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H Hinrichsen

Publications and source records attributed to H Hinrichsen.

At least 19 recordsLinked to original sources
PubMed2002

Prevalence and risk factors of hepatitis C virus infection in haemodialysis patients: a multicentre study in 2796 patients.

BACKGROUND: Hepatitis C virus (HCV) infection is a significant problem in the management of haemodialysis patients. A high prevalence of HCV infection in haemodialysis patients has been reported. Risk factors such as the number of blood transfusions or duration on haemodialysis have been identified. AIM: To determine the prevalence of HCV by antibody testing and HCV-RNA determination by polymerase chain reaction (PCR) in haemodialysis patients. Furthermore, liver function tests were performed and epidemiological data were obtained to determine risk factors for HCV in this cohort of patients. RESULTS: A total of 2796 patients from 43 dialysis centres were enrolled. The overall prevalence of HCV (HCV antibody and/or HCV-RNA positivity) was 7.0% (195 patients). Antibody positivity occurred in 171 patients (6.1%). Viraemia was detectable in 111 patients (4.0%). Twenty four of 111 HCV RNA positive patients (21.6%) were negative for HCV antibodies. Thus 0.8% of the entire study population was HCV positive but could not be diagnosed by routine HCV antibody testing. Major risk factors identified by a standard questionnaire in 1717 of 2796 patients were the number of blood transfusions individuals had received and duration of dialysis, the latter including patients who received no blood transfusions. Sequencing of the 5'untranslated region of the genome showed a dominant genotype 1 (77.6%) within the cohort. Further reverse transcription-PCR of the NS5b and core region were performed to document phylogenetic analysis. Comparing nucleic acid sequences detected by PCR, no homogeneity was found and thus nosocomial transmission was excluded. CONCLUSIONS: HCV is common in German haemodialysis patients but screening for HCV antibodies alone does not exclude infection with HCV.

Adult↗
PubMed2001

Unusual scaling for pulsed laser deposition.

We show that a simple model for pulsed laser deposition exhibits an unusual type of scaling behavior for the island density in the submonolayer regime. This quantity is studied as a function of pulse intensity and deposition time. We find a data collapse for the ratios of the logarithms of these quantities, whereas conventional scaling as observed in molecular beam epitaxy involves ratios of powers.

Journal Article↗
PubMed2001

Critical coarsening without surface tension: the universality class of the voter model.

We show that the two-dimensional voter model, usually considered to be only a marginal coarsening system, represents a broad class of models for which phase ordering takes place without surface tension. We argue that voter-like growth is generically observed at order-disorder nonequilibrium transitions solely driven by interfacial noise between dynamically symmetric absorbing states.

Journal Article↗
PubMed2001

Binary spreading process with parity conservation.

Recently there has been a debate concerning the universal properties of the phase transition in the pair contact process with diffusion (PCPD) 2A-->3A, 2A-->0. Although some of the critical exponents seem to coincide with those of the so-called parity-conserving universality class, it was suggested that the PCPD might represent an independent class of phase transitions. This point of view is motivated by the argument that the PCPD does not conserve parity of the particle number. In the present work we question what happens if the parity conservation law is restored. To this end, we consider the reaction-diffusion process 2A-->4A, 2A-->0. Surprisingly, this process displays the same type of critical behavior, leading to the conclusion that the most important characteristics of the PCPD is the use of binary reactions for spreading, regardless of whether parity is conserved or not.

Journal Article↗
PubMed2001

Increased plasma homocysteine in liver cirrhosis.

Background: Homocysteine (Hcy), is an atherogenic and thrombogenic risk factor which has also been proposed to be involved in hepatic fibrinogenesis. Hcy metabolism, depends on the cofactors folate, vit. B12, and the vit. B6 vitamer pyridoxalphosphate (PLP). Metabolism of these vitamins is frequently disturbed in cirrhotics, but little is known about plasma Hcy levels in these patients. Methods: Plasma levels of Hcy, methionine, serine, cysteine, PLP, vit. B12 and folate, and standard clinical/biochemical parameters of liver disease were measured in 43 postabsorptive patients with biopsy proven cirrhosis of different origin. Results: 74% of the patients had elevated plasma Hcy levels defined as >13.4 µmol/l (mean+2SD of healthy age matched controls). Increased plasma Hcy concentrations were seen in alcoholic as well as in non-alcoholic cirrhosis. Excluding patients with impaired renal function (n=7), Hcy concentrations remained elevated in 69% of the patients. We found a high prevalence of pathological plasma vitamin concentrations of 33% for increased vit. B12 levels and 5% and 80% for decreased folate and vit. B6 levels, respectively. Mean plasma vitamin B12 concentrations increased, folate remained unchanged and PLP concentrations decreased with deteriorating liver function. Hcy concentrations were correlated with levels of creatinine (r=0.44, P<0.01), serine (r=-0.46, P<0.01), and cysteine (r=0.38, P<0.05), but showed no association with parameters of liver function and with plasma levels of folate, vit. B12 und vit. B6. This was contrary to data obtained in healthy individuals. In a stepwise multiple regression serine and cysteine best explained the variance in Hcy levels. Conclusions: Elevated basal Hcy-plasma levels are frequently seen cirrhotic patients. Variations of Hcy concentration in liver cirrhosis are not explained by plasma levels of cofactors of Hcy metabolism.

Journal Article↗
PubMed2001

Pair contact process with diffusion: anew type of nonequilibrium critical behavior?

In the preceding article Carlon et al. investigate the critical behavior of the pair contact process with diffusion. Using density matrix renormalization group methods, they estimate the critical exponents, raising the possibility that the transition might belong to the same universality class as branching annihilating random walks with even numbers of offspring. This is surprising since the model does not have an explicit parity-conserving symmetry. In order to understand this contradiction, we estimate the critical exponents by Monte Carlo simulations. The results suggest that the transition might belong to a different universality class that has not been investigated before.

Journal Article↗
PubMed2001

Idiosyncratic drug allergic phenprocoumon-induced hepatitis with subacute liver failure initially misdiagnosed as autoimmune hepatitis.

BACKGROUND: Coumarin anticoagulants are known to cause hepatotoxicity, but only a few cases have been reported. Coumarins are usually administered following cardiovascular surgery and the differential diagnosis is post-transfusion hepatitis. METHODS: We report the case of a 46-year-old woman who presented with jaundice, elevated liver function tests, positive antinuclear and smooth muscle antibodies following prodromal signs of fatigue and nausea. The patient had been treated with phenprocoumon for 5 months in order to prevent thromboembolism after two strokes assumed to be due to an open foramen ovale and an aneurysmatic atrial septum. RESULTS: There was no evidence of viral or other causes of hepatitis. The patient rapidly developed subacute liver failure with encephalopathy and phenprocoumon treatment was stopped. With intensive care support, as well as high-dose prednisolone treatment, she recovered. Owing to positive antinuclear and smooth muscle antibodies, the initial diagnosis 'acute autoimmune hepatitis with liver failure was made. CONCLUSION: The lack of hypergammaglobulinaemia and the rapid recurrence of hepatitis following re-exposure to phenprocoumon led to the final diagnosis of phenprocoumon-induced idiosyncratic drug allergic hepatitis with secondary autoimmune phenomena.

Anti-Inflammatory Agents↗
PubMed2000

First-order phase transition with a logarithmic singularity in a model with absorbing states.

Recently, Lipowski [Phys. Rev. E 62, 4401 (2000)] investigated a stochastic lattice model which exhibits a discontinuous transition from an active phase into infinitely many absorbing states. Since the transition is accompanied by an apparent power-law singularity, it was conjectured that the model may combine features of first- and second-order phase transitions. In the present work it is shown that this singularity emerges as an artifact of the definition of the model in terms of products. Instead of a power law, we find a logarithmic singularity at the transition. Moreover, we generalize the model in such a way that the second-order phase transition becomes accessible. As expected, this transition belongs to the universality class of directed percolation.

Journal Article↗
PubMed2000

First-order phase transition in a (1+1)-dimensional nonequilibrium wetting process

A model for nonequilibrium wetting in 1+1 dimensions is introduced. It comprises adsorption and desorption processes with a dynamics that generically does not obey detailed balance. Depending on the rates of the dynamical processes the wetting transition is either of first or second order. It is found that the wet (unbound) and the nonwet (pinned) states coexist and are both thermodynamically stable in a domain of the dynamical parameters that define the model. This is in contrast with equilibrium transitions where coexistence of thermodynamically stable states takes place only on the transition line.

Journal Article↗
PubMed1999

Nonequilibrium critical behavior in unidirectionally coupled stochastic processes.

Phase transitions from an active into an absorbing, inactive state are generically described by the critical exponents of directed percolation (DP), with upper critical dimension d(c)=4. In the framework of single-species reaction-diffusion systems, this universality class is realized by the combined processes A-->A+A, A+A-->A, and A-->0. We study a hierarchy of such DP processes for particle species A,B,..., unidirectionally coupled via the reactions A-->B, ...(with rates mu(AB),...). When the DP critical points at all levels coincide, multicritical behavior emerges, with density exponents beta(i) which are markedly reduced at each hierarchy level i> or =2. This scenario can be understood on the basis of the mean-field rate equations, which yield beta(i)=1/2(i-1) at the multicritical point. Using field-theoretic renormalization-group techniques in d=4-epsilon dimensions, we identify a new crossover exponent phi, and compute phi=1+O(epsilon(2)) in the multicritical regime (for small mu(AB)) of the second hierarchy level. In the active phase, we calculate the fluctuation correction to the density exponent on the second hierarchy level, beta(2)=1/2-epsilon/8+O(epsilon(2)). Outside the multicritical region, we discuss the crossover to ordinary DP behavior, with the density exponent beta(1)=1-epsilon/6+O(epsilon(2)). Monte Carlo simulations are then employed to confirm the crossover scenario, and to determine the values for the new scaling exponents in dimensions d< or =3, including the critical initial slip exponent. Our theory is connected to specific classes of growth processes and to certain cellular automata, and the above ideas are also applied to unidirectionally coupled pair annihilation processes. We also discuss some technical as well as conceptual problems of the loop expansion, and suggest some possible interpretations of these difficulties.

Journal Article↗
PubMed1999

Critical behavior of roughening transitions in parity-conserving growth processes.

We investigate a class of parity-conserving solid-on-solid models that describes the growth of an interface by the deposition and evaporation of dimers. As a key feature of the models, evaporation of dimers takes place only at the edges of terraces, leading to a roughening transition between a smooth and a rough phase. We consider several variants of growth models in order to identify universal and nonuniversal properties. Moreover, a parity-conserving polynuclear growth model is proposed. All variants display the same type of universal critical behavior at the roughening transition. Because of parity conservation, the critical behavior at the first few layers can be explained in terms of unidirectionally coupled branching annihilating random walks with an even number of offspring.

Journal Article↗
PubMed1998

Evaluation of a cacao drink as a simple oral stimulus to assess gallbladder contraction.

UNLABELLED: Gallbladder contractility plays an important role in the pathogenesis of gallstones and in the course of cholelithiasis. Furthermore, a functioning gallbladder is an important condition for performing a successful disolution of gallstones by bile acids. Therefore, a reliable simple physiological test is desired to assess gallbladder contractility. In ten volunteers gallbladder contraction was stimulated by 50 g chocolate, 330 ml cacao drink or in comparison by intramuscular injection of 0.3 microgram/kg ceruletide. Gallbladder volume was measured sonographically and CCK in serum was determined by radioimmunoassay (RIA) after 0, 15, 30 and 45 min. Additionally gallbladder contraction was determined in 20 patients with symptomatic gallstones using cacao drink on ceruletide. In health volunteers remaining gallbladder volume after 30 min was 28% +/- 5% using ceruletide and 37% +/- 7% using cacao. Stimulation by chocolate resulted in a remaining volume of 59% +/- 12% after 45 min only. Simultaneously to gallbladder contraction an increase of CCK in serum was registered. 30 min after cacao CCK had increased from 0.9 to 3.3 pmol/l. Using chocolate an increase of CCK amounted to 2.1 pmol/l after 45 min only. In patients with gallstones the positive predictive value of the cacao test for a functioning gallbladder was 91% and the negative predictive value was 78% in comparison to the unphysiologic stimulation by ceruletide injection. CONCLUSION: Cacao test but not chocolate is suitable and reliable to assess gallbladder contraction in patients with symptomatic gallstones.

Adult↗
PubMed1997

Thyroid autoantibodies and thyroid dysfunction during treatment with interferon-alpha for chronic hepatitis C.

Interferon-alpha (2a or 2b) is increasingly used for treatment of chronic hepatitis C virus (HCV) infection. Recent reports suggested a correlation between increases in thyroid autoantibodies and the development of thyroid dysfunction during interferon-alpha therapy. In this study, we analyzed thyroid hormones and antithyroid antibodies at monthly intervals in 53 patients who received interferon alpha for chronic active hepatitis C infection. Of five patients with initially elevated levels of antithyroid peroxydase antibodies (anti-TPO), the antibodies increased further in two of them. Ten patients, who started interferon therapy with normal antibody levels, developed elevated anti-TPO antibodies for limited times during treatment. Levels of anti-TPO antibodies showed a marked fluctuation, and only three patients had increased anti-TPO antibodies persisting for longer than 3 mo. Antithyroglobulin antibodies appeared in four patients, all of whom were also positive for anti-TPO antibodies. No changes in TRAB levels were observed. All of these patients with elevated antithyroid antibodies remained in an euthyroid state. One patient with normal antithyroid antibodies developed thyroiditis with severe thyrotoxicosis after 9 wk of interferon therapy. These findings suggest that the induction of antithyroid antibodies during treatment with interferon-alpha does not indicate clinical relevant thyroid dysfunction. Routine measurement of antithyroid antibodies during interferon-alpha therapy does not seem to be mandatory.

Adult↗