia/reoxygenation. Isolated hearts of guinea pigs were subjected to either normoxic perfusion (hemoglobin-free Krebs-Henseleit buffer equilibrated with 95% oxygen), 20 minutes hypoxic perfusion (buffer equilibrated with 21% oxygen) followed by 20 minutes reoxygenation, or 20 minutes stopped-flow ischemia followed by 20 minutes normoxic reperfusion (n = 7 each). Coronary venous effluent was collected separately from so-called transudate, a mixture of interstitial fluid and lymphatic fluid appearing on the epicardial surface. Adenosine and inosine were determined in both fluid compartments using high-performance liquid chromatography. Damage to the glycocalyx was evident after ischemia/reperfusion and hypoxia/reoxygenation. Adenosine concentrations rose to a level of 1 μM in coronary effluent during hypoxic perfusion, but remained one order of magnitude lower in the interstitial fluid. There was only a small rise in the level during postischemic perfusion. In contrast, inosine peaked at over 10 μM in interstitial fluid during hypoxia and also during reperfusion, while effluent levels remained relatively unchanged at lower levels. We conclude that only inosine attains levels in the interstitial fluid of hypoxic and postischemic hearts that are sufficient to explain the activation of mast cells via stimulation of A3-type receptors.

Plasma potassium-lowering effect of oral glucose, sodium bicarbonate, and the combination thereof in healthy neonatal dairy calves

Hyperkalemia is a common complication in neonatal diarrheic dairy calves and is corrected by administration of glucose or sodium bicarbonate. Although the hypokalemic effect of glucose is well established in other species, controversial results are reported for sodium bicarbonate. Our objective was to study the effect and mechanism of action of glucose and sodium bicarbonate on the potassium homeostasis of healthy neonatal dairy calves. Nine healthy neonatal Holstein-Friesian calves underwent 3 oral treatments with 2L of NaHCO(3) (150 mmol/L), glucose (300 mmol/L), and glucose+NaHCO(3) solution (300 mmol/L+150 mmol/L) in randomized order. Blood was obtained before treatment (T(0)) and at 30-min intervals thereafter. Changes between each time point and T(0) were determined for all parameters. Urine was collected volumetrically to determine total renal potassium excretion over an 8-h posttreatment period. Plasma volume changes were extrapolated from changes in plasma protein concentration. Treatment and time effects were tested with repeated-measures ANOVA. Multivariate stepwise regression analysis using dummy variable coding was conducted to identify associations between changes in plasma potassium concentration ([K]) and changes in plasma glucose concentration ([glucose]), blood base excess, and plasma volume. Oral glucose and sodium bicarbonate treatments decreased [K] by 25 and 19%, respectively, whereas the combination of both compounds caused an intermediate [K] decline (22%). For the glucose treatment, the decline in [K] was only associated with changes in plasma [glucose] (partial R(2)=0.19). In NaHCO(3)-treated calves, [K] decline was associated with change of extracellular volume (partial R(2)=0.31) and blood base excess (partial R(2)=0.19). When glucose and NaHCO(3) were combined, [K] decline was associated with changes in plasma volume (partial R(2)=0.30), BE (R(2)=0.22), and [glucose] (partial R(2)=0.03). Our results indicate that glucose lowers plasma [K] mainly through an insulin-dependent intracellular translocation of K, whereas NaHCO(3) causes hypokalemia through hemodilution followed by intracellular translocation of K caused by the strong ion effect. The combination of glucose and NaHCO(3) at the dosage used in this study does not have an additive hypokalemic effect. When combined, hemodilution and strong ion effect have the strongest effect on plasma [K], whereas the insulin-dependent effect of glucose appears to be blunted.

Shedding of the coronary endothelial glycocalyx: effects of hypoxia/reoxygenation vs ischaemia/reperfusion

BACKGROUND

Vascular endothelium is covered by a glycocalyx. Damage to the glycocalyx after systemic inflammation or ischaemia/reperfusion contributes to increased vascular permeability and leucocyte adhesion. The underlying mechanisms leading to ischaemia/reperfusion-induced glycocalyx shedding are incompletely understood, in terms of lack of oxygen, absence of flow, or return of oxygen.

METHODS

Isolated guinea pig hearts perfused with Krebs-Henseleit buffer at 37°C underwent 20 min of either stopped-flow ischaemia or hypoxic perfusion with subsequent reperfusion/reoxygenation (n = 6 each). Hearts perfused with normoxic buffer served as time controls. Epicardial transudate was collected to assess coronary net fluid filtration, colloid extravasation, and histamine release by mast cells. Syndecan-1 and heparan sulphate were measured in coronary effluent, together with lactate, purines, and the release of mast-cell tryptase β. Additional hearts were perfusion-fixed to visualize the glycocalyx.

RESULTS

Both ischaemia and hypoxia with reperfusion/reoxygenation resulted in significant increases in net fluid filtration (P < 0.05) and release of syndecan-1 and heparan sulphate in coronary effluent. These effects were already seen with the onset of hypoxic perfusion. Histamine was released during hypoxia and reoxygenation and also reperfusion, as was tryptase β, and high concentrations of adenosine (>1 µmol litre⁻¹, hypoxia group) and inosine (> 7 µmol litre⁻¹, ischaemia group) were measured in effluent (P < 0.05). Damage to the coronary glycocalyx was evident upon electron microscopy.

CONCLUSIONS

Both ischaemic and hypoxic hypoxia initiate glycocalyx degradation, promoting an increase in permeability. A contributing mechanism could be purine-mediated degranulation of resident mast cells, with liberated tryptase β acting as potential 'sheddase'.

Serious head injury in young children: birth trauma versus non-accidental head injury

Birth injury of the skull and central nervous system can be a complication of a difficult delivery, especially following forceps or vacuum-assisted delivery. Birth trauma of the head can also mimic the appearance of a non-accidental head injury and is therefore an important differential diagnosis. We report on two young infants with serious head injuries. The difficult differential diagnosis birth trauma versus non-accidental head injury is discussed and the necessity for cooperation between clinicians, forensic doctors and specialized neuroradiologists is emphasized.

Recurrent upper motor neuron facial weakness of possible epileptic etiology: a case report

We report on an otherwise healthy infant who presented with clusters of alternating central facial nerve paresis. At 11 months of age, the patient showed intermittent facial asymmetry compatible with right-sided upper motor neuron facial paresis and accompanying incomplete upper motor neuron hypoglossal paresis. Laboratory work-up and imaging studies did not reveal signs of infection, infarction or structural lesions, and after one week, symptoms spontaneously resolved. Similar episodes affecting alternate sides were noted at ages of 17, 27 and 49 months lasting for 4-14 days. At 49 months, EEG showed right temporo-occipital benign sharp waves with activation during drowsiness and sleep. A diagnosis of benign focal epilepsy with negative motor phenomena was made. She is now 60 months old and no further episodes have occurred without antiepileptic treatment. Ictal orofacial phenomena are the clinical hallmark of benign focal epilepsy with centro-temporal sharp waves (BECTS). As in our patient, negative epileptic motor phenomena frequently lead to a broad diagnostic work-up. In infants presenting with episodic central facial nerve paresis, the possibility of negative epileptic motor phenomena should be considered.