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Biomedical subjects

H Bock

Publications and source records attributed to H Bock.

At least 19 recordsLinked to original sources
PubMed2006

[Effectiveness of antiviral therapy in patients with chronic hepatitis C treated by private practice gastroenterologists].

The standard treatment for patients with chronic hepatitis C consists of pegylated interferon (PegIFN) alpha in combination with ribavirin. Information on treatment effectiveness outside clinical trials is sparse. To study community-based health care, a regional network supported by the German network of competence for hepatitis (Hep-Net) was created between gastroenterologists in private practice and a tertiary referral centre. A treatment register containing evidence-based guidelines was established and 212 consecutive patients who were treated with either PegIF Nalpha 2a/ribavirin (n = 126) or PegIFNalpha2b/ribavirin (n = 86) for 24 weeks (HCV genotype 2, 3) and 48 weeks (HCV genotype 1, 4, 5), respectively, were included and followed prospectively. Twenty-four weeks after cessation of antiviral treatment a sustained virological response was achieved in 54 % of the patients. By univariate analyses, infection with HCV genotypes 2 or 3 (p < 0.0001), younger age (p < 0.0001), normal gamma-glutamyltransferase levels before initiation of treatment (p = 0.003), and absence of language communication problems (p = 0.023) were associated with a sustained virological response. The presence of liver cirrhosis in patients with HCV genotype 1, 4, 5 infection was associated with lower sustained response rates (p = 0.025). Patients infected with HCV genotype 1 in whom the PegIFNalpha dose was reduced had higher virological relapse rates (p = 0.049). With regard to the treating physician, sustained virological response rates ranged from 26 - 67 % in patients infected with HCV genotype 1. Our study shows that virological response rates similar to those in international randomised clinical trials can be achieved by private practice gastroenterologists. The presented network allows characterization of the treatment outcome in chronic hepatitis C not only with regard to virus- and host-related factors but also on an individual physician basis.

Adult↗
PubMed2005

Solid/solid phase transitions in confined thin films: a zero temperature approach.

We report a density functional theory study of confinement induced solid/solid phase transitions in a thin film (modeled as methane) at T=0. The solid film is confined by two graphite surfaces represented by a mean-field potential. As the wall separation is varied the structure of the confined film changes, which influences its density and the solvation force. Using the directly accessible grand canonical potential density we determine the stable phases and calculate the exact location of the phase transitions. We observe a series of phases having square and triangular symmetry. At low wall separations we find zig-zag buckling and an asymmetric buckled phase, whose structure is consistent with the strongest buckling instability of a triangular monolayer predicted by Chou and Nelson [Phys. Rev. E 48, 4611 (1993)] but, to our knowledge, has not been observed as a stable phase before. We find that the two-dimensional order parameters Psi(4) (square symmetry) and Psi(6) (triangular symmetry) show unphysical behavior in the transition region between square and triangular symmetry. Thus, in the present model they fail to predict the right location of the phase transitions.

Journal Article↗
PubMed2004

Anomalous temperature dependence of surfactant self-assembly from aqueous solution.

The self-assembly of surfactant molecules from aqueous solutions exhibits anomalous and as yet unexplained temperature dependence. These effects include (a) a decrease in surfactant solubility, (b) an increase of the critical micelle concentration, and (c) increasing self-assembly on solid surfaces with increasing temperature near ambient temperature. These are the opposite of what one intuitively expects based on increasing molecular motion with temperature, and of what is observed for simpler fluids. Using a lattice gas theory that allows for inhomogeneity, hydrogen bonding, and micelle formation, we show conclusively that all of these phenomena arise from hydrogen bonding between water and the surfactant headgroups. While theory and experiment show very good qualitative agreement when such H bonding is included, its omission leads to complete reversal of the temperature dependence.

Journal Article↗
PubMed2003

Sudden death due to a haemoglobin variant.

A previous healthy 35-year-old man was found dead in his truck. Shortly before death he merely complained of influenza-like symptoms. The histological examination revealed evidence of a massive accumulation of sickle cells in smaller blood vessels. After molecular genetic analysis, the preliminary diagnosis of "sickle cell disease" was finally changed to the diagnosis of a sickle cell trait. It is presumed that an epileptic attack which also has to be considered as a concurring cause of death, precipitated sickling of the erythrocytes and led to a fatal sickle cell crisis.

Adult↗
PubMed2003

Ciliary neurotrophic factor in the olfactory bulb of rats and mice.

Ciliary neurotrophic factor (CNTF) is primarily regarded as an astrocytic lesion factor, promoting neuronal survival and influencing plasticity processes in deafferented areas of the CNS. Postnatal loss of neurons in CNTF-deficient mice indicates a function of the factor also under physiological conditions. In the olfactory bulb, where neurogenesis, axo- and synaptogenesis continue throughout life, CNTF content is constitutively high. The cellular localization of CNTF in the rat olfactory bulb is not fully resolved, and species differences between mouse and rat are not yet characterized. In the present study, four different CNTF antibodies and double immunolabeling with specific markers for glial and neuronal cells were used to study the cellular localization of CNTF in rat and mouse olfactory bulb. Specificity of the detection was checked with tissue from CNTF-deficient mice, and investigations were complemented by immunolocalization of reporter protein in mice synthesizing beta-galactosidase under control of the CNTF promoter (CNTF lacZ-knock-in mice). In both species, CNTF localized to ensheathing cell nuclei, cell bodies and axon-enveloping processes. Additionally, individual axons of olfactory neurons were CNTF immunoreactive. Both CNTF protein content and immunoreaction intensity were lower in mice than in rats. Scattered lightly CNTF-reactive cells were found in the granular and external plexiform layers in rats. Some CNTF-positive cells were associated with immunoreactivity for the polysialylated form of the neural cell adhesion molecule, which is expressed by maturing interneurons derived from the rostral migratory stream. In CNTF lacZ-knock-in mice, beta-galactosidase reactivity was found in ensheathing cells of the olfactory nerve layer, and in cells of the glomerular, external plexiform and granular layers. The study proves that CNTF is localized in glial and neuronal structures in the rodent olfactory bulb. Results in mice provide a basis for investigations concerning the effects of a lack of the factor in CNTF-deficient mice.

Animals↗
PubMed2002

Unusual craniocerebral injury caused by a pneumatic nail gun.

A man was found unconscious near a ladder in a house. After resuscitation he was brought to a hospital and X-rays of the skull showed that two 12-cm long nails had completely penetrated the cranial cavity. The nails were operatively removed and after treatment for 5 weeks, the patient was transferred to a rehabilitation centre with a decreasing hemiparesis on the left side and general deterioration and then, after an attempted suicide to a psychiatric hospital. The perforating cranio-cerebral injury from a pneumatic nail gun known to reach only low muzzle velocities is a very unusual finding.

Accidents, Occupational↗
PubMed2001

Role of nanoscopic liquid bridges in static friction.

Interpretations of recent experiments on the effects of humidity on friction hypothesize that liquid-water bridges can span nanoscopic gaps at the interface between the sliding surfaces. By means of a lattice-gas model the mechanisms by which such bridges may engender static friction at a single ideal nanoscopic contact were studied. The model contact consists of a simple (spherically symmetric) fluid constrained between two plane-parallel substrates decorated with weakly and strongly attractive stripes that alternate periodically in one transverse direction. In analogy with the experiments the shear yield stress (yield strength) tau(s) of the contact was computed as a function of the chemical potential mu of the fluid (the analog of humidity). The influence of other thermodynamic state variables, such as temperature and distance between the substrates, and of the relative strength of the stripes on the yield-strength curves (i.e., tau(s) versus mu) was explored. Some intriguing correlations between experiment and theory are observed.

Journal Article↗
PubMed2001

[Prevention and therapy of diabetic foot syndrome. Preventing complications].

Selective prevention and stage-orientated treatment of the diabetic foot syndrome helps to avoid late complications. A prerequisite is good blood sugar control, early use of ACE inhibitors, CSE inhibitors and--based on the vascular situation, with consideration given to indications--platelet aggregation inhibitors. Regular inspection of the feet must be taken seriously. Every diabetic should be taught the rules of behavior in young years. The primary physician is responsible for coordinating further treatment and early referral to specialized foot clinics. In the event of an infection, specific treatment of the usually polymicrobial infection should be initiated. Long-term antibiotic treatment is not to be recommended. Wherever necessary, the calculated antibiotic therapy must be corrected on the basis of the results of antibiotic sensitivity testing of swabs taken from deep tissue (better: exudate from the floor of the wound. In the case of superinfected ulcers, wound debridement by the specialist surgeon is considered a must. Also, late stages of diabetic foot can be successfully managed in specialized centers by "foot-relieving" measures, revascularization, arthrodesis, etc.

Aged↗
PubMed2000

Single crystals of an ionic anthracene aggregate with a triplet ground state

Crystalline supramolecular aggregates consisting of charged organic molecules, held together through metal-cluster-mediated Coulomb interactions, have attracted interest owing to their unusual structural, chemical and electronic properties. Aggregates containing metal cation clusters 'wrapped' by lipophilic molecular anions have, for example, been shown to be kinetically stable and soluble in nonpolar liquids such as saturated hydrocarbons. The formation of supramolecular aggregates can even be exploited to generate aromatic hydrocarbons that carry four negative charges and crystallize in the form of organic poly(metal cation) clusters or helical polymers. Here we report the anaerobic crystallization of an ionic organic aggregate--a contact ion septuple consisting of a fourfold negatively charged 'tripledecker' of three anthracene molecules bridged by four solvated potassium cations. Its electronic ground state is shown experimentally, using temperature-dependent electron paramagnetic resonance spectroscopy, to be a triplet. Although the spins in this biradical ionic solid are separated by a considerable distance, density functional theory calculations indicate that the triplet ground state is 84 kJ mol(-1) more stable than the first excited singlet state. We expect that the successful crystallization of the ionic solid we report here, and that of a covalent organic compound with a triplet ground state at room temperature, will stimulate further attempts to develop new triplet-ground-state materials for practical use.

Journal Article↗
PubMed2000

Suicide in a lions' den.

The case of a young man who committed suicide in a lions' den of a zoo is presented. Special attention is paid to the injury pattern which was characterised by numerous penetrating, stab-like wounds and lesions. The remarkable circumstances and history of this incident are most likely connected to a psychological or psychiatric disorder of the victim.

Animals↗
PubMed2000

Rifabutin-based triple therapy after failure of Helicobacter pylori eradication treatment: preliminary experience.

Despite continuous improvement of Helicobacter pylori (Hp) eradication therapy, new treatment regimens are necessary if established first-line treatments fail. In the present pilot study, a recently described rifabutin-based triple therapy was evaluated after preceding failure of triple therapy. Rifabutin (150 mg), amoxicillin (1 g), and lansoprazole (30 mg) were administered twice daily for 1 week to 25 patients infected with Hp who had previously failed to respond to eradication treatment and/or who had developed resistance to macrolides and nitroimidazoles. Four patients were lost to follow-up. Eradication rate of rifabutin-based triple therapy was 86% (18/21; per protocol) and 72% (18/25; intention-to-treat). Side effects were minimal. It is concluded that this new drug combination is an effective therapy for Hp strains resistant to clarithromycin or metronidazole; however, rifabutin-based treatment regimens for Hp eradication should be restricted to patients infected with resistant strains.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2000

Dimorphism and inclusion compounds of N,N'-di(benzenesulfonyl)-p-phenylenediamine

Crystal structures of a new polymorph of N,N'-(p-phenylene)bis(benzenesulfonamide) (C18H16N2O4S2) and of two inclusion compounds with acetone [(CH3)2CO] and dimethyl sulfoxide [2(CH3)2SO], respectively, have been determined at 150 K. For a more reliable comparison, the structure of the already known polymorph of N,N'-di(benzenesulfonyl)-p-phenylenediamine has been redetermined under identical conditions. In addition, the phase transformation behavior has been examined by differential scanning calorimetry and the crystallization conditions of both polymorphs including their formation by weathering of the inclusion compounds were investigated.

Journal Article↗
PubMed2000

Seroepidemiology of varicella-zoster in Pakistan.

The availability of safe and effective vaccines has renewed interest in the epidemiology of varicella worldwide. To date published data on the epidemiology of varicella in Pakistan is very scarce. Therefore, we conducted a study to determine the age-specific seroprevalence rate of varicella-zoster virus (VZV) antibodies in Pakistan. Between December 1997 and March 1998, 1,509 healthy volunteers aged between 1 month and 30 years were recruited from the Islamabad, Karachi, Lahore and Rawalpindi areas. Demographic information, socioeconomic status and past medical history were obtained by questionnaire. Serum samples were assayed for IgG antibodies against VZV by enzyme-linked immunosorbent assay. Overall 41.8% (600/1,435) of those tested were found to be seropositive for VZV antibodies. No difference was found in results obtained from the different cities. A higher seroprevalence was observed among women (45.2%) compared to men (39.6%). Seroprevalence rates increased with age and were 28.4% in those aged 0-5 years, 41.5% in the 6-10 year age group, 42.5% in the 11-15 year age group, 46.7% in the 16-20 year age group and 53.6% in those aged 21-30 years. Socioeconomic status was not a significant risk factor for VZV seropositivity. This is the first report of the seroepidemiology of VZV in Pakistan. The results indicate that seroprevalence of VZV increases with age in the Pakistani population studied. As in other tropical countries, there is greater susceptibility to varicella among the adolescent and young adult population. The results of this study suggest that these at-risk groups should be included in vaccination programs aimed at reducing the public health impact of varicella.

Adolescent↗
PubMed1999

The Li(+)-Initiated Twofold Dehydrogenation and C-C Bond Formation of Hexaphenylbenzene to the Dilithium Salt of the 9,10-Diphenyltetrabenz

Partly solvent-separated and partly solvent-shared, the contact ion triple of the 9,10-diphenyltetrabenz[a,c,h,j]anthracene dianion is formed by the ultrasonically activated reaction of hexaphenylbenzene with lithium metal powder in 1,2-dimethoxyethane (dme) [Eq. (1)]. The proposed microscopic pathway for this reaction-twofold dehydrogenation and C-C bond formation-is supported by quantum-chemical calculations.

Journal Article↗
PubMed1998

Eradication of Helicobacter pylori with lansoprazole, roxithromycin and metronidazole--an open pilot study.

BACKGROUND: The most extensively studied Helicobacter pylori eradication regimen comprises omeprazole, clarithromycin and metronidazole. Macrolide antibiotics other than clarithromycin should achieve similar efficacy, but they have not yet been thoroughly tested. AIM: To determine the efficacy and safety of a triple therapy regimen using lansoprazole, roxithromycin, and metronidazole on the basis of multicentre outpatient care in an open pilot study. METHODS: 163 patients with duodenal ulcer and proven H. pylori infection received lansoprazole 30 mg b.d., roxithromycin 300 mg b.d. and metronidazole 500 mg b.d. for 7 days followed by another 7 days of lansoprazole 30 mg once daily. H. pylori status was determined by urease quick test, histology, microbiology and 13C-urea breath test before starting and at least 4 weeks after completing treatment. RESULTS: 150 patients were available for evaluation; H. pylori was successfully eradicated in 84.7% (127/ 150) as determined by urease quick test, 78.0% (117/150) by histology, 81.3% (109/134) by 13C-urea breath test; and in 75.3% (113/150), at least two tests were negative. Side-effects were reported in 34 patients (most commonly diarrhoea and changes in liver function tests), in two cases the study medication was interrupted. Prior to treatment, 23% of the H. pylori isolates were resistant against metronidazole and 3.4% against roxithromycin. After unsuccessful treatment, 84% of the isolates were resistant against metronidazole and 21% against roxithromycin. Primary resistance to metronidazole increased the chance of treatment failure approximately sevenfold (7% vs. 53%). CONCLUSIONS: For H. pylori eradication, the combination of lansoprazole, roxithromycin and metronidazole proved to be as safe as other current triple therapy regimens, while a comparison of efficacy rates yet remains to be assessed in prospective controlled trials. The metronidazole-resistant H. pylori is not rare in Germany and, in the present study, has strongly influenced treatment success.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1997

[Calcitonin, a proximal-tubular-acting diuretic: lithium clearance measurements in humans].

Lithium clearance was used to investigate the effect of calcitonin on renal sodium excretion. Two sequential renal function tests, calcitonin and placebo treated, were performed in 6 healthy students. Intravenous administration of 0.5 mg human calcitonin (hCT) (Cibacalcin, Ciba-Geigy, Basel, Switzerland) significantly raised fractional excretion of sodium (FENa), from 1.73% (0.97%) to 3.63% (0.89%) (p < 0.001), and lithium clearance (Cli), from 35.1 (5.4) to 53.9 (8.5) ml/ min x 1.73 m2 (p < 0.01). By using inulin and lithium clearance we calculated proximal (PFR), distal (DFR) and total excreted sodium (TAN). Our results clearly demonstrate that hCT has a proximal diuretic effect in humans and that a calcitonin induced proximal sodium loss is compensated by increased sodium reabsorption within 80 minutes after hCT application. Calcitonin increases the excretion of lithium and has a potential to be used in lithium intoxication.

Adult↗