Design of percutaneous transluminal coronary angioplasty balloon catheters.

BACKGROUND: Eight commercially available percutaneous transluminal coronary angioplasty (PTCA), including semi-compliant and non-compliant balloons, have been assessed in detail on their tip, balloon, shaft, RX-Port, and hypotube design. Important performance characteristics such as tip deformation, balloon elongation, and deflation rate have been quantified. METHODS: Five catheters of each model were evaluated during various tests. The robustness of the tips was evaluated through compression, measuring any occurrence of damage. The longitudinal growth of the balloons was recorded during inflation up to Rated Burst Pressure (RBP). The forces required to move the catheter forward and retract it into the guide catheter were measured in a simulated use test setup. The deflation behavior was studied by measuring extracted contrast media over time. Furthermore, balloon compliance and catheter dimensions were investigated. RESULTS: The outer dimensions of the catheter were found to be smallest at the hypotube (0.59-0.69 mm) and highest at the balloon, respectively, the crossing profile (0.9-1.2 mm). The tip diameter increased after compression by 1.7-22%. Cross-sections of the folded balloons revealed a tri- and two-fold, respectively. The measured balloon elongation ranged from 0.6 to 2.0 mm. After the inflation of the balloon, an increase in friction between the guide wire and the catheter was observed on four catheters. A maximum increase of 0.12 N to 1.07 N was found. Cross-sections of the RX-Port revealed a semicircular-shaped inflation lumen and a circular guide wire lumen. The measured deflation rate ranged from 0.004 to 0.013 µL/s, resulting in an estimated balloon deflation time of 10.2-28.1 s. CONCLUSION: This study provides valuable insights into the design characteristics of RX PTCA balloon catheters, which can contribute to facilitating the development of improved catheter designs and enhancing clinical outcomes. Distinctions between SC and NC catheters, such as balloon performance and dimensions, are evident. It is important to note that no single catheter excels in all aspects, as each possesses unique strengths. Therefore, it is essential to consider individual intervention requirements when selecting a catheter. The research also identifies specific catheter weaknesses, such as reduced wall thickness, fringes at the tip, and reduced performance characteristics.

Transcriptomic analysis of the mouse retina after acute and chronic normobaric and hypobaric hypoxia.

Oxygen delivery to the retinal pigment epithelium and the outer retina is essential for metabolism, function, and survival of photoreceptors. Chronically reduced oxygen supply leads to retinal pathologies in patients and causes age-dependent retinal degeneration in mice. Hypoxia can result from decreased levels of inspired oxygen (normobaric hypoxia) or reduced barometric pressure (hypobaric hypoxia). Since the response of retinal cells to chronic normobaric or hypobaric hypoxia is mostly unknown, we examined the effect of six hypoxic conditions on the retinal transcriptome and photoreceptor morphology. Mice were exposed to short- and long-term normobaric hypoxia at 400 m or hypobaric hypoxia at 3450 m above sea level. Longitudinal studies over 11 weeks in normobaric hypoxia revealed four classes of genes that adapted differentially to the hypoxic condition. Seventeen genes were specifically regulated in hypobaric hypoxia and may affect the structural integrity of the retina, resulting in the shortening of photoreceptor segment length detected in various hypoxic groups. This study shows that retinal cells have the capacity to adapt to long-term hypoxia and that consequences of hypobaric hypoxia differ from those of normobaric hypoxia. Our datasets can be used as references to validate and compare retinal disease models associated with hypoxia.

[Linguistic Validation of the "German Lung Fibrosis Health Related Quality of Life Questionnaire"]. / Sprachliche Validierung des Fibrose-Fragebogens zur Erfassung der Lebensqualität bei Patienten mit idiopathischer Lungenfibrose und idiopathischer nichtspezifischer interstitieller Pneumonie.

Health status and quality of life are impaired in patients with idiopathic pulmonary fibrosis (IPF) and idiopathic non-specific interstitial fibrosis (iNSIP). In Germany exists only the K-BILD questionnaire for patients with ILD 1 in a professional translation by Kreuter et al. 2 This questionnaire focuses on the main problems in patients with progressive lung fibrosis in a limited manner. Therefore a new quality of life questionnaire for patients with idiopathic pulmonary fibrosis was developed and linguistically validated. METHODS: The linguistic validation of our questionnaire was carried out in a multistage process in collaboration with the developer of the questionnaire and bilingual, professional translators. Review by the developers and back translations as well as clinical assessment by IPF- and iNSIP-patients ensured that the translated questionnaire reflected the intention of the original English version of our questionnaire.Cross-validation was carried out with the St. Georges Respiratory Questionnaire (SGRQ). RESULTS: The new questionnaire concerning the health status was composed in English and German language. The questions cover five scales (sensitivity, selectivity and symptoms like breathlessness and cough and a visual analog scale on general health status) with 23 items. CONCLUSIONS: The results show that the FFB maps the special needs of the patients with IPF and iNSIP well and can support clinical and scientific questions and can be helpful in monitoring the clinical course.

Artificial intelligence solution to classify pulmonary nodules on CT.

PURPOSE: The purpose of this study was to create an algorithm to detect and classify pulmonary nodules in two categories based on their volume greater than 100 mm3 or not, using machine learning and deep learning techniques. MATERIALS AND METHOD: The dataset used to train the model was provided by the organization team of the SFR (French Radiological Society) Data Challenge 2019. An asynchronous and parallel 3-stages pipeline was developed to process all the data (a data "pre-processing" stage; a "nodule detection" stage; a "classifier" stage). Lung segmentation was achieved using 3D U-NET algorithm; nodule detection was done using 3D Retina-UNET and classifier stage with a support vector machine algorithm on selected features. Performances were assessed using area under receiver operating characteristics curve (AUROC). RESULTS: The pipeline showed good performance for pathological nodule detection and patient diagnosis. With the preparation dataset, an AUROC of 0.9058 (95% confidence interval [CI]: 0.8746-0.9362) was obtained, 87% yielding accuracy (95% CI: 84.83%-91.03%) for the "nodule detection" stage, corresponding to 86% specificity (95% CI: 82%-92%) and 89% sensitivity (95% CI: 84.83%-91.03%). CONCLUSION: A fully functional pipeline using 3D U-NET, 3D Retina-UNET and classifier stage with a support vector machine algorithm was developed, resulting in high capabilities for pulmonary nodule classification.

[German Guideline for Idiopathic Pulmonary Fibrosis]. / S2K-Leitlinie zur Diagnostik der idiopathischen Lungenfibrose.

Idiopathic pulmonary fibrosis (IPF) is a severe and often fatal disease. Diagnosis of IPF requires considerable expertise and experience. Since publication of the international IPF guideline in the year 2011 and Update 2018 several studies and technical advances occurred, which made a new assessment of the diagnostic process mandatory. In view of the antifibrotic drugs which have been approved for the treatment of IPF patients, the goal of this guideline is to foster early, confident and effective diagnosis of IPF. The guideline focusses on the typical clinical setting of an IPF patient and provides tools to exclude known causes of interstitial lung disease including standardised questionnaires, serologic testing and cellular analysis of bronchoalveolar lavage. High resolution computed tomography remains crucial in the diagnostic work-up. If it is necessary to obtain specimen for histology transbronchial lung cryobiopsy is the primary approach, while surgical lung biopsy is reserved for patients who are fit for it and in whom bronchoscopic diagnosis did not provide the information needed. Despite considerable progress, IPF remains a diagnosis of exclusion and multidisciplinary discussion remains the golden standard of diagnosis.

Three artificial intelligence data challenges based on CT and MRI.

PURPOSE: The second edition of the artificial intelligence (AI) data challenge was organized by the French Society of Radiology with the aim to: (i), work on relevant public health issues; (ii), build large, multicentre, high quality databases; and (iii), include three-dimensional (3D) information and prognostic questions. MATERIALS AND METHODS: Relevant clinical questions were proposed by French subspecialty colleges of radiology. Their feasibility was assessed by experts in the field of AI. A dedicated platform was set up for inclusion centers to safely upload their anonymized examinations in compliance with general data protection regulation. The quality of the database was checked by experts weekly with annotations performed by radiologists. Multidisciplinary teams competed between September 11th and October 13th 2019. RESULTS: Three questions were selected using different imaging and evaluation modalities, including: pulmonary nodule detection and classification from 3D computed tomography (CT), prediction of expanded disability status scale in multiple sclerosis using 3D magnetic resonance imaging (MRI) and segmentation of muscular surface for sarcopenia estimation from two-dimensional CT. A total of 4347 examinations were gathered of which only 6% were excluded. Three independent databases from 24 individual centers were created. A total of 143 participants were split into 20 multidisciplinary teams. CONCLUSION: Three data challenges with over 1200 general data protection regulation compliant CT or MRI examinations each were organized. Future challenges should be made with more complex situations combining histopathological or genetic information to resemble real life situations faced by radiologists in routine practice.

The impact of COPD on polyneuropathy: results from the German COPD cohort COSYCONET.

BACKGROUND: Peripheral neuropathy is a common comorbidity in COPD. We aimed to investigate associations between alterations commonly found in COPD and peripheral neuropathy, with particular emphasize on the distinction between direct and indirect effects. METHODS: We used visit 4 data of the COPD cohort COSYCONET, which included indicators of polyneuropathy (repeated tuning fork and monofilament testing), excluding patients with diabetes a/o increased HbA1c. These indicators were analysed for the association with COPD characteristics, including lung function, blood gases, 6-min walk distance (6-MWD), timed-up-and-go-test (TUG), exacerbation risk according to GOLD, C-reactive protein (CRP), and ankle-brachial index (ABI). Based on the results of conventional regression analyses adjusted for age, BMI, packyears and gender, we utilized structural equation modelling (SEM) to quantify the network of direct and indirect relationships between parameters. RESULTS: 606 patients were eligible for analysis. The indices of polyneuropathy were highly correlated with each other and related to base excess (BE), ABI and TUG. ABI was linked to neuropathy and 6-MWD, exacerbations depended on FEV1, 6-MWD and CRP. The associations could be summarized into a SEM comprising polyneuropathy as a latent variable (PNP) with three measured indicator variables. Importantly, PNP was directly dependent on ABI and particularly on BE. When also including patients with diabetes and/or elevated values of HbA1c (n = 742) the SEM remained virtually the same. CONCLUSION: We identified BE and ABI as major determinants of peripheral neuropathy in patients with COPD. All other associations, particularly those with lung function and physical capacity, were indirect. These findings underline the importance of alterations of the micromilieu in COPD, in particular the degree of metabolic compensation and vascular status.

The natural course of lung function decline in asbestos exposed subjects with pleural plaques and asbestosis.

While there is a good knowledge of the natural course of lung function in interstitial lung diseases (ILD) like idiopathic lung fibrosis (IPF), many ambiguities remain in patients with asbestosis. Therefore, we evaluated the change in lung function in asbestos exposed subjects with pleural plaques and asbestosis and analysed corresponding morphology of computer tomography of the thorax. METHODS: 93 asbestos exposed subjects with pleural plaques and asbestosis were analysed retrospectively at the Klinikum Bergmannsheil of the Ruhr-University of Bochum. Parameters of lung function were obtained at least twice and annual changes of FVC, TLC and DLCOsb were calculated. In addition, we assessed the predominant pattern in high-resolution computer tomography of the thorax (HRCT) and differentiated three phenotypes: p (pleural) -type, f (fibrosis) -type and m (mixed) -type. RESULTS: FU data are available in 56/93 (60.2%) patients. The annual deterioration (Mean ±â€¯SEM) of FVC is -31.46 ±â€¯17.34 ml, of TLC -55.55 ±â€¯25.67 ml, of DLCOsb -0.38 ±â€¯0.07 mmol/min/kPa and of DLCOva -0.05 ±â€¯0.01 mmol/min/kPa/L. A categorical change of FVC > -100 ml was found in 12/56 (21.4%) and 18/56 (32.1%) patients showed an annual loss of TLC > -100 ml. The greatest annual decline of FVC was observed in patients with the fibrotic phenotype on HRCT (-76.76 ±â€¯66.43 ml) and the mixed phenotype (-81.52 ±â€¯24.79 ml), while the pleural phenotype was less affected (-10.52 ±â€¯25.07 ml). CONCLUSION: More than 20% of our cohort have a progressive disease with an annual loss of FVC > -100 ml. Patients with the fibrotic-phenotype or mixed-phenotype on HRCT are particularly at risk.

Posterior interosseous nerve of the elbow at the arcade of Frohse: Ultrasound appearance in asymptomatic subjects.

PURPOSE: To assess the normal values of the antero-posterior (AP) diameter of the posterior interosseous nerve (PIN) of the elbow as it passes beneath the arcade of Frohse and to search for PIN-diameter differences between the upstream, entry point and downstream of the arcade. MATERIAL AND METHODS: Thirty asymptomatic patients prospectively underwent bilateral B-mode ultrasound of the PIN of the elbow. There were 15 men and 15 women with a mean age of 30.2±5.31 (SD) years (range: 26-43 years). Of these, 23 patients were right-handers (23/30; 77%) and 7 were left handers (7/30; 23%). AP diameter of the PIN was measured in long axis at three different locations including the entry point of the arcade, 5-mm upstream and 5-mm downstream the arcade. A comparison between the three measurements was performed using paired t-test. RESULTS: The mean AP diameters of the PIN were 0.83±0.21 (SD) mm (range: 0.43-1.31mm), 0.6±0.17 (SD) mm (range: 0.29-1.16mm) and 0.49±0.13 (SD) mm (range: 0.26-0.86mm) at 5-mm upstream, entry point of the arcade and 5-mm downstream the arcade of Frohse, respectively. Significant drops in PIN diameter were found between upstream and the arcade (-0.23mm; 27%; P<0.001), between the arcade and downstream (-0.11mm; 17%; P<0.001), and between upstream and downstream the arcade (-0.34mm; 40%; P<0.001). CONCLUSION: Disparity in AP diameter of the PIN of the elbow in the arcade of Frohse is a normal finding and should not be erroneously interpreted as entrapment when present alone.

Five simultaneous artificial intelligence data challenges on ultrasound, CT, and MRI.

PURPOSE: The goal of this data challenge was to create a structured dynamic with the following objectives: (1) teach radiologists the new rules of General Data Protection Regulation (GDPR), while building a large multicentric prospective database of ultrasound, computed tomography (CT) and MRI patient images; (2) build a network including radiologists, researchers, start-ups, large companies, and students from engineering schools, and; (3) provide all French stakeholders working together during 5 data challenges with a secured framework, offering a realistic picture of the benefits and concerns in October 2018. MATERIALS AND METHODS: Relevant clinical questions were chosen by the Société Francaise de Radiologie. The challenge was designed to respect all French ethical and data protection constraints. Multidisciplinary teams with at least one radiologist, one engineering student, and a company and/or research lab were gathered using different networks, and clinical databases were created accordingly. RESULTS: Five challenges were launched: detection of meniscal tears on MRI, segmentation of renal cortex on CT, detection and characterization of liver lesions on ultrasound, detection of breast lesions on MRI, and characterization of thyroid cartilage lesions on CT. A total of 5,170 images within 4 months were provided for the challenge by 46 radiology services. Twenty-six multidisciplinary teams with 181 contestants worked for one month on the challenges. Three challenges, meniscal tears, renal cortex, and liver lesions, resulted in an accuracy>90%. The fourth challenge (breast) reached 82% and the lastone (thyroid) 70%. CONCLUSION: Theses five challenges were able to gather a large community of radiologists, engineers, researchers, and companies in a very short period of time. The accurate results of three of the five modalities suggest that artificial intelligence is a promising tool in these radiology modalities.

Diversity and anaerobic growth of Pseudomonas spp. isolated from modified atmosphere packaged minced beef.

AIMS: This study aimed to monitor development of spoilage-associated microbiota on high-oxygen modified atmosphere packaged (MAP) minced beef, assess diversity of Pseudomonas sp. therein employing a polyphasic approach and probe their ability to grow anaerobically in the presence of carbon dioxide. METHODS AND RESULTS: Headspace atmosphere and total viable count of MAP minced beef were monitored, and spoilage-associated microbiota was identified using matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). Pseudomonas spp. represented a major part of the spoilage-associated microbiota throughout the spoilage process and were characterized with a polyphasic approach including MALDI-TOF, randomly amplified polymorphic DNA biotyping, 16S rDNA and rpoD sequence analysis, and carA multiplex polymerase chain reaction. Pseudomonas isolates displayed high diversity and varying assertiveness under conditions employed in MAP minced beef with P. fragi, P. lundensis and P. weihenstephanensis as dominant species. CONCLUSIONS: The polyphasic approach enabled high-throughput characterization of Pseudomonas sp. Their adapted capability to grow anaerobically and resistance to high levels of CO2 is suggested to be a general feature within the genus, which is hitherto underexplored. SIGNIFICANCE AND IMPACT OF THE STUDY: This study shows that diverse Pseudomonas generally regarded as strict aerobes and CO2 -sensitive appear well adapted to grow under MAP conditions, leading to high cell counts in minced beef and ultimately contribute to spoilage of the product.

Kidney cortex segmentation in 2D CT with U-Nets ensemble aggregation.

PURPOSE: This work presents our contribution to one of the data challenges organized by the French Radiology Society during the Journées Francophones de Radiologie. This challenge consisted in segmenting the kidney cortex from coronal computed tomography (CT) images, cropped around the cortex. MATERIALS AND METHODS: We chose to train an ensemble of fully-convolutional networks and to aggregate their prediction at test time to perform the segmentation. An image database was made available in 3 batches. A first training batch of 250 images with segmentation masks was provided by the challenge organizers one month before the conference. An additional training batch of 247 pairs was shared when the conference began. Participants were ranked using a Dice score. RESULTS: The segmentation results of our algorithm match the renal cortex with a good precision. Our strategy yielded a Dice score of 0.867, ranking us first in the data challenge. CONCLUSION: The proposed solution provides robust and accurate automatic segmentations of the renal cortex in CT images although the precision of the provided reference segmentations seemed to set a low upper bound on the numerical performance. However, this process should be applied in 3D to quantify the renal cortex volume, which would require a marked labelling effort to train the networks.

Acid stress response of Staphylococcus xylosus elicits changes in the proteome and cellular membrane.

AIMS: Coagulase-negative Staphylococcus xylosus strains are used as starter organisms for sausage fermentation. As those strains have to cope with low pH-values during fermentation, the aim of this study was to identify the acid adaptation mechanisms of S. xylosus TMW 2.1523 previously isolated from salami. METHODS AND RESULTS: A comparative proteomic study between two different acid tolerant mutants was performed. Therefore, both S. xylosus mutants were grown pH-static under acid stress (pH 5·1) and reference conditions (pH 7·0). Proteomic data were supported by metabolite and cell membrane lipid analysis. Staphylococcus xylosus acid stress adaptation is mainly characterized by a metabolic change towards neutral metabolites, enhanced urease activity, reduced ATP consumption, an increase in membrane fluidity and changes in the membrane thickness. CONCLUSION: This study corroborates mechanisms as previously described for other Gram-positive bacteria. Additionally, the adjustment of membrane structure and composition in S. xylosus TMW 2.1523 play a prominent role in its acid adaptation. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrates for the first time changes in the membrane lipid composition due to acid stress adaptation in staphylococci.

Precision Measurement of the ß Asymmetry in Spin-Polarized

Using Triumf's neutral atom trap, Trinat, for nuclear ß decay, we have measured the ß asymmetry with respect to the initial nuclear spin in ^{37}K to be A_{ß}=-0.5707(13)_{syst}(13)_{stat}(5)_{pol}, a 0.3% measurement. This is the best relative accuracy of any ß-asymmetry measurement in a nucleus or the neutron, and is in agreement with the standard model prediction -0.5706(7). We compare constraints on physics beyond the standard model with other ß-decay measurements, and improve the value of V_{ud} measured in this mirror nucleus by a factor of 4.

[DGP Interstitial Lung Disease Patient Questionnaire]. / Patientenfragebogen zur Erfassung der Ursachen interstitieller und seltener Lungenerkrankungen ­ klinische Sektion der DGP.

BACKGROUND: Interstitial lung diseases (ILD) encompass different heterogeneous, mainly chronic diseases of the pulmonary interstitium and/or alveoli with known and unknown reasons. The diagnostic of ILD is challenging and should be performed interdisciplinary. The medical history is of major importance and therefore, in German-speaking countries the Frankfurter Bogen (published in 1985) was utilised to scrutinise the medical history of the patient. This by now more than 30-years-old questionnaire requires a revision with regard to content and language. METHOD: Under the auspices of the clinical section of the DGP the new Interstitial Lung Disease Patient Questionnaire was developed in collaboration amongst pulmonologist, occupational medicine physicians and psychologists and supported by patient support groups. The questionnaire was finally optimised linguistically with the help of patients. RESULTS: The newly developed patient questionnaire for interstitial and rare lung diseases encompasses different domains: initial and current symptoms, medical history questions including prior drug treatments, previous pulmonary and extrapulmonary diseases, potential exposition at home, work and leisure time as well as family history and travelling. CONCLUSION: The newly developed questionnaire can facilitate the diagnosis in patients with suspicion on interstitial lung disease in clinical routine.

Airway-centered interstitial fibrosis - an under-recognized subtype of diffuse parenchymal lung diseases.

Airway centered interstitial fibrosis (ACIF) has been recently suggesed as a rare histological pattern of interstitial lung disease of variable etiology and outcome. It is characterized by fibrosis of the respiratory bronchioles and the peribronchiolar interstitium. We describe the clinical features of 13 patients (7 female, mean age 55 years) with histologically proven ACIF in 12 cases and long-term follow up. In ten patients, exogenous agents could be detected (mould n=5, wood n=2, leather exposure n=1, occupational exposure n=2). Two patients had rheumatoid arthritis and 1 patient suffered from recurrent aspiration. In three patients no associated exposure could be detected. Eight patients were never-smokers, while five were ex- smokers. At time of diagnosis patients presented with a moderate restrictive ventilation impairment and sever reduction in diffusion capacity (VC 61%, TLC 66%, DLCOc-SB 38% pred.). All patients were started on immunosuppressive therapy with steroids which were combined with azathioprine in seven and with mycophenolate mofetil in one patient. Median time of follow up was 52 months (2-127 months). Patients with ACIF due to exogenous agents or associated with RA were stable with immunosuppressive therapy. One patient with idiopathic ACIF showed a progressive deterioration within 29 months despite immunosuppression and died while on a waiting-list for lung transplantation. In our experience ACIF is a rare finding, which is relatively frequently observed in the context of hypersensitivity pneumonitis, aspiration and rheumatoid arthritis, while idiopathic ACIF was a minority. In the majority of patients, ACIF showed a favorable long-term outcome with immunosuppressive therapy. (Sarcoidosis Vasc Diffuse Lung Dis 2018; 35: 218-229).

Posaconazole liquid vs tablet formulation in lung transplant recipients.

Posaconazole is an extended-spectrum triazole antifungal used in the treatment and prophylaxis of Aspergillus infections. It is available as oral suspension (POS-Liq) and delayed-release tablets (POS-Tab). The aim of this longitudinal, retrospective study was to compare the clinical effectiveness, toxicity and pharmacokinetics of POS-Liq vs POS-Tab in lung transplant recipients (LTx-recipients), who were treated with both formulations subsequently. Twenty-four consecutive LTx-recipients with 191 documented posaconazole trough levels (PTLs) for POS-Liq or POS-Tab were included. The administered daily doses were 300 mg for POS-Tab and 600 mg (prophylaxis) or 800 mg (therapy) for POS-Liq. Target PTLs were ≥700 ng/mL (prophylaxis) and ≥1250 ng/mL (therapy). The overall prophylactic and therapeutic response rates were 78% and 67%, respectively. No cases of hepatotoxicity or QT-prolongation were observed with either formulation. The achieved target PTLs were tripled under POS-Tab compared to POS-Liq with fewer risk factors for sub-therapeutic PTLs. Concomitant administration of POS-Tab significantly reduced the tacrolimus concentration-to-dose ratio (P = .001). We suggest the use of POS-Tab is appropriate for prophylaxis and therapy of Aspergillus infections in LTx-recipients, since POS-Tab displayed more reliable PTLs with no added adverse events. However, we recommend regular drug monitoring for POS-Liq and for therapy with POS-Tab and that immunosuppressant levels are monitored closely when the posaconazole formulation is switched.

Monitoring of spoilage-associated microbiota on modified atmosphere packaged beef and differentiation of psychrophilic and psychrotrophic strains.

AIMS: This study aimed to explore the discriminatory power of MALDI-TOF MS as a high-throughput method to monitor growth dynamics of meat-spoiling bacteria on modified atmosphere packaged (MAP) beef and to differentiate psychrophilic and psychrotrophic spoilage-associated strains. METHODS AND RESULTS: MAP beef steaks were incubated for 21 days at constant 4 and 10°C. Development of headspace gas composition, pH, CFU and spoilage-associated microbial composition were monitored. MALDI-TOF MS exhibited high discriminatory power for reliable, high-throughput identification of spoilage-associated, psychrotrophic microbiota. Microbiota development was highly dependent on initial abundance of specific species. Organoleptic onset of spoilage was concomitant with an alteration of headspace atmosphere and pH. Screening for psychrophiles at 4°C on beef revealed the abundance of Leuconostoc gelidum subsp. gelidum TMW2·1998 with characteristic psychrophilic growth behaviour. CONCLUSIONS: We suggest that control of initial contaminants is crucial to predict the onset of spoilage and that headspace atmosphere and pH are important parameters with spoilage-indicative potential. SIGNIFICANCE AND IMPACT OF THE STUDY: MALDI-TOF MS proved suitable for high-resolution monitoring of psychrotrophic and psychrophilic spoilage-associated microbiota and enables improved insights in the spoilage progress. The presence of psychrophilic strains on beef is the likely causative for unexplained spoilage events.