Differential Amino Acid Uptake and Depletion in Mono-Cultures and Co-Cultures of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus in a Novel Semi-Synthetic Medium.

The mechanistic understanding of the physiology and interactions of microorganisms in starter cultures is critical for the targeted improvement of fermented milk products, such as yogurt, which is produced by Streptococcus thermophilus in co-culture with Lactobacillus delbrueckii subsp. bulgaricus. However, the use of complex growth media or milk is a major challenge for quantifying metabolite production, consumption, and exchange in co-cultures. This study developed a synthetic medium that enables the establishment of defined culturing conditions and the application of flow cytometry for measuring species-specific biomass values. Time courses of amino acid concentrations in mono-cultures and co-cultures of L. bulgaricus ATCC BAA-365 with the proteinase-deficient S. thermophilus LMG 18311 and with a proteinase-positive S. thermophilus strain were determined. The analysis revealed that amino acid release rates in co-culture were not equivalent to the sum of amino acid release rates in mono-cultures. Data-driven and pH-dependent amino acid release models were developed and applied for comparison. Histidine displayed higher concentrations in co-cultures, whereas isoleucine and arginine were depleted. Amino acid measurements in co-cultures also confirmed that some amino acids, such as lysine, are produced and then consumed, thus being suitable candidates to investigate the inter-species interactions in the co-culture and contribute to the required knowledge for targeted shaping of yogurt qualities.

Genome-Scale Metabolic Modeling Combined with Transcriptome Profiling Provides Mechanistic Understanding of Streptococcus thermophilus CH8 Metabolism.

Streptococcus thermophilus is a lactic acid bacterium adapted toward growth in milk and is a vital component of starter cultures for milk fermentation. Here, we combine genome-scale metabolic modeling and transcriptome profiling to obtain novel metabolic insights into this bacterium. Notably, a refined genome-scale metabolic model (GEM) accurately representing S. thermophilus CH8 metabolism was developed. Modeling the utilization of casein as a nitrogen source revealed an imbalance in amino acid supply and demand, resulting in growth limitation due to the scarcity of specific amino acids, in particular sulfur amino acids. Growth experiments in milk corroborated this finding. A subtle interdependency of the redox balance and the secretion levels of the key metabolites lactate, formate, acetoin, and acetaldehyde was furthermore identified with the modeling approach, providing a mechanistic understanding of the factors governing the secretion product profile. As a potential effect of high expression of arginine biosynthesis genes, a moderate secretion of ornithine was observed experimentally, augmenting the proposed hypothesis of ornithine/putrescine exchange as part of the protocooperative interaction between S. thermophilus and Lactobacillus delbrueckii subsp. bulgaricus in yogurt. This study provides a foundation for future community modeling of food fermentations and rational development of starter strains with improved functionality. IMPORTANCE Streptococcus thermophilus is one the main organisms involved in the fermentation of milk and, increasingly, also in the fermentation of plant-based foods. The construction of a functional high-quality genome-scale metabolic model, in conjunction with in-depth transcriptome profiling with a focus on metabolism, provides a valuable resource for the improved understanding of S. thermophilus physiology. An example is the model-based prediction of the most significant route of synthesis for the characteristic yogurt flavor compound acetaldehyde and identification of metabolic principles governing the synthesis of other flavor compounds. Moreover, the systematic assessment of amino acid supply and demand during growth in milk provides insights into the key challenges related to nitrogen metabolism that is imposed on S. thermophilus and any other organism associated with the milk niche.

Aortic Valve Stenosis Increases Helical Flow and Flow Complexity: A Study of Intra-Operative Cardiac Vector Flow Imaging.

Aortic valve stenosis alters blood flow in the ascending aorta. Using intra-operative vector flow imaging on the ascending aorta, secondary helical flow during peak systole and diastole, as well as flow complexity of primary flow during systole, were investigated in patients with normal, stenotic and replaced aortic valves. Peak systolic helical flow, diastolic helical flow and flow complexity during systole differed between the groups (p < 0.0001), and correlated to peak systolic velocity (R = 0.94, 0.87 and 0.88, respectively). The study indicates that aortic valve stenosis increases helical flow and flow complexity, which are measurable with vector flow imaging. For assessment of aortic stenosis and optimization of valve surgery, vector flow imaging may be useful.

Vector Flow Imaging Compared with Conventional Doppler Ultrasound and Thermodilution for Estimation of Blood Flow in the Ascending Aorta.

Transverse oscillation (TO) is a real-time ultrasound vector flow method implemented on a commercial scanner. The TO setup was examined on a flowrig with constant and pulsatile flow. Subsequently, 25 patients undergoing cardiac bypass surgery were scanned intraoperatively with TO on the ascending aorta and compared to transesophageal echocardiography (TEE) and pulmonary artery catheter thermodilution (PACTD). On the flowrig, TO had a precision of 5.5%, 9.4% and 14.7%, a percentage error of 18.2%, 14.6% and 40.7%, and a mean bias of 0.4 cm/s, 36.8 ml/min and 32.4 ml/min for velocity and flow rate (constant and pulsatile) estimation. The correlation coefficients for all flowrig evaluations were 0.99 indicating systematic bias. After bias correction, the percentage error was reduced to 11.5%, 12.6% and 15.9% for velocity and flow rate (constant and pulsatile) estimation. In the in vivo setup, TO, TEE, and PACTD had a precision of 21.9%, 13.7%, and 12.0%. TO compared with TEE and PACTD had a mean bias of 12.6 cm/s and -0.08 l/min, and a percentage error of 23.4%, and 36.7%, respectively. The percentage error was reduced to 22.9% for the TEE comparison, but increased to 43.8% for the PACTD comparison, after correction for the systematic bias found in the flowrig. TO is a reliable and precise method for velocity and flow rate estimation on a flowrig. However, TO with the present setup, is not interchangeable with PACTD for cardiac volume flow estimation, but is a reliable and precise angle-independent ultrasound alternative for velocity estimation of cardiac flow.

Intra-Operative Vector Flow Imaging Using Ultrasound of the Ascending Aorta among 40 Patients with Normal, Stenotic and Replaced Aortic Valves.

Stenosis of the aortic valve gives rise to more complex blood flows with increased velocities. The angle-independent vector flow ultrasound technique transverse oscillation was employed intra-operatively on the ascending aorta of (I) 20 patients with a healthy aortic valve and 20 patients with aortic stenosis before (IIa) and after (IIb) valve replacement. The results indicate that aortic stenosis increased flow complexity (p < 0.0001), induced systolic backflow (p < 0.003) and reduced systolic jet width (p < 0.0001). After valve replacement, the systolic backflow and jet width were normalized (p < 0.52 and p < 0.22), but flow complexity was not (p < 0.0001). Flow complexity (p < 0.0001), systolic jet width (p < 0.0001) and systolic backflow (p < 0.001) were associated with peak systolic velocity. The study found that aortic stenosis changes blood flow in the ascending aorta and valve replacement corrects some of these changes. Transverse oscillation may be useful for assessment of aortic stenosis and optimization of valve surgery.

Transcriptome analysis of Lactococcus lactis subsp. lactis during milk acidification as affected by dissolved oxygen and the redox potential.

Performance of Lactococcus lactis as a starter culture in dairy fermentations depends on the levels of dissolved oxygen and the redox state of milk. In this study the microarray analysis was used to investigate the global gene expression of L. lactis subsp. lactis DSM20481(T) during milk acidification as affected by oxygen depletion and the decrease of redox potential. Fermentations were carried out at different initial levels of dissolved oxygen (dO2) obtained by milk sparging with oxygen (high dO2, 63%) or nitrogen (low dO2, 6%). Bacterial exposure to high initial oxygen resulted in overexpression of genes involved in detoxification of reactive oxygen species (ROS), oxidation-reduction processes, biosynthesis of trehalose and down-regulation of genes involved in purine nucleotide biosynthesis, indicating that several factors, among them trehalose and GTP, were implicated in bacterial adaptation to oxidative stress. Generally, transcriptional changes were more pronounced during fermentation of oxygen sparged milk. Genes up-regulated in response to oxygen depletion were implicated in biosynthesis and transport of pyrimidine nucleotides, branched chain amino acids and in arginine catabolic pathways; whereas genes involved in salvage of nucleotides and cysteine pathways were repressed. Expression pattern of genes involved in pyruvate metabolism indicated shifts towards mixed acid fermentation after oxygen depletion with production of specific end-products, depending on milk treatment. Differential expression of genes, involved in amino acid and pyruvate pathways, suggested that initial oxygen might influence the release of flavor compounds and, thereby, flavor development in dairy fermentations. The knowledge of molecular responses involved in adaptation of L. lactis to the shifts of redox state and pH during milk fermentations is important for the dairy industry to ensure better control of cheese production.

Analysis of Systolic Backflow and Secondary Helical Blood Flow in the Ascending Aorta Using Vector Flow Imaging.

Secondary rotational flow and systolic backflow are seen in the ascending aorta and, in this study, were analyzed with the vector velocity method transverse oscillation. Twenty-five patients were scanned intra-operatively, and the vector velocities were related to estimates of transesophageal echocardiography and pulmonary artery catheter thermodilution, and associated with gender, age, aortic diameter, atherosclerotic plaques, left ventricular ejection fraction and previous myocardial infarctions. Secondary flow was present for all patients. The duration and rotational frequency (p < 0.001) and the duration and flow direction of the secondary flow (p < 0.002) were associated. Systolic backflow was present in 40% of the patients and associated with systolic velocities (p < 0.002) and the presence of atherosclerotic plaques (p < 0.001). No other significant associations were observed. The study indicates that backflow is injurious and that secondary flow is a normal flow phenomenon. The study also shows that transverse oscillation can provide new information on blood flow in the ascending aorta.

Valvular Excrescences: A Possible Transient Phenomenon.

The thrombogenic potential of Lambl excrescences (LE) is minimal unlike the benign tumour fibroelastoma wherefrom thrombi often originate. We present a patient with multiple strokes within a six-year period. A possible locus on the aortic valve was found and diagnosed as fibroelastoma. Before aortic valve substitution prior finding could not be visualized and surgery was aborted. Due to review of earlier Transesophageal Echocardiography (TEE) and the transient component, LE was accepted as the most plausible diagnosis. This illustrates the need for TEE just before surgery.

Aortic valve bypass: experience from Denmark.

OBJECTIVES: In aortic valve bypass (AVB) a valve-containing conduit is connecting the apex of the left ventricle to the descending aorta. Candidates are patients with symptomatic aortic valve stenosis rejected for conventional aortic valve replacement (AVR) or transcatheter aortic valve implantation (TAVI). During the last one and a half year, 10 patients otherwise left for medical therapy have been offered this procedure. We present the Danish experiences with the AVB procedure with a focus on patient selection, operative procedure and short-term results. METHODS: AVB is performed through a left thoracotomy. A 19-mm Freestyle(®) valve (Medtronic) is anastomosed to a vascular graft and an apex conduit. The anastomosis to the descending aorta is made prior to connecting the conduit to the apex. In 1 patient, we used an automated coring and apical connector insertion device (Correx(®)). The device results in a simultaneous coring and insertion of an 18-mm left ventricle connector in the apical myocardium. AVB is routinely performed without circulatory assistance. RESULTS: Ten patients have been operated on since April 2011: eight females and 2 males with a median age of 76 (65-91) years. Seven patients had a severely calcified ascending aorta. Three of these had previously had a sternotomy, but did not have an AVR because of porcelain aorta. Six patients had a very small left ventricle outflow tract (<18 mm). The median additive EuroSCORE was 12 (10-15). Seven patients were operated on without circulatory assistance. Two patients had a re-exploration for bleeding and 1 developed a ventricle septum defect 1 month postoperatively and was treated with surgical closure. The median follow-up was 7 (2-15) months and was without mortality. New York Heart Association class was reduced from 2.5 to 2 at the follow-up, but some patients were still in the recovery period. The total valve area (native plus conduit) was 2.2 (1.9-2.5) cm(2) and 1.34 (1.03-1.46) cm(2)/m(2), indexed to the body surface area. There was no AV block or stroke. CONCLUSIONS: AVB can be performed with low mortality and acceptable results in selected patients. The procedure can be offered to patients rejected for conventional aortic valve replacement and TAVI and results in a larger total valve area than by insertion of standard bioprosthesis.

Comparable three months' outcome of total arterial revascularization versus conventional coronary surgery: Copenhagen Arterial Revascularization Randomized Patency and Outcome trial.

OBJECTIVE: The in-hospital safety of total arterial revascularization for coronary artery bypass surgery seems to be comparable to conventional revascularization, but randomized trials evaluating this are few and data on complications in the postoperative months are sparse. METHODS: In a randomized single-center trial, 331 patients underwent total arterial revascularization using single or bilateral internal thoracic and radial arteries versus conventional revascularization using the left internal thoracic artery and saphenous vein grafts. We report the results from 3 months' follow-up. RESULTS: The mean age of patients was 59 +/- 8 years, and 39 were women (12%). The median EuroSCORE was 2 (interquartile range 1-4). The arterial group comprised 161 patients, and the conventional group comprised 170 patients. The mean number of bypasses in the arterial group was 2.9 +/- 0.9 versus 3.2 +/- 0.9 in the conventional group (P = .004). Three months' follow-up for the arterial versus conventional groups showed the following: deaths: 1 (0.6%) versus 0; stroke: 3 (1.9%) versus 3 (1.8%); myocardial infarction: 6 (3.7%) versus 4 (2.4%); sternal wound reoperation: 4 (2.5%) versus 0 (P = .054); arm and leg wound complications requiring hospitalization: 3 (1.9%) versus 6 (3.5%) (P = .50), respectively. CONCLUSION: These results confirm previous reports that total arterial revascularization can be performed with low in-hospital morbidity and mortality. Further, in the 3 postoperative months, total arterial revascularization did not lead to more complications or admissions than conventional surgery. Arterial grafting was performed with significantly fewer bypasses, but no differences in anginal status were seen after 3 months. A tendency toward more sternal complications after arterial grafting was observed, but clinical outcomes were comparable to conventional grafting.

Another pitfall in minimally invasive mitral valve repair.

We report a case of severe systolic anterior motion (SAM) and dynamic left ventricular outflow obstruction after repair of a flail posterior leaflet of the mitral valve. The reason for SAM was found to be due to traction on the pericardial stay sutures placed to expose the surgical field. The SAM and the outflow obstruction were completely resolved by cutting these sutures. Our case demonstrates the contribution of geometric factors in the development of SAM and left ventricular outflow obstruction and emphasizes the need to evaluate the heart in its natural position within the mediastinum.

[Transthoracic ultrasound: a necessary standard within intensive, acute and pre-hospital medicine]. / Transtorakal ultralyd: en nødvendig standard inden for intensiv, akut og praehospital medicin.

The introduction of focus assessed transthoracic echocardiographic (FATE) protocols has brought ultrasound into the first line in evaluating the critically ill patient. The technical advancements within ultrasound technology with miniaturisation and refinements of equipment have made the advantages of imaging available in the hemodynamic monitoring, and this modality now surpasses more conventional methods in feasibility and specificity. It seems reasonable to expect echocardiography to be incorporated as a new standard in the immediate assessment of the critically ill patient in the emergency and the intensive care unit as well as in the pre-hospital setting.

Management of cancer pain in Denmark: a nationwide questionnaire survey.

A questionnaire survey was carried out with the aim of evaluating knowledge about and practice of cancer pain treatment in Denmark. A questionnaire was sent out to a 10% random sample of Danish physicians. Of these 1411 physicians, 1068 (76%) returned the questionnaires and after exclusion of those doctors who never treated cancer patients, 577 (54%) were analyzed. Their knowledge of the principles and practice of cancer pain treatment was evaluated by means of 14 multiple-choice and open questions. Their ability to apply their knowledge in practice was evaluated by analyzing their suggested treatment of 3 simulated patient cases. The results show that a vast majority (97%) of the physicians were prepared to use opioids conventionally administered for severe pain and that 39% reported the use of other treatment modalities (psychological treatment, antineoplastic therapy, transcutaneous nerve stimulation/acupuncture, etc.). Ninety-seven percent of the physicians recognized difficulties in cancer pain treatment, the most frequent being side effects of drugs and inadequate pain relief. Seventy-five percent considered that their knowledge about pain treatment was fair or better. The overall evaluation of the proposals for pain treatment of the patient cases was primarily based on drug therapy. Adequate doses, correct dose intervals and selection of drugs, routes of administration and other treatments were the requirements for satisfactory answers. It appears that the majority the physicians could treat both pain from bone metastasis (75%) and visceral pain (78%) satisfactorily, while very few suggested co-analgesics for neuropathic pain conditions (20%). Older physicians performed less well than their younger colleagues. Basic pain treatment skills have been acquired by the Danish physicians but, in the future, emphasis should be placed on the treatment of neuropathic pain with co-analgesics and the management of opioid side effects.