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Biomedical subjects

C Jung

Publications and source records attributed to C Jung.

At least 73 records · Page 4Linked to original sources
PubMed2000

Assignment of heme methyl 1H-NMR resonances of high-spin and low-spin ferric complexes of cytochrome p450cam using one-dimensional and two-dimensional paramagnetic signals enhancement (PASE) magnetization transfer experiments.

An 1H-NMR study of ferric cytochrome P450cam in different paramagnetic states was performed. Assignment of three heme methyl resonances of the isocyanide adduct of cytochrome P450 in the ferric low-spin state was recently performed using electron exchange in the presence of putidaredoxin [Mouro, C., Bondon, A., Jung, C., Hui Bon Hoa, G., De Certaines, J.D., Spencer, R.G.S. & Simonneaux, G. (1999) FEBS Lett. 455, 302-306]. In this study, heme methyl protons of cytochrome P450 in the native high-spin and low-spin states were assigned through one-dimensional and two-dimensional magnetization transfer spectroscopy using the paramagnetic signals enhancement (PASE) method. The order of the methyl proton chemical shifts is inverted between high-spin and low-spin states. The methyl order observed in the ferric low-spin isocyanide complexes is related to the orientation of the cysteinate ligand.

Camphor↗
PubMed2000

Flexibility and stability of the structure of cytochromes P450 3A4 and BM-3.

The flexibility of the structure and compressibility of the respective active site of cytochromes P450 3A4 (CYP3A4) and BM-3 (CYP102) were studied using absorption spectroscopy in the ultraviolet and visual regions. Conformational changes in the overall protein structures of both CYP3A4 and CYP102 due to the effects of temperature and pressure are reversible. However, the enzymes differ in the properties of their active sites. The CYP3A4 enzyme denatures to the inactive P420 form relatively easy, at 3000 bar over half is converted to P420. The compressibility of its active site is lower than that of CYP102 and is greater with the substrate bound, which is in line with the observed lack of a stabilizing effect of the substrate on its conformation under pressure. In contrast, CYP102, although having the most compressible active site among the P450s, possesses a structure that does not denature easily to the inactive (P420) form under pressure. In this respect, it resembles the P450 isolated from acidothermophilic archaebacteria [McLean, M.A., Maves, S.A., Weiss, K.E., Krepich, S. & Sligar, S.G. (1998) Biochem. Biophys. Res. Commun. 252, 166-172].

Bacterial Proteins↗
PubMed2000

Characterization of novel neutralizing monoclonal antibodies specific to human neurturin.

Neurturin (NTN) a structural and functional relative of glial cell line-derived neurotrophic factor, was originally identified based on its ability to support the survival of sympathetic neurons in culture. Similar to glial cell line-derived neurotrophic factor (GDNF), Neurturin has been shown to bind to a high affinity glycosylphosphatidylinositol (GPI)-linked receptor (GFRalpha2) and induce phosphorylation of the tyrosine kinase receptor Ret, resulting in the activation of the mitogen activated protein kinase (MAPK) signalling pathway. A panel of six novel murine monoclonal antibodies (MAbs) specific to human Neurturin has been developed and characterized. Four of the MAbs tested inhibit, to varying degrees, binding of NTN to the GPI-linked GFRalpha2 receptor. Three MAbs cross-react with the murine homolog. These antibodies have been shown to be useful reagents for Western blotting, immunohistochemistry, and also for the development of a sensitive, quantitative enzyme-linked immunosorbent assay (ELISA) for human NTN. Novel, specific MAbs with varying epitope specificities and blocking activity will be valuable tools for both the in vitro and in vivo characterization of NTN and its relationship to the GFRalpha2 and Ret receptors.

Animals↗
PubMed2000

An example of immunodominance: engagement of synonymous TCR by invariant CDR3 beta.

The structural basis of the T cell response against immunodominant tetanus toxin (TT)-derived peptides was investigated using TT-specific T cell clones raised from a DRB1*0301 homozygous donor. Three peptides forming T cell epitopes were identified, including one, TT(1272-1284), that stimulated four different TT-specific T cell clones. TCR sequence analysis revealed that these synonymous TCR shared only arginine at the third position of the CDR3 beta loop. This prominent residue may form a salt bridge with a corresponding aspartate at the relative position 8 (P8) of the antigenic peptide TT(1272-1284) as suggested from amino acid replacement analysis. A similar scenario was observed for a second TT epitope, TT(279-296), and its corresponding TCR. These examples show that immunodominance may result from a single strong amino acid interaction between TCR CDR3 beta loops here in contact with the C-terminus of the antigenic peptide. Such a dominant interaction could compensate for weaker contacts between other residues of the TCR and the antigenic peptide, and would allow the recognition of a single peptide-MHC complex by a broader synonymous TCR repertoire and could thus contribute to its immunodominance.

Amino Acid Sequence↗
PubMed2000

Molecular characterization and chromosomal distribution of species-specific repetitive DNA sequences from Beta corolliflora, a wild relative of sugar beet.

Repetitive DNA sequences have been isolated from a Sau3AI plasmid library of tetraploid Beta corolliflora (2n = 4x = 36), a wild relative of sugar beet (B. vulgaris). The library was screened by differential hybridization with genomic DNA of B. corolliflora and B. vulgaris. When used as probes for Southern hybridization of genomic DNA, six clones were determined to represent highly repetitive DNA families present only in the B. corolliflora genome. Five other sequences were highly repetitive in B. corolliflora and low or single copy in B. vulgaris. The insert size varied between 43 bp and 448 bp. Two sequences pBC1279 and pBC1944 displayed strong homology to a previously cloned satellite DNA from B. nana. With one exception, sequences are tandemly arranged as revealed by a typical ladder pattern after genomic Southern hybridization. The chromosomal distribution of five probes was determined by fluorescence in situ hybridization (FISH) of mitotic metaphases from B. corolliflora and a triploid hybrid between B. vulgaris and B. corolliflora. Three sequences were spread along all chromosome arms of B. corolliflora while one sequence was present on only six chromosomes. The chromosome-specific sequence pBC216 was found in close vicinity to the 5S rDNA located on B. corolliflora chromosome IV. This set of species-specific sequences has the potential to be used as probes for the identification of monosomic alien addition lines and for marker-assisted gene transfer from wild beet to cultivated beet.

Base Sequence↗
PubMed1999

Changes in secondary structure and salt links of cytochrome P-450cam induced by photoreduction: a Fourier transform infrared spectroscopic study.

Tris(2,2'-bipyridyl)ruthenium(II) was used as a light-induced artificial electron donor for the transfer of the first electron to cytochrome P-450(cam) bound with (1R)-camphor and camphane substrates, and in the substrate-free form. Fourier transform infrared spectroscopy was used to detect changes of the amide I' band and the CO ligand stretch vibration of heme-bound carbon monoxide associated with the heme redox transition. The reduced-minus-oxidized difference spectra show that not only the heme group but also the protein backbone and individual amino acid side chains were affected by the redox transition. Observed secondary structure changes were almost identical for (1R)-camphor-bound and camphane-bound cytochrome P-450(cam), with a remarkable negative signal at 1724.3 cm(-)(1) and a positive signal at 1716.0 cm(-)(1). These signals were not observed in substrate-free P-450(cam). On the basis of known crystallographic data, we assign these signals to a change of hydrogen bonds of a salt link between Arg112, His355, and the heme 6-propionic group.

2,2'-Dipyridyl↗
PubMed1999

[Abdominal actinomycosis after stomach surgery in a patient with long-term rheumatoid arthritis treated with methotrexate].

HISTORY AND ADMISSION FINDINGS: A 78-year-old woman had a 30-year history of rheumatoid arthritis, of late treated with prednisolone and methotrexate. A week before admission she had first noticed a mass about 3 cm in diameter, at the lower end of a scar from a Billroth II gastric resection for gastric ulcer, performed 4 months before. She reported to have lost 6.5 kg in weight. On admission a moderately mobile, hard mass was palpated on the abdomen. INVESTIGATIONS: Ultrasound and computed tomography revealed a superficial, inhomogenous space-occupying lesion with poorly circumscribed margins. TREATMENT AND COURSE: After two days the skin over the mass became reddened and a laparotomy was performed because an incarcerated herniation was suspected. An abscess and inflammatory adhesions were found in the area of the transverse colon, histologically shown to be a chronic purulent abscess with granular clusters of pathogens indicating actinomycosis. After 3 weeks' treatment with imipenem i.v. the patient became free of symptoms, oral doxycyclin was continued for a further 6 months. CONCLUSION: Actinomycosis should be considered in the differential diagnosis of a tumour of undetermined benignity in the region of the head, chest or abdomen in immunosuppressed patients. This bacterial infection should be thought of especially if the gastrointestinal mucosa has been penetrated by invasive procedures.

Abdominal Abscess↗
PubMed1999

Proton nuclear magnetic resonance study of the binary complex of cytochrome P450cam and putidaredoxin: interaction and electron transfer rate analysis.

A 1H nuclear magnetic resonance study of the complex of cytochrome P450cam-putidaredoxin has been performed. Isocyanide is bound to cytochrome P450cam in order to increase the stability of the protein both in the reduced and the oxidized state. Diprotein complex formation was detected through variation of the heme methyl proton resonances which have been assigned in the two redox states. The electron transfer rate at equilibrium was determinated by magnetization transfer experiments. The observed rate of oxidation of reduced cytochrome P450 by the oxidized putidaredoxin is 27 (+/- 7) per s.

Camphor 5-Monooxygenase↗
PubMed1999

Regulation of neurofilament axonal transport by phosphorylation in optic axons in situ.

Axonal transport of neurofilament (NFs) is considered to be regulated by phosphorylation. While existing evidence for this hypothesis is compelling, supportive studies have been largely restricted to correlative evidence and/or experimental systems involving mutants. We tested this hypothesis in retinal ganglion cells of normal mice in situ by comparing subunit transport with regional phosphorylation state coupled with inhibition of phosphatases. NF subunits were radiolabeled by intravitreal injection of 35S-methionine. NF axonal transport was monitored by following the location of the peak of radiolabeled subunits immunoprecipitated from 9x1.1 mm segments of optic axons. An abrupt decline transport rate was observed between days 1 and 6, which corresponded to translocation of the peak of radiolabeled subunits from axonal segment 2 into segment 3. Notably, this is far downstream from the only caliber increase of optic axons at 150 mu from the retina. Immunoblot analysis demonstrated a unique threefold increase between segments 2 and 3 in levels of a "late-appearing" C-terminal NF-H phospho-epitope (RT97). Intravitreal injection of the phosphatase inhibitor okadaic acid increased RT97 immunoreactivity within retinas and proximal axons, and markedly decreased NF transport rate out of retinas and proximal axons. These findings provide in situ experimental evidence for regulation of NF transport by site-specific phosphorylation.

Animals↗
PubMed1999

Expression of TGFalpha in meningiomas.

The objective of this study was to examine the expression of transforming growth factor alpha (TGFalpha), a mitogen for many cell types, and its receptor in basic subtypes of meningiomas as well as in meningiomas of varying grade. Formalin-fixed tissues from 26 meningiomas including 15 benign (5 meningothelial, 5 transitional, and 5 fibrous variants), 6 atypical, and 5 malignant examples were immunohistochemically examined for both TGFalpha protein and EGF/TGFalpha receptor protein. In addition, in situ hybridization (ISH) was used to detect TGFalpha mRNA expression. Immunostaining for TGFalpha was strongest in fibrous and atypical meningiomas, followed closely by transitional and malignant tumors. Only weak reactivity was observed in the meningothelial variant. In all but 4 tumors (2 fibrous, 2 atypical), ISH showed TGFalpha mRNA to be present, the signal being stronger in malignant than in conventional or atypical tumors. Lastly, immunostaining for EGF/TGFalpha receptor was positive in all tumors studied. Strong TGFalpha protein expression in meningiomas is commonly associated with fibrous morphology. Although the frequent detection of both TGFalpha protein and its mRNA, as well as of EGF/TGFalpha receptor within tumors of all type and grades, suggests that TGFalpha serves to promote tumor growth, its possible role in tumorigenesis or malignant progression is uncertain. In summary, demonstration of these substances is of no utility in the classification or grading of this common tumor because the differences in their expression among the various meningioma subtypes were not statistically significant.

Adult↗
PubMed1999

AFLPs represent highly repetitive sequences in Asparagus officinalis L.

The chromosomal and genomic organization of 5 cloned AFLP fragments in asparagus (Asparagus officinalis L.) were investigated. Two of the 5 AFLP loci were sex-linked. The fragments, amplified with EcoRI/Mse I primers, ranged from 107 to 267 bp and were AT-rich. Southern hybridization gave interspersed, middle repetitive to high copy sequence signals. Fluorescence in-situ hybridization (FISH) exhibited hybridization signals on all chromosomes with dispersed distribution pattern and varying signal intensities. Repetitive signals in the form of clusters were observed on all chromosomes. In addition, the 5S rRNA gene was physically mapped on one pair of chromosomes and the 18S-5.8S-25S rRNA genes on three pairs. The results of the FISH and Southern analyses showed that the AFLP marker technology relies on repetitive sequences. Since repetitive DNA sequences represent a fraction of the plant genome undergoing rapid changes during the course of evolution, the question of whether such molecular markers originating from repetitive DNA sequences remain stable is discussed.

DNA Probes↗
PubMed1999

Immunohistochemical investigation of the cellular infiltrates at the sites of allergoid-induced late-phase cutaneous reactions associated with pollen allergen-specific immunotherapy.

BACKGROUND: Reduction in the size of the allergen-induced late-phase reaction (LPR) is seen as a consequence of successful allergen specific immunotherapy. OBJECTIVE: It was the aim of this study to characterize the cellular infiltrate at the sites of cutaneous LPR that may occur following injection of a depot pollen allergoid (Allergovit(R)) during immunotherapy and thereby determine the immunological nature of the response. METHODS: Punch biopsies were taken 24 h after subcutaneous injection of a depot pollen allergoid from eight patients that showed LPR and a further five patients that did not. Additional biopsies taken 24 h after injection of allergoid-free depot in the same patients served as controls. Immunoenzymatic labelling of the cryostat sections with different antibodies was performed with the APAAP technique. Results were expressed as cells/field (400 x magnification). RESULTS: Similar dermal cellular infiltrations were seen following depot allergoid injections in patients both with and without LPR. Patients with LPR showed statistically significant increases in total cells, CD4+ cells, CD11c+ cells, CD45RO+ cells, CD45RB+ cells and activated eosinophils at the reactions sites as compared with control sites. In patients without LPR CD11c+ cells, HLA-DR+ cells and CD45RA+ T cells increased significantly. CD8+, CD1a+, NP57+, CD23+ and CD25+ cells did not differ significantly in either group. CONCLUSION: These results indicate that activation of T cells, monocytes/macrophages and eosinophils at the sites of LPR following injection of depot allergoid are comparable with those following injection of allergen. Even in the absence of a cutaneous LPR, subsets of T cells and monocytes/macrophages increased. These cell activations may reflect events associated with the mechanisms of allergoid-based specific immunotherapy, and suggest that at least part of the late-phase reaction may be independent of IgE.

Adult↗
PubMed1999

[Ranking of 20 MHz sonography of malignant melanoma and pigmented lesions in routine diagnosis].

PURPOSE: Eleven dermatology clinics from all over Germany took part in our multicenter prospective study with the aim of evaluating 20 MHz sonography in the preoperative diagnosis of malignant melanomas and other pigmented skin tumours. It was to be assessed how effective sonographic measurement of thickness would compare to histology and the clinical palpation of tumour thickness and also the significance of differential diagnosis in sonography of malignant melanomas. METHOD: The prospective multicenter study proceed as follows. To the end of August 1997 264 patients with a primary malignant melanoma and 417 patients with benign skin tumours were examined via 20 MHz sonography. Two different examiners estimated the clinical thickness of the tumour by palpation. The tumour was then excised and examined for postoperative correlation with the histology sections. RESULTS: The final results showed good correlation between the histological and sonographic estimation of tumour thickness (r = 0.97). Estimation of tumour thickness by palpation showed no correlation with the histology (r = 0.59). Most of the benign (44%) and malignant tumours (38.7%) were spindle shaped. There was no significant difference between the benign and malignant tumour groups in relation to the sonographic presented shapes or echo signs. No different diagnosis could be made. CONCLUSION: The technique of high frequency sonography in relation to preoperative diagnosis of malignant melanomas has high priority. In contrast to clinical estimation of tumour thickness, sonography provided a good correlation to histology. The effectiveness of sonography with regard to the valence of the skin tumours is limited and there is no possibility of differentiating between malignant and benign tumours from the morphological face value. Hence, there is a demand for developing a 150 MHz apparatus which will be able to supply evidence regarding the valence of skin tumours.

Diagnostic Tests, Routine↗
PubMed1999

Phase transitions in open quantum systems.

We consider the behavior of open quantum systems through the dependence of the coupling to one decay channel by introducing the coupling parameter alpha, which is proportional to the average degree of overlapping. Under critical conditions, a reorganization of the spectrum takes place that creates a bifurcation of the time scales with respect to the lifetimes of the resonance states. We derive analytically the conditions under which the reorganization process can be understood as a second-order phase transition and illustrate our results by numerical investigations. The conditions are fulfilled, e.g., for a uniform picket-fence level distribution with equal coupling of the states to the continuum. Energy dependencies within the system are included. We consider also the case of an unfolded Gaussian orthogonal ensemble and of a spectrum bounded from below. In all these cases, the reorganization of the spectrum occurs at the critical value alpha(crit) of the control parameter globally over the whole energy range of the spectrum. All states act cooperatively.

Journal Article↗
PubMed1998

Dithionite reduced carbon monoxide complex of cytochrome P450cam is a monomer.

Sedimentation experiments on cytochrome P450cam (CYP101) has been performed to compare the molecular mass of the protein in the oxidized state and as carbon monoxide complex. The oxidized protein in the absence of beta-mercaptoethanol is a dimer with a molecular mass of 92 kDa. Addition of mercaptoethanol avoids completely the dimerization. Dithionite reduced P450cam in the presence of carbon monoxide has been found to be a monomeric protein.

Camphor 5-Monooxygenase↗
PubMed1998

New ligands for HLA DRB1*0301 by random selection of favourable amino acids ranked by competition studies with undecapeptide amide sublibraries.

An efficient screening procedure for the identification of high affinity HLA class II ligands and their binding pattern has been established to characterize peptide specificities for the HLA allele DRB1*0301. The method is based on the screening of 209 synthetic undecapeptide amide sublibraries O/X10-NH2 representing collections of 19(10) individual peptides in a competition ELISA using HLA DRB1*0301 protein and the biotinylated natural ligand ApoB 2877-2894. Screening results represent the effect on competition induced by an individual amino acid residue in its sequence position of undecapeptide amides. Amino acids clustered as active in their position were randomly selected for the same position of a restricted set of 96 individual undecapeptide amides. This novel approach for the design of ligands was introduced to compensate for the inaccuracy induced by the translational invariance of amino acids in peptide libraries characterized by one defined amino acid. Translational invariance is facilitated by shifted docking of O/X10-NH2 libraries in the binding cleft and protrusion from the ends of the cleft. A second more directed deduced set of 24 peptides was obtained by combination of the most favourable residues in each position. All individual peptides were investigated in the competition assay. The most active HLA DRB1*0301 ligands were obtained by random selection of favourable amino acids and six of them showed improved affinity in comparison to the model ligand alpha AChR 310-325.

Alleles↗
PubMed1998

Resolution of severe Kaposi's sarcoma after initiation of antiretroviral triple therapy.

OBJECTIVES: To study the relationship between effective antiretroviral therapy, monitored by CD4 counts, and it s influence on the clinical course of AIDS associated Kaposi's sarcoma. METHODS: Four representative cases with AIDS and advanced Kaposi's sarcoma (KS) showed improvement of histologically proven KS s in various sites, including pulmonary disease, treated with liposomal doxorubicin. CD4 counts increased significantly during administration of triple antiretroviral therapy. In three cases chemotherapy cycles were extended and subsequently discontinued for 4, 14 and 4 months, respectively, without any relapse. In one other case interferonalpha therapy has been started overlapping with doxorubicin prior to permanent discontinuation of doxorubicin. CONCLUSIONS: Data of those patients suggest that in patients with increasing CD4 counts KS's chemotherapy intervals should be extended or even discontinued. In some patients change of therapy to interferon alpha can be considered. A potent combined antiretroviral therapy may enhance efficiency of KS treatment even in patients with high CD4 counts.

Adult↗