[Business intelligence in radiology. Challenges and opportunities]

Due to economic pressures and need for higher transparency, a ubiquitous availability of administrative information is needed. Therefore radiology managers should consider implementing business intelligence (BI) solutions. BI is defined as a systemic approach to support decision-making in business administration. It is an important part of the overall strategy of an organization. Implementation and operation is initially associated with costs and for a successful launch important prerequisites must be fulfilled. First, a suitable product must be selected, followed by the technical and organizational implementation. After consideration of the type of data to be collected and a system of key performance indicators must be established. BI replaces classic retrospective business reporting with multidimensional and multifactorial analyses, real-time monitoring, and predictive analyses. The benefits of BI include the rapid availability of important information and the depth of possible data analysis. The simple and intuitive use of modern BI applications by the users themselves (!) combined with a continuous availability of information is the key to success. Professional BI will be an important part of management in radiology in the future.

Effects of plasmid DNA injection on cyclophosphamide-accelerated diabetes in NOD mice

Type 1 diabetes results in most cases from the destruction of insulin-secreting beta cells by the immune system. Several immunization methods based on administration of autoantigenic polypeptides such as insulin and glutamic acid decarboxylase (GAD) have been used to prevent autoimmune diabetes in the non-obese diabetic (NOD) mouse. In the work presented here, a gene-based approach was taken for a similar purpose. A plasmid carrying different cDNAs was used to investigate the effects of injecting naked DNA on cyclophosphamide-accelerated diabetes in female NOD mice. Four-week-old animals received intramuscular injections of plasmid DNA encoding either intracellular GAD, a secreted form of GAD, or a secreted form of a soft coral luciferase. Monitoring of glycosuria and hyperglycemia indicated that injection of plasmid DNA encoding secreted GAD and secreted luciferase could prevent and delay diabetes, respectively. In contrast, injection of DNA encoding intracellular GAD did not suppress the disease significantly. Analysis of anti-GAD IgG(1) antibody titers in animal sera indicated that diabetes prevention after injection of GAD-encoding DNA was possibly associated with increased Th2-type activity. These results suggest that cellular localization of GAD is a factor to consider in the design of GAD-based genetic vaccines for the prevention of autoimmune diabetes.

Visualizing and quantifying protein secretion using a Renilla luciferase-GFP fusion protein

We have shown previously that an engineered form of Renilla luciferase (SRUC) can be secreted as a functional enzyme by mammalian cells, and that fusing wild-type Renilla luciferase with the green fluorescent protein from Aequorea victoria (GFP) yields a chimeric protein retaining light-emission properties similar to that of unfused Renilla luciferase and GFP. In the work presented here, SRUC was fused with GFP to determine whether it could be used to both visualize and quantify protein secretion in mammalian cells. Simian COS-7 and Chinese hamster ovary (CHO) cells were transiently transfected with gene constructs encoding a secreted or an intracellular version of a Renilla luciferase-GFP fusion protein. Renilla luciferase activity was measured from COS-7 cell lysates and culture media, and GFP activity was detected in CHO cells using fluorescence microscopy. Data indicated that the SRUC-GFP fusion protein was secreted as a chimeric protein that had both Renilla luciferase and GFP activity. This fusion protein could be a useful marker for the study of protein secretion in mammalian cells.

Improved assay sensitivity of an engineered secreted Renilla luciferase

We have previously reported the construction of a functional Renilla luciferase enzyme secreted by mammalian cells when fused to the signal peptide of human interleukin-2. The presence of three predicted cysteine residues in the amino acid sequence of Renilla luciferase suggested that its secreted form could contain oxidized sulfhydryls, which might impair enzyme activity. In this work, four secreted Renilla luciferase mutants were constructed to investigate this possibility: three luciferase mutants in which a different cysteine residue was replaced by an alanine residue, and one luciferase mutant in which all three cysteine residues were replaced by alanine residues. Simian cells were transfected with the genes encoding these mutant luciferases, as well as with the original gene construct, and cell culture media were assayed for bioluminescence activity. Only media containing a mutated luciferase with a cysteine to alanine substitution at position 152 in the preprotein showed a marked increase in bioluminescence activity when compared to media containing the original secreted Renilla luciferase. This increase in light emission was due in part to enhanced stability of the mutant enzyme. This new enzyme represents a significant improvement in the sensitivity of the secreted Renilla luciferase assay for monitoring gene expression.

Secretion of functional Renilla reniformis luciferase by mammalian cells

The soft coral Renilla reniformis luciferase enzyme is a monomeric soluble intracellular protein that is used increasingly as a marker of gene expression. Here the Renilla luciferase gene was engineered to encode a protein product secreted by mammalian cells. The 5' end of the Renilla luciferase gene was fused in frame with the 3' end of a short DNA sequence encoding the signal peptide from human interleukin-2 (IL-2) protein. This construct was cloned under transcriptional control of the cytomegalovirus (CMV) promoter in a mammalian expression vector. Simian COS-7 cells were transiently transfected with the construct, and light emission was measured from cell lysates and from cell culture media. The results of these experiments indicated that Renilla luciferase was secreted as a functional enzyme by mammalian cells. The advantages and disadvantages of secreted Renilla luciferase as a marker of gene expression in comparison to other secreted protein markers are discussed.

Luciferase assembly after transport into mammalian microsomes involves molecular chaperones and peptidyl-prolyl cis/trans-isomerases

The assembly of a heterodimeric luciferase was studied after de novo synthesis of corresponding precursor proteins in reticulocyte lysate and concomitant transport into dog pancreas microsomes. This cytosolic luciferase from a prokaryotic organism (Vibrio harveyi) was specifically used as a model protein to investigate (i) whether the eukaryotic cytosol and the microsomal lumen have similar folding capabilities and (ii) whether the requirements of a polypeptide for certain molecular chaperones and folding catalysts are determined by the polypeptide or the intracellular compartment. The two luciferase subunits were fused to the preprolactin signal peptide. Data indicate that efficient assembly of luciferase occurs in the mammalian microsomes. Furthermore, it was observed that luciferase assembly can be separated in time from synthesis and membrane transport, depends on ATP hydrolysis, is partially sensitive to cyclosporin A and FK506, and in the absence of lumenal proteins is less efficient as compared with the presence of lumenal proteins. Thus, heterodimeric luciferase depends on functionally related molecular chaperones and folding catalysts during its assembly in either the eukaryotic cytosol or the microsomal lumen.

Enzyme assembly after de novo synthesis in rabbit reticulocyte lysate involves molecular chaperones and immunophilins

The folding kinetics of two luciferases were studied after synthesis in reticulocyte lysates to investigate whether molecular chaperones and/or folding catalysts are involved in the folding reactions. Two bacterial luciferases were used as model proteins: heterodimeric Vibrio harveyi luciferase (LuxAB), and a monomeric luciferase fusion protein (Fab2). Data indicate that folding of these enzymes to the native state occurs in the translation system, and that the extent of folding can be quantified. It was found that (i) folding of LuxAB and Fab2 can clearly be separated in time from synthesis, (ii) folding of Fab2 and LuxAB is slow because it involves either transient (Fab2) or permanent (LuxAB) interaction of polypeptides, (iii) preservation of the assembly competent state of LuxA and/or LuxB and folding of Fab2 depend on ATP-hydrolysis, (iv) folding of Fab2 and LuxAB is partially sensitive to cyclosporin A (CsA) and FK506, i.e. inhibitors of two distinct peptidylprolyl cis/trans-isomerases. Thus, bacterial luciferases provide a unique system for direct measurement of the effects of ATP-dependent molecular chaperones on protein folding and enzyme assembly in reticulocyte lysates. Furthermore, these two luciferases provide the first direct evidence documenting the involvement of peptidylprolyl cis/trans-isomerases in protein biogenesis in a eukaryotic cytosol.

Low-light image analysis of transgenic organisms using bacterial luciferase as a marker

Methods for measurement of a novel light-emitting reporter gene system in bacteria, yeast, plant cells, plant tissues and intact plant organs are described. The principle underlying the assay procedures is the bacterial luciferase catalysed oxidation of reduced flavin mononucleotide (FMNH2) in the presence of the ten carbon aldehyde decanal, to yield FMN, decanoic acid, water and a photon of light at 490 nm which can be captured by X-ray film, a photomultiplier tube or, for in vivo measurements, an image-intensifier coupled to a video camera. This light measuring assay system is sensitive, easy to use, inexpensive, does not require radioactivity, and has been used successfully for rapid detection of bacterial transformants, the quantitative measurement of transient and stable gene expression in bacteria and yeast, and in vivo measurement of temporal and spatial gene expression throughout plant and animal development.

GroE-mediated folding of bacterial luciferases in vivo

In this study we present evidence indicating that GroE chaperonins mediate de novo protein folding of heterodimeric and monomeric luciferases under heat shock or sub-heat shock conditions in vivo. The effects of additional groESL and groEL genes on the bioluminescence of Escherichia coli cells expressing different bacterial luciferase genes at various temperatures were directly studied in cells growing in liquid culture. Data indicate that at 42 degrees C GroESL chaperonins are required for the folding of the beta subunit polypeptide of the heterodimeric alpha beta luciferase from the mesophilic bacterium Vibrio harveyi MAV (B392). In contrast, the small number of amino acid substitutions present in the luciferase beta subunit polypeptide from the thermotolerant V. harveyi CTP5 suppresses this requirement for GroE chaperonins, and greatly reduces interaction between the beta subunit polypeptide and GroEL chaperonin. In addition, GroESL are required for the de novo folding at 37 degrees C of a MAV alpha beta luciferase fusion polypeptide that is functional as a monomer. No such requirement for luciferase activity is observed at that temperature with a fusion of the CTP5 alpha and beta subunit polypeptides, although GroE chaperonins can still mediate folding of the CTP5 fusion luciferase. Bacterial luciferases provide a unique system for direct observation of the effects of GroE chaperonins on protein folding and enzyme assembly in living cells. Furthermore, they offer a sensitive and simple assay system for the identification of polypeptide domains required for GroEL protein binding.

The beta subunit polypeptide of Vibrio harveyi luciferase determines light emission at 42 degrees C

The nucleotide sequence of the luxA and luxB genes encoding the alpha beta heterodimeric luciferase from thermotolerant Vibrio harveyi CTP5 was determined. The DNA sequence of the CTP5 luxA and luxB genes is identical to the DNA sequence of the luxA and luxB genes from mesophilic V. harveyi MAV (B 392), with minor exceptions. The sequence differences result in 5 amino acid substitutions in the alpha subunit polypeptide and 7 amino acid substitutions in the beta subunit polypeptide. Escherichia coli cells grown on solid medium and expressing CTP5 or MAV luxAB genes emit similar amounts of light at 37 degrees C, while at 42 degrees C cells containing CTP5 luxAB genes show more than tenfold increased bioluminescence compared to cells with MAV luxAB genes. When grown in liquid medium E. coli cells with CTP5 or MAV luxAB genes emit equivalent amounts of light at 37 degrees C; however, in liquid medium at 42 degrees C cells containing CTP5 luxAB genes show only three times higher bioluminescence than cells with MAV luxAB genes. Expression of T7 promoter-linked hybrid luxAB transcriptional units luxACTP5-luxBMAV and luxAMAV-luxBCTP5 in E. coli reveals that (i) the MAV luxB gene product is responsible for the decreased activity of MAV luciferase at 42 degrees C; (ii) the CTP5 luxB gene encodes the information required for most of the increased activity of CTP5 luciferase relative to MAV luciferase at 42 degrees C; and (iii) E. coli cells containing MAV luxB gene show an increase in bioluminescence when grown in liquid medium at 42 degrees C, which coincides with elevated GroEL chaperonin levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Engineering of monomeric bacterial luciferases by fusion of luxA and luxB genes in Vibrio harveyi

Luciferase (Lux)-encoding sequences are very useful as reporter genes. However, a drawback when applying Vibrio harveyi Lux as a reporter enzyme in eukaryotic cells, is that it is a heterodimeric enzyme, thus requiring simultaneous synthesis of both Lux subunits to be active. To overcome this disadvantage, luxA and luxB genes encoding the A and B subunits of this light-emitting heterodimeric Lux, were fused and expressed in Escherichia coli. Comparative analysis of four fused monomeric Lux enzymes by in vivo enzyme assay, immunoblotting and partial enzyme purification, showed that the fused Lux were active both as AB or as BA monomers, albeit at different levels (up to 80% activity for AB and up to 2% for BA, as compared with the wild type binary A + B construct). One of the LuxAB fusion proteins was stably expressed in calli of Nicotiana tabacum, and displayed very high Lux activity, thus demonstrating its potential as a reporter enzyme in eukaryotic systems.

Bacterial luciferase alpha beta fusion protein is fully active as a monomer and highly sensitive in vivo to elevated temperature

A 2.2-kilobase-pair (kbp) DNA fragment from Vibrio harveyi contains the luxA and luxB genes separated by a 26-base-pair (bp) intergenic region. The two genes were converted to a single open reading frame by site-specific mutagenesis. A full-length fusion protein is obtained when the new gene is placed under transcriptional control of a T7 promoter in Escherichia coli. Bioluminescence of colonies containing the gene fusion is 0.002% of the wild-type luciferase [alkanal monooxygenase (FMN-linked); alkanal, reduced-FMN:oxygen oxidoreductase (1-hydroxylating, luminescing), EC 1.14.14.3] at 37 degrees C. Growth at 23 degrees C results in a greater than 50,000-fold increase in light emission in cells containing fusion protein, whereas only a 3-fold increase in observed with cells containing the luxAB dicistron. Purified fusion protein isolated from E. coli grown at 19 degrees C exists in both monomeric and dimeric forms with specific bioluminescence activities comparable to the heterodimeric wild-type enzyme at 23 degrees C and 37 degrees C. These findings show that the alpha beta fusion polypeptide is functional as a monomer and suggest that its folding is drastically affected at elevated temperature. We hypothesize that the two-subunit bacterial luciferase may have evolved from a monomer as a result of a temperature increase in the environment.

[Clinical aspects and pathology of chondromatous tumors of the larynx]

Two cases of chondroma of the larynx are presented: After the first laryngofissure and excision both tumours recurred so that several operations became necessary. A transformation from chondroma to chondrosarcoma was observed based on repeated histological examinations. In the first patient pulmonary metastases and a recurrence at the tracheostomy appeared 11 years after presentation and 41/2 years after laryngectomy. In the other female patient no obvious signs of the neoplasm are present 9 years after presentation, and 4 months after the last operation for recurrence, but the prognosis remains undetermined. 101 cases of chondrosarcoma from the literature plus our 2 observations are listed and compared with 130 chondrosarcomas of the skeleton. Contrary to previous opinions, we conclude that chondrosarcoma of the larynx behaves in the same malignant manner as those of the skeleton. Some develop metastases quickly, others only after years and after at least one operation for recurrence. We could demonstrate that a detailed histological examination allows the prognosis to be assessed. Additional risk factors were also investigated. These two cases enable a better and more reliable judgement to be made of the prospective biological behaviour of chondromatous tumours of the larynx and at an earlier period of time of the process.