In microbial processes for production of proteins, biomass and nitrogen-containing commodity chemicals, ATP requirements for nitrogen assimilation affect product yields on the energy producing ...substrate. In Saccharomyces cerevisiae, a current host for heterologous protein production and potential platform for production of nitrogen-containing chemicals, uptake and assimilation of ammonium requires 1 ATP per incorporated NH3. Urea assimilation by this yeast is more energy efficient but still requires 0.5 ATP per NH3 produced. To decrease ATP costs for nitrogen assimilation, the S. cerevisiae gene encoding ATP-dependent urease (DUR1,2) was replaced by a Schizosaccharomyces pombe gene encoding ATP-independent urease (ure2), along with its accessory genes ureD, ureF and ureG. Since S. pombe ure2 is a Ni2+-dependent enzyme and Saccharomyces cerevisiae does not express native Ni2+-dependent enzymes, the S. pombe high-affinity nickel-transporter gene (nic1) was also expressed. Expression of the S. pombe genes into dur1,2Δ S. cerevisiae yielded an in vitro ATP-independent urease activity of 0.44±0.01µmolmin−1mg protein−1 and restored growth on urea as sole nitrogen source. Functional expression of the Nic1 transporter was essential for growth on urea at low Ni2+ concentrations. The maximum specific growth rates of the engineered strain on urea and ammonium were lower than those of a DUR1,2 reference strain. In glucose-limited chemostat cultures with urea as nitrogen source, the engineered strain exhibited an increased release of ammonia and reduced nitrogen content of the biomass. Our results indicate a new strategy for improving yeast-based production of nitrogen-containing chemicals and demonstrate that Ni2+-dependent enzymes can be functionally expressed in S. cerevisiae.
•To decrease ATP costs for nitrogen assimilation, the ATP-dependency of urease was changed.•Functional S. pombe urease in S. cerevisiae required expression of ure2, D, F and G.•Functional expression of Nic1 was needed for growth on urea at low Ni concentration.•In urea C-limited chemostat, the engineered strain showed a different N management.•This work is the first case of expression of Ni-dependent enzyme in S. cerevisiae.
This study investigated the mental health of people with psoriasis undergoing patient education in climate therapy. A prospective design included a baseline assessment and two follow‐ups after a ...3‐week patient education program. Participants were 254 adults. Positive mental health was measured by the mental health continuum short form (0–70), and negative mental health by the emotional distress subscale (1–4) of the health education impact questionnaire. Paired‐samples t‐tests were used to evaluate changes in mental health from baseline to follow‐up. Multiple linear regression was used to analyse the ability of socio‐demographic and clinical variables and emotional distress to predict changes in positive mental health. To predict change in negative mental health we repeated the same analysis but with a change in negative mental health as a dependent variable and positive mental health as an independent variable. The results show that positive mental health and health‐related emotional distress improved significantly from before to after the intervention by 7.1 points, p < 0.001 and 0.21 points, p < 0.001) respectively. At the second follow‐up, health‐related emotional distress remained significantly improved compared with baseline levels by 0.11 points, p = 0.004. The longer participants had lived with psoriasis ( β = 146, p = 0.027), and the presence of co‐morbid health problems (β = 111, p = 0.051) the greater the improvement in the positive mental health immediately after the intervention. No predictors were identified for negative mental health. This study indicates that the promotion of positive mental health needs to be integrated into the climate therapy program, and sustained in their home context.
Myocardial perfusion imaging with SPECT/CT or with PET/CT is a mainstay in clinical practice for the diagnostic assessment of downstream, flow-limiting effects of epicardial lesions during hyperemic ...flows and for risk stratification of patients with known or suspected coronary artery disease (CAD). In patients with multivessel CAD, the relative distribution of radiotracer uptake in the left ventricular myocardium during stress and rest accurately identifies flow-limiting epicardial lesions or the most advanced, so called culprit, lesion. Often, less severe obstructive CAD lesions may go undetected or underdiagnosed. The concurrent ability of PET/CT with radiotracer kinetic modeling to determine myocardial blood flow (MBF) in absolute terms (mL/g/min) at rest and during vasomotor stress allows the computation of regional myocardial flow reserve (MFR) as an adjunct to the visual interpretation of myocardial perfusion studies. Adding the noninvasive evaluation and quantification of MBF and MFR by PET imaging to the visual analysis of myocardial perfusion may (1) identify subclinical CAD, (2) better characterize the extent and severity of CAD burden, and (3) assess “balanced” decreases of MBF in all 3 major coronary artery vascular territories. Recent investigations have demonstrated that PET-determined reductions in hyperemic MBF or MFR in patients with subclinical or clinically manifest CAD are predictive of increased relative risk of future cardiovascular events and clinical outcome. Quantifying MFR with PET enables the identification and characterization of coronary vasodilator dysfunction as functional precursor of the CAD process, which offers the unique opportunity to monitor its response to lifestyle or risk factor modification by preventive medical care. Whether an improvement or even normalization of hyperemic MBF or the MFR in subclinical or in clinically manifest CAD confers an improved long-term cardiovascular outcome remains untested. Nonetheless, given the recent growth in the clinical utilization of myocardial perfusion PET, image-guided and personalized preventive care of vascular health may become a reality in the near future.
Abstract The Australian, Chinese, European, Indian, and North American pulsar timing array (PTA) collaborations recently reported, at varying levels, evidence for the presence of a nanohertz ...gravitational-wave background (GWB). Given that each PTA made different choices in modeling their data, we perform a comparison of the GWB and individual pulsar noise parameters across the results reported from the PTAs that constitute the International Pulsar Timing Array (IPTA). We show that despite making different modeling choices, there is no significant difference in the GWB parameters that are measured by the different PTAs, agreeing within 1 σ . The pulsar noise parameters are also consistent between different PTAs for the majority of the pulsars included in these analyses. We bridge the differences in modeling choices by adopting a standardized noise model for all pulsars and PTAs, finding that under this model there is a reduction in the tension in the pulsar noise parameters. As part of this reanalysis, we “extended” each PTA’s data set by adding extra pulsars that were not timed by that PTA. Under these extensions, we find better constraints on the GWB amplitude and a higher signal-to-noise ratio for the Hellings–Downs correlations. These extensions serve as a prelude to the benefits offered by a full combination of data across all pulsars in the IPTA, i.e., the IPTA’s Data Release 3, which will involve not just adding in additional pulsars but also including data from all three PTAs where any given pulsar is timed by more than a single PTA.
A multipurpose sampler (Gerstel MPS), designed for liquid large volume, gaseous and headspace samples was used for the GC–MS analysis of organic volatiles in human urine. Headspace sampling with a ...volume-, temperature- and speed-controlled gas-tight syringe was combined with a temperature-controlled cold injection system (CIS) for cold trapping, enrichment and focusing of analytes. Regular 2-ml GC vials filled with 1 ml acidified urine were used as headspace sampling vials. A 100-vial autosampler tray was equipped with an additional temperature and heating time controlled “preheating station” for five vials. Profiles of organic volatiles in human urine were determined and 34 components identified. Trimethylamine (TMA) and 4-heptanone as two metabolites of medical interest were quantified. Calibration curves and intra assay imprecision for 4-heptanone concentrations in the range of 40 to 800 ng/ml showed a correlation coefficient of
r=0.9980 and a relative standard deviation (RSD) between 3.0 and 3.4%. Calibration curves and intra-assay imprecision for TMA concentrations in the range of medical interest from 0.5 to 20 μg/ml showed a correlation coefficient of
r=0.9968 and a RSD between 4.1 and 6.8%. The high practicability of the multipurpose sampler for both gaseous and liquid samples together with the here shown good reproducibility and sensitivity make this single CIS-GC–MS system very attractive for routine clinical use in metabolic profiling of organic volatiles (headspace) and non-volatiles (liquid).
The incremental diagnostic value of integrated positron emission tomography–computed tomography (PET/CT) or single-photon emission computed tomography (SPECT)/CT images compared with PET or SPECT ...alone, or PET or SPECT correlated with a CT obtained at a different time includes the following: (1) improvement in lesion detection on both CT and PET or SPECT images, (2) improvement in the localization of foci of uptake resulting in better differentiation of physiological from pathologic uptake, (3) precise localization of the malignant foci, for example, in the skeleton vs soft tissue or liver vs adjacent bowel or node (4) characterization of serendipitous lesions, and (5) confirmation of small, subtle, or unusual lesions. The use of these techniques can occur at the time of initial diagnosis, in assessing the early response of disease to treatment, at the conclusion of treatment, and in continuing follow-up of patients. PET/CT and SPECT/CT fusion images affect the clinical management in a significant proportion of patients with a wide range of diseases by (1) guiding further procedures, (2) excluding the need of further procedures, (3) changing both inter- and intramodality therapy, including soon after treatment has been initiated, and (4) by providing prognostic information. PET/CT fusion images have the potential to provide important information to guide the biopsy of a mass to active regions of the tumor and to provide better maps than CT alone to modulate field and dose of radiation therapy. It is expected that the role of PET/CT and SPECT/CT in changing management will continue to evolve in the future and that these tools will be fundamental components of the truly “personalized medicine” we are striving to deliver.
Metabonomics, the study of metabolites and their roles in various disease states, is a novel methodology arising from the post-genomics era. This methodology has been applied in many fields, ...including work in cardiovascular research and drug toxicology. In this study, metabonomics method was employed to the diagnosis of Type 2 diabetes mellitus (DM2) based on serum lipid metabolites. The results suggested that serum fatty acid profiles determined by capillary gas chromatography combined with pattern recognition analysis of the data might provide an effective approach to the discrimination of Type 2 diabetic patients from healthy controls. And the applications of pattern recognition methods have improved the sensitivity and specificity greatly.
The combination of a new thermodesorption module with a cooled injection system now provides a powerful system for direct analysis of volatile trace compounds in gaseous, liquid and solid samples by ...gas chromatography–mass spectrometry (GC–MS). As a cooled injection system is used for the cryofocusing of the desorbed volatiles the GC–MS system still can be used for the regular analysis of liquid samples. Although plasticizers usually are analyzed by GC–MS after solvent extraction, contaminated solvents and glassware are very well known problems. Analysis of plasticizers in plastic materials by direct thermodesorption instead saves time and avoids cross contaminations. Many medical products are made of plasticized polyvinyl chloride. Extraction of the common plasticizer di(2-ethylhexyl) phthalate (DEHP) into blood will occur, and harmful effects of DEHP in the human body have been suggested. We therefore analyzed 21 different plastic devices which are used for various invasive techniques in medicine by direct thermodesorption GC-MS. In some of the plastics up to 30 different components were identified. By far the most common plasticizer found was DEHP, followed by diethyl and dibutyl phthalates.
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