Piezo-modulated active grating for selecting X-ray pulses separated by one nanosecond

We present a novel method of temporal modulation of X-ray radiation for time resolved experiments. To control the intensity of the X-ray beam, the Bragg reflection of a piezoelectric crystal is modified using comb-shaped electrodes deposited on the crystal surface. Voltage applied to the electrodes induces a periodic deformation of the crystal that acts as a diffraction grating, splitting the original Bragg reflection into several satellites. A pulse of X-rays can be created by rapidly switching the voltage on and off. In our prototype device the duty cycle was limited to ∼1 ns by the driving electronics. The prototype can be used to generate X-ray pulses from a continuous source. It can also be electrically correlated to a synchrotron light source and be activated to transmit only selected synchrotron pulses. Since the device operates in a non-resonant mode, different activation patterns and pulse durations can be achieved.

Efficacy of Retreatment After Failed Direct-acting Antiviral Therapy in Patients With HCV Genotype 1-3 Infections

Hepatitis C virus infection is causing chronic liver disease, cirrhosis, and hepatocellular carcinoma. By combining direct-acting antivirals (DAAs), high sustained virologic response rates (SVRs) can be achieved. Resistance-associated substitutions (RASs) are commonly observed after DAA failure, and especially nonstructural protein 5A (NS5A) RASs may impact retreatment options.^1-3 Data on retreatment of DAA failure patients using first-generation DAAs are limited.^4-7 Recently, a second-generation protease- and NS5A-inhibitor plus sofosbuvir (voxilaprevir/velpatasvir/sofosbuvir [VOX/VEL/SOF]) was approved for retreatment after DAA failure.⁸ However, this and other second-generation regimens are not available in many resource-limited countries or are not reimbursed by regular insurance, and recommendations regarding the selection of retreatment regimens using first-generation DAAs are very important. This study aimed to analyze patients who were re-treated with first-generation DAAs after failure of a DAA combination therapy.

Reciprocal space slicing: A time-efficient approach to femtosecond x-ray diffraction

An experimental technique that allows faster assessment of out-of-plane strain dynamics of thin film heterostructures via x-ray diffraction is presented. In contrast to conventional high-speed reciprocal space-mapping setups, our approach reduces the measurement time drastically due to a fixed measurement geometry with a position-sensitive detector. This means that neither the incident (ω) nor the exit ( 2 θ ) diffraction angle is scanned during the strain assessment via x-ray diffraction. Shifts of diffraction peaks on the fixed x-ray area detector originate from an out-of-plane strain within the sample. Quantitative strain assessment requires the determination of a factor relating the observed shift to the change in the reciprocal lattice vector. The factor depends only on the widths of the peak along certain directions in reciprocal space, the diffraction angle of the studied reflection, and the resolution of the instrumental setup. We provide a full theoretical explanation and exemplify the concept with picosecond strain dynamics of a thin layer of NbO₂.

Tracking picosecond strain pulses in heterostructures that exhibit giant magnetostriction

We combine ultrafast X-ray diffraction (UXRD) and time-resolved Magneto-Optical Kerr Effect (MOKE) measurements to monitor the strain pulses in laser-excited TbFe₂/Nb heterostructures. Spatial separation of the Nb detection layer from the laser excitation region allows for a background-free characterization of the laser-generated strain pulses. We clearly observe symmetric bipolar strain pulses if the excited TbFe₂ surface terminates the sample and a decomposition of the strain wavepacket into an asymmetric bipolar and a unipolar pulse, if a SiO₂ glass capping layer covers the excited TbFe₂ layer. The inverse magnetostriction of the temporally separated unipolar strain pulses in this sample leads to a MOKE signal that linearly depends on the strain pulse amplitude measured through UXRD. Linear chain model simulations accurately predict the timing and shape of UXRD and MOKE signals that are caused by the strain reflections from multiple interfaces in the heterostructure.

Grueneisen-approach for the experimental determination of transient spin and phonon energies from ultrafast x-ray diffraction data: gadolinium

We study gadolinium thin films as a model system for ferromagnets with negative thermal expansion. Ultrashort laser pulses heat up the electronic subsystem and we follow the transient strain via ultrafast x-ray diffraction. In terms of a simple Grueneisen approach, the strain is decomposed into two contributions proportional to the thermal energy of spin and phonon subsystems. Our analysis reveals that upon femtosecond laser excitation, phonons and spins can be driven out of thermal equilibrium for several nanoseconds.

Procedural and shunt-related complications and mortality of the transjugular intrahepatic portosystemic shunt (TIPSS)

BACKGROUND

The implantation of a transjugular intrahepatic portosystemic shunt (TIPSS) is a complex angiographic procedure performed in patients with end-stage liver disease. Numerous case reports and narrative reviews have been published so far; however, studies systematically investigating procedural and shunt-related complications are lacking.

AIM

To systematically investigate complications and mortality occurring during the index hospital stay and the early (4-week) period after TIPSS implantation.

METHODS

The study includes 389 patients who received a TIPSS implantation between 2004 and 2014. Data were obtained from the clinical records and technical reports of the TIPSS implantation.

RESULTS

During the index hospital stay, procedure-related complications occurred in 42 patients (10.8%) with intraperitoneal bleeding in 8 patients (2.1%) and infections in 14 patients (3.6%). Shunt- and disease-related complications consisted of hepatic encephalopathy (1-year incidence 29%), non-procedural infections (8.7%) and acute hepatic decompensation (4.1%). Nine patients (2.3%) died during the index hospital stay from procedure-related (two patients, 0.5%), shunt-related (four patients, 1%) or disease-related causes (three patients, 0.8%). 23 patients (5.9%) died during 4 weeks after TIPSS implantation. The 1-year probability of survival was 67.7% and was negatively associated with severe hepatic encephalopathy and acute hepatic decompensation.

CONCLUSIONS

Except hepatic encephalopathy, severe procedure- and shunt-related complications are rare and early mortality is low.

Azobenzene - functionalized polyelectrolyte nanolayers as ultrafast optoacoustic transducers

We introduce azobenzene-functionalized polyelectrolyte multilayers as efficient, inexpensive optoacoustic transducers for hyper-sound strain waves in the GHz range. By picosecond transient reflectivity measurements we study the creation of nanoscale strain waves, their reflection from interfaces, damping by scattering from nanoparticles and propagation in soft and hard adjacent materials like polymer layers, quartz and mica. The amplitude of the generated strain ε∼ 5 × 10(-4) is calibrated by ultrafast X-ray diffraction.

Coupling of GHz phonons to ferroelastic domain walls in SrTiO3

We study the linear and nonlinear acoustic response of SrTiO3 across its ferroelastic transition at Ta=105  K by time domain Brillouin scattering. Above Ta we observe that for a strain amplitude of ∼0.18% the sound velocity for compressive strain exceeds the tensile strain velocity by 3%. Below Ta we find a giant slowing down of the sound velocity by 12% and attribute this to the coupling of GHz phonons to ferroelastic twin domain walls. We propose a new mechanism for this coupling on the ultrafast time scale, providing an important new test ground for theories used to simulate atomic motion in domain forming crystals.

Efficacy and safety of transjugular intrahepatic portosystemic shunt (TIPSS) in 40 patients with hepatocellular carcinoma

BACKGROUND

Portal hypertension and hepatocellular carcinoma (HCC) are major complications of advanced liver cirrhosis. Thus, patients are often affected by both complications. Transjugular intrahepatic portosystemic shunt (TIPSS) is an effective treatment for portal hypertension and its complications. However, no established guidelines for the treatment of symptomatic portal hypertension in HCC patients are currently available. In addition, only limited information exists about the consequence of TIPSS implantation in patients with HCC.

AIM

To evaluate the efficacy, safety and overall survival in HCC patients who underwent TIPSS implantation.

METHODS

Forty HCC patients with portal hypertension who were treated with TIPSS between 1995 and 2012 were included in the analysis. Medical records and imaging studies were analysed. The indication for TIPSS implantation, procedure-related complications, treatment success and overall survival were assessed.

RESULTS

TIPSS implantation was performed in 23 patients (57.5%) due to treatment refractory ascites, in 14 patients (35.0%) due to recurrent variceal bleeding and in three patients (7.5%) due to ascites and variceal bleeding. Primary technical success was assessed in all patients. After TIPSS implantation, no variceal bleeding reoccurred and ascites was controlled in 74.1%. No severe procedure-related complications and no deterioration of liver function were observed. Post-TIPSS hepatic encephalopathy occurred in 40.0% of all patients. 30-day, 90-day-, 1-year- and 5-year survival rates were 97.5%, 75.0%, 42.5% and 7.5%, respectively. Median overall survival after TIPSS implantation was 180 days.

CONCLUSION

Transjugular intrahepatic portosystemic shunt implantation is an effective and safe treatment for portal hypertension in patients with HCC.

Electric-field-induced polar order and localization of the confined electrons in LaAlO3/SrTiO3 heterostructures

With ellipsometry, x-ray diffraction, and resistance measurements we investigated the electric-field effect on the confined electrons at the LaAlO3/SrTiO3 interface. We obtained evidence that the localization of the electrons at negative gate voltage is induced, or at least enhanced, by a polar phase transition in SrTiO3 which strongly reduces the lattice polarizability and the subsequent screening. In particular, we show that the charge localization and the polar order of SrTiO3 both develop below ∼50  K and exhibit similar, unipolar hysteresis loops as a function of the gate voltage.

Osteopathology associated with bone resorption inhibitors - which role does Actinomyces play? A presentation of 51 cases with systematic review of the literature

BACKGROUND

Bone resorption inhibitor-related osteopathology of the jaw (BRIOJ) is a severe complication in patients treated with bisphosphonates or denosumab. However, the precise pathogenesis of BRIOJ is not yet fully understood. Recent studies discovered the presence of Actinomyces colonies in biopsy material from BRIOJ patients. The aim of this study was to analyze current knowledge concerning the impact of Actinomyces on the pathogenesis of this condition and to present data from our own patients.

METHODS

Data from 51 patients with histopathological diagnoses of BRIOJ were retrospectively analyzed. In addition, a systematic literature search for studies describing the presence of Actinomyces was performed.

RESULTS

Actinomyces was present in 86% of our cases and 63.3% of 371 cases presented in the literature. All of our patients and 85% of patients described in the literature had a clearly defined local focus in association with osteopathology. A clear picture of whether Actinomyces colonizes the previously necrotic bone or contributes to inflammation causing subsequent bone necrosis is lacking in the literature.

CONCLUSION

The pathogenesis of BRIOJ remains unknown; however, there seems to be a role for Actinomyces, and possibly other pathogens, in the development of osteopathology of the jaws, which is not exclusive to bisphosphonate therapy. This study supports the hypothesis that an infectious component is of utmost importance for the pathogenesis of BRIOJ.

Evidence of a precursor superconducting phase at temperatures as high as 180 K in RBa2Cu3O(7-δ) (R=Y, Gd, Eu) superconducting crystals from infrared spectroscopy

We show that a multilayer analysis of the infrared c-axis response of RBa2Cu3O(7-δ) (R=Y, Gd, Eu) provides important new information about the anomalous normal-state properties of underdoped cuprate high temperature superconductors. In addition to competing correlations which give rise to a pseudogap that depletes the low-energy electronic states below T*≫T(c), it enables us to identify the onset of a precursor superconducting state below T(ons)>T(c). We map out the doping phase diagram of T(ons) which reaches a maximum of 180 K at strong underdoping and present magnetic field dependent data which confirm our conclusions.

Coexistence and competition of magnetism and superconductivity on the nanometer scale in underdoped BaFe1.89Co0.11As2

We report muon spin rotation (μSR) and infrared spectroscopy experiments on underdoped BaFe1.89Co0.11As2 which show that bulk magnetism and superconductivity (SC) coexist and compete on the nanometer length scale. Our combined data reveal a bulk magnetic order, likely due to an incommensurate spin density wave (SDW), which develops below T(mag)≈32  K and becomes reduced in magnitude (but not in volume) below Tc=21.7  K. A slowly fluctuating precursor of the SDW seems to develop already below the structural transition at T(s)≈50  K. The bulk nature of SC is established by the μSR data which show a bulk SC vortex lattice and the IR data which reveal that the majority of low-energy states is gapped and participates in the condensate at T≪T(c).

Dynamical response and confinement of the electrons at the LaAlO3/SrTiO3 interface

With infrared ellipsometry and transport measurements we investigated the electrons at the interface between LaAlO3 and SrTiO3. We obtained a sheet carrier concentration of N(s) approximately = 5-9x10(13) cm(-2), an effective mass of m*=3.2+/-0.4m(e), and a strongly frequency dependent mobility. The latter are similar as in bulk SrTi(1-x)Nb(x)O3 and therefore suggestive of polaronic correlations. We also determined the vertical concentration profile which has a strongly asymmetric shape with a rapid initial decay over the first 2 nm and a pronounced tail that extends to about 11 nm.

Coexistence of static magnetism and superconductivity in SmFeAsO(1-x)F(x) as revealed by muon spin rotation

The recent observation of superconductivity with critical temperatures (Tc) up to 55 K in the pnictide RFeAsO(1-x)F(x), where R is a lanthanide, marks the first discovery of a non-copper-oxide-based layered high-Tc superconductor. It has raised the suspicion that these new materials share a similar pairing mechanism to the cuprate superconductors, as both families exhibit superconductivity following charge doping of a magnetic parent material. In this context, it is important to follow the evolution of the microscopic magnetic properties of the pnictides with doping and hence to determine whether magnetic correlations coexist with superconductivity. Here, we present a muon spin rotation study on SmFeAsO(1-x)F(x), with x=0-0.30 that shows that, as in the cuprates, static magnetism persists well into the superconducting regime. This analogy is quite surprising as the parent compounds of the two families have rather different magnetic ground states: itinerant spin density wave for the pnictides contrasted with the Mott-Hubbard insulator in the cuprates. Our findings therefore suggest that the proximity to magnetic order and associated soft magnetic fluctuations, rather than strong electronic correlations in the vicinity of a Mott-Hubbard transition, may be the key ingredients of high-Tc superconductors.

Giant superconductivity-induced modulation of the ferromagnetic magnetization in a cuprate-manganite superlattice

Artificial multilayers offer unique opportunities for combining materials with antagonistic orders such as superconductivity and ferromagnetism and thus to realize novel quantum states. In particular, oxide multilayers enable the utilization of the high superconducting transition temperature of the cuprates and the versatile magnetic properties of the colossal-magnetoresistance manganites. However, apart from exploratory work, the in-depth investigation of their unusual properties has only just begun. Here we present neutron reflectometry measurements of a [Y(0.6)Pr(0.4)Ba(2)Cu(3)O(7) (10 nm)/La(2/3)Ca(1/3)MnO(3) (10 nm)](10) superlattice, which reveal a surprisingly large superconductivity-induced modulation of the vertical ferromagnetic magnetization profile. Most surprisingly, this modulation seems to involve the density rather than the orientation of the magnetization and is highly susceptible to the strain, which is transmitted from the SrTiO(3) substrate. We outline a possible explanation of this unusual superconductivity-induced phenomenon in terms of a phase separation between ferromagnetic and non-ferromagnetic nanodomains in the La(2/3)Ca(1/3)MnO(3) layers.

Coexistence of magnetic fluctuations and superconductivity in the pnictide high temperature superconductor SmFeAsO1-xFx measured by muon spin rotation

Muon spin rotation experiments were performed on the pnictide high temperature superconductor SmFeAsO1-xFx with x=0.18 and 0.3. We observed an unusual enhancement of slow spin fluctuations in the vicinity of the superconducting transition which suggests that the spin fluctuations contribute to the formation of an unconventional superconducting state. An estimate of the in-plane penetration depth lambda ab(0)=190(5) nm was obtained, which confirms that the pnictide superconductors obey an Uemura-style relationship between Tc and lambda ab(0);(-2).

Superconducting energy gap and c-axis plasma frequency of (Nd,Sm)FeAsO0.82F0.18 superconductors from infrared ellipsometry

We present far-infrared ellipsometric measurements of polycrystalline samples of the pnictide superconductor RFeAsO0.82F0.18 (R=Nd and Sm). We find evidence that the electronic properties are strongly anisotropic such that the optical spectra are dominated by the weakly conducting c-axis response similar to the cuprate high-temperature superconductors. We deduce an upper limit of the c-axis superconducting plasma frequency of omega pl,c(SC)< or =260 cm(-1) corresponding to a lower limit of the c-axis magnetic penetration depth of lambda c > or =6 microm and lambda c/lambda ab > or =30 as compared to lambda ab=185 nm from muon spin rotation [A. Drew, arXiv:0805.1042 [Phys. Rev. Lett. (to be published)]]. We also observe a gaplike suppression of the conductivity in the superconducting state with a shoulderlike feature at omegaSC* approximately 300 cm(-1) and spectral shape which is consistent with an unconventional order parameter with 2Delta approximately omegaSC* approximately 37 meV.

A clinical trial on absorption and N-acetylation of oral and rectal mesalazine

BACKGROUND

Mesalazine (5-ASA) is a standard treatment for ulcerative colitis. Extent of absorption and N-acetylation determine systemic exposure to 5-ASA, and are thereby relevant for the safety of the treatment. The aim of the study was to compare absorption and N-acetylation of 5-ASA following rectal or oral drug administration. Healthy subjects were compared to patients with ulcerative colitis to evaluate the impact of chronic inflammation of colorectal mucosa on disposition of 5-ASA.

MATERIALS AND METHODS

First, 12 healthy adults were randomized to receive 2 g of 5-ASA by each of four different formulations: oral delayed release granules, 30 mL enema, 60 mL rectal foam, and 120 mL rectal foam. Second, 12 patients with active ulcerative colitis received 60 mL rectal foam. Pharmacokinetic analysis was performed by determination of 5-ASA and its acetylated, pharmacologically inactive metabolite (Ac-5-ASA) in plasma and urine.

RESULTS

First, systemic exposure to 5-ASA was markedly lower after rectal drug administration as compared to oral dosing (P < 0.001; e.g. median relative bioavailability of 60 mL rectal foam: 36%). Second, N-acetylation of rectal 5-ASA was lower in patients than in healthy subjects [area under the curve (AUC) ratio Ac-5-ASA/5-ASA: 1.6 +/- 0.5 vs. 2.3 +/- 0.4, mean +/- SD, P < 0.01]. High peak plasma concentrations of 5-ASA were correlated with high microscopic disease activity (r = 0.67, P < 0.05).

CONCLUSIONS

Rectal delivery of 5-ASA results in low systemic drug exposure with potentially reduced toxicity in comparison with oral drug administration. Chronic inflammation of colorectal mucosa might be a relevant source of variability in pharmacokinetics of 5-ASA.

Transgenic animals in experimental xenotransplantation models: orthotopic heart transplantation in the pig-to-baboon model

Pig organs are at risk for hyperacute and acute vascular rejection mediated by anti-pig antibodies, mainly binding to the Galalpha(1,3)Gal epitope. Acute cellular rejection is characterized by progressive infiltration of mononuclear cells. There is an ongoing search for immunosuppressive regimens that provide adequate protection against all patterns of xenograft rejection, but have no severe impact on the condition of xenograft recipients. Herein orthotopic heart transplantations were performed from hDAF or hCD46 piglets to nonsplenectomized baboons. Basic immunosuppression consisted of tacrolimus, sirolimus, GAS914, steroids, and ATG. Group 1 received basic immunosuppression. Group 2 was additionally treated with rituximab and group 3 with half-dose cyclophosphamide. Group 4 received cyclophosphamide and an anti-HLA-DR antibody. Three baboons received GAS914 and TPC. Monitoring included the regular assessment of anti-porcine antibodies, blood counts, therapeutic drug monitoring, and graft histology. Two grafts failed due to technical mistakes. In group 1, baboons died after 1 and 9 days. In group 2, maximum survival was 30 hours. In group 3, baboons lived 20 hours, 25 days, and 14 days. Group 4 survival times were 9.5 hours, 5.5 hours, 4 days, 34 hours, and 3 days. An increase of non-Galalpha(1,3)Gal antibodies was observed. Depositions of immunoglobulins and complement revealed a humoral rejection process. No cellular infiltration could be observed. In conclusion, suppressing cellular rejection with half-dose cyclophosphamide together with tacrolimus and sirolimus produced longer graft survival with a good general condition. Prevention of acute xenograft rejection further needs inhibition of non-Galalpha(1,3)Gal cytotoxicity by sufficient depression of B-cell activation.

The use of a polytetrafluoroethylene-covered stent graft for transjugular intrahepatic portosystemic shunt (TIPS): Long-term follow-up of 100 patients

PURPOSE

To retrospectively evaluate results and clinical outcome of transjugular intrahepatic portosystemic shunt (TIPS) after implantation of a polytetrafluoroethylene (PTFE)-covered stent graft.

MATERIAL AND METHODS

The stent graft was used in 112 patients with higher risk of primary (i.e. patients with Budd-Chiari syndrome) or secondary shunt failure (patients with occlusion of a previous uncovered stent), or a complicated TIPS procedure with an imminent technical complication requiring covered stent. Patients were scheduled at 3- to 6-month intervals for duplex-sonographic control of shunt function. Radiological revision was performed in patients with a decrease in shunt function by >25%, primary non-response, or relapse of the index symptom.

RESULTS

Twelve patients were lost to follow-up, and 100 patients were followed for 22+/-15 months. The actuarial rates of shunt patency were 90, 84, and 74% at 1, 2, and 3 years of follow-up, respectively. Two patients developed early (within 1 month) and 14 patients late shunt failure. Except for one transient rise in liver enzymes due to outflow obstruction by the stent graft, no technical complications were seen. Primary response to treatment was seen in 97% of patients treated for variceal bleeding and 84% of patients treated for refractory ascites. A relapse of the index symptom was seen in 13% of bleeders and 9% of patients treated for refractory ascites.

CONCLUSION

TIPS created with a PTFE-covered stent graft showed favorable long-term results.

Mechanical manipulation of molecular lattice parameters in smectic elastomers

Smectic liquid crystalline elastomers (SLCE) represent unique materials that combine a 1-D molecular lattice arrangement and orientational order with rubber-elasticity mediated by a polymer network. Such materials may exhibit large thermo-mechanical, opto-mechanical and electro-mechanical effects, due to the coupling of macroscopic sample geometry and microscopic structural features. It is shown that the molecular layer dimensions in the smectic phases can be influenced reversibly by macroscopic strain of the material. We present a microscopic model on the basis of experimental results obtained by mechanical dilatation measurements, optical interferometry, X-ray scattering, (13)C NMR, FTIR and polarizing microscopy data. The model gives an explanation of the controversial results obtained in different types of smectic elastomers.

Effect of vardenafil, an inhibitor of phosphodiesterase-5, on portal haemodynamics in normal and cirrhotic liver -- results of a pilot study

BACKGROUND

Dysregulation of the cyclic guanosine 3',5' monophosphate-nitric oxide system is in part responsible for portal hypertension in cirrhosis.

AIM

To test the effects of inhibitors of phosphodiesterase-5 on portal haemodynamics.

METHODS

To 18 healthy subjects and 18 patients with Child A liver cirrhosis, 10 mg of vardenafil, an inhibitor of phosphodiesterase-5, were administered orally. Doppler sonographic measurements of hepatic and splanchnic blood flow, systemic blood pressure and heart rate were recorded before, 1 h after, and 48 h after the application. Vardenafil plasma levels were determined after 1 h. In five patients, invasive registration of free and wedged hepatic vein pressure was performed.

RESULTS

Portal venous flow increased in patients from 0.82 +/- 0.30 L/min (mean +/- s.d.) by 26% (CI: 16-37%, P = 0.0004) and in healthy subjects from 0.75 +/- 0.20 L/min (mean +/- s.d.) by 19% (CI: 9-28%; P = 0.0010). Celiac and hepatic artery resistivity indices rose significantly. Systemic blood pressure decreased slightly in patients. The wedged hepatic venous pressure gradient decreased in four of five patients with liver cirrhosis. Vardenafil plasma levels were higher in patients (14 +/- 10 microg/L) than in healthy subjects (9 +/- 6 microg/L; n.s.).

CONCLUSIONS

Inhibition of phosphodiesterase-5 increases portal flow and lowers portal pressure by a decrease in sinusoidal resistance and may be a novel therapeutic strategy for portal hypertension.

[A rare cause of subacute parotitis. The pathogenetic role of crystals from an infarcted Whartin's tumour?]

The etiology of a subacute inflammatory swelling in the area of the right parotid gland in a 62-years old man could not be resolved clinically. The histomorphological examination of the surgical specimen showed an intraglandular area of predominantly chronic histiocytic inflammation with foreign body reaction in the intimate neighbourhood of a small, subtotally infarcted Warthin's tumour. Not birefringent spindle-shaped crystals could be demonstrated both within the parotitis or intraluminally in vital parts of the Warthin's tumour. In terms of the possible causes of the severe intraglandular inflammation, all arguments favour a primary infarction of the Warthin's tumour with the release of intraluminal preformed crystals which secondarily induce a massive inflammation with foreign body reaction, corresponding to the clinical presentation of a subacute parotitis.

Structural Processes during Starch Granule Hydration by Synchrotron Radiation Microdiffraction

Starch granule hydration has been examined on the level of a single potato starch granule by static and dynamic synchrotron radiation (SR) microdiffraction techniques. A cryofrozen, hydrated granule was mapped through a 5 microm SR-beam in order to investigate its internal organization. The edge of the granule showed fiber texture scattering due to radially oriented amylopectin helices. The variation of fiber texture across the granule center supports the model of concentric shells. The crystalline phase appears, however, to increase strongly toward the granule center due to a random amylopectin fraction, which could be related to crystallization of short-range ordered amylopectin during hydration. During gelatinization, the shell structure breaks down and remaining fiber-textured amylopectin domains belong probably to the swollen starch granule envelope. Hydration of a granule was initiated by a microdrop generator and followed in situ by SR-microdiffraction. A fast hydration process with a half time of about 7 s seems to reflect the porous nature of starch granules. The size of the hydrated domains suggests that this process is limited to the level of amylopectin side chain clusters. Longer hydration times are assumed to involve remaining short-range ordered amylopectin and results in larger domains.

[Chronic circumferential aortic dissection with intimo-intimal intussusception]

A circumferential aortic dissection with so-called intimo-intimal intussusception is a very rare complication of a dissecting aneurysm, in which the sock-like intimal flap is upended in the true lumen by the blood stream. The few cases reported thus far are based on radiological or intraoperative findings in acute dissections. The present postmortem study documents the very rare case of long-term survival of a chronic circumferential dissection with intimo-intimal intussusception.

How much reduction in portal pressure is necessary to prevent variceal rebleeding? A longitudinal study in 225 patients with transjugular intrahepatic portosystemic shunts

OBJECTIVES

This longitudinal study determines the risk of rebleeding in relation to the reduction of the portosystemic pressure gradient in patients with a transjugular intrahepatic portosystemic shunt (TIPS) for variceal bleeding.

METHODS

The study included 225 patients in whom a TIPS revision was indicated by the endoscopic finding of varices with a high risk for rebleeding (n = 167) or a recent variceal rebleed (n = 58). The portosystemic pressure gradient was determined before and after TIPS placement and at revision performed after a mean of 10 +/- 15 months.

RESULTS

The portosystemic pressure gradient at revision approached the index pressure gradient before TIPS implantation (23.1 +/- 5.5 mm Hg) by 8.4 +/- 31%. Rebleeding was inversely correlated with the reduction in index pressure gradient found at revision. Thus, 80% of rebleedings occurred with pressure gradients close to the index pressure gradient (< 25% reduction) or with gradients equal to or greater than the index pressure gradient. In contrast, only one patient (0.4%) and three patients (1.3%) rebled with a pressure gradient of < 12 mm Hg or a reduction of the index pressure gradient by > 50%, respectively. Kaplan-Meier analysis of rebleeding, which included the 225 patients at risk, showed a probability of rebleeding of 18%, 7%, and 1% for a reduction of the index pressure gradient by 0%, 25-50%, and > 50%, respectively.

CONCLUSIONS

Most rebleedings occurred with pressure gradients similar to the index-pressure gradient measured at first bleeding. Accordingly, a graded reduction by 25-50% sufficiently prevents rebleeding. It can be assumed that, in comparison with the widely used threshold value of 12 mm Hg, a reduction by 25-50% may have a favorable benefit-to-risk ratio with respect to shunt-induced hepatic encephalopathy and liver failure. It should therefore be a goal in the decompressive treatment of portal hypertension and maintained during follow-up of patients with variceal bleeding.

Quantification of mucosal leucocyte endothelial cell interaction by in vivo fluorescence microscopy in experimental colitis in mice

Leucocyte recruitment to sites of intestinal inflammation is a crucial, multi-step process that leads ultimately to the accumulation of cells in the inflamed tissue. We established a new in vivo model system of experimental colitis to quantify leucocyte-endothelial cell interaction and leucocyte extravasation in the inflamed mucosa of the colon. Furthermore, we investigated the pathophysiological role of ICAM-1 in the intestinal microcirculation in vivo. Using the model of dextran sodium sulphate (DSS)-induced acute and chronic colitis in mice, in vivo microscopy was performed in the colonic submucosal postcapillary venules and the submucosal collecting venules in normal or inflamed murine colonic segments. ICAM-1 expression was blocked by an anti-ICAM-1 monoclonal antibody or by suppressing NF-kappaB activation by gliotoxin. Significant increases in leucocyte adhesiveness (51-fold in postcapillary venules, 30-fold in collecting venules, P < 0.01) and extravasation (6.5-fold) could be demonstrated as early as day 2 of DSS-application in acute colitis (P < 0.01). This was paralleled by increases in both the histological damage scores and myeloperoxidase activities. In chronic dextran sodium sulphate-induced colitis significant increases in leucocyte-endothelium interactions and leucocyte extravasation were observed. Blocking ICAM-1 expression with a monoclonal antibody or gliotoxin, leucocyte sticking and extravasation were significantly down-regulated in vivo compared to controls (> 70%; P < 0.01). This new model system offers the possibility to specifically assess the role of adhesion molecules in the colonic mucosa in vivo as well as to investigate and quantify the effectiveness of experimental therapeutic approaches in acute or chronic intestinal inflammation.

Treatment of refractory hepatic hydrothorax with transjugular intrahepatic portosystemic shunt: long-term results in 40 patients

BACKGROUND/AIMS

Hepatic hydrothorax is a complication of portal hypertension secondary to ascites. In this study, we investigated retrospectively the effects of the transjugular intrahepatic portosystemic shunt (TIPS) on hepatic hydrothorax refractory to diuretic treatment.

METHODS

Forty patients (Child-Pugh class B, 24 patients; Child-Pugh class C, 16 patients) with hydrothorax refractory to diuretic treatment, pleurocenteses or pleurodesis were included. The TIPS implantation was successful in all patients, who were then followed for 16 +/- 14 months (range 1 day-54 months).

RESULTS

TIPS reduced the portosystemic pressure gradient from 26 +/- 6 to 10 +/- 5 mmHg. In the 17 patients whom we followed for 12 months or longer, improvements were found for the Child--Pugh score (8.6 +/- 1.8 v. 6.7 +/- 1.5), serum albumin concentration (3.1 +/- 0.5 v. 3.6 +/- 0.5 g/l), and urinary sodium excretion (22 +/- 29 v. 89 +/- 43 mmol/24 h) (P< 0.05). Two patients developed severe hepatic encephalopathy requiring shunt occlusion. Hydrothorax improved in 82% of patients and resolved in 71% of patients. Fifty per cent of patients developed shunt insufficiency within 7 +/- 9 months, contributing to a probability of relapse-free 1-year survival of 35%. In these patients, shunt revision resulted in a secondary response rate of 82.3%. The 1-year survival was 64%. Both hydrothorax response and survival showed a significant inverse correlation with age over 60 years (P< 0.01 and P< 0.003, respectively) but not with other biomedical variables.

CONCLUSION

TIPS is effective for hydrothorax refractory to diuretic treatment and other standard interventions to bridge the time to transplantation. Patients older than 60 years have a poor response and short survival.

Prevention of rebleeding from oesophageal-gastric varices

Endoscopic sclerotherapy or ligation and/or drugs are the standard treatments for the prevention of variceal rebleeding. Failure of this treatment indicates the need for rescue transjugular intrahepatic portosystemic shunt (TIPS) implantation. The current practice to use endoscopic treatment as first-line and TIPS as second-line treatment is, however, not based on evidence since, in unselected patients, both treatments have a comparable survival. In addition, the timing for a change from endoscopic treatment to TIPS is not exactly defined. According to the randomized studies available a change may be recommended when uncontrolled rebleeding or more than two rebleedings within a time interval of 6-12 months indicate failure of the endoscopic treatment. This regimen may be reconsidered when future developments improve outcome of one or the other treatment. In this regard the TIPS treatment has a potential of improvement if further reduction of the rate of rebleeding can be achieved with less stenosis, and/or reduced encephalopathy.

Helicobacter pylori infection does not correlate with plasma ammonia concentration and hepatic encephalopathy in patients with cirrhosis

BACKGROUND/AIMS

In patients with cirrhosis, infection of the stomach with Helicobacter pylori may increase ammonia production and, consequently, the incidence of hepatic encephalopathy. To test this hypothesis a retrospective analysis was performed in patients with a transjugular intrahepatic portosystemic shunt. These patients are regarded to be ideal candidates for such a study since they have a high bioavailability of gut-derived ammonia and many of them develop spontaneous hepatic encephalopathy.

METHODOLOGY

In 132 patients (Child-Pugh class A: 24%, B: 49%, C: 27%) with stable transjugular intrahepatic portosystemic shunt function for more than 3 months (mean follow-up: 15.5 +/- 10.8 months) the diagnosis of H. pylori infection was established by a specific and sensitive immunoblot assay for IgG- and IgA-antibodies. During follow-up, hepatic encephalopathy was assessed by clinical examination and a structured questionnaire. Venous plasma ammonia concentration was measured at the time of antibody determination (end of study period).

RESULTS

Eighty-four patients (64%) had negative and 48 patients (36%) had positive immunoblots for H. pylori. The groups were comparable with respect to age, gender, etiology of cirrhosis, Child-Pugh class, follow-up after transjugular intrahepatic portosystemic shunt, and shunt function. The ammonia concentrations of the patients without (group 1) and with antibodies against H. pylori (group 2) were 73 +/- 27 and 69 +/- 28 mumol/L (mean +/- SD), respectively. Hepatic encephalopathy occurred in 23 of 84 patients (27%) of group 1 and in 11 of 48 patients (23%) of group 2.

CONCLUSIONS

A positive immunoblot for H. pylori antibodies neither correlates with plasma ammonia concentration nor with the incidence of hepatic encephalopathy in patients with cirrhosis of the liver and portosystemic shunt.

Severe veno-occlusive disease after allogeneic bone marrow or peripheral stem cell transplantation--role of transjugular intrahepatic portosystemic shunt (TIPS)

AIMS

Veno-occlusive disease of the liver is a severe complication of allogeneic bone marrow or peripheral stem cell transplantation with a high mortality. In its severe form, the portal vein is used as an outflow tract for the arterial hepatic perfusion. A portosystemic side-to-side shunt, e.g. a transjugular intrahepatic portosystemic shunt, may facilitate portal outflow thus increasing hepatic (i.e. arterial) perfusion.

METHODS

The effect of a transjugular shunt on liver function and blood flow was studied in three patients receiving shunt treatment 0-2 days after the diagnosis of severe veno-occlusive disease occurring 28, 20, and 17 days after allogeneic transplantation for acute myeloid leukemia, Hodgkin's disease and chronic myeloid leukemia, respectively.

RESULTS

The transjugular shunt reduced the portosystemic pressure gradient from 23 to 8, 18 to 5, and 33 to 13 mmHg in patients 1, 2, and 3, respectively, increased the stagnant portal vein flow to normal, and decreased the arterial resistive index, indicating an increase in the arterial perfusion of the liver. This was accompanied by rapid relief from abdominal pain and removal of ascites. The AST concentration dropped from 1230, 417, and 2930 U/l before to 93, 20, and 41 U/l and the PT-time ratio improved 3-7 days after shunt treatment while the bilirubin concentration continued to rise until the patients died 26, 42, and 33 days after transplantation from multiorgan failure (two patients) or intracerebral hemorrhage.

CONCLUSIONS

The transjugular shunt may have improved abdominal and hepatic perfusion and prevented further necrosis of hepatocytes. It did not, however, affect jaundice or survival, which was limited by extrahepatic complications.

A comparison of paracentesis and transjugular intrahepatic portosystemic shunting in patients with ascites

BACKGROUND

In patients with cirrhosis and ascites, creation of a transjugular intrahepatic portosystemic shunt may reduce the ascites and improve renal function. However, the benefit of this procedure as compared with that of large-volume paracentesis is uncertain.

METHODS

We randomly assigned 60 patients with cirrhosis and refractory or recurrent ascites (Child-Pugh class B in 42 patients and class C in 18 patients) to treatment with a transjugular shunt (29 patients) or large-volume paracentesis (31 patients). The mean (+/-SD) duration of follow-up was 45+/-16 months among those assigned to shunting and 44+/-18 months among those assigned to paracentesis. The primary outcome was survival without liver transplantation.

RESULTS

Among the patients in the shunt group, 15 died and 1 underwent liver transplantation during the study period, as compared with 23 patients and 2 patients, respectively, in the paracentesis group. The probability of survival without liver transplantation was 69 percent at one year and 58 percent at two years in the shunt group, as compared with 52 percent and 32 percent in the paracentesis group (P=0.11 for the overall comparison, by the log-rank test). In a multivariate analysis, treatment with transjugular shunting was independently associated with survival without the need for transplantation (P=0.02). At three months, 61 percent of the patients in the shunt group and 18 percent of those in the paracentesis group had no ascites (P=0.006). The frequency of hepatic encephalopathy was similar in the two groups. Of the patients assigned to paracentesis in whom this procedure was unsuccessful, 10 received a transjugular shunt a mean of 5.5+/-4 months after randomization; 4 had a response to this rescue treatment.

CONCLUSIONS

In comparison with large-volume paracentesis, the creation of a transjugular intrahepatic portosystemic shunt can improve the chance of survival without liver transplantation in patients with refractory or recurrent ascites.

Conformational rearrangements of an archaeal chaperonin upon ATPase cycling

Chaperonins are double-ring protein assemblies with a central cavity that provides a sequestered environment for in vivo protein folding. Their reaction cycle is thought to consist of a nucleotide-regulated alternation between an open substrate-acceptor state and a closed folding-active state. The cavity of ATP-charged group I chaperonins, typified by Escherichia coli GroEL [1], is sealed off by a co-chaperonin, whereas group II chaperonins--the archaeal thermosome and eukaryotic TRiC/CCT [2]--possess a built-in lid [3-5]. The mechanism of the lid's rearrangements requires clarification, as even in the absence of nucleotides, thermosomes of Thermoplama acidophilum appear open in vitrified ice [6] and closed in crystals [4]. Here we analyze the conformation of the thermosome at each step of the ATPase cycle by small-angle neutron scattering. The apo-chaperonin is open in solution, and ATP binding induces its further expansion. Closure seems to occur during ATP hydrolysis and before phosphate release, and represents the rate-limiting step of the cycle. The same closure can be triggered by the crystallization buffer. Thus, the allosteric regulation of group II chaperonins appears different from that of their group I counterparts.

Complementary visualization of mitotic barley chromatin by field-emission scanning electron microscopy and scanning force microscopy

The surface structure of mitotic barley chromatin was studied by field-emission scanning electron microscopy (FESEM) and scanning force microscopy (SFM). Different stages of the cell cycle were accessible after a cell suspension was dropped onto a glass surface, chemical fixed, and critically point dried. Imaging was carried out with metal-coated specimen or uncoated specimen (only for SFM). The spatial contour of the chromatin could be resolved by SFM correlating to FESEM data. The experimentally determined volume of the residue chromatin during mitosis was within the range of 65-85 microm(3). A comparison with the theoretically calculated volume indicated a contribution of about 40% of internal cavities. Decondensation of chromosomes by proteinase K led to a drastic decrease in the chromosome volume, and a 3-D netlike architecture of the residue nucleoprotein material, similar to that in the intact chromosome, was obvious. Incubation of metaphase chromosomes in citrate buffer permitted access to different levels of chromatin packing. We imaged intact chromosomes in liquid by SFM without any intermediate drying step. A granular surface was obvious but with an appreciably lower resolution. Under similar imaging conditions proteinase K-treated chromosomes exhibited low topographic contrast but were susceptible to plastic deformations.

Cardiac function and haemodynamics in alcoholic cirrhosis and effects of the transjugular intrahepatic portosystemic stent shunt

BACKGROUND

A portosystemic stent shunt may impair cardiac function and haemodynamics.

AIMS

To investigate the effects of a transjugular intrahepatic portosystemic shunt (TIPS) on cardiac function and pulmonary and systemic circulation in patients with alcoholic cirrhosis.

PATIENTS/METHODS

17 patients with alcoholic cirrhosis and recent variceal bleeding were evaluated by echocardiography and catheterisation of the splanchnic and pulmonary circulation before and after TIPS. The period of catheter measurement was extended to nine hours in nine of the patients. The portal vein was investigated by Doppler ultrasound before and nine hours after TIPS.

RESULTS

Baseline echocardiography showed the left atrial diameter to be slightly increased and the left ventricular volume to be in the upper normal range. Nine hours after TIPS, the left atrial diameter and left ventricular end diastolic volume were increased (by 6% (p<0.01) and 7% (p<0.01) respectively); end systolic volume had not changed significantly. Invasive measurements showed a sharp increase in right atrial pressure (by 101%; p<0.01), mean pulmonary artery pressure (by 92%; p<0.01), pulmonary capillary wedge pressure (by 111%; p<0.01), and cardiac output (8.1 (1.6) to 11.9 (2.4) l/min; p<0.01). Systemic vascular resistance decreased (824 (242) to 600 (265) dyn.s.cm-5 p<0.01), and total pulmonary resistance increased (140 (58.5) to 188 (69.5) dyn.s.cm-5; p<0.05). Total pulmonary resistance (12%; NS), cardiac output (1.4 l/min; p<0. 05), and portal vein blood flow (1.4 l/min; p<0.05) remained elevated for nine hours after TIPS in the subgroup. Portoatrial pressure gradient (43%; p<0.05), portohepatic vascular resistance (72%; p<0.05), and systemic vascular resistance (27%; p<0.01) were consistently reduced.

CONCLUSIONS

The increase in the left atrial diameter, the pulmonary capillary wedge pressure, and total pulmonary resistance observed after the TIPS procedure reflected diastolic dysfunction of the hyperdynamic left ventricle in patients with alcoholic cirrhosis. The haemodynamic effects of the portosystemic stent shunt itself on the splanchnic circulation seem to be mainly responsible for the further decrease in systemic vascular resistance. TIPS may unmask a coexisting preclinical cardiomyopathy in patients with alcoholic cirrhosis and portal hypertension.