LVR-Klinik Köln

BACKGROUND: In advanced prostate cancer (APC), successful drug development as well as advances in imaging and molecular characterisation have resulted in multiple areas where there is lack of evidence or low level of evidence. The Advanced Prostate Cancer Consensus Conference (APCCC) 2017 addressed some of these topics. OBJECTIVE: To present the report of APCCC 2017. DESIGN, SETTING, AND PARTICIPANTS: Ten important areas of controversy in APC management were identified: high-risk localised and locally advanced prostate cancer; "oligometastatic" prostate cancer; castration-naïve and castration-resistant prostate cancer; the role of imaging in APC; osteoclast-targeted therapy; molecular characterisation of blood and tissue; genetic counselling/testing; side effects of systemic treatment(s); global access to prostate cancer drugs. A panel of 60 international prostate cancer experts developed the program and the consensus questions. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The panel voted publicly but anonymously on 150 predefined questions, which have been developed following a modified Delphi process. RESULTS AND LIMITATIONS: Voting is based on panellist opinion, and thus is not based on a standard literature review or meta-analysis. The outcomes of the voting had varying degrees of support, as reflected in the wording of this article, as well as in the detailed voting results recorded in Supplementary data. CONCLUSIONS: The presented expert voting results can be used for support in areas of management of men with APC where there is no high-level evidence, but individualised treatment decisions should as always be based on all of the data available, including disease extent and location, prior therapies regardless of type, host factors including comorbidities, as well as patient preferences, current and emerging evidence, and logistical and economic constraints. Inclusion of men with APC in clinical trials should be strongly encouraged. Importantly, APCCC 2017 again identified important areas in need of trials specifically designed to address them. PATIENT SUMMARY: The second Advanced Prostate Cancer Consensus Conference APCCC 2017 did provide a forum for discussion and debates on current treatment options for men with advanced prostate cancer. The aim of the conference is to bring the expertise of world experts to care givers around the world who see less patients with prostate cancer. The conference concluded with a discussion and voting of the expert panel on predefined consensus questions, targeting areas of primary clinical relevance. The results of these expert opinion votes are embedded in the clinical context of current treatment of men with advanced prostate cancer and provide a practical guide to clinicians to assist in the discussions with men with prostate cancer as part of a shared and multidisciplinary decision-making process.

According to the weak equivalence principle, all bodies should fall at the same rate in a gravitational field. The MICROSCOPE satellite, launched in April 2016, aims to test its validity at the 10^{-15} precision level, by measuring the force required to maintain two test masses (of titanium and platinum alloys) exactly in the same orbit. A nonvanishing result would correspond to a violation of the equivalence principle, or to the discovery of a new long-range force. Analysis of the first data gives δ(Ti,Pt)=[-1±9(stat)±9(syst)]×10^{-15} (1σ statistical uncertainty) for the titanium-platinum Eötvös parameter characterizing the relative difference in their free-fall accelerations.

Importance: Diverse models have been developed to predict psychosis in patients with clinical high-risk (CHR) states. Whether prediction can be improved by efficiently combining clinical and biological models and by broadening the risk spectrum to young patients with depressive syndromes remains unclear. Objectives: To evaluate whether psychosis transition can be predicted in patients with CHR or recent-onset depression (ROD) using multimodal machine learning that optimally integrates clinical and neurocognitive data, structural magnetic resonance imaging (sMRI), and polygenic risk scores (PRS) for schizophrenia; to assess models' geographic generalizability; to test and integrate clinicians' predictions; and to maximize clinical utility by building a sequential prognostic system. Design, Setting, and Participants: This multisite, longitudinal prognostic study performed in 7 academic early recognition services in 5 European countries followed up patients with CHR syndromes or ROD and healthy volunteers. The referred sample of 167 patients with CHR syndromes and 167 with ROD was recruited from February 1, 2014, to May 31, 2017, of whom 26 (23 with CHR syndromes and 3 with ROD) developed psychosis. Patients with 18-month follow-up (n = 246) were used for model training and leave-one-site-out cross-validation. The remaining 88 patients with nontransition served as the validation of model specificity. Three hundred thirty-four healthy volunteers provided a normative sample for prognostic signature evaluation. Three independent Swiss projects contributed a further 45 cases with psychosis transition and 600 with nontransition for the external validation of clinical-neurocognitive, sMRI-based, and combined models. Data were analyzed from January 1, 2019, to March 31, 2020. Main Outcomes and Measures: Accuracy and generalizability of prognostic systems. Results: A total of 668 individuals (334 patients and 334 controls) were included in the analysis (mean [SD] age, 25.1 [5.8] years; 354 [53.0%] female and 314 [47.0%] male). Clinicians attained a balanced accuracy of 73.2% by effectively ruling out (specificity, 84.9%) but ineffectively ruling in (sensitivity, 61.5%) psychosis transition. In contrast, algorithms showed high sensitivity (76.0%-88.0%) but low specificity (53.5%-66.8%). A cybernetic risk calculator combining all algorithmic and human components predicted psychosis with a balanced accuracy of 85.5% (sensitivity, 84.6%; specificity, 86.4%). In comparison, an optimal prognostic workflow produced a balanced accuracy of 85.9% (sensitivity, 84.6%; specificity, 87.3%) at a much lower diagnostic burden by sequentially integrating clinical-neurocognitive, expert-based, PRS-based, and sMRI-based risk estimates as needed for the given patient. Findings were supported by good external validation results. Conclusions and Relevance: These findings suggest that psychosis transition can be predicted in a broader risk spectrum by sequentially integrating algorithms' and clinicians' risk estimates. For clinical translation, the proposed workflow should undergo large-scale international validation.

In a prospective phase I/II clinical study, we treated eight patients suffering from recurrent glioblastoma multiform with stereotactically guided intratumoral convection-enhanced delivery of an HSV-1-tk gene-bearing liposomal vector and systemic ganciclovir. Noninvasive identification of target tissue together with assessment of vector-distribution volume and the effects of gene therapy were achieved using magnetic resonance imaging and positron emission tomography. The treatment was tolerated well without major side effects. In two of eight patients, we observed a greater than 50% reduction of tumor volume and in six of eight patients focal treatment effects. Intracerebral infusion of contrast medium before vector application displayed substantial inhomogeneity of tissue staining indicating the need of test infusions to monitor the mechanical distribution of vectors. Visualization of therapeutic effects on tumor metabolism and documentation of gene expression using positron emission tomography indicated that molecular imaging technology appears to be essential for the further development of biological treatment strategies.

The objective of this prospective study was to assess safety and efficacy of exercise training in a large cohort of patients with different forms and World Health Organization (WHO) functional classes of chronic pulmonary hypertension (PH). 183 patients with PH (pulmonary arterial hypertension (PAH), chronic thromboembolic PH and PH due to respiratory or left heart diseases received exercise training in hospital for 3 weeks and continued at home. Adverse events have been monitored during the in-hospital training programme. Efficacy parameters were evaluated at baseline, and after 3 and 15 weeks. After 3 and 15 weeks, patients significantly improved the distance walked in 6 min (6MWD) compared to baseline, scores of quality of life, WHO functional class, peak oxygen consumption, oxygen pulse, heart rate and systolic pulmonary artery pressure at rest and maximal workload. The improvement in 6MWD was similar in patients with different PH forms and functional classes. Even in severely affected patients (WHO functional class IV), exercise training was highly effective. Adverse events, such as respiratory infections, syncope or presyncope, occurred in 13% of patients. Exercise training in PH is an effective but not a completely harmless add-on therapy, even in severely diseased patients, and should be closely monitored.

The mechanisms by which subcritical and critical damage develops in several lamination geometries of T300/5208 and T300/914C graphite/epoxy material during tension-tension fatigue were closely examined. A damage analogue in the form of stiffness reduction was used to provide a framework by which the sequence of damage development could be correlated with mechanical response. Stiffness reduction, measured continuously during the course of cyclic loading, was shown to provide a reproducible characteristic correlation with percent of life expended. The relationship was observed to differ markedly among lamination geometries, but for a given geometry was found to clearly indicate the partition of the mechanical response into distinct regions in these characteristic curves. These regions, moreover, were shown to be predominated by particular damage mechanisms—some already discussed in the literature, others less well-recognized. Results of the observed damage development sequence for cross-ply and quasi-isotropic laminates are presented along with a preliminary association between this damage and the characteristic stiffness reduction curves for these geometries. The geometries used were characterized by distinct, predominant, early subcritical damage conditions. This secondary and subsequent damage development was examined in relation to known, predictable beginning state. Of particular emphasis in each case was the role of this developing damage state in the fracture of fibers in the 0-deg plies. Damage detection and characterization was accomplished using both nondestructive and microscopic techniques. Two techniques proved to be of considerable utility: penetrant-enhanced stereo X-ray radiography and scanning electron microscopy of coupons taken from penetrant-enhanced deplied, damaged specimens. A number of significant damage conditions, not heretofore reported, were observed: the production of interior delaminations at the 0/90-deg interfaces of [0,902]s laminates by the gradual growth of longitudinal cracks in the 0-deg plies; the existence of a dense distributed microcrack condition at all distinct interfaces of [0,90,±45]s laminates; the segregation of 0-deg fiber breaks in all laminates into zones coincidental with cracks in the adjacent plies; and, the appearance of shear fracture in 0-deg fibers associated with the passage of longitudinal splits. Mechanisms for each of these damage conditions are proposed in terms of the micromechanics of the predominant damage condition with which they are associated and the global stress state.

Background: Predicted increases in suicide were not generally observed in the early months of the COVID-19 pandemic. However, the picture may be changing and patterns might vary across demographic groups. We aimed to provide a timely, granular picture of the pandemic's impact on suicides globally. Methods: We identified suicide data from official public-sector sources for countries/areas-within-countries, searching websites and academic literature and contacting data custodians and authors as necessary. We sent our first data request on 22nd June 2021 and stopped collecting data on 31st October 2021. We used interrupted time series (ITS) analyses to model the association between the pandemic's emergence and total suicides and suicides by sex-, age- and sex-by-age in each country/area-within-country. We compared the observed and expected numbers of suicides in the pandemic's first nine and first 10-15 months and used meta-regression to explore sources of variation. Findings: We sourced data from 33 countries (24 high-income, six upper-middle-income, three lower-middle-income; 25 with whole-country data, 12 with data for area(s)-within-the-country, four with both). There was no evidence of greater-than-expected numbers of suicides in the majority of countries/areas-within-countries in any analysis; more commonly, there was evidence of lower-than-expected numbers. Certain sex, age and sex-by-age groups stood out as potentially concerning, but these were not consistent across countries/areas-within-countries. In the meta-regression, different patterns were not explained by countries' COVID-19 mortality rate, stringency of public health response, economic support level, or presence of a national suicide prevention strategy. Nor were they explained by countries' income level, although the meta-regression only included data from high-income and upper-middle-income countries, and there were suggestions from the ITS analyses that lower-middle-income countries fared less well. Interpretation: Although there are some countries/areas-within-countries where overall suicide numbers and numbers for certain sex- and age-based groups are greater-than-expected, these countries/areas-within-countries are in the minority. Any upward movement in suicide numbers in any place or group is concerning, and we need to remain alert to and respond to changes as the pandemic and its mental health and economic consequences continue. Funding: None.

Sources of atmospheric odd nitrogen and hydrogen are reviewed and their role m ozone photochemistry is discussed. A model, containing few adjustable parameters, gives good agreement with observed distributions of stratospheric and mesospheric ozone. Nitric oxide emitted by supersonic aircraft would lead to a significant reduction in the concentration of atmospheric ozone if the globally averaged source of NO should exceed 2 × 10 7 molecules cm −2 s −1 . A traffic model projected by Broderick etal. for 1990 could lead to a reduction of about 2% in the column density of O 3 .Sources of atmospheric chlorine are discussed. It is argued that HCl should be the dominant form of atmospheric chlorine and that it is produced mainly from aerosols of marine origin. The atmospheric source strength is about 2 × 10 8 tons per year according to Chesselet etal. and HCl may be removed by gas phase reaction with NH 3 . The role of chlorine compounds as a catalyst for recombination of odd oxygen is discussed and shown to play no major role in the normal atmosphere. Reactions of OH and HO 2 with O 3 may provide an important sink for tropospheric odd oxygen such that O 3 may not be a passive tracer for tropospheric motions.

Recently, doubts were raised about the existence of the bilingual advantage in cognitive control. The aim of the present review was to investigate the bilingual advantage and its modulating factors. We searched the Medline, ScienceDirect, Scopus, and ERIC databases for all original data and reviewed studies on bilingualism and cognitive control, with a cut-off date of 31 October 2018, thereby following the guidelines of the preferred reporting items for systematic reviews and meta-analysis (PRISMA) protocol. The results of the 46 original studies show that indeed, the majority, 54.3%, reported beneficial effects of bilingualism on cognitive control tasks; however, 28.3% found mixed results and 17.4% found evidence against its existence. Methodological differences seem to explain these mixed results: Particularly, the varying selection of the bilingual participants, the use of nonstandardized tests, and the fact that individual differences were often neglected and that longitudinal designs were rare. Therefore, a serious risk for bias exists in both directions (i.e., in favor of and against the bilingual advantage). To conclude, we found some evidence for a bilingual advantage in cognitive control; however, if significant progress is to be made, better study designs, bigger data, and more longitudinal studies are needed.

The MICROSCOPE mission was designed to test the weak equivalence principle (WEP), stating the equality between the inertial and the gravitational masses, with a precision of 10^{-15} in terms of the Eötvös ratio η. Its experimental test consisted of comparing the accelerations undergone by two collocated test masses of different compositions as they orbited the Earth, by measuring the electrostatic forces required to keep them in equilibrium. This was done with ultrasensitive differential electrostatic accelerometers onboard a drag-free satellite. The mission lasted two and a half years, cumulating five months worth of science free-fall data, two-thirds with a pair of test masses of different compositions-titanium and platinum alloys-and the last third with a reference pair of test masses of the same composition-platinum. We summarize the data analysis, with an emphasis on the characterization of the systematic uncertainties due to thermal instabilities and on the correction of short-lived events which could mimic a WEP violation signal. We found no violation of the WEP, with the Eötvös parameter of the titanium and platinum pair constrained to η(Ti,Pt)=[-1.5±2.3(stat)±1.5(syst)]×10^{-15} at 1σ in statistical errors.

Butterflies are a diverse and charismatic insect group that are thought to have evolved with plants and dispersed throughout the world in response to key geological events. However, these hypotheses have not been extensively tested because a comprehensive phylogenetic framework and datasets for butterfly larval hosts and global distributions are lacking. We sequenced 391 genes from nearly 2,300 butterfly species, sampled from 90 countries and 28 specimen collections, to reconstruct a new phylogenomic tree of butterflies representing 92% of all genera. Our phylogeny has strong support for nearly all nodes and demonstrates that at least 36 butterfly tribes require reclassification. Divergence time analyses imply an origin ~100 million years ago for butterflies and indicate that all but one family were present before the K/Pg extinction event. We aggregated larval host datasets and global distribution records and found that butterflies are likely to have first fed on Fabaceae and originated in what is now the Americas. Soon after the Cretaceous Thermal Maximum, butterflies crossed Beringia and diversified in the Palaeotropics. Our results also reveal that most butterfly species are specialists that feed on only one larval host plant family. However, generalist butterflies that consume two or more plant families usually feed on closely related plants.

Biogenesis of mitochondria is happening constantly due to the physiological and developmental situation of a cell. As mitochondrial biogenesis is a complex process producing about 20 % of cellular protein, the expression of the 1000 genes involved is expected to be coordinated and regulated tightly. The variety of physiological stimuli and differentiation states lead to the idea of a complex network connecting many different regulatory pathways. By analysing nuclear encoded mitochondrial genes some of the factors involved in the regulation and coordination of mitochondrial gene expression were identified. These factors include general transcription factors such as Sp1 or YY1, as well as transcription factors specific for mitochondrial genes like the nuclear respiratory factors NRF1 and 2. An important control function linked to the physiological situation of a cell is triggered by hormones such as steroid and thyroid hormones. Even cell type-specific regulatory proteins like the myogenin transcription factor family have a strong influence on some mitochondrial genes in the specific cellular background. The regulatory function of most of these proteins can be modulated and enhanced by the coactivators PGC-1a and b and PRC. Although regulatory pathways have been characterized in more detail in recent years, no regulation mechanism has been shown to work on all analysed mitochondrial genes, and the general concept of mitochondrial regulation still remains unclear.

During hypertrophy, proliferation of mitochondria does not keep pace with the increasing energy demand of the heart. This probably contributes importantly to cardiac failure, together with other phenotypic changes occurring during the growth process. The problem may be even aggravated if defects of mitochondrial function itself and not external factors cause the hypertrophic process. Here we review the basic mechanisms controlling mitochondrial biogenesis, especially the pathways coordinating expression of nuclear encoded mitochondrial genes and the small mitochondrial genome, and how these mechanisms may be connected to the cardiomyocyte differentiation program during development as well as under physiological and pathological circumstances.

BACKGROUND AND OBJECTIVES: New potential prognostic indicators aside from the TNM classification have been proposed. The aim of this study was to analyze the prognostic relevance of tumor length as well as number of involved regional lymph nodes (LNM) in patients with esophageal carcinoma. METHODS: Two hundred thirteen patients with esophageal carcinoma (116 squamous cell- and 97 adenocarcinoma) were included in this study. Treatment of choice was subtotal en bloc esophagectomy including "2-field" lymphadenectomy. The median number of examined lymph nodes (LNs) was 28. Eighty patients (38%) received preoperative radio-chemotherapy according to a standardized protocol. Histopathology consisted of tumor stage, residual tumor, grading, and number of examined and involved LN. Univariate and multivariate prognostic values were calculated. RESULTS: Length of tumor correlated with pT/ypT-category (P<0.01). Univariate but not multivariate analysis showed better survival for tumors<or=3 cm (P<0.05). Patients with 1-5 LNM had significantly better prognoses than those with more than 5 LNM (Hazard ratio 2.7, 95% CI=1.7-4.2) (P<0.01). Patients without LNM and more than 15 examined LN showed significantly better prognosis than those with fewer examined LN (Hazard ratio=0.3, 95% CI=0.1-0.6) (P<0.01). CONCLUSIONS: A revision of the TNM classification for esophageal carcinoma should subdivide the pN1-category according to the number of LNM.

As part of a project to study different methods for the disinfection of effluent water, the inactivation of different microorganisms (Escherichia coli, Deinococcus radiodurans and spores of Bacillus subtilis) using a combination of a photosensitizer (Rose Bengal) with simulated sunlight and oxygen was determined under various environmental conditions (temperature, pH index). In parallel, the singlet-oxygen (1O2) production was also measured under the same conditions. Whereas the vegetative cells could be inactivated much more efficiently at increased temperature and altered index of pH, the production of 1O2 remained essentially the same under these alterations. Additionally, the relations among the sensitivities of different cell types to be killed by our photodynamic treatments (PDT) were opposite to those found after exposure to ionizing radiation. The results of photodynamic experiments do not reflect the cells' capacity to repair DNA strand breaks. Spores of B. subtilis, as a nonvegetative system, could not be inactivated by illuminations up to 100 J cm-2. Together, these findings indicate that DNA is not the primary target, the inactivation of which leads to the killing of our test organisms. Instead, the cellular envelope appears to be the component being assaulted by our PDT.

The Microscopic Imager on the Opportunity rover analyzed textures of soils and rocks at Meridiani Planum at a scale of 31 micrometers per pixel. The uppermost millimeter of some soils is weakly cemented, whereas other soils show little evidence of cohesion. Rock outcrops are laminated on a millimeter scale; image mosaics of cross-stratification suggest that some sediments were deposited by flowing water. Vugs in some outcrop faces are probably molds formed by dissolution of relatively soluble minerals during diagenesis. Microscopic images support the hypothesis that hematite-rich spherules observed in outcrops and soils also formed diagenetically as concretions.

The basic concept of virosomes is the controlled in vitro assembly of virus-like particles from purified components. The first generation of influenza virosomes developed two decades ago is successfully applied in licensed vaccines, providing a solid clinical safety and efficacy track record for the technology. In the meantime, a second generation of influenza virosomes has evolved as a carrier and adjuvant system, which is currently applied in preclinical and clinical stage vaccine candidates targeting various prophylactic and therapeutic indications. The inclusion of additional components to optimize particle assembly, to stabilize the formulations, or to enhance the immunostimulatory properties have further improved and broadened the applicability of the platform.

Mouse nongenotoxic hepatocarcinogens phenobarbital (PB) and chlordane induce hepatomegaly characterized by hypertrophy and hyperplasia. Increased cell proliferation is implicated in the mechanism of tumor induction. The relevance of these tumors to human health is unclear. The xenoreceptors, constitutive androstane receptors (CARs), and pregnane X receptor (PXR) play key roles in these processes. Novel "humanized" and knockout models for both receptors were developed to investigate potential species differences in hepatomegaly. The effects of PB (80 mg/kg/4 days) and chlordane (10 mg/kg/4 days) were investigated in double humanized PXR and CAR (huPXR/huCAR), double knockout PXR and CAR (PXRKO/CARKO), and wild-type (WT) C57BL/6J mice. In WT mice, both compounds caused increased liver weight, hepatocellular hypertrophy, and cell proliferation. Both compounds caused alterations to a number of cell cycle genes consistent with induction of cell proliferation in WT mice. However, these gene expression changes did not occur in PXRKO/CARKO or huPXR/huCAR mice. Liver hypertrophy without hyperplasia was demonstrated in the huPXR/huCAR animals in response to both compounds. Induction of the CAR and PXR target genes, Cyp2b10 and Cyp3a11, was observed in both WT and huPXR/huCAR mouse lines following treatment with PB or chlordane. In the PXRKO/CARKO mice, neither liver growth nor induction of Cyp2b10 and Cyp3a11 was seen following PB or chlordane treatment, indicating that these effects are CAR/PXR dependent. These data suggest that the human receptors are able to support the chemically induced hypertrophic responses but not the hyperplastic (cell proliferation) responses. At this time, we cannot be certain that hCAR and hPXR when expressed in the mouse can function exactly as the genes do when they are expressed in human cells. However, all parameters investigated to date suggest that much of their functionality is maintained.

Background: Mitral valve-in-valve (ViV) and valve-in-ring (ViR) are alternatives to surgical reoperation in patients with recurrent mitral valve failure after previous surgical valve repair or replacement. Our aim was to perform a large-scale analysis examining midterm outcomes after mitral ViV and ViR. Methods: Patients undergoing mitral ViV and ViR were enrolled in the Valve-in-Valve International Data Registry. Cases were performed between March 2006 and March 2020. Clinical endpoints are reported according to the Mitral Valve Academic Research Consortium (MVARC) definitions. Significant residual mitral stenosis (MS) was defined as mean gradient ≥10 mm Hg and significant residual mitral regurgitation (MR) as ≥ moderate. Results: A total of 1079 patients (857 ViV, 222 ViR; mean age 73.5±12.5 years; 40.8% male) from 90 centers were included. Median STS-PROM score 8.6%; median clinical follow-up 492 days (interquartile range, 76–996); median echocardiographic follow-up for patients that survived 1 year was 772.5 days (interquartile range, 510–1211.75). Four-year Kaplan-Meier survival rate was 62.5% in ViV versus 49.5% for ViR ( P &lt;0.001). Mean gradient across the mitral valve postprocedure was 5.7±2.8 mm Hg (≥5 mm Hg; 61.4% of patients). Significant residual MS occurred in 8.2% of the ViV and 12.0% of the ViR patients ( P =0.09). Significant residual MR was more common in ViR patients (16.6% versus 3.1%; P &lt;0.001) and was associated with lower survival at 4 years (35.1% versus 61.6%; P =0.02). The rates of Mitral Valve Academic Research Consortium–defined device success were low for both procedures (39.4% total; 32.0% ViR versus 41.3% ViV; P =0.01), mostly related to having postprocedural mean gradient ≥5 mm Hg. Correlates for residual MS were smaller true internal diameter, younger age, and larger body mass index. The only correlate for residual MR was ViR. Significant residual MS (subhazard ratio, 4.67; 95% CI, 1.74–12.56; P =0.002) and significant residual MR (subhazard ratio, 7.88; 95% CI, 2.88–21.53; P &lt;0.001) were both independently associated with repeat mitral valve replacement. Conclusions: Significant residual MS and/or MR were not infrequent after mitral ViV and ViR procedures and were both associated with a need for repeat valve replacement. Strategies to improve postprocedural hemodynamics in mitral ViV and ViR should be further explored.

Mitochondrial transcription factor A (TFAM) stimulates transcription from mitochondrial DNA (mtDNA) promoters in vitro and in organello. To investigate whether changes of TFAM levels also modulate transcription and replication in situ, the protein was transiently overexpressed in cultured cells. Mitochondrial mRNAs were significantly elevated at early time points, when no expansion of the TFAM pool was yet observed, but were decreased when TFAM levels had doubled, resemb-ling in vitro results. HEK cells contain about 35 molecules of TFAM per mtDNA. High levels of TFAM were not associated with increases of full-length mtDNA, but nucleic acid species sensitive to RNAse H increased. Stimulation of transcription was more evident when TFAM was transiently overexpressed in cells pre-treated with ethidium bromide (EBr) having lowered mtDNA, TFAM and mitochondrial transcript levels. EBr rapidly inhibited mtDNA transcription, while decay of mtDNA was delayed and preferentially slowly migrating, relaxed mtDNA species were depleted. In conclusion, we show that transcription of mtDNA is submaximal in cultured cells and that a subtle increase of TFAM within the matrix is sufficient to stimulate mitochondrial transcription. Thus, this protein meets all criteria for being a key factor regulating mitochondrial transcription in vivo, but other factors are necessary for increasing mtDNA copy number, at least in cultured cells.