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Biomedical subjects

H Berger

Publications and source records attributed to H Berger.

At least 55 records · Page 3Linked to original sources
PubMed2000

Stability and activity of alcohol dehydrogenases in W/O-microemulsions: enantioselective reduction including cofactor regeneration.

Microemulsions provide an interesting alternative to classical methods for the conversion of less water-soluble substrates by alcohol dehydrogenase, but until now stability and activity were too low for economically useful processes. The activity and stability of the enzymes are dependent on the microemulsion composition, mostly the water and the surfactant concentration. Therefore, it is necessary to know the exact phase behavior of a given microemulsion reaction system and the corresponding enzyme behavior therein. Because of their economic and ecologic suitability polyethoxylated fatty alcohols were investigated concerning their phase behavior and their compatibility with enzymes in ternary mixtures. The phase behavior of Marlipal O13-60 (C13EO6 in industrial quality)/cyclohexane/water and its effect on the activity and stability of alcohol dehydrogenase from Yeast (YADH) and horse liver (HLADH) and the carbonyl reductase from Candida parapsilosis (CPCR) is presented in this study. Beside the macroscopic phase behavior of the reaction system, the viscosity of the system indicates structural changes of aggregates in the microemulsion. The changes of the enzyme activities with the composition are discussed on the basis of transitions from reverse micelles to swollen reverse micelles and finally, the transition to the phase separation. The formate dehydrogenase from Candida boidinii was used for the NADH-regeneration during reduction reactions. While the formate dehydrogenase did not show any kinetic effect on the microemulsion composition, the other enzymes show significant changes of activity and stability varying the water or surfactant concentration of the microemulsion. Under certain conditions, stability could be maintained with HLADH for several weeks. Successful experiments with semi-batch processes including cofactor regeneration and product separation were performed.

Alcohol Dehydrogenase↗
PubMed2000

Electronic structure of solids with competing periodic potentials.

When electrons are subject to a potential with two incommensurate periods, translational invariance is lost, and no periodic band structure is expected. However, model calculations based on nearly free one-dimensional electrons and experimental results from high-resolution photoemission spectroscopy on a quasi-one-dimensional material do show dispersing band states with signatures of both periodicities. Apparent band structures are generated by the nonuniform distribution of electronic spectral weight over the complex eigenvalue spectrum.

Journal Article↗
PubMed2000

Pressure induced quantum critical point and non-fermi-liquid behavior in BaVS3

The phase diagram of BaVS3 is studied under pressure using resistivity measurements. The temperature of the metal to nonmagnetic Mott insulator transition decreases under pressure, and vanishes at the quantum critical point p(cr) = 20 kbar. We find two kinds of anomalous conducting states. The high-pressure metallic phase is a non-Fermi liquid described by Deltarho approximately T(n) where n = 1.2-1.3 at 1<T<40 K. At p<p(cr), the transition is preceded by a wide precursor region with critically increasing resistivity which we ascribe to the opening of a soft Coulomb gap.

Journal Article↗
PubMed2000

Joys and pitfalls of fermi surface mapping in Bi(2)Sr(2)CaCu(2)O(8+delta) using angle resolved photoemission

On the basis of angle-scanned photoemission data recorded using unpolarized radiation, with high (E,k) resolution, and an extremely dense sampling of k space, we resolve the current controversy regarding the normal state Fermi surface (FS) in Bi(2)Sr(2)CaCu(2)O(8+delta). The true picture is simple, self-consistent, and robust: the FS is holelike, with the form of rounded tubes centered on the corners of the Brillouin zone. Two further types of features are also clearly observed: shadow FSs, which are most likely to be due to short range antiferromagnetic spin correlations, and diffraction replicas of the main FS caused by passage of the photoelectrons through the modulated Bi-O planes.

Journal Article↗
PubMed2000

[Hepatocellular carcinoma with extension per continuitatem into the right atrium].

HISTORY AND CLINICAL FINDINGS: A 61-year-old asymptomatic patient presented with a hepatocellular carcinoma and a history of 11 cycles of transarterial chemoembolization. Staging investigations revealed an enlarged hepatic tumour and a right atrial mass. INVESTIGATIONS: Computed tomography of chest and abdomen showed a progressive tumour in both hepatic lobes with extension to the inferior vena cava, through the diaphragma and to the right atrium. TREATMENT AND COURSE: The patient received supportive treatment and died 3 months later. CONCLUSION: Inspite the incidence of 1-4%, hepatocellular carcinoma with extension to the heart has been diagnosed rarely. Although treatment is limited, early diagnosis by abdominal echography or echocardiography is necessary for the interpretation of cardiogenic symptoms and the prognosis.

Abdomen↗
PubMed2000

Dynamical properties of the one-dimensional band insulator (NbSe4)3I

Optical and photoemission experiments reveal unexpected spectral signatures of one-dimensional band insulators. In the model compound (NbSe (4))3I the optical conductivity decays as a power law sigma(1)(omega) approximately omega(-4.25) above a sharp gap edge. Photoemission observes both the valence and a shadow band, produced by a commensurate superstructure. We identify an optical and photoemission band gap consistent with other measurements but much smaller than the energy scale defined by the dispersion of the band peak in the photoemission spectra.

Journal Article↗
PubMed2000

Expression of IFNgamma, coexpression of TNFalpha and matrix metalloproteinases and apoptosis of T lymphocytes and macrophages in granuloma annulare.

Granuloma annulare, a prototype noninfectious granulomatous dermatitis, is morphologically characterized by a necrobiotic core surrounded by a cellular infiltrate. Because of many morphological similarities to tuberculosis, granuloma annulare has been suggested to represent a delayed-type hypersensitivity (Th1) reaction in the course of which inflammatory cells elicit matrix degradation. In the present study we (1) investigated the expression of interferon-gamma as the most important Th1-associated cytokine, (2) sought in situ evidence for the coexpression of the proinflammatory cytokine tumor necrosis factor-alpha and cytokine-regulated matrix metalloproteinases 2 (gelatinase A) and 9 (gelatinase B), and (3) sought to determine whether shrunken cells seen within necrobiotic areas of granuloma annulare are apoptotic cells. In situ hybridization combined with immunofluorescence showed that large numbers of infiltrating CD3+ lymphocytes express interferon-gamma. Application of catalyzed signal amplification in immunodetection revealed that the vast majority of CD3+ lymphocytes and CD68+ macrophages contained tumor necrosis factor-alpha. Immunohistochemistry demonstrated that macrophages producing tumor necrosis factor-alpha coexpress matrix metalloproteinases 2 and 9. In situ end-labeling combined with immunofluorescence detected few apoptotic T cells in perivascular regions and numerous apoptotic macrophages within necrobiotic areas. These results suggest that in granuloma annulare interferon-gamma+ Th-1 lymphocytes may cause a delayed-type hypersensitivity reaction whereby macrophages are differentiated to aggressive effector cells expressing tumor necrosis factor-alpha and matrix metalloproteinases. In parallel, activation-induced apoptosis in lymphocytes and macrophages may serve to restrict the destructive potential of the inflammatory cells.

Antigens, CD↗
PubMed2000

The nociceptin/orphanin FQ receptor ligand acetyl-RYYRIK-amide exhibits antagonistic and agonistic properties.

The hexapeptide acetyl-RYYRIK-amide (Ac-RYYRIK-NH(2)) has recently been reported to act as partial agonist of the nociceptin/orphanin FQ (noc/OFQ) receptor expressed in CHO cells. In addition, this peptide acts as a competitive antagonist of noc/OFQ-stimulated GTPgamma(35)S binding in rat brain membranes as well as of the noc/OFQ-evoked chronotropic effect in rat cardiomyocytes. In contrast to this antagonism, in the present study, Ac-RYYRIK-NH(2) was found to behave as an agonist at noc/OFQ receptors, affecting spontaneous locomotor activity. When administered intracerebroventricularly (i.c.v.), noc/OFQ and Ac-RYYRIK-NH(2) inhibited spontaneous locomotor activity in mice with ID(50) of 1.1 and 0.07 nmol, respectively. Co-administration of both peptides lead to additive effects. The higher potency of Ac-RYYRIK-NH(2) could not be clearly explained by differential metabolism, because in vivo microdialysis in rat striatum and in vitro metabolic inactivation by rat and mouse brain membranes revealed extensive inactivation of both peptides. Similar to Ac-RYYRIK-NH(2), [Phe(1)psi(CH(2)-NH)Gly(2)]noc/OFQ(1-13)-NH(2) ([F/G]NC(1-13)NH(2)) inhibited the noc/OFQ-stimulated GTPgamma(35)S binding in rat brain membranes (Schild constant 3.83 nM) and mouse brain sections, although several reports have shown that this peptide exhibits agonist activity of noc/OFQ in the CNS. Changes in the optimum conditions of the in vitro assay for GTP binding increased low partial agonism of Ac-RYYRIK-NH(2) in GTP binding response. To explain the discrepancy between the in vitro antagonism of G protein coupling of the noc/OFQ receptor and in vivo agonism of Ac-RYYRIK-NH(2) and of [F/G]NC(1-13)NH(2), it is suggested that low partial agonism of receptor/G protein coupling in native systems may be sufficient to evoke full biologic responses. The extent of partial agonism for GTP binding and of coupling reserve may vary in different systems, thus explaining why [F/G]NC(1-13)NH(2) and Ac-RYYRIK-NH(2) were reported to exhibit antagonist, partial agonist, or even full agonist properties, depending on the system studied.

Animals↗
PubMed2000

Acetyl-RYYRIK-NH(2) is a highly efficacious OP(4) receptor agonist in the cardiovascular system of anesthetized rats.

Nociceptin, the endogenous ligand of the OP(4) or ORL(1) (opioid receptor-like(1)) receptor, decreases blood pressure and heart rate in anesthetized rats. Since the OP(4) receptor antagonist [Phe(1)Psi(CH(2)-NH)Gly(2)]-nociceptin(1-13)NH(2) possesses an agonistic effect in this model, we examined whether other purported OP(4) receptor antagonists, acetyl-RYYRIK-NH(2) and naloxone benzoylhydrazone, antagonize the depressant effects of nociceptin. Acetyl-RYYRIK-NH(2), like nociceptin and [Phe(1)Psi(CH(2)-NH)Gly(2)]-nociceptin(1-13)NH(2) and unlike naloxone benzoylhydrazone, decreased diastolic blood pressure and heart rate (rank order of potencies: nociceptin approximately equal to acetyl-RYYRIK-NH(2) >> [Phe(1)Psi(CH(2)-NH)Gly(2)]-nociceptin(1-13)NH(2)). The depressant effects were insensitive to the OP(1-3) receptor antagonist naloxone but diminished by naloxone benzoylhydrazone. In conclusion, the hypotensive and bradycardic effects of nociceptin in the anesthetized rat are mediated via OP(4) receptors, at which acetyl-RYYRIK-NH(2) is a highly potent and efficacious agonist.

Anesthesia↗
PubMed2000

Pseudomonas aeruginosa bacteremia in children: analysis of trends in prevalence, antibiotic resistance and prognostic factors.

OBJECTIVE: To determine the factors predisposing to Pseudomonas aeruginosa bacteremia as well as the prevalence, source of infection, outcome and prognostic factors in pediatric patients. METHODS: Retrospective review of pediatric patients with P. aeruginosa bacteremia, at a large tertiary care hospital during a 6.5-year period. RESULTS: Seventy patients with P. aeruginosa bacteremia were identified. The annual rate of P. aeruginosa bacteremia remained unchanged during the study period. Antibiotic susceptibility remained unchanged except for two patients with extensive burns who developed resistant strains. Underlying diseases were malignancy (50%), prematurity (6%), burns (7%) and others (37%). The overall mortality associated with P. aeruginosa bacteremia was 20%. The fatality rate was higher among the young infants (compared with older children) and those who received previous antibiotic therapy (P = 0.02). Mortality rate was higher in nosocomial than in community-acquired infections (25% compared with 11.5%). The mortality rate of low birth weight and burns patients was significantly higher when compared with oncology patients or other patients, 75 and 40% compared with 11 and 19%, P = 0.01. Multiple regression analysis revealed a correlation only between the underlying disease and mortality (P = 0.02). In the oncology patients the only significant risk factor for mortality was absolute neutrophil count < or =0.1 x 10(9)/l (P = 0.06). CONCLUSION: P. aeruginosa bacteremia, although apparently not increasing in incidence and antibiotic resistance, is still a common serious complication in immunocompromised children with a high mortality rate. We conclude that the underlying disease is the main determinant of the clinical outcome.

Anti-Bacterial Agents↗
PubMed2000

Comparative study of the expression of DNA mismatch repair genes, the adenomatous polyposis coli gene and growth arrest DNA damage genes in melanoma recurrences and metastases.

The main goal of this study was to examine the expression of DNA mismatch repair genes (MLH1, MSH2, PMS1 and PMS2), the adenomatous polyposis coli (APC) gene and growth arrest DNA damage inducible (GADD) genes (GADD34, GADD45 and GADD153) in the different stages of melanoma recurrences and metastases, and to identify any mutual consistencies in their expression pattern. All the cases of primary melanoma examined showed a reduced expression of DNA repair genes. These results demonstrate that disturbances of DNA repair begin in the early stages of melanoma. No significant differences were found in the expression of these markers between cutaneous melanomas and their recurrences and metastases (P> 0.05). Eighteen significant correlations between markers were found in the primary melanomas, and 10 significant correlations were observed in the first recurrences of melanoma. In contrast, 27 statistically significant relationships were demonstrated in metastatic lymph nodes. The different correlations found in primary and metastatic tumours confirmed the hypothetical difference in marker interaction in the diagnostic groups investigated. Our results suggest that DNA repair genes may play an important role in the recurrence and metastasis of melanomas.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Multimicrobial sepsis including Clostridium perfringens after chemoembolization of a single liver metastasis from common bile duct cancer.

A 65-year-old woman underwent resection of a distal common bile duct carcinoma (Whipple's procedure). Twelve months later a single hepatic metastasis was detected and a chemoembolization was performed. Immediately after chemoembolization the patient developed a multimicrobial sepsis including Clostridium perfringens. CT scans depicted pathognomonic signs of gas-containing abscess in the necrotic liver metastasis. She was subsequently treated with broad-spectrum antibiotics, abscess drainage and hyperbaric oxygen therapy. We conclude that antibiotic prophylaxis is recommendable for chemoembolization of liver metastasis in patients with risk factors like intestinal biliary reflux (bilioenteric anastomosis or papillotomy and biliary stenting) and bile duct cancer, otherwise severe sepsis including clostridium bacteremia may occur.

Aged↗
PubMed2000

[Nphe(1)]NC(1-13)NH(2) selectively antagonizes nociceptin/orphanin FQ-stimulated G-protein activation in rat brain.

[Phe(1)psi(CH(2)-NH)Gly(2)]noc/OFQ(1-13)-amide ([F/G]NC(1-13)NH(2)) and acetyl-RYYRIK-amide (Ac-RYYRIK-NH(2)), two peptidic ligands of the nociceptin/orphanin FQ (noc/OFQ) receptor, have been shown to exert both agonist and antagonist activity in different in vitro and in vivo systems. This is despite the observation that both peptides competitively antagonized the coupling of the activated receptor to G-proteins in brain preparations, measured in GTPgamma(35)S binding assays. In this study, [Nphe(1)]NC(1-13)-amide ([Nphe(1)]NC(1-13)NH(2)), a new noc/OFQ analog recently characterized as a pure and selective noc/OFQ receptor antagonist in several in vitro and in vivo assay systems, was shown to competitively inhibit the noc/OFQ-stimulated GTPgamma(35)S binding to rat cerebral cortex membranes with pA(2) of 7.76 (Schild analysis). This antagonism of noc/OFQ receptor G-protein coupling was selective because the peptide inhibited the noc/OFQ-evoked GTPgamma(35)S binding to rat brain membranes but not that evoked by selective agonists of the mu-, delta-, and kappa-opioid receptors. In rat cortical membranes, the effects of [F/G]NC(1-13)NH(2) and Ac-RYYRIK-NH(2) on the binding of GTPgamma(35)S were clearly differentiated from the effect of [Nphe(1)]NC(1-13)NH(2) when the concentration of GDP, competing with GTPgammaS for binding, was lowered from 100 microM (assay optimum) to 5 microM. At 5 microM GDP, the former peptides showed clear partial agonist activity, whereas [Nphe(1)]NC(1-13)NH(2) did not. These data indicate that only [Nphe(1)]NC(1-13)NH(2) was a pure antagonist of noc/OFQ receptor G-protein coupling. Furthermore, it is suggested that the variable behavior of [F/G]NC(1-13)NH(2) and Ac-RYYRIK-NH(2) (agonist, partial agonist, and antagonist) in different in vitro and in vivo systems may be explained by different partial GTP binding agonism and the existence of a GTP binding stimulus/response reserve (coupling reserve).

Amino Acid Sequence↗
PubMed1999

T lymphocytes and altered keratinocytes express interferon-gamma and interleukin 6 in lichen planus.

Lichen planus is assumed to represent a delayed hypersensitivity reaction, in the course of which cytokines control the proliferation and differentiation of cytotoxic T lymphocytes which attack the epidermis and cause apoptosis of undifferentiated keratinocytes. Since interferon-gamma and interleukin 6 are known to be markedly generated in lichen planus, we investigated the cellular localization of these cytokines in affected skin/oral mucosa biopsy specimens using in situ hybridization for interferon-gamma and in situ reverse transcription-polymerase chain reaction for interleukin 6 mRNA. In the upper subepithelial connective tissue interferon-gamma mRNA was noted within proliferating CD3+ T lymphocytes. In this tissue compartment interleukin 6 mRNA was detected in infiltrating CD4+ and CD8+ T lymphocytes. In the epithelium, expression of interferon-gamma mRNA and interleukin 6 mRNA was observed in the basal and suprabasal keratinocytes of altered skin/oral mucosa. In contrast, normal skin did not reveal any interferon-gamma or interleukin 6 expression, although a few CD4+ and CD8+ T lymphocytes were noted in the dermis as well as the epidermis. These findings indicate that in lichen planus the proinflammatory cytokines interferon-gamma and interleukin 6 are produced not only by activated T lymphocytes but also by altered keratinocytes, and suggest that stimulated keratinocytes may amplify the course of lichen planus.

Biopsy↗
PubMed1999

Antagonism by acetyl-RYYRIK-NH2 of G protein activation in rat brain preparations and of chronotropic effect on rat cardiomyocytes evoked by nociceptin/orphanin FQ.

For the further elucidation of the central functions of nociceptin/orphanin FQ (noc/OFQ), the endogenous ligand of the G protein-coupled opioid receptor-like receptor ORL1, centrally acting specific antagonists will be most helpful. In this study it was found that the hexapeptide acetyl-RYYRIK-NH2 (Ac-RYYRIK-NH2), described in literature as partial agonist on ORL1 transfected in CHO cells, antagonizes the stimulation of [35S]-GTPgammaS binding to G proteins by noc/OFQ in membranes and sections of rat brain. The antagonism of the peptide was competitive, of high affinity (Schild constant 6.58 nM), and specific for noc/OFQ in that the stimulation of GTP binding by agonists for the mu-, delta-, and kappa-opioid receptor was not inhibited. The hexapeptide also fully inhibited the chronotropic effect of noc/OFQ on neonatal rat cardiomyocytes. It is suggested that Ac-RYYRIK-NH2 may provide a promising starting point for in vivo tests for antagonism of the action of noc/OFQ and for the further development of highly active and specific antagonists.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗