Biomedical subjects

P Braun

Publications and source records attributed to P Braun.

At least 19 recordsLinked to original sources

PubMed2006

Refluxing chimney versus nonrefluxing LeDuc ureteroileal anastomosis for orthotopic ileal neobladder: a comparative analysis for patients with bladder cancer.

PURPOSE: Radical cystectomy and various techniques of urinary diversion are gold standard treatments for invasive bladder cancer. However, postoperative hydronephrosis is a common complication in these patients. A special focus was placed on the type of ureteroileal anastomosis used with 2 different techniques performed at 1 institution. MATERIALS AND METHODS: Between 1995 and 2003 a total of 106 consecutive patients with bladder cancer underwent cystectomy followed by construction of an ileal neobladder. The nonrefluxing technique of ureter tunneling described by LeDuc and the refluxing chimney technique used for ureter implantation into the ileum-neobladder were compared. Hydronephrosis due to ureteral strictures was studied immediately following surgery and up to 5 years after surgery. RESULTS: A total of 204 RU were included in the study. The LeDuc technique was used in 132 RU (64%) and the chimney technique was used in 72 RU (36%). Hydronephrosis rate of 2% were found in each of the 2 groups after 5 years of followup. CONCLUSIONS: Postoperative hydronephrosis due to ureteral strictures is observed at the same rate during long-term followup with the LeDuc and chimney techniques. We favor the chimney technique compared to the LeDuc tunnel due to easier technical preparation and a better chance to identify the ureters endoscopically at a later time. The chimney does give extra length to reach the ureteral stump, especially in cases of distal ureteral carcinoma in situ.

Adult↗

PubMed2005

Predictive modelling of growth and measurement of enzymatic synthesis and activity by a cocktail of selected Enterobacteriaceae and Aeromonas hydrophila.

The possibility was examined of developing a predictive model that would predict food spoilage by combining microbial growth (increase in cellular number) with extracellular enzymatic activity of a cocktail of five strains of Enterobacteriaceae: Escherichia coli, Enterobacter agglomerans, Klebsiella oxytoca, Klebsiella pneumoniae and Proteus vulgaris and one Aeromonas hydrophila strain. Estimations of growth and enzyme activity were made within a three-dimensional matrix of conditions: temperature 2-20 degrees C, pH value 4.0-7.5 and water activity (a(w)) 0.95-0.995. A mathematical model was constructed which predicted growth based on increases in cell number. However, although notable effects of extracellular lipases and proteases were detected, it was not possible to model enzymatic activity and prepare a combined model because the data did not follow the characteristic profile that would allow curve-fitting. Nevertheless, the model for microbial growth and information relating to enzyme activity will be made freely available in a database on the internet.

Aeromonas hydrophila↗

PubMed2005

High pressure near infrared study of the mutated light-harvesting complex LH2.

The pressure sensitivities of the near infrared spectra of the light-harvesting (LH2) complex and a mutant complex with a simplified BChl-B850 binding pocket were compared. In the mutant an abrupt change in the spectral properties occurred at 250 MPa, which was not observed with the native sample. Increased disorder due to collapse of the chromophore pocket is suggested.

Escherichia coli↗

PubMed2004

Predictive modelling of growth and measurement of enzymatic synthesis and activity by a cocktail of Brochothrix thermosphacta.

The possibility was examined of developing a predictive model that combined microbial growth (increase in cellular number) and extracellular enzyme activity of a cocktail of three strains of Brochothrix thermosphacta. Estimations of growth and enzyme activity were made within a three-dimensional matrix of conditions: temperature 2-20 degrees C, pH value 4.0-7.5 and water activity (a(w)) 0.95-0.995. A model which predicted growth based on increases in cell number was constructed. No extracellular lipases were detected, but slight proteolytic reactions were observed. Although it was not possible to model protease activity, the growth model and information relating to enzyme activity will be made freely available in a database on the Internet.

Colony Count, Microbial↗

PubMed2003

Identification of intramembrane hydrogen bonding between 13(1) keto group of bacteriochlorophyll and serine residue alpha27 in the LH2 light-harvesting complex.

Intramembrane hydrogen bonding and its effect on the structural integrity of purple bacterial light-harvesting complex 2, LH2, have been assessed in the native membrane environment. A novel hydrogen bond has been identified by Raman resonance spectroscopy between a serine residue of the membrane-spanning region of LH2 alpha-subunit, and the C-13(1) keto carbonyl of bacteriochlorophyll (BChl) B850 bound to the beta-subunit. Replacement of the serine by alanine disrupts this strong hydrogen bond, but this neither alters the strongly red-shifted absorption nor the structural arrangement of the BChls, as judged from circular dichroism. It also decreases only slightly the thermal stability of the mutated LH2 in the native membrane environment. The possibility is discussed that weak H-bonding between the C-13(1) keto carbonyl and a methyl hydrogen of the alanine replacing serine(-4) or the imidazole group of the nearby histidine maintains structural integrity in this very stable bacterial light-harvesting complex. A more widespread occurrence of H-bonding to C-13(1) not only in BChl, but also in chlorophyll proteins, is indicated by a theoretical analysis of chlorophyll/polypeptide contacts at <3.5 A in the high-resolution structure of Photosystem I. Nearly half of the 96 chlorophylls have aa residues suitable as hydrogen bond donors to their keto groups.

Bacterial Proteins↗

PubMed2003

Predictive modelling of growth and enzyme production and activity by a cocktail of Pseudomonas spp., Shewanella putrefaciens and Acinetobacter sp.

The possibility was examined of developing a predictive model that combined microbial growth (increase in cellular number) with extracellular lipolytic and proteolytic enzyme activity of a cocktail of four strains of Pseudomonas spp. and one strain each of Acinetobacter sp. and Shewanella putrefaciens. Environmental conditions within the following matrix of conditions were examined: temperature 2-20 degrees C, pH value 4.0-7.5 and water activity (a(w)) 0.95-0.995 and a model was constructed, which predicted growth based on increase in cell number. Data on lipase production and protease activity were generated and will be available as a database, but no function could be identified, which was a good fit to these data, since most enzymatic production and activity occurred, as expected, during transition from exponential to stationary phase. Even at lower cell numbers, in more unfavourable conditions, hydrolysing effects were detectable, which made it difficult to construct a model combining both microbiological and enzymatic data.

Acinetobacter↗

PubMed2003

Trace analysis of technical nonylphenol, bisphenol A and 17alpha-ethinylestradiol in wastewater using solid-phase microextraction and gas chromatography-mass spectrometry.

To enable high sample throughput, an automated solid-phase microextraction (SPME) method coupled with GC-MS for the trace analysis of technical nonylphenol, bisphenol A and 17alpha-ethinylestradiol was developed. The extraction performance of different SPME fibre coatings was examined, with polyacrylate proving most suitable. Although study of the extraction time showed that the analytes have not reached equilibrium after 3 h, as a compromise an extraction time of 1 h was applied in all the experiments with detection limits between 0.04 and 1 microg l(-1) for wastewater effluent. The mean reproducibility of the technique is 8% RSD. Carry-over effects are negligible. The linearity of calibration curves ranges over three orders of magnitude. The method was tested for determining the analytes in influents and effluents of constructed wetland plants and in model wastewater used in laboratory experiments.

Benzhydryl Compounds↗

PubMed2003

[Chlamydial and human heat shock protein 60 homologues in acute coronary syndromes. (Auto-)immune reactions as a link between infection and atherosclerosis].

Recent studies provide evidence that infectious agents play a causal role in the pathogenesis of atherosclerosis. In this respect, a chronic persistent Chlamydia pneumoniae infection, indicated by the presence of chlamydial heat shock protein 60 (cHSP 60), is of central interest. Both cHSP60 and endogenous human (h) HSP60 are upregulated under stress conditions in intimal cells and serve as a target for cross-reactive cytotoxic HSP-serum-antibodies. Therefore, the present study evaluates the expressions of both HSP60 homologues in advanced human coronary lesions and a correlation between intimal tissuebound protein and serum antibodies (Ab) to HSP65. Coronary atherectomy specimens retrieved from 114 primary target lesions of patients with acute coronary syndrome (ACS; n=46) or stable angina (SA; n=68) were assessed immunohistochemically for the presence of cHSP60 and hHSP60. Chronic persistency of Chlamydia pneumoniae was additionally examined by transmission electron microscopy. Blood samples from30 patients were tested for anti-Chlamydia pneumoniae-IgG/IgA- and anti-HSP65-Ab titers and for serum CRP levels. Coronary plaques revealed immunoreactive cHSP60 in 47% and hHSP60 in 57% of the lesions colocalized within macrophages/foam cells. Chlamydia in foam cells most often presented ultrastructural patterns that pointed to the persistency of the pathogen. Intact, non-atherosclerotic vessels showed no signals. Mean expressions were 3.1% for cHSP60 and 3.3% for hHSP60. As a central finding, the expression of both HSP homologues was significantly (each p<0.001) higher in ACS lesions compared to SA lesions (cHSP60: 6.2 vs 1.0%, and hHSP60: 7.2 vs 0.7%). Moreover, we found positive correlations between both determinants in ACS and SA lesions (r=0.41, r=0.37; p<0.01). Most interestingly, cHSP60 revealed no relationship with anti-Chlamydia pneumoniae-IgG/IgA titers, whereas expression of cHSP60 as well as that of hHSP60 correlated with anti-HSP65-Ab titers (r=0.50, p<0.01, and r=0.42, p<0.05, respectively).cHSP60 and hHSP60 colocalize within coronary primary atheroma, most prevalent in lesions associated with ACS. For the first time, our data demonstrate a significant correlation between the intimal expression of these HSP60 homologues and serum HSP65 antibodies, thereby suggesting that humoral immune reactions to bacterial and human HSPs may play an important role in coronary atherosclerosis and plaque instability.

Acute Disease↗

PubMed2003

[Prevalence of intimal pathogen burden in acute coronary syndromes].

Increasing evidence supports a link between serological evidence of prior exposure to infectious pathogens, pathogen burden, and the risk for future myocardial infarction and death in patients with coronary artery disease. Based on this concept, we evaluated the intimal presence of four pathogens in human coronary atheroma, clinically associated with acute coronary syndromes (ACS) and stable angina (SA), and the effect of pathogen burden on the expression of human heatshock protein 60 (hHSP60), a key protein in (auto-)immune pathogenesis of atherosclerosis. Coronary atherectomy specimens retrieved from 53 primary target lesions of patients with ACS (n=33) or SA (n=20) were assessed immunohistochemically for the presence of Chlamydia pneumoniae (C. pn.), Helicobacter pylori (H.p.), Cytomegalovirus (CMV) and Epstein-Barr Virus (EBV), and for the expression of hHSP60. Chlamydia pneumoniae was present in 74%, Helicobacter pylori in 32%, CMV in 13% and EBV in 42%. Exclusively C.pn. revealed a prevalence in ACS (91%) vs SA (45%; p<0.001). Immunohistochemical analysis revealed 6 lesions without, 21 lesions with 1, 17 lesions with 2, 6 lesions with 3 and 3 lesions with 4 infectious agents. As an important finding, the mean value in ACS lesions was significantly increased compared to those in SA (1.9 vs 1.1; p<0.01). ACS-subgroup analysis revealed the highest mean value in patients with pain at rest within the last two days (Braunwald class III). In addition, expression of hHSP60 was significantly higher in ACS (8.7%) compared to SA (1.3%; p<0.001). Pathogen burden correlated highly significant (p<0.01) with the expression of hHSP60 (r=0.44).Our data demonstrate the impact of intimal pathogen burden in plaque instability, and suggest the presence of (auto-)immunoreactions against upregulated hHSP60 as an important pathomechanism that may contribute to acute coronary syndromes.

Acute Disease↗

PubMed2003

[The role of intravascular ultrasound examination for assessment of graft vasculopathy].

Long-run development of heart transplanted patients is predominantly determined by the occurrence of graft vasculopathy. Due to the commonly diffuse and concentrical appearance of plaque in the coronary vessels, the disease defies, at least in the early stage, the conventionally used angiographic diagnostic procedures with radiocontrast agents. With the possibility to differentiate not only the lumen but also structures of the vessel walls and different tissue types, intracoronary ultrasound (IVUS) of coronary vessels yields entirely new insights in the development, the course and the prognostic importance of graft vasculopathy. Besides the extended scientific application in order to investigate the pathophysiology of graft vasculopathy and the assessment of therapeutic strategies, regular follow-ups with IVUS are nowadays used in many centers in routine care after heart transplant.

Coronary Artery Disease↗

PubMed2002

Assembly of light-harvesting bacteriochlorophyll in a model transmembrane helix in its natural environment.

The transmembrane, bacteriochlorophyll-binding region of a bacterial light-harvesting complex, (LH2-alpha from the photosynthetic bacterium Rhodobacter sphaeroides) was redesigned and overexpressed in a mutant of Rb. sphaeroides lacking LH2. Bacteriochlorophyll served as internal probe for the fitness of this new region for the assembly and energy transfer function of the LH2 complex. The ability to absorb and transfer light energy is practically undisturbed by the exchange of the transmembrane segment, valine -7 to threonine +6, of LH2-alpha with a 14 residue Ala-Leu sequence. This stretch makes up the residues of the transmembrane helix that are in close contact (< or =4.5 A) with the bacteriochlorophyll molecules that are coordinated through His of both the alpha and beta-subunits. In this Ala-Leu stretch, neither alpha-His0, which binds the bacteriochlorophyll, nor the adjacent alpha-Ile-1, were replaced. Novel LH2 complexes composed of LH2-alpha with a model transmembrane sequence and a normal LH2-beta are assembled in vivo into a complex, the biochemical and spectroscopic properties of which closely resemble the native one. In contrast, the additional insertion of four residues just outside the C-terminal end of the model transmembrane helix leads to complete loss of functional antenna complex. The results suggest that light energy can be harvested and transferred efficiently by bacteriochlorophyll molecules attached to only few key residues distributed over the polypeptide, while residues at the bacteriochlorophyll-helix interface seem to be largely dispensable for the functional assembly of this membrane protein complex. This novel antenna with a simplified transmembrane domain and a built-in probe for assembly and function provides a powerful model system for investigation of the factors that contribute to the assembly of chromophores in membrane-embedded proteins.

Amino Acid Sequence↗

PubMed2002

[C-reactive protein in coronary plaques -- prevalence with acute coronary syndrome].

Inflammatory mechanisms are central in human atherosclerosis. Although C-reactive protein (CRP) as a serum marker is highly predictive for cardiovascular events, the intimal expression of CRP in clinically relevant coronary lesions is unknown, in particular in acute coronary syndromes (ACS). Shown by reduced CRP serum values, statins have antiinflammatory and plaque-stabilizing effects. In the present study, the presence of CRP in coronary atheromas with ACS versus stable angina (SA) as well as its possible modification by chronic statin medication was assessed. Coronary atherectomy probes from 90 primary stenoses were immunohistochemically analyzed with regard to the presence and the localization of CRP. Intimal results of patients with ACS (n=36), categorized according to the Braunwald classification, were compared with those of patients with SA (n=54). In 40 of 90 lesions (44%), immunoreaction specific for CRP was observed demonstrating a mean CRP expression of 1.7%. CRP was focally localized in a maximum of 69% of all plaque cells, the most in macrophages/foam cells, infrequently in smooth muscle cells. CRP-positive plaques showed more thrombus than plaques without CRP (63% vs 41%). Intact non-atherosclerotic control tissue revealed no signaling. As a central finding, intimal presence and expression were higher (each p<0.001) with ACS (69% and 3.1%, respectively) compared to SA (28% and 0.8%, respective). Subgroup analysis of target lesions associated with ACS according to the clinical Braunwald classification showed an increase of intimal CRP with classes I-III. In the presence of statin medication, intimal CRP was significantly lower than that without statin therapy (29 and 1.3%, vs 61 and 2.6%, respectively; p<0.01), in particular in the subgroup of ACS patients. Intimal CRP is frequently found in coronary primary stenoses, very often with macrophages/foam cells, and shows a highly significant prevalence with ACS. In this subgroup of patients, statin therapy is associated with significantly reduced intimal CRP. Our in situ findings as shown might explain the well-known serum constellations with statin therapy.

Anticholesteremic Agents↗

PubMed2001

The promoter of a lysosomal membrane transporter gene, CTNS, binds Sp-1, shares sequences with the promoter of an adjacent gene, CARKL, and causes cystinosis if mutated in a critical region.

Although >55 CTNS mutations occur in patients with the lysosomal storage disorder cystinosis, no regulatory mutations have been reported, because the promoter has not been defined. Using CAT reporter constructs of sequences 5' to the CTNS coding sequence, we identified the CTNS promoter as the region encompassing nucleotides -316 to +1 with respect to the transcription start site. This region contains an Sp-1 regulatory element (GGCGGCG) at positions -299 to -293, which binds authentic Sp-1, as shown by electrophoretic-mobility-shift assays. Three patients exhibited mutations in the CTNS promoter. One patient with nephropathic cystinosis carried a -295 G-->C substitution disrupting the Sp-1 motif, whereas two patients with ocular cystinosis displayed a -303 G-->T substitution in one case and a -303 T insertion in the other case. Each mutation drastically reduced CAT activity when inserted into a reporter construct. Moreover, each failed either to cause a mobility shift when exposed to nuclear extract or to compete with the normal oligonucleotide's mobility shift. The CTNS promoter region shares 41 nucleotides with the promoter region of an adjacent gene of unknown function, CARKL, whose start site is 501 bp from the CTNS start site. However, the patients' CTNS promoter mutations have no effect on CARKL promoter activity. These findings suggest that the CTNS promoter region should be examined in patients with cystinosis who have fewer than two coding-sequence mutations.

Adult↗

PubMed2001

Maturation of Pseudomonas aeruginosa elastase. Formation of the disulfide bonds.

Elastase of Pseudomonas aeruginosa is synthesized as a preproenzyme. After propeptide-mediated folding in the periplasm, the proenzyme is autoproteolytically processed, prior to translocation of both the mature enzyme and the propeptide across the outer membrane. The formation of the two disulfide bonds present in the mature enzyme was examined by studying the expression of the wild-type enzyme and of alanine for cysteine mutant derivatives in the authentic host and in dsb mutants of Escherichia coli. It appeared that the two disulfide bonds are formed successively. First, DsbA catalyzes the formation of the disulfide bond between Cys-270 and Cys-297 within the proenzyme. This step is essential for the subsequent autoproteolytic processing to occur. The second disulfide bond between Cys-30 and Cys-57 is formed more slowly and appears to be formed after processing of the proenzyme, and its formation is catalyzed by DsbA as well. This second disulfide bond appeared to be required for the full proteolytic activity of the enzyme and contributes to its stability.

Bacterial Proteins↗

PubMed2001

FLEXGene repository: from sequenced genomes to gene repositories for high-throughput functional biology and proteomics.

The vast amount of information generated by the human genome sequencing project and related projects has given rise to a new paradigm in experimental biology. This new paradigm invokes the experimentation and data analysis at genome-wide scales, as well as the generation of new technologies and resources that take full advantage of the available sequence information. The Institute of Proteomics at Harvard Medical School is building a comprehensive, characterized, arrayed and flexible gene repository that will allow full exploitation of the genomic information by enabling functional genomics as well as protein expression, purification and analysis at genome wide scale. The FLEXGene repository (Full Length EXpression-ready) will contain clones representing the complete set of open reading frames (ORFs) of different organisms including H. sapiens and several pathogens and model organisms. The clones are constructed using recombination-based cloning technology so that hundreds or thousands of coding regions can be transferred into any expression vector in a parallel and timely mode, allowing the broadest variety of experiments to be carried out.

Animals↗

PubMed2001

Cloning of a catalytic subunit of cAMP-dependent protein kinase from the honeybee (Apis mellifera) and its localization in the brain.

In the honeybee the cAMP-dependent signal transduction cascade has been implicated in processes underlying learning and memory. The cAMP-dependent protein kinase (PKA) is the major mediator of cAMP action. To characterize the PKA system in the honeybee brain we cloned a homologue of a PKA catalytic subunit from the honeybee. The deduced amino acid sequence shows 80-94% identity with catalytic subunits of PKA from Drosophila melanogaster, Aplysia californica and mammals. The corresponding gene is predominantly expressed in the mushroom bodies, a structure that is involved in learning and memory processes. However, expression can also be found in the antennal and optic lobes. The level of expression varies within all three neuropiles.

Amino Acid Sequence↗

PubMed2001

[Quantitative occurrence of lipolytic and proteolytic enzymes in food of animal origin].

Proteolytic and lipolytic enzymatic activities of microorganisms are the most important cause for food spoilage and a limited shelf life. Until now the determination of the total aerobic count is the base of shelf life evaluations. Our investigations show the proportion of proteolytes and lipolytes to the total germ count in different kinds of food (milk and milk products, meat products and fish) which is in part surprisingly high. Results were observed on different media--proteolytic germs were counted on protein containing agar (casein, meat protein, fish protein) and lipolytic organisms on fat containing agar (tributyrin, olive oil, butterfat). Using the predictive microbiology and the knowledge about the activity of microbial enzymes under different milieu conditions in food the results give an important tool for a better shelf life evaluation.

Animals↗

PubMed2000

Combinatorial roles for pRB, p107, and p130 in E2F-mediated cell cycle control.

Numerous studies have implicated the pRB family of nuclear proteins in the control of cell cycle progression. Although over-expression experiments have revealed that each of these proteins, pRB, p107, and p130, can induce a G(1) cell cycle arrest, mouse knockouts demonstrated distinct developmental requirements for these proteins, as well as partial functional redundancy between family members. To study the mechanism by which the closely related pRB family proteins contribute to cell cycle progression, we generated 3T3 fibroblasts derived from embryos that lack one or more of these proteins (pRB(-/-), p107(-/-), p130(-/-), pRB(-/-)/p107(-/-), pRB(-/-)/p130(-/-), and p107(-/-)/p130(-/-)). By comparing the growth and cell cycle characteristics of these cells, we have observed clear differences in the manner in which they transit through the G(1) and S phases as well as exit from the cell cycle. Deletion of Rb, or more than one of the family members, results in a shortening of G(1) and a lengthening of S phase, as well as a reduction in growth factor requirements. In addition, the individual cell lines showed differential regulation of a subset of E2F-dependent gene promoters, as well as differences in cell cycle-dependent kinase activity. Taken together, these observations suggest that the closely related pRB family proteins affect cell cycle progression through distinct biochemical mechanisms and that their coordinated action may contribute to their diverse functions in various physiological settings.

3T3 Cells↗