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Biomedical subjects

M Truss

Publications and source records attributed to M Truss.

At least 19 recordsLinked to original sources
PubMed2006

[Laparoscopic surgery in urology: Taining and education].

Relatively long learning curves and, therefore, initially longer operating times compared to conventional procedures are still a matter of debate. Today, there are numerous possibilities for learning laparoscopic techniques and establishing one's own laparoscopic programs, including various pelvitrainers and virtual reality computer programs. One useful and realistic way involves "wet lab" training programs for ablative and reconstructive procedures using the pig model. Today, laparoscopic urological surgery includes procedures with low (e.g. laparoscopy for undescended testicles), intermediate (laparoscopic pyeloplasty) and high level (laparoscopic/endoscopic prostatectomy) complexity. Therefore, laparoscopy should be an integral part of training in urology. A defined number of possibly multi-institutional training centers with well structured educational programs are needed. The main goal should be the standardization of surgical procedures as well as educational training programs in order to shorten individual learning curves and generate common quality standards.

Animals↗
PubMed2006

Laparoscopic transabdominal pyeloplasty in children is feasible irrespective of age.

PURPOSE: We assessed the feasibility of laparoscopic transabdominal dismembered pyeloplasty in 46 infants and children with regard to patient age. MATERIALS AND METHODS: A total of 46 consecutive infants and children (31 male and 15 female) underwent laparoscopic transabdominal dismembered pyeloplasty using a 3 to 4-trocar technique. All patients had confirmed unilateral deterioration of renal function on isotope renography. The 46 patients were divided into 3 age groups--1 to 12 months (group 1, 14 patients), 1 to 7 years (group 2, 15 patients) and 7 to 18 years (group 3, 17 patients). Followup included clinical and ultrasound assessment, and isotope renography at 3 months. RESULTS: Laparoscopic pyeloplasty was feasible in 44 of 46 patients (96%). Mean operative time was 175 minutes (range 120 to 270). The operation was converted due to impracticality of stenting the PUJ in 1 patient, and due to bleeding in 1. Mean operative time in 44 successful laparoscopic procedures was not significantly different among the 3 age groups (171 minutes in group 1, 169 minutes in group 2 and 173 minutes in group 3). Two patients required operative intervention for PUJ leakage, and 1 underwent percutaneous nephrostomy with a further uneventful course. Mean followup was 29 months (range 3 to 86). A total of 44 patients (96%) were asymptomatic and had improved PUJ drainage on isotope renography. Two patients underwent redo pyeloplasty due to recurrent hydronephrosis at 1 month and 2 years. CONCLUSIONS: Laparoscopic transabdominal dismembered pyeloplasty is effective and safe in infants and children. The feasibility is also excellent in patients younger than 1 year. The transabdominal approach revealed good exposition without a disadvantage for the patient.

Abdomen↗
PubMed2000

Glucocorticoid effects on NF-kappaB binding in the transcription of the ICAM-1 gene.

Glucocorticoid hormones are potent antiinflammatory drugs. A key mechanism in the antiinflammatory action is repression of the nuclear factor kappa B (NF-kappaB) signaling pathway. This results in transcriptional repression of inflammatory genes controlled by NF-kappaB, including the intercellular adhesion molecule-1 (ICAM-1). We have investigated expression levels, nuclear translocation and DNA binding of NF-kappaB in vitro and in vivo in U937 cells during activation and repression. Repression of NF-kappaB signaling by glucocorticoids does not prevent NF-kappaB translocation or DNA binding. However interestingly, in vivo foot printing of the NF-kappaB site in the ICAM-1 gene indicates that glucocorticoids change the conformation of the protein complex binding to the NF-kappaB site. These results suggests that NF-kappaB interaction with the glucocorticoid receptor does not displace NF-kappaB from its DNA binding site but rather changes the complex into a transcriptionally inert form.

Base Sequence↗
PubMed1999

Hormone-dependent recruitment of NF-Y to the uteroglobin gene enhancer associated with chromatin remodeling in rabbit endometrial epithelium.

Expression of the rabbit uteroglobin gene is hormonally induced in cells of the endometrial epithelium during the preimplantation phase of pregnancy. Here we show that progesterone activation of the gene is mediated by two clusters of hormone responsive elements located between 2.4 and 2.7 kilobase pairs upstream of the transcriptional start site. Between these two clusters, genomic footprinting studies in the intact endometrial epithelium reveal the hormone-inducible occupancy of several cis-acting elements. One of the protected elements shows sequence homology to the consensus binding site of the transcription factor NF-Y, which binds to the element in gel shift experiments. This uteroglobin Y box is essential for enhancer activity in transient transfection experiments with endometrial and non-endometrial cell lines, in accordance with the ubiquitous expression of NF-Y. To understand why binding of this ubiquitous factor to the uteroglobin Y box in endometrium depends on hormone induction, we examined the chromatin structure of the relevant gene region. In the uninduced state, the enhancer region appears to be organized into positioned nucleosomes. Upon hormone induction, this nucleosomal pattern is lost and the enhancer region becomes hypersensitive to nucleases, suggesting that a hormone-induced change in the local chromatin structure unmasks previously unaccessible binding sites for transcription factors. Our results emphasize the limitations of using transient transfection assays for the functional analysis of cis-acting elements and underline the need for including the native chromatin organization in this kind of studies.

Animals↗
PubMed1998

The mouse mammary tumour virus promoter positioned on a tetramer of histones H3 and H4 binds nuclear factor 1 and OTF1.

Modulation of eukaryotic gene expression is influenced by the organization of regulatory DNA-elements in chromatin. The mouse mammary tumor virus (MMTV) promoter exhibits regularly positioned nucleosomes that reduce the accessibility of the binding sites for sequence-specific transcription factors, in particular nuclear factor (NF1). Hormonal induction of the MMTV promoter is accompanied by remodeling of the nucleosomal structure, but the biochemical nature of these structural changes is unknown. Using recombinant histones, we have now assembled the MMTV promoter in particles containing either an octamer of the histones H3, H4, H2A and H2B or a tetramer of histones H3 and H4, and have compared the two particles in terms of structure, positioning, and exclusion of transcription factors. Using site-directed hydroxy radicals to map histone locations, two main nucleosome positions are found with dyads at position -107 and at -127. The same two main positions are found for particles containing only the H3/H4 tetramer, showing that the absence of H2A/H2B dimers does not alter positioning. The rotational orientation of the DNA double helix in both types of particles is essentially identical. However, the ends of the nucleosomal DNA as well as its central region are more accessible to cleavage reagents in the tetramer particle than in the octamer particle. In agreement with these structural features, the transcription factors NF1 and OTF1 were able to bind to their cognate sites on the tetramer particle, while they could not gain access to the same sites on the surface of the octamer particle. The DNase I digestion pattern of octamers treated with partially purified SWI/SNF complex from HeLa cells in the presence of ATP is indistinguishable from that of tetramer particles, suggesting that the SWI/SNF complex promotes ATP-dependent remodeling of the octamer particle but not of tetramer particles. These results are compatible with a hormone-induced removal of histone H2A/H2B during MMTV induction.

Adenosine Triphosphatases↗
PubMed1998

Hormone-induced recruitment of Sp1 mediates estrogen activation of the rabbit uteroglobin gene in endometrial epithelium.

Steroid hormones activate gene expression by interaction of their receptors with hormone-responsive DNA elements and tissue-specific or ubiquitous factors. To monitor the molecular changes on the promoter of the rabbit uteroglobin gene during early pseudopregnancy in vivo, we have applied the genomic footprinting methodology to endometrial tissue. Estrogen induction results in the simultaneous occupancy of an estrogen-responsive element and an adjacent GC/GT box in the promoter. DNA binding assays demonstrate that the corresponding regulatory factors are the ligand-induced estrogen receptor and the ubiquitous transcription factor Sp1. Both factors functionally synergize in primary endometrial cells, showing that the GC/GT box is an essential part of a composite estrogen-responsive unit. However, the estrogen receptor and Sp1 do not bind cooperatively to their sites in vitro, suggesting that other mechanisms might be responsible for the hormone-dependent binding of Sp1 in vivo. Since hormone treatment leads to the appearance of a distinct DNase I-hypersensitive site over the promoter chromatin, an estrogen-induced change in the local chromatin structure could facilitate binding of Sp1 in vivo.

Animals↗
PubMed1997

Binding of NF1 to the MMTV promoter in nucleosomes: influence of rotational phasing, translational positioning and histone H1.

To analyse the role of rotational orientation and translational positioning of nucleosomal DNA on transcription factor binding we have generated a series of mutant MMTV promoters containing insertions of various lengths between the hormone-responsive region and the binding site for NF1. These various MMTV promoter fragments were assembled in mononucleosomes and used for structural studies and binding experiments. We show that the insertions change the rotational phase and translational positioning of the NF1 site as predicted if the sequences upstream of the insertion site were the main determinants of nucleosome phasing. In band shift experiments with recombinant NF1 we cannot detect binding of the protein to NF1 sites included within the limits of a nucleosome, independent of their rotational orientation. Moving the NF1 site closer to the nucleosome border also did not permit NF1 binding. This behaviour probably reflects the way NF1 binds DNA, namely it almost completely surrounds the circumference of the double helix establishing a large number of contacts with the bases and the backbone. In contrast to the wild-type and short insertion mutants, NF1 bound readily to nucleosomes containing 30 or 50 bp insertions which placed the NF1 site at the nucleosome edge or within linker DNA. NF1 binding to the linker DNA was unaffected by incorporation of histone H1 into the nucleosome particle. These findings are discussed in relation to chromatin remodelling initiated by steroid hormones during induction of the MMTV promoter.

Animals↗
PubMed1997

Crosslinking of progesterone receptor to DNA using tuneable nanosecond, picosecond and femtosecond UV laser pulses.

UV laser crosslinking is a potentially powerful tool to investigate transient DNA-protein interactions and binding kinetics in intact cells. As the processes underlying UV laser crosslinking are not fully understood, we have performed a study of the influence of laser pulses with different physical parameters on crosslinking of the progesterone receptor to an oligonucleotide containing a hormone-responsive element. We also studied the influence of the various parameters on the amount of laser-irradiated DNA that can be correctly primer extended as an operational measurement of DNA integrity. A strong influence of pulse intensity and pulse length on the crosslink yield was found, likely due to a change in the 'two photon' processes responsible for crosslinking. The highest efficiency of protein crosslinking to DNA was achieved with femtosecond pulses and should be sufficient to enable use of this technique for in vivo studies.

Animals↗
PubMed1997

Prognostic relevance of intracaval neoplastic extension for patients with renal cell cancer.

OBJECTIVE: To assess the diagnosis of vena caval thrombosis (VCT) in patients with renal cell carcinoma (RCC) as an independent indicator of prognostic importance and when combined with additional tumour characteristics in a controlled multivariate analysis. PATIENTS AND METHODS: The clinical course of 53 patients (41 men and 12 women, mean age 60 years, range 35-79) with RCC and VCT was compared with that of a control group of 47 patients (37 men and 10 women, mean age 57 years, range 32-76) with RCC but no neoplastic extension into the vena cava. RESULTS: With a follow-up of 1-154 months and a mean long-term survival of 32 and 35 months, respectively, for patients with and without VCT, neither the propagation of the tumour into the vena cava (P = 0.391) nor the cranial extension of the thrombosis (P = 0.158) were identified as having any prognostic value during univariate or multivariate statistical analysis. The presence of regional lymph node (P < 0.001) or distant metastases (P = 0.009) was an independent prognostic variable for patients with RCC, with a significant decrease in long-term survival (13 and 14 months for patients with lymph node and distant metastases, respectively). CONCLUSION: A radical surgical approach is essential as standard therapy for the treatment of patients with RCC and neoplastic extension into the vena cava. Because they have a significantly decreased life expectancy, asymptomatic patients with lymph node or distant metastases should be treated conservatively.

Adult↗
PubMed1997

Computer-assisted evaluation of the smooth-muscle electromyogram of the corpora cavernosa by fast Fourier transformation.

OBJECTIVE: The aim of our study was to investigate analogous and digital recording of corpus cavernosum EMGs (CC-EMGs) in normal men according to criteria that were recently agreed upon in an international consensus workshop. METHODS: CC-EMGs were analogously and digitally registered from 37 normal subjects. Power spectra in the frequency domain were determined via fast Fourier transformation (FFT). RESULTS: Thirty-one of men showed identical or at least very similar electrical activity patterns in the analogous and digital registration. Needle penetration artifacts (investigated in 18 subjects) were found in 17/18 CC-EMGs during the first 20 min. Power spectra show a maximum of power at a frequency of 0.3 Hz with more than 90% of the power located between 0 and 5 Hz. CONCLUSIONS: Registration of CC-EMGs in normal men resulted in interindividually reproducible recordings. Age hardly affected CC-EMGs. Computer-assisted evaluation by FFT after elimination of artifacts was feasible. Thus, interpretation of the CC-EMG signals by a computer-aided expert system seems to be promising for clinical routine, in particular with respect to an increase in objectivity and a decrease in time needed for interpretation.

Adolescent↗
PubMed1996

Moderate increase in histone acetylation activates the mouse mammary tumor virus promoter and remodels its nucleosome structure.

The mouse mammary tumor virus (MMTV) promoter is regulated by steroid hormones through a hormone-responsive region that is organized in a positioned nucleosome. Hormone induction leads to a structural change of this nucleosome which makes its DNA more sensitive to cleavage by DNase I and enables simultaneous binding of all relevant transcription factors. In cells carrying either episomal or chromosomally integrated MMTV promoters, moderate acetylation of core histones, generated by treatment with low concentrations of the histone deacetylase inhibitors sodium butyrate or trichostatin A, enhances transcription from the MMTV promoter in the absence of hormone and potentiates transactivation by either glucocorticoids or progestins. At higher concentrations, histone deacetylase inhibitors reduce basal and hormone induced MMTV transcription. Inducing inhibitor concentrations lead to the same type of nucleosomal DNase I hypersensitivity as hormone treatment, suggesting that moderate acetylation of core histone activates the MMTV promoter by mechanisms involving chromatin remodeling similar to that generated by the inducing hormones.

Acetylation↗
PubMed1996

17beta-Estradiol induces cyclin D1 gene transcription, p36D1-p34cdk4 complex activation and p105Rb phosphorylation during mitogenic stimulation of G(1)-arrested human breast cancer cells.

MCF-7 human breast cancer cells express functional estrogen receptor and grow in response to estrogen stimulation. G(1)-synchronized MCF-7 cells, made quiescent by exposure to the HMG-CoA reductase inhibitor Simvastatin in estrogen-free medium, readily resume cell cycle progression upon stimulation with 17beta-estradiol (E(2)), even under conditions where polypeptide growth factor-triggered signal transduction pathways are inhibited by the continuous presence of Simvastatin in the culture medium. Under these conditions, cyclin D(1) gene transcription is transiently induced within the first 1-9 h of stimulation, as shown by the accumulation of cyclin D(1) mRNA and protein (p36(D(1))) in the cell and by enhanced expression of stably transfected D(1) promoter-luciferase hybrid genes. Estrogen-induced p36(D(1)) associates readily with p32(cdk2) and p34(cdk4), but not with p31(cdk5), which is however abundantly expressed in these cells. Only p36(D(1))-p34(cdk4) complexes are activated by E(2), as detected in cell extracts by immunoprecipitation with anti-D(1) antibodies followed by assessment of phosphotransferase activity toward the retinoblastoma (Rb) gene product and by analysis of p105(Rb) phosphorylation in vivo. An estrogen-responsive regulatory region has been mapped within the first 944 bp upstream of the transcriptional startsite of the human D(1) gene. Sequence analysis of this DNA region reveals that the cis-acting elements responsive to estrogen are likely to be different in this case from the canonical EREs.

Breast Neoplasms↗
PubMed1996

Chromatin structure of the MMTV promoter and its changes during hormonal induction.

1. The packaging of nuclear DNA in chromatin determines the conversion of the genetic information into a defined phenotype by influencing the availability of DNA sequences for interactions with regulatory proteins and transcription factors. 2. We have studied the influence of the first level of chromatin organization, the nucleosome, on the activity of the mouse mammary tumor virus (MMTV) promoter. The MMTV promoter is strongly transcribed in response to steroid hormones but is virtually silent in the absence of hormonal stimuli. Full hormonal induction requires binding of the hormone receptors to four hormone-responsive elements (HREs), as well as binding of nuclear factor I (NFI) and the octamer transcription factor 1 (OTF-1 or Oct-1) to sites located between the HREs and the TATA box. A full loading with transcription factors cannot be achieved on free DNA due to steric hindrance between hormone receptor and NFI and between NFI and OTF-1. 3. The low basal activity of the MMTV promoter is most likely due to its organization in a positioned nucleosome. In the intact cell, as well in reconstituted chromatin, the regulatory region of the MMTV promoter is wrapped around a histone octamer in a precise rotational orientation, which permits access of the hormone receptors to only two of the four HREs, while precluding binding of NFI and OTF-1 to their respective sites. Upon hormone induction, the nucleosome is remodeled and the path of its DNA altered in a way which makes the nucleosomal dyad axis more accessible to DNase I and enables occupancy of all relevant sites: the four HREs, as well as the binding sites for NFI and OTF-1. 4. These results suggest that the nucleosomal organization of the MMTV promoter not only is responsible for the low activity prior to hormone treatment, but also may be a prerequisite for full loading with transcription factors after hormone induction. We conclude that the DNA contains topological information which modulates the expression of the genetic program.

Animals↗
PubMed1996

Transcriptional regulation by steroid hormones.

Steroid hormones influence the transcription of a large number of genes by virtue of their interaction with intracellular receptors, which are modular proteins composed of a ligand binding domain, a DNA binding domain, and several transactivation functions distributed along the molecule. The DNA binding domain is organized around two zinc ions and allows the receptors to bind as homodimers to palindromic DNA sequences, the hormones responsive elements (HRE), is such a way that each homodimer contacts one half of the palindrome. Since the two halves are separated by three base pairs, the two homodimers contact the same face of the double helix. Before hormone binding, the receptors are part of a complex with multiple chaperones which maintain the receptor in its steroid binding conformation. Following hormone binding, the complex dissociates and the receptors bind to HREs in chromatin. Regulation of gene expression by hormones involves an interaction of the DNA-bound receptors with other sequence-specific transcription factors and with the general transcription factors, which is partly mediated by co-activators and co-repressors. The specific array of cis regulatory elements in a particular promoter/enhancer region, as well as the organization of the DNA sequences in nucleosomes, specifies the network of receptor interactions. Depending on the nature of these interactions, the final outcome can be induction or repression of transcription. The various levels at which these interactions are modulated are discussed using as an example the promoter of the Mouse Mammary Tumor Virus and its organization in chromatin.

Animals↗
PubMed1996

Interaction of steroid hormone receptors with transcription factors involves chromatin remodelling.

The mechanism by which steroid hormones modulate promoter utilization is not clear. Evidence from transfection studies and cell-free assays points to an interaction of the hormone receptors with general transcription factors, as well as with sequence-specific transcription factors. Moreover co-activators or transcription intermediary factors, have been identified which could mediate some of the transcriptional effects of the hormone-receptor complex. However, in addition to this interaction of receptors with proteins directly involved in transcription, a participation of chromatin structure in gene regulation by steroid hormones is becoming increasingly evident. In the case of the MMTV promoter, the nucleosomal organization seems to be responsible for transcriptional repression prior to hormonal stimulation. This effect is due to occlusion by a nucleosome positioned on the MMTV promoter sequences in such a way that essential transcription factors cannot access their recognition sites. Following hormone induction, a remodelling of the nucleosome structure takes place which enables a whole complement of sequence specific transcription factors to assemble on the promoter. Since a complete occupancy of binding sites does not take place when the promoter is present as naked DNA, the nucleosomal organization appears to be required for the proper synergism between transcription factors following hormonal induction. According to this model, the positioning of a nucleosome sets the stage for constitutive repression and hormone induction of the MMTV promoter.

Amino Acid Sequence↗
PubMed1996

[Functional electromyostimulation of the penile corpus cavernosum (FEMCC)]. Initial results of a new therapeutic option of erectile dysfunction].

Transcutaneous application of low-frequency electric current in the treatment of partially or temporarily denervated striated muscles is widely used to prevent or treat muscular atrophy. Due to the high regenerative capacity of smooth muscle cells, this approach should be beneficial in the treatment of diseases with smooth muscle degeneration due to partial denervation. Our study was done to evaluate the possible beneficial effect of transcutaneous application of low-frequency electric current to the corpus cavernosum penis in the treatment of erectile dysfunction. After a comprehensive work-up, 22 patients with chronic erectile dysfunction (21/22 vasoactive nonresponders) received daily (3-5 x 20 min) transcutaneous functional electromyostimulation of the corpus cavernosum smooth muscles (FEMCC; zero line symmetric impulses of trapezoid shape, two-channel device with alternating stimulations, f = 10-20 Hz for channel I and 20-35 Hz for channel II; t(i) = 100-2000 microseconds, approx. 12 mA, rise time 0.5 s, stimulation time 5 s per channel, interval between stimulations 0.5 s). Five of 22 patients (23%) regained full spontaneous erections and another three (14%) responded to vasoactive drugs after FEMCC. Fourteen were FEMCC failures, including two who subjectively 'improved'. In a similar group of patients evaluated during the same period but receiving no therapy, no spontaneous improvement of the erectile function was observed. Our preliminary results suggest that FEMCC is feasible and results in an improvement of the erectile capacity in a significant proportion (37%) of patients. Further studies will be carried out to corroborate our results, to improve stimulation parameters and to evaluate selection criteria for FEMCC.

Adult↗
PubMed1995

Cell cycle regulation of cdc25C transcription is mediated by the periodic repression of the glutamine-rich activators NF-Y and Sp1.

The late S/G2-specific transcription of the human cdc25C gene is dependent on an initiator-proximal repressor element (CDE) and an upstream activating sequence (UAS) of undefined nature. We now show that these upstream sequences harbour multiple in vivo protein binding sites that interact with transcriptional activators and form separable, context-independent functional modules. Major components of the UAS are a bona fide Sp1 site and three direct sequence repeats (Yc-boxes). The Yc-boxes interact with the CCAAT-box binding protein NF-Y and are critically dependent on synergistic interactions for efficient transcription activation. The NF-Y complexes, as well as Sp1, are constitutive activators, whose activation function is periodically repressed through the CDE. These observations indicate that the cell cycle regulation of cdc25C transcription is mainly due to the CDE-mediated repression of glutamine-rich activators.

3T3 Cells↗