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Biomedical subjects

D Eberhard

Publications and source records attributed to D Eberhard.

18 recordsLinked to original sources
PubMed1999

The partial homeodomain of the transcription factor Pax-5 (BSAP) is an interaction motif for the retinoblastoma and TATA-binding proteins.

Pax-5 codes for the transcription factor BSAP, which plays an important role in midbrain patterning, B cell development, and lymphoma formation. Pax-5 is known to control gene expression by recognizing its target genes via the NH2-terminal paired domain and by regulating transcription through a COOH-terminal regulatory module consisting of activating and inhibitory sequences. The central region of Pax-5 contains a sequence with significant homology to the first alpha-helix of the paired-type homeodomain. This partial homeodomain has been highly conserved throughout vertebrate evolution because it is found not only in Pax-5 but also in the related Pax-2 and Pax-8 members of the same Pax subfamily. Here we report that the partial homeodomain binds the TATA-binding protein (TBP) and retinoblastoma (Rb) gene product. Both TBP and Rb were shown by coimmunoprecipitation experiments to directly associate with Pax-5 in vivo. The conserved core domain of TBP and the pocket region as well as COOH-terminal sequences of Rb are required for interaction with the partial homeodomain of Pax-5 in in vitro binding assays. Furthermore, Pax-5 was specifically bound only by the underphosphorylated form of Rb. These data indicate that Pax-5 is able to contact the basal transcription machinery through the TBP-containing initiation factor TFIID, and that its activity can be controlled by the cell cycle-regulated association with Rb.

Amino Acid Sequence↗
PubMed1998

[Results of restoration of continuity in peripheral nerves in childhood and adolescence].

According to several studies, results after reconstructive procedures in children are generally superior compared to those in adults. In the present retrospective study, 20 patients after reconstruction of one or more major nerves in the upper limb (median, ulnar, and radial nerves) were examined. At the time of operation, the patients' age was 8.9 years on the average, the follow-up time ranged between 29 and 173 months. In six cases the nerve lesion had been treated by direct nerve coaptation, in 14 patients a primary or secondary nerve grafting procedure had been applied. The results were classified according to Millesi's examination system, which takes several factors such as mobility, sensibility, skill, and force of the hand into account. Besides two patients, one after reconstruction of the median and ulnar nerves by grafts with significant destruction of the muscles in the lower arm, and the second one after primary coaptation of the median and ulnar nerves in the elbow region, all patients showed a hand function of more than 70% according to Millesi's scoring system. In patients older than ten years at the time of the reconstructive procedure, results were slightly worse than in younger individuals. Children up to ten years of age were nearly always able to move their hand and fingers normally. The results after nerve grafting were sometimes even superior to those after primary neurorrhaphy. Therefore, the present study supports the findings of previous authors describing the excellent regenerative potential of the growing peripheral nervous system. Furthermore, Millesi's scoring system better revealed some subtle differences in hand function when compared to other classifications.

Adolescent↗
PubMed1998

[Actinic brachial plexus lesion].

Radiation-induced brachial plexus lesions are progressive and irreversible complications. Until now, there is no way to successful prevention and treatment of this problem. In our series, relief of pain could be achieved by neurolysis in some cases, but there was no recovery of sensory and motor function. In order to improve the vascularity and nerve tissue regeneration, we performed muscle or gliding tissue flaps after neurolysis in our department. Since 1975, 25 patients who developed radiation-induced plexopathy were treated in our department. We followed 18 patients to evaluate the benefits of our surgical intervention. None of the patients had improvement of their sensory or motor impairment. Relief of severe pain was achieved in 83% either by neurolysis only with or without muscle or gliding tissue flap. In some cases, paresis worsened postoperatively. We also observed a return of severe pain after the operation.

Adult↗
PubMed1997

Transposition of the bicipital tuberosity for treatment of fixed supination contracture in obstetric brachial plexus lesions.

In nine patients with obstetric brachial plexus lesions (Klumpke type), an impingement of the bicipital tuberosity on the ulna was the main cause for the forearm and hand to be fixed in supination. A surgical technique using reinsertion of the biceps tendon on the bicipital tuberosity is described in detail. It has substantially improved all patients. After a mean follow-up of 29.4 months the hand was in a more functional position than preoperatively in all patients. In seven cases pronation could be increased by contraction of the biceps muscle. By relaxing the biceps muscle and by contraction of the supinator muscle a limited active supination was possible in six cases.

Adolescent↗
PubMed1996

Split nerve grafting.

Twenty-five patients with severe brachial plexus lesions (having a rather poor prognosis in general), were subjected to a variety of split nerve graft procedures, with 22 achieving useful functional recovery. Thirty-eight nerves were reconstructed, with 32 of them achieving useful recovery. Results in these patients were no better nor worse than those obtained with other types of nerve grafts (e.g., free cutaneous nerve grafts, vascularized nerve grafts, etc.). The technique of splitting the nerve for the use of split fascicle groups as free nerve grafts is nevertheless recommended as an alternative to the application of the ulnar nerve as a vascularized nerve graft. The plexiform arrangement of the fascicles within the ulnar nerve apparently does not preclude the possibility of harvesting sufficiently long nerve grafts.

Adolescent↗
PubMed1996

Species specificity of ribosomal gene transcription: a factor associated with human RNA polymerase I prevents transcription of mouse rDNA.

An intrinsic property of class I gene transcription by RNA polymerase I (Pol I) is the species specificity of the initiation reaction. Previous studies have demonstrated that species-specific rDNA promoter recognition is brought about by a TBP-TAF complex, termed TIF-IB in mouse and SL1 in man. We have compared the ability of affinity-purified TIF-IB and SL1 to direct transcription from the homologous rDNA template both in a reconstituted transcription system and in nuclear extracts prepared from mouse and human cells. We show that Pol I from both species and the individual transcription factors, with the exception of TIF-IB/SL1, are functionally interchangeable in the reconstituted transcription system containing purified proteins. In nuclear extracts, however, species-specific differences are obvious. Whereas SL1 reprograms a heterologous mouse extract to recognize the human promoter, TIF-IB fails to reprogram a human extract unless it is complemented with mouse Pol I. Crude human, but not mouse, Pol I exhibits species-specific differences that disappear after purification. We propose that in extracts and less purified fractions human Pol I exists as 'holoenzyme' containing associated protein(s) that prevent assembly of TIF-IB-directed initiation complexes at the murine rDNA promoter.

Animals↗
PubMed1994

The conserved core domain of the human TATA binding protein is sufficient to assemble the multisubunit RNA polymerase I-specific transcription factor SL1.

The human ribosomal RNA polymerase (Pol) I promoter selectivity factor SL1 is a complex consisting of the TATA binding protein (TBP) and three TBP-associated factors (TAFs). We have investigated which elements of TBP are involved in the assembly of Pol I-specific TBP-TAF complexes by comparing SL1 isolated from two human cell lines, one expressing epitope-tagged full-length TBP and another expressing a deletion of nearly the entire N-terminal domain (e delta NTBP). We have immunopurified epitope-tagged full-length TBP- and e delta NTBP-TAF complexes and show that e delta NTBP reconstitutes SL1 activity almost as well as full-length TBP. Moreover, e delta NTBP is shown to be associated with all three Pol I-specific TAFs. Thus, the core of TBP alone is sufficient for the correct assembly of the Pol I-specific TBP-TAF complex, and the variable N-terminal region of human TBP is not required for transcriptional activity. We also demonstrate by an in vitro protein-protein interaction assay that TBP directly interacts with the smallest TAF, TAFI48.

Amino Acid Sequence↗
PubMed1994

TBP-associated factors interact with DNA and govern species specificity of RNA polymerase I transcription.

Unlike genes transcribed by RNA polymerases II and III, transcription by RNA polymerase I is highly species-specific. Ribosomal promoter selectivity is brought about by a multisubunit transcription factor (SL1/TIF-IB) which consists of the TATA-binding protein (TBP) and three TBP-associated factors (TAFs). To determine the basis for the inability of SL1/TIF-IB to recognize heterologous rDNA, the transcriptional properties and the subunit composition of the murine and the human factor, as well as a chimeric complex containing epitope-tagged human TBP and murine TAFs, have been compared. We show that TBP can be exchanged between the human and mouse factor indicating that the variable N-terminal domain of TBP does not play a significant role in rDNA promoter selectivity. Instead, DNA binding is brought about by the TAFs. UV crosslinking experiments demonstrate that binding to the ribosomal gene promoter is mediated by two TAFs (TAFI48 and TAFI68) which have the same electrophoretic mobility in the human and mouse factor. The largest TAF is different in both species and is suggested to play a role in the species-specific assembly of productive preinitiation complexes. Thus, evolutionary changes of rDNA promoter sequences have been accompanied by changes in specific TAFs.

Amino Acid Sequence↗
PubMed1994

The N-terminal domain of the human TATA-binding protein plays a role in transcription from TATA-containing RNA polymerase II and III promoters.

In eukaryotes, the TATA box binding protein (TBP) is an integral component of the transcription initiation complexes of all three classes of nuclear RNA polymerases. In this study we have investigated the role of the N-terminal region of human TBP in transcription initiation from RNA polymerase (Pol) I, II and III promoters by using three monoclonal antibodies (mAbs). Each antibody recognizes a distinct epitope in the N-terminal domain of human TBP. We demonstrate that these antibodies differentially affect transcription from distinct classes of promoters. One antibody, mAb1C2, and a synthetic peptide comprising its epitope selectively inhibited in vitro transcription from TATA-containing, but not from TATA-less promoters, irrespective of whether they were transcribed by Pol II or Pol III. Transcription by Pol I, on the other hand, was not affected. Two other antibodies and their respective epitope peptides did not affect transcription from any of the promoters tested. Order of addition experiments indicate that mAb1C2 did not prevent binding of TBP to the TATA box or the formation of the TBP-TFIIA-TFIIB complex but rather inhibited a subsequent step of preinitiation complex formation. These data suggest that a defined region within the N-terminal domain of human TBP may be involved in specific protein-protein interactions required for the assembly of functional preinitiation complexes on TATA-containing, but not on TATA-less promoters.

Antibodies, Monoclonal↗
PubMed1994

The human EPRS locus (formerly the QARS locus): a gene encoding a class I and a class II aminoacyl-tRNA synthetase.

Glutamyl-tRNA synthetase and prolyl-tRNA synthetase belong to different classes of aminoacyl-tRNA synthetases that are thought to have evolved along independent evolutionary pathways. However, both enzymes are on one polypeptide chain encoded by a single human gene, the EPRS locus, which is transcribed as one long mRNA. We report the structure of the human EPRS gene, which consists of 29 exons spread over at least 90 kb of genomic DNA. The exons, encoding the glutamyl-specific and the prolyl-specific parts of the enzyme, are each clustered in 10-kb sections located at opposite ends of the gene. These two exon clusters are separated by a long intervening DNA section with a number of exons, encoding functions that may be involved in the organization of the mammalian multienzyme synthetase complex. The upstream gene region shows structural features of a regulated gene, and preliminary experiments suggest that the gene is expressed at specific times in growth-stimulated cultured cells. We have localized the gene to the distal long arm of human chromosome 1 and to a corresponding site in mouse chromosome 1.

Amino Acid Sequence↗
PubMed1993

A TBP-containing multiprotein complex (TIF-IB) mediates transcription specificity of murine RNA polymerase I.

TIF-IB is a transcription factor which interacts with the mouse ribosomal gene promoter and nucleates the formation of an initiation complex containing RNA polymerase I (Pol I). We have purified this factor to near homogeneity and demonstrate that TIF-IB is a large complex (< 200 kDa) which contains several polypeptides. One of the subunits present in this protein complex is the TATA-binding protein (TBP) as revealed by copurification of TIF-IB activity and TBP over different chromatographic steps including immunoaffinity purification. In addition to TBP, three tightly associated proteins (TAFs-I) with apparent molecular weights of 95, 68, and 48 kDa are contained in this multimeric complex. This subunit composition is similar--but not identical--to the analogous human factor SL1. Depletion of TBP from TIF-IB-containing fractions by immunoprecipitation eliminates TIF-IB activity. Neither TBP alone nor fractions containing other TBP complexes are capable of substituting for TIF-IB activity. Therefore, TIF-IB is a unique complex with Pol I-specific TAFs distinct from other TBP-containing complexes. The identification of TBP as an integral part of the murine rDNA promoter-specific transcription initiation factor extends the previously noted similarity of transcriptional initiation by the three nuclear RNA polymerases and underscores the importance of TAFs in determining promoter specificity.

Animals↗
PubMed1993

[Pain syndromes of the tibial nerve at the leg-foot transition].

The prognosis of surgical treatment of the tarsal tunnel syndrome (TTS) with regard to total pain relief is worse than following surgery of the carpal tunnel syndrome. In TTS, additional static factors play a role. The indication for surgery, therefore, is made with utmost reluctance. The surgical strategy is described extensively. In the majority of patients a considerable improvement of symptoms can be achieved. There are, however, individual patients in whom surgical intervention is followed by increased pain. Three such patients are reported. This pain syndrome is caused and increased by recurrent fibrosis of the nerve bed, eventually including the integument and inducing entrapment neuropathy by the contracted dermal covering. Surgical resolution of this problem is transplantation of soft tissues to surround the nerve and skin grafting to augment the covering dermal layer.

Adult↗
PubMed1992

Exons encoding the highly conserved part of human glutaminyl-tRNA synthetase.

Aminoacyl-tRNA synthetases are important components of the genetic apparatus. In spite of common catalytic properties, synthetases with different amino acid specificities are widely diverse in their primary structures, subunit sizes, and subunit composition. However, synthetases with given amino acid specificities are well conserved throughout evolution. We have been studying the human glutaminyl-tRNA synthetase possessing a sequence of about 400 amino acid residues (the core region) that is very similar to sequences in the corresponding enzymes from bacteria and yeast. The conserved sequence appears to be essential for the basic function of the enzyme, the charging of tRNA with glutamine. As a first step to a better understanding of the evolution of this enzyme, we determined the coding region for the conserved part of the human glutaminyl-tRNA synthetase. The coding region is composed of eight exons. It appears that individual exons encode defined secondary structural elements as parts of functionally important domains of the enzyme. Evolution of the gene by assembly of individual exons seems to be a viable hypothesis; alternative pathways are discussed.

Amino Acid Sequence↗
PubMed1992

[The use of the "cine-technic" in the MRT diagnosis of the temporomandibular joint].

A new cine-technique in a prospective study using rapid gradient echo sequences was evaluated for the MRT investigation of the temporo-mandibular joint. A newly developed hydraulic apparatus was used to produce progressive opening of the jaw and MRT appearances were recorded during predetermined points of mandibular movement. The investigation included 16 normals and 34 patients. A modified gradient echo sequence was combined with an optimised surface coil or a special double coil and this provided good spatial resolution of the articular disc and of the muscular and bony structure. Amongst the abnormal findings were luxation of the disc (15 cases), tears in the disc (5 cases), late effects of internal derangements (12 cases) and condylar hypermotility (7 cases). The new cine-technique provides specific images in any chosen position of the mandible depending on the clinical disability of the patient.

Equipment Design↗
PubMed1991

[MR tomographic diagnosis of internal derangement of the temporomandibular joint].

On the basis of MR imaging studies in 150 temporomandibular joints (TMJ) a classification system for internal derangement of the TMJ was defined. Clinically, internal derangement is characterized by disc displacement and disorders of the mandibular condyle. MR imaging enables a differentiation of early stages (I,II) with disc displacement, the intermediate stage (III), and the later stages (IV,V) with osseous destruction. Optimal diagnostic results (n = 140) allowed the use of proton-density sequences in both open and closed joint positions (TR/TE = 1000/28). Dynamic imaging of the TMJ was performed using fast-gradient echo sequences and a self-developed hydraulic opening device (n = 20). MR imaging has proved to be the method of choice for the pre- and post-therapeutic evaluation of internal derangement of the TMJ.

Adult↗
PubMedDate not supplied

Incremental hydraulic jaw opener for MR imaging of the temporomandibular joint.

Magnetic resonance (MR) imaging in the open- and closed-mouth positions is the method of choice for visualizing the temporomandibular joint (TMJ). To analyze the TMJ in response to various degrees of mouth opening, the authors constructed a hydraulic incremental jaw opener. This apparatus enables obtaining of reproducible and stable positions of TMJ articulation. With modified gradient pulse sequences, the technique yields good spatial resolution of joint anatomy, including that of the articular disk. The application of a cine program allows cinematographic display of TMJ motion, which in conjunction with static open- and closed-mouth views can be useful in the diagnosis of TMJ dysfunction. The authors used the incremental jaw opener to examine the disk-condyle complex at each open-mouth position, with particular attention to extreme open-mouth positions.

Equipment Design↗
PubMedDate not supplied

Grants management skills keep funded projects on target.

An often neglected but equally relevant aspect of program development and nursing research is the management of funded projects from the time an idea is generated to the final submission of project report. When effective grants management skills are used to oversee the development of a program proposal and the oversight of the funded project, the likelihood for successful outcome is increased. In this article several steps have been described in the grants management process that can be used to assure that projects are developed and proceed according to plan.

Budgets↗