Biomedical subjects

U Mueller

Publications and source records attributed to U Mueller.

At least 19 recordsLinked to original sources

PubMed2006

Induction of immunity and inflammation by interleukin-12 family members.

The interleukin (IL)-12 family is composed of three heterodimeric cytokines, IL-12 (p40p35), IL-23 (p40p19), and IL-27 (EBI3p28), and of monomeric and homodimeric p40. This review focuses on the three heterodimeric members of the IL-12 family. The p40 and p40-like (EBI3) subunits have homology to the IL-6R, the other subunits (p35, p19, and p28) are homologous to each other and to members of the IL-6 superfamily. On the basis of their structural similarity, it was expected that the members of the IL-12 family have overlapping pro-inflammatory and immunoregulatory functions. However, it was surprising that they also show very distinct activities. IL- 12 has a central role as a Th1-inducing and -maintaining cytokine, which is essential in cell-mediated immunity in nonviral infections and in tumor control. IL-23 recently emerged as an end-stage effector cytokine responsible for autoimmune chronic inflammation through induction of IL-17 and direct activation of macrophages. Very recently, IL-27 was found to exert not only a pro-inflammatory Thl-enhancing but also a significant anti-inflammatory function.

Animals↗

PubMed2005

Synapses form in skeletal muscles lacking neuregulin receptors.

The formation of the neuromuscular junction (NMJ) is directed by reciprocal interactions between motor neurons and muscle fibers. Neuregulin (NRG) and Agrin from motor nerve terminals are both implicated. Here, we demonstrate that NMJs can form in the absence of the NRG receptors ErbB2 and ErbB4 in mouse muscle. Postsynaptic differentiation is, however, induced by Agrin. We therefore conclude that NRG signaling to muscle is not required for NMJ formation. The effects of NRG signaling to muscle may be mediated indirectly through Schwann cells.

Agrin↗

PubMed2004

Expedient synthesis of highly substituted fused heterocoumarins.

[reaction: see text] Highly substituted fused coumarins can be prepared in two steps starting from the appropriate boronic acids and enol triflates. The synthesis of fused pyrano[2,3-d]pyrimidin-7-one (1) is a key example to demonstrate the potential of the method in the elaboration of new coumarin scaffolds.

Journal Article↗

PubMed2002

Causes of sexual decline in aging married men: Germany and America.

Married men in Germany (n=48) and America (n=50) between 50 and 80 years old, none in poor health, provided comparable information on sexual behavior and attitudes, and gave saliva samples from which testosterone was assayed. Sexuality declines with age, as expected. Neither testosterone nor psychological depression explain levels of sexuality. In both nations, wife's desire for intercourse, subject's ability to maintain an erection, and subject's imagination about other women, explain certain aspects of sexuality. Subject's health and marital satisfaction are related to sexuality among Americans but not among Germans. Behavioral models for the two nations are compared.

Coitus↗

PubMed2002

Measurement of steroid levels in saliva in a population-based survey of lifestyle, medical conditions, marriage, sex life and hormone status in aging men: a feasibility study.

Some population-based studies on male aging measure testosterone and cortisol in saliva instead of serum, but very few measure estradiol and dehydroepiandrosterone sulfate (DHEA-S), suggesting further testing is needed for reliability and comparative validity. In addition, the effects of interview stress and circadian hormone secretion need to be checked. In a pilot study on the overall sexual capacity of aging men, 48 randomly selected, healthy, heterosexual, cohabiting men aged 50-80 years, from Mannheim, Germany, and 50 from the State College, Pennsylvania, USA, were administered a standardized interview covering medical biography, present and previous life and work, marriage and emotional status. Two saliva samples were collected from each subject for measurement of testosterone, cortisol, estradiol and DHEA-S levels before and after the interview, and each subject completed a confidential self-administered questionnaire on intercourse, masturbation, orgasm, fantasies, libido and arousal. Questionnaires, hormone measurement techniques and the survey protocol had been extensively pretested. Prior to the pilot study, the kits for measuring testosterone and DHEA-S in saliva were checked for comparative validity against established measuring techniques in serum in 31 cases for testosterone and in 24 different cases for DHEA-S. These 55 cases underwent clinical diagnosis and were not otherwise involved in this study. The cases had been referred to the Andrology Unit of the University Hospital, Marburg, for reasons unrelated to this study. Given the biological differences for both steroids between their presence in blood and in saliva, a perfect correspondence between the two values was not expected and was not observed. The correlations obtained, however, support the assumption that all statistical relationships between testosterone and DHEA-S values in serum and clinical, as well as behavioral, variables reported to date may be replicated for testosterone and DHEA-S values in saliva.

Aged↗

PubMed2001

Crystal structures of mutant forms of the Bacillus caldolyticus cold shock protein differing in thermal stability.

The cold shock proteins Bc-Csp from the thermophile Bacillus caldolyticus and Bs-CspB from the mesophile Bacillus subtilis differ significantly in their conformational stability, although the two proteins differ by only 12 out of 67 amino acid residues. The three-dimensional structure of these small and compact beta-barrel proteins without disulfide bonds, cis-proline residues or tightly bound cofactors is very similar. Previous work has shown that Bc-Csp displays a twofold increase in the free energy of stabilization relative to its homolog Bs-CspB, and indicated that electrostatic interactions are, in part, responsible for this effect. It was further described that the stability difference is almost exclusively due to surface-exposed charged residues at sequence positions 3 and 66 of Bc-Csp and Bs-CspB, whereas all other amino acid changes between both proteins have no net effect on stability. To investigate how two surface residues determine the stability of Bc-Csp, Arg3 and Leu66 were replaced by glutamic acid, corresponding to the Bs-CspB sequence. The crystal structures of the resultant protein variants, Bc-Csp R3E and Bc-Csp L66E, were determined at 1.4 A and 1.27 A resolution, and refined to R values of 13.9 % and 15.8 %, respectively. Both structures closely resemble Bc-Csp in their global fold and show different hydrogen bonding and salt-bridge patterns when two independent molecules in the asymmetric unit of the crystal are compared. To extend the study to neighbored residues that help determine the surface charge around Arg3 and Leu66, the mutant proteins Bc-Csp E46A, Bc-Csp R3E/E46A/L66E and Bc-Csp V64T/L66E/67A were crystallized. Their structures were determined at resolutions of 1.8 A, 1.32 A and 1.8 A and refined to R values of 18.5 %, 13.8 % and 19.3 %, respectively. A systematic comparison of the crystal structures of all forms of the B. caldolyticus cold shock protein shows varying patterns of hydrogen bonds and electrostatic interactions around residues 3 and 66. Thermal destabilization of the protein by mutation appears to correlate with the extent of an acidic surface patch near the C-terminal carboxylate group.

Amino Acid Sequence↗

PubMed2001

Development of a technology for automation and miniaturization of protein crystallization.

The usage of standard 96 well microplates for the screening of crystallization conditions of recombinant proteins offers several advantages when compared to commonly used crystallization plate formats. The adoption of robotic technology for plate and glass slide preparation within a "hanging drop" vapour diffusion crystallization experiment enables to work with an increased throughput at reduced costs. In addition to commercial pipetting devices with a 96-channel aspirator/dispenser, solenoid ink-jet technology was applied to form 250 nl droplets with a diameter of approximately 1 mm. This allows miniaturization of crystallization screening set-ups with an estimated ten-fold cost reduction when compared to commonly used 24 well plates.

Concanavalin A↗

PubMed2000

Thermal stability and atomic-resolution crystal structure of the Bacillus caldolyticus cold shock protein.

The bacterial cold shock proteins are small compact beta-barrel proteins without disulfide bonds, cis-proline residues or tightly bound cofactors. Bc-Csp, the cold shock protein from the thermophile Bacillus caldolyticus shows a twofold increase in the free energy of stabilization relative to its homolog Bs-CspB from the mesophile Bacillus subtilis, although the two proteins differ by only 12 out of 67 amino acid residues. This pair of cold shock proteins thus represents a good system to study the atomic determinants of protein thermostability. Bs-CspB and Bc-Csp both unfold reversibly in cooperative transitions with T(M) values of 49.0 degrees C and 77.3 degrees C, respectively, at pH 7.0. Addition of 0.5 M salt stabilizes Bs-CspB but destabilizes Bc-Csp. To understand these differences at the structural level, the crystal structure of Bc-Csp was determined at 1.17 A resolution and refined to R=12.5% (R(free)=17.9%). The molecular structures of Bc-Csp and Bs-CspB are virtually identical in the central beta-sheet and in the binding region for nucleic acids. Significant differences are found in the distribution of surface charges including a sodium ion binding site present in Bc-Csp, which was not observed in the crystal structure of the Bs-CspB. Electrostatic interactions are overall favorable for Bc-Csp, but unfavorable for Bs-CspB. They provide the major source for the increased thermostability of Bc-Csp. This can be explained based on the atomic-resolution crystal structure of Bc-Csp. It identifies a number of potentially stabilizing ionic interactions including a cation-binding site and reveals significant changes in the electrostatic surface potential.

Amino Acid Sequence↗

PubMed2000

Two exposed amino acid residues confer thermostability on a cold shock protein.

Thermophilic organisms produce proteins of exceptional stability. To understand protein thermostability at the molecular level we studied a pair of cold shock proteins, one of mesophilic and one of thermophilic origin, by systematic mutagenesis. Although the two proteins differ in sequence at 12 positions, two surface-exposed residues are responsible for the increase in stability of the thermophilic protein (by 15.8 kJ mol-1 at 70 degrees C). 11.5 kJ mol-1 originate from a predominantly electrostatic contribution of Arg 3 and 5.2 kJ mol-1 from hydrophobic interactions of Leu 66 at the carboxy terminus. The mesophilic protein could be converted to a highly thermostable form by changing the Glu residues at positions 3 and 66 to Arg and Leu, respectively. The variation of surface residues may thus provide a simple and powerful approach for increasing the thermostability of a protein.

Amino Acid Sequence↗

PubMed1999

[What significance does "reproductive health" have for the dermatologist?].

"Reproductive rights embrace certain human rights that are already recognized in national laws, international human rights documents and other relevant UV consensus documents. These rights rest on the recognition of the basic right of all couples and individuals to decide freely and responsibly the number, spacing and timing of their children and to have the information and means to do so, and the right to attain the highest standard of sexual and reproductive health. They also include the right of all to make decisions concerning reproduction free of discrimination, coercion and violence. Full attention should be given to promoting mutually respectful and equitable gender relations and particularly to meeting the educational and service needs of adolescents to enable them to deal in a positive and responsible way with their sexuality." (The International Conference on Population and Development (ICPD), held in Cairo, Egypt, from 5 to 13 September 1994).

Diagnosis, Differential↗

PubMed1999

Crystal structure of acceptor stem of tRNA(Ala) from Escherichia coli shows unique G.U wobble base pair at 1.16 A resolution.

The acceptor stem of Escherichia coli tRNA(Ala), rGGGGCUA.rUAGCUCC (ALAwt), contains the main identity element for the correct aminoacylation by the alanyl tRNA synthetase. The presence of a G3.U70 wobble base pair is essential for the specificity of this reaction, but there is a debate whether direct minor-groove contact with the 2-amino group of G3 or a distortion of the acceptor stem induced by the wobble pair is the critical feature recognized by the synthetase. We here report the structure analysis of ALAwt at near-atomic resolution using twinned crystals. The crystal lattice is stabilized by a novel strontium binding motif between two cis-diolic O3'-terminal riboses. The two independent molecules in the asymmetric unit of the crystal show overall A-RNA geometry. A comparison with the crystal structure of the G3-C70 mutant of the acceptor stem (ALA(C70)) determined at 1.4 A exhibits a modulation in ALAwt of helical twist and slide due to the wobble base pair, but no recognizable distortion of the helix fragment distant from the wobble base pair. We suggest that a highly conserved hydration pattern in both grooves around the G3.U70 wobble base pair may be functionally significant.

Base Pairing↗

PubMed1999

Disorder and twin refinement of RNA heptamer double helices.

An RNA helix with seven base pairs which was derived from the acceptor stem of Escherichia coli tRNA(Ala), rGGGGCUA.rUAGCUCC (ALA(wt)), as well as a variant, rGGGGCUA.rUAGCCCC (ALA(C70)), in which the single G.U wobble base pair of ALA(wt) was replaced by G.C, crystallize in space group C2. Both non-isomorphic crystal forms display a complex packing pattern, which can be described alternatively as disorder or pseudo-merohedral twinning. The structure of ALA(wt) was determined by SIRAS phasing using an isomorphous iodine derivative, rGGGGCi(5)UA.rUAGCUCC (ALA(I)). All three RNA structures were subsequently subjected to twin refinement in space group P1, using anisotropic thermal displacement parameters at resolutions of 1.16, 1.23 and 1.4 A for ALA(wt), ALA(I) and ALA(C70), respectively. Alternatively, the structure of ALA(wt) was refined in space group C2 assuming twofold disorder of the molecular orientation. The refined structures are of reasonable quality according to all available indicators. There are no systematic differences between the molecular models resulting from twin refinement and disorder refinement.

Base Sequence↗

PubMed1998

Crystal structure of an eight-base pair duplex containing the 3'-DNA-RNA-5' junction formed during initiation of minus-strand synthesis of HIV replication.

During initiation of minus-strand synthesis by HIV-1 reverse transcriptase, a 3'-DNA-RNA-5' junction is formed involving the 3'-end of tRNAlys,3. The HIV-RT-associated RNase H cleaves the RNA template strand specifically, opposite the newly synthesized DNA strand. We have determined the crystal structure at 1.9 A resolution of an eight-base pair hybrid duplex representing the junction to identify global or local structural perturbations which may be recognized by HIV-RT RNase H. The junction octamer is in a global A-type conformation throughout. A base pair step with distinct stacking geometry and variable backbone conformation is located next to the main endonucleolytic cleavage site. This base pair step may serve as a recognition site for HIV-RT RNase H.

Base Composition↗

PubMed1998

Long-term follow-up of rheumatic patients undergoing left-sided valve replacement with tricuspid annuloplasty--validity of preoperative echocardiographic criteria in the decision to perform tricuspid annuloplasty.

Between September 1989 and December 1991, modified De Vega tricuspid annuloplasty was performed in 43 patients who survived surgery for mitral or mitral plus aortic valve replacement. The preoperative indications for tricuspid annuloplasty were moderate to severe tricuspid regurgitation (TR) in 33 patients and mild or no TR but with a dilated tricuspid annulus (> or =30 mm) as measured by 2-dimensional echocardiography at end-diastole in 10 patients. The mean age was 31 +/- 13 years. The mean duration of follow-up was 57 +/- 18 months. Overall long-term mortality was 12%. On Doppler color flow mapping, postoperative severe TR was present in 1 patient and moderate TR in 4 patients at latest follow-up. The tricuspid annulus diameter decreased from 37 +/- 5 mm preoperatively to 24 +/- 6 mm at latest follow-up. During the study period, an additional 77 patients underwent mitral valve replacement or double valve replacement, but without tricuspid annuloplasty. Within this group, 38 patients had a preoperative tricuspid annulus diameter of > or =30 mm, and 5 of these patients (13%) developed moderate or severe TR in the postoperative period, which may have been prevented had clinicians adhered to the preoperative indications for tricuspid annuloplasty. Thus, preoperative echocardiographically documented moderate or severe TR or a tricuspid annulus diameter of > or =30 mm are valid indications for performing tricuspid annuloplasty; modified De Vega tricuspid annuloplasty is a durable procedure in rheumatic patients; it appears that reducing the diastolic tricuspid annulus diameter to 24 mm is adequate to prevent residual TR in the long term.

Adult↗

PubMed1998

Isolation and characterization of fission yeast sns mutants defective at the mitosis-to-interphase transition.

pim1-d1ts was previously identified in a visual screen for fission yeast mutants unable to complete the mitosis-to-interphase transition. pim1+ encodes the guanine nucleotide exchange factor (GEF) for the spi1 GTPase. Perturbations of this GTPase system by either mutation or overproduction of its regulatory proteins cause cells to arrest with postmitotic condensed chromosomes, an unreplicated genome, and a wide medial septum. The septation phenotype of pim1-d1ts was used as the basis for a more extensive screen for this novel class of sns (septated, not in S-phase) mutants. Seventeen mutants representing 14 complementation groups were isolated. Three strains, sns-A3, sns-A5, and sns-A6, representing two different alleles, are mutated in the pim1+ gene. Of the 13 non-pim1ts sns complementation groups, 11 showed genetic interactions with the spi1 GTPase system. The genes mutated in 10 sns strains were synthetically lethal with pim1-d1, and six sns strains were hypersensitive to overexpression of one or more of the known components of the spil GTPase system. Epistasis analysis places the action of the genes mutated in nine of these strains downstream of pim1+ and the action of one gene upstream of pim1+. Three strains, sns-A2, sns-B1, and sns-B9, showed genetic interaction with the spil GTPase system in every test performed. sns-B1 and sns-B9 are likely to identify downstream targets, whereas sns-A2 is likely to identify upstream regulators of the spi1 GTPase system that are required for the mitosis-to-interphase transition.

Alleles↗

PubMed1997

Signal generation in a non-EU country.

One of the most important objects of post-marketing surveillance is the early detection of serious, unknown and unexpected adverse events. As spontaneous reported adverse events vary considerably in their signal-generating value the Swiss Drug Monitoring Center SANZ implemented an early signal detection system in 1991. With a set of screening criteria the individual case reports are automatically checked by the system and read into a signal file. Subsequently these potential signals are processed to quantify the signal generating value of the particular case. According to the screening criteria 2072 (53%) of the reported cases were considered as potential signals. After validating and quantifying their signal value 27% (565) were drug-related and unlabelled, 8% (173) were also rated as serious. On the basis of these cases 114 labelling changes were made. Some of the most interesting cases are discussed. This computer-assisted early signal generation model in a small country with 7 million inhabitants has a high detectability of new, rare, serious and quality of life affecting adverse drug reactions (ADRs). These newly detected ADRs must be interpreted in cognizance of the limitations and restrictions of spontaneous reporting and do not allow pharmacoepidemiologic conclusions.

Journal Article↗

PubMed1997

Which glycosaminoglycans are suitable for antithrombogenic or athrombogenic coatings of biomaterials? Part I: Basic concepts of immobilized GAGs on partially cationized cellulose membrane.

Six different GAGs of different natural origin such as unfractionated heparin (HE), chondroitin sulfate (CS), dermatan sulfate (DS), keratan sulfate (KS), endothelial cell surface heparan sulfate (ESHS), and hyaluronan (HA) have been ionically immobilized onto partially cationized cellulose membranes with a substitution degree of 0.06. The GAGs have been characterized in terms of total sulfate content and relative molecular weight. The amount of immobilized GAGs was 10(3) times higher than the theoretical amount for monomolecular side-to-side coordination on polymer surfaces. In a standardized perfusion system with shear rates of 1050 sec-1, 37 degrees C, and 5 minutes with citrated blood, the level of platelet adhesion was 100% for partially cationized membrane, 90% for HA, 75% for each HE, CS, DS, KS, 5% for unmodified cellulose membrane, and 5% for confluent bovine aorta endothelial cells, referred to subendothelial matrix as standard for 100% platelet adhesion. ESHS-coated membranes were completely inert to platelets. The amount of ionically released GAGs during perfusion was also estimated. The partial cationic membrane is a suitable polymer surface in combination with the perfusion system to estimate the hemocompatibility of ionically immobilized water-soluble polyanions in terms of platelet adhesion at defined shear rates. The results of platelet adhesion are discussed in terms of structure and analytical parameter of the immobilized GAGs.

Animals↗

PubMed1996

Dis3, implicated in mitotic control, binds directly to Ran and enhances the GEF activity of RCC1.

Using the two-hybrid method, we isolated a Saccharomyces cerevisiae cDNA encoding a protein homologous to Schizosaccharomyces pombe protein Dis3sp, using as bait, human GTPase Ran. The DIS3 gene is essential for viability and complements S.pombe mutant dis3-54 which is defective in mitosis. Although Dis3sc has no homology to RanBP1, it bound directly to Ran and the S.cerevisiae Ran homologue Cnr1, but not to the S.cerevisiae RCC1 homologue Srm1. Upon binding to Ran with a 1:1 molar ratio, Dis3sc enhanced a nucleotide-releasing activity of RCC1 on Ran. In the presence of Dis3sc, the K(m) of RCC1 on Ran decreased by half, while the kcat was unchanged. In vivo, Dis3sp was present as oligomers of M(r) 670-200 kDa as previously reported, and the 200 kDa oligomer of Dis3sp was found to include Spi1 and Pim1, the S.pombe homologues of Ran and RCC1, respectively. Although the biological function of the heterotrimeric oligomer consisting of Dis3, Spi1 and Pim1 is unknown, our results indicate that Dis3 is a component of the RCC1-Ran pathway.

Amino Acid Sequence↗