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Biomedical subjects

B Otto

Publications and source records attributed to B Otto.

At least 19 recordsLinked to original sources
PubMed1999

The Nicotiana tabacum plasma membrane aquaporin NtAQP1 is mercury-insensitive and permeable for glycerol.

A new aquaporin from Nicotiana tabacum (cv. Samsun) was characterized. It shares sequence homology to the Arabidopsis thaliana PIP1 protein family. By two-phase partitioning and immunoblot analysis, plasma membrane localization could be demonstrated. The corresponding mRNA is highly abundant in roots and flowers, while it is rarely expressed in leaves and stems. Functional expression in Xenopus oocytes revealed that NtAQP1 can mediate glycerol transport in addition to water flow. However, NtAQP1 is impermeable for Na+, K+ and Cl- ions. The water permeability and selectivity could not be modulated by addition of mercurials or the activity of cAMP-dependent protein kinases.

Animals↗
PubMed1998

Interferon-gamma variants with deletions in the AB surface loop--flexibility is a critical point for receptor binding.

The receptor-binding AB loop of recombinant human interferon-gamma (IFN-gamma) has multiple contacts with the extracellular part of the IFN-gamma receptor a chain (IFN-gammaRalpha). We explored the possible length of truncated AB loops and their conformations by molecular modelling. Deletions of two amino acids at the tip of the loop were tolerated in the model without van der Waals collisions of the AB loop with helix F. Based on these modelling results, two deletion mutants were constructed by overlap-extension PCR mutagenesis: des-(A23, D24)-IFN-gamma and des-(N25, G26)-IFN-gamma. Both mutations were tolerated by the folding pattern of recombinant human IFN-gamma, as proved by CD spectroscopy. The stability of both mutants against cosolvent-induced unfolding was equal to that of wild-type IFN-gamma. In contrast to the biophysical similarities of wild-type and mutant IFN-gamma proteins, the biological activities of both mutants dropped significantly. Antiviral activity and human leucocyte antigen (HLA)-DR induction of des-(N25, G26)-IFN-gamma was 10% that of wild-type activity. des-(A23, D24)-IFN-gamma had only 1% remaining activity. Receptor-binding experiments confirmed that both deletions had a negative influence on the affinity of recombinant human IFN-gamma to its cellular receptor. We conclude from this combined molecular modelling and mutagenesis experiments, that the reduced flexibility of the truncated AB loop abrogates the possibility of the formation of a 3(10) helix in the receptor-bound state as observed in the X-ray structure of the IFN-gammaRalpha-IFN-gamma complex.

Antiviral Agents↗
PubMed1998

Myelography with a dimeric (iodixanol) and a monomeric (iohexol) contrast medium: a clinical multicentre comparative study.

The purpose of this study was to evaluate and compare the radiographic efficacy and safety of iodixanol (Visipaque; 270 and 320 mg I/ml) and iohexol (Omnipaque; 300 mg I/ml) in myelography. The study was randomized, double-blind and comparative including 398 patients from five European university clinics. The radiographic visualisation was evaluated as poor, good or excellent. Adverse events were recorded by interviewing the patients after the myelography, and each patient was given a questionnaire to be returned after 1 week. In cervical myelography with cervical puncture more films with excellent quality was obtained after iodixanol 320 mgI/ml compared with iohexol 300 mgI/ml (p = 0.009). Also in lumbar myelography iodixanol 320 mgI/ml compared favourably with iohexol 300 mgI/ml (p = 0.006). The most frequent adverse event was headache, which occurred in 5-35 % of patients during the first 24 h and in 19-61 % within the first 7 days, depending on the centre. There was no difference in frequency and severity of the adverse effects between the contrast media.

Adolescent↗
PubMed1998

The response of peritoneal macrophages after implantation of several ceramics as measured by the change of ectoenzyme activity.

The bioactive calcium phosphate ceramics with various calcium: phosphorus ratios: Ca/P = 1.67 (hydroxyapatite, HA), Ca/P = 1.6 and Ca/P = 1.5 (tricalcium phosphate, beta-TCP), the bioinert aluminium oxide ceramic (Al2O3) and the toxic calcium oxide ceramic (CaO) have been investigated with respect to their ability to activate peritoneal macrophages of NMRI-mice and with respect to their influence on the extracellular nucleotide degradation of these macrophages. Two weeks after the intraperitoneal injection of a suspension of ceramic particles in an isotone salt solution (phosphate-buffered saline = PBS), we observed that the peritoneal macrophages were only slightly activated into the responsive state, independent of the type of ceramic. 5'Nucleotidase (5'N) ectoenzyme hydrolyses adenosine monophosphate (AMP) and a decrease of its activity is a general biochemical marker of activated macrophages. This ectoenzyme activity was slightly reduced after ceramic implantation. The lacking rise of the extracellular diadenosine tetraphosphate (Ap4A)-catabolism by the macrophage ectoenzyme alkaline phosphodiesterase I (APD) demonstrated that the peritoneal macrophages did not completely reach the responsive state. After the implantation of calcium phosphate ceramics the extracellular adenosine triphosphate (ATP)-reduction was slightly diminished. After the implantation of tricalcium phosphate ceramic about 30% more peritoneal exsudate cells (PEC) were obtained from the peritoneal cavity than after injections of pure PBS (used as non-inflammatory control). Similar to the phenomena following the injection of thioglycollate (Tg, inflammation producing control agent) a slightly but not significantly increased proportion of pseudopodia-building cells was observed after the implantation of the ceramic with Ca/P = 1.6.

5'-Nucleotidase↗
PubMed1997

[Therapy with mitomycin C, folic acid and 5-fluorouracil in treatment of metastatic, refractory urinary bladder carcinoma--phase II study].

We performed a phase II trial with second-line chemotherapy in patients with refractory, metastatic cancer of the bladder. Second-line therapy consists of 2.6 cycles of mitomycin-C, 5-fluorouracil and folic acid. Two patients suffered from WHO grade III side effects (nephrotoxicity, leukocytopenia). We did not find any complete or partial remission. Four patients had a stable disease; 3.3 months after therapy, patients developed tumor progression with a median survival of 9 months. Four patients reported an improvement in quality of life. Since all patients received supportive care, improvement in quality of life cannot be related to chemotherapy alone. In conclusion, second-line chemotherapy with mitomycin-C, 5-fluorouracil and folic acid has no effect on refractory, metastatic cancer of the bladder and is no alternative for cisplatin and methotrexate-based chemotherapy.

Aged↗
PubMed1997

Idiopathic hypertrophic cranial pachymeningitis mimicking multiple meningiomas: case report and review of the literature.

A case of idiopathic hypertrophic cranial pachymeningitis with an unusual and misleading manifestation is reported. Computed tomography scan, angiographic and magnetic resonance imaging findings were suggestive of multiple meningeal neoplasms and a correct diagnosis was made only after meningeal biopsy. This 44-year-old patient had a previous history of an ill-defined systemic disorder associating episcleritis, erythroderma nodosa and multiple peripheral arthritis. We review previous reports of idiopathic cranial pachymeningitis with emphasis on radiological investigation techniques, histopathology and possible dysimmune mechanisms of pathogenesis.

Adult↗
PubMed1997

Spinal ischaemia after surgery for abdominal infrarenal aortic aneurysm. Diagnosis with nuclear magnetic resonance.

A 76-year-old man underwent surgery for an infrarenal aortic aneurysm reaching 6 cm in maximal transverse diameter. The aorta was crossclamped below the level of the renal arteries. A tube graft was interposed and tend between the infrarenal aorta and the aortic bifurcation. Due to leakage on the suture line two consecutive episodes of crossclamping for a total duration of 40 min. were required. No hypotension was noted during or after the procedure. After operation, the patient complained of difficulties to move both legs and neurologic examination demonstrated paraparesis, with mild sensory deficit. Faecal and urinary incontinences were also noted and urodynamic testing demonstrated sphincterovesical palsy. Nuclear magnetic resonance imaging detected an ischaemic zone in the spinal cord at the level of T11. Faecal incontinence and motor deficit partially resolved but no bladder function recovery was observed. Spinal ischaemia is a rare complication after abdominal aortic surgery. Several risk factors have been suggested which include level and duration of the aortic crossclamping, possible interruption of the spinal cord blood supply via the greater medullary artery (the so-called artery of Adamkiewicz), presence of intra- or postoperative episodes of hypotension, atheromatous embolization, underlying occlusive arteriosclerosis of spinal arteries, and respect or not of the hypogastric circulation. In our case, the duration of the crossclamping and interruption of the blood flow in lumbar arteries probably supplying the distal spinal cord were likely contributive factors.

Aged↗
PubMed1996

Role of Rho proteins in carbachol-induced contractions in intact and permeabilized guinea-pig intestinal smooth muscle.

1. The aim of this study was to determine whether the low molecular mass GTPase RhoA or related proteins are involved in carbachol- and high-K(+)-induced contractions in intact intestinal smooth muscle as well as the carbachol-induced increase in Ca2+ sensitivity of the myofilaments in permeabilized preparations. 2. The carbachol-induced increase in the Ca2+ sensitivity of force production in beta-escin-permeabilized intestinal smooth muscle was enhanced in preparations that were loaded with the constitutively active mutant of RhoA, Val14RhoA, and was inhibited by exoenzyme C3 from Clostridium botulinum, which ADP-ribosylates and inactivates small GTPases of the Rho family. The effect of C3 on Ca2+ sensitivity in the absence of the agonist was negligible, while the maximal Ca(2+)-activated force was inhibited by about 20%. 3. Inhibition of carbachol-induced force was associated with an increase in ADP-ribosylation of a protein band with a molecular mass of approximately 22 kDa, corresponding to Rho, and was partially reversed in the presence of Ile41RhoA, which is not a substrate for C3. Val14RhoA did not restore carbachol-induced Ca2+ sensitization in C3-treated smooth muscle. 4. In intact intestinal smooth muscle, toxin B from Clostridium difficile, which monoglucosylates members of the Rho family, inhibited high-K(+)-induced contractions and the initial phasic response to carbachol by about 30%. The delayed contractile response to carbachol was completely inhibited. 5. In smooth muscle preparations that were permeabilized with beta-escin after treatment with toxin B, carbachol-and GTP gamma S-induced Ca2+ sensitization was significantly inhibited. 6. These findings are consistent with a role for Rho or Rho-like proteins in agonist-induced increase in Ca2+ sensitivity of force production in intact and permeabilized intestinal smooth muscle.

Adenosine Diphosphate Ribose↗
PubMed1996

Nucleotide sequence analysis of a 32,500 bp region of the right arm of Saccharomyces cerevisiae chromosome IV.

We have sequenced a region containing 32.5 kb of the right arm of chromosome IV of Saccharomyces cerevisiae. Twenty open reading frames (ORFs) greater than 100 amino acids could be identified in this region. Six ORFs correspond to known yeast genes, including DOA4, UBC5 and UBC3, the gene products of which are involved in ubiquitin metabolism. UBC5 is preceded by the two tRNA genes tRNA-Arg2 and tRNA-Asp. Six genes were discovered with homologies to non-yeast genes or with homologies to other yeast ORFs. One of these could be identified as ribosomal protein gene RPS13. The putative function of eight ORFs remains unclear because comparison to different DNA or protein databases revealed no significant patterns. The sequence from cosmid 2F21 was obtained entirely by a combined subcloning and walking primer strategy, and has been deposited in the EMBL data library under Accession Number X84162.

Base Composition↗
PubMed1996

Computer-aided modeling of structure stabilizing disulfide bonds in recombinant human interferon-gamma.

We present a general search algorithm for possible insertion sites of disulfide bonds in proteins based on the coordinates of the solved X-ray or NMR structure, allowing the insertion of disulfide bonds with a minimum of conformational tension and backbone rearrangements. The FORTRAN 77 program "Ssuitable' was written for this purpose. This methodological approach was applied to recombinant human interferon-gamma (rhu-IFN-gamma), a cytokine of great pharmaceutical interest with a wide variety of biological activities including antiviral, antiproliferative and immunomodulatory effects. A model based on the C alpha-coordinates obtained from the Brookhaven data base was built. Four different insertion sites were selected in the model, connecting the two subunits of the homodimer. The thermodynamic stability of rhu-IFN-gamma is low, limiting its clinical application. We expect that the insertion of additional new disulfide bonds will enhance the thermodynamic stability as well as protect the protein against proteolytic degradation.

Amino Acid Sequence↗
PubMed1996

Engineered disulfide bonds in recombinant human interferon-gamma: the impact of the N-terminal helix A and the AB-loop on protein stability.

Insertion sites for cysteines with optimal stereochemistry for the formation of unstrained disulfide bridges were identified in recombinant human interferon-gamma (rhu-IFN-gamma) by computer modelling. We have engineered two different disulfide cross-linked mutants, containing a pair of symmetry-related disulfide bonds, which stabilize the N-termini of both monomers of the homodimeric protein. Mutations E7C and S69C allow the formation of an intramonomer disulfide bond between helices A and D. In contrast, the A17C and H111C mutations lead to a covalent cross-link between both monomers. The AB-loop is linked to helix F. The fluorescence properties of native and disulfide cross-linked proteins were studied as a function of guanidine hydrochloride concentration. Melting temperatures (Tm) were calculated from the decrease in CD ellipticity at 220 nm. The induction of the antiviral effect was measured using A549 fibroblast cells infected with encephalomyocarditis virus. The ability to induce the expression of the HLA-DR antigen in Colo 205 cells was determined by fluorescence-activated cell scanning analysis. The stability of both mutants was strongly enhanced against temperature- and cosolvent-induced unfolding. The delta Tm of mutant IFN-gamma E7C/S69C was 15 degrees C. All measured biological activities of this mutant were equal to wild type. In the case of the other mutant IFN-gamma A17C/H111C, the delta Tm value was 25 degrees C. This mutation abolishes nearly the entire biological activity (< 1%) with no detectable changes of secondary structure in the CD spectrum. Our results illustrate the importance of the N-terminal helix A and the AB-loop for the unfolding pathway and thermodynamic stability of rhu-IFN-gamma.

Circular Dichroism↗
PubMed1995

Evaluation of exposure to noise in seafarers on several types of vessels in Polish Merchant Navy.

Noise was measured on merchant ships of 3 types, during routine sea voyages. It was found that the equivalent noise levels calculated for engine crew members exceeded the accepted hygienic norm by 1-2 dB. Also audiometric examinations at the beginning and on completion of a voyage were performed, enrolling seamen from the engine room and from the deck crews. They showed statistically significant differences of temporary shift of the hearing threshold, more pronounced in the engine room crew.

Adult↗
PubMed1994

Trefoil peptides. Coming up clover.

Now that information on trefoil domain structure is available from X-ray crystallographic and nuclear magnetic resonance spectroscopy studies, we can begin to understand the functions of these unusual protein motifs.

Amino Acid Sequence↗
PubMed1993

[Interferon. An overview of the state of basic research with special regard to interferon-gamma].

Interferons / An overview on the state of basic research with special regard to interferon-gamma Interferons are multifunctional glycoproteins with a broad range of antiviral, antiproliferative and immunoregulatory effects on the target cell. This review deals with the basics as well as with more recent developments in interferon research. A historic overview of 35 years of interferon research since the discovery of interferons by Isaacs and Lindenmann in 1957 introduces the most important milestones in this field and appreciates the work of the participating researchers. A brief description of the classification of interferons based on different tissue sources, different antigenic properties and different induction behaviour is made. The main part of this review focuses on human interferon-gamma. We discuss recent work on the structure-function relationship of interferon-gamma. The interferon-gamma receptor and its role in signal transduction is another part of this paper. The structure and length of the C-terminal region of interferon-gamma seems to be important for receptor binding and expression of biological activities. A conservative estimate is that the family of IFN-activated genes numbers 15-20 in most cells.

Animals↗
PubMed1992

Temperature treatments of dark-grown pea seedlings cause an accelerated greening in the light at different levels of gene expression.

We have previously shown that heat-shock in the dark evokes photomorphogenesis-like effects and circadian rhythmicity at the level of mRNAs when applied to emerging pea plantlets during several consecutive days [15]. Here we extend these findings by showing that a temperature shift to 10 degrees C above average and a single heat-shock are sufficient for induction of circadian rhythmicity and changes in morphogenesis. The maximum response to a single heat-shock occurs at days 2 to 3 after sowing indicating additional developmental control of the response. An increasing number of heat-shock treatments intensifies the morphogenetic effect. The heat-shocked plantlets have an elevated level of the xanthophyll lutein in the dark. Upon illumination of heat-shocked plantlets accumulation of chloroplast pigments as well as that of individual thylakoid membrane proteins and their corresponding mRNAs occur much faster than in the etiolated controls. This is reflected in an accelerated formation of grana stacks. Therefore, heat-shock seems to evoke a responsiveness of plantlets similar to that obtained earlier by other authors using pre-illumination. The working hypothesis is put forward that induction or synchronization of circadian rhythmicity by either light or heat-shock might be sufficient to explain the observed morphogenetic changes.

Adaptation, Physiological↗