Modeling the Interplay of Pseudomonas putida EIIA with the Potassium Transporter KdpFABC.

The nitrogen phosphotransferase system (PTS(Ntr)) of Pseudomonas putida is a key regulatory device that participates in controlling many physiological processes in a posttranscriptional fashion. One of the target functions of the PTS(Ntr) is the regulation of potassium transport. This is mediated by the direct interaction of one of its components with the sensor kinase KdpD of the two-component system controlling transcription of the kdpFABC genes. From a detailed experimental analysis of the activity of the kdpF promoter in P. putida wild-type and pts mutant strains with varying potassium concentrations, we had highly time-resolved data at hand, describing the influence of the PTS(Ntr) on the transcription of the KdpFABC potassium transporter. Here, this data was used to construct a mathematical model based on a black box approach. The model was able to describe the data quantitatively with convincing accuracy. The qualitative interpretation of the model allowed the prediction of two general points describing the interplay between the PTS(Ntr) and the KdpFABC potassium transporter: (1) the influence of cell number on the performance of the kdpF promoter is mainly by dilution by growth and (2) potassium uptake is regulated not only by the activity of the KdpD/KdpE two-component system (in turn influenced by PtsN). An additional controller with integrative behavior is predicted by the model structure. This suggests the presence of a novel physiological mechanism during regulation of potassium uptake with the KdpFABC transporter and may serve as a starting point for further investigations.

Interplay of the PtsN (EIIA(Ntr)) protein of Pseudomonas putida with its target sensor kinase KdpD.

The nitrogen phosphotransferase system (PTS(Ntr) ) of Pseudomonas putida is a multi-component regulatory device that participates in controlling a variety of physiological processes in a post-translational fashion. A general survey of genes regulated by PtsN exposed transcription of the kdpFABC operon is most conspicuously affected. Measurements of kdpFp promoter activity in different pts mutants showed that PtsN is responsible for repression of kdpFABC transcription. This effect could be assigned mainly to PtsN∼P, depending on the external K(+) concentration. Bacterial two-hybrid assays demonstrated that kdpFp regulation is implemented through direct interaction of the PtsN protein with the sensor kinase KdpD of the KdpD/KdpE two-component system. Interaction between KdpD and PtsN was detectable with a PtsN variant that imitates the non-phosphorylated form as well as with a PtsN type mimicking the phosphorylated form of PtsN. These results raise a regulatory scenario in which the Kdp system is regulated by the action of PtsN through direct interaction with the sensor kinase KdpD, and the outcome of such an interaction depends on the phosphorylation state of PtsN as well as on the external K(+) concentration.

Changes in body composition during weight loss in obese subjects in the NUGENOB study: comparison of bioelectrical impedance vs. dual-energy X-ray absorptiometry.

AIM: We studied the accuracy of bioelectrical impedance analysis (BIA) to assess changes in body composition during moderate weight loss in obese subjects. METHODS: Estimates of changes in fat mass (FM) and fat-free mass (FFM) by BIA were compared with those by dual-energy X-ray absorptiometry (DXA) as the reference method during a 10-week standardized weight-loss intervention. In obese women (age: 20-50 years, mean BMI: 33.8 kg/m(2)) participating in a European multicentre trial (nutrient-gene interactions in human obesity [NUGENOB]), body composition was assessed by BIA (Bodystat QuadScan 4000) and DXA (Lunar DPX-IQ at two centres, Hologic QDR 2000 at another centre) at baseline (n=131) and at week 10 (n=105) after a mean weight loss of -5.7 kg. RESULTS: At baseline, BIA significantly overestimated FFM and underestimated FM (by 1-3 kg on average) compared with DXA, and the limits of agreement were wide (mean ± 7-8.5 kg). For body-composition changes, although biases were generally non-significant, the limits of agreement were also wide (mean ± 3.7-4.6 kg). An FFM prediction equation for BIA data was developed in subjects scanned with Lunar instruments and cross-validated in an independent sample of 31 obese women undergoing similar weight loss. However, no major improvement in limits of agreement was found. CONCLUSION: During moderate diet-induced weight loss, the use of BIA leads to estimates of changes in body composition at the individual level that can differ substantially from those assessed by DXA, indicating that BIA and DXA cannot be used interchangeably. However, BIA in this context may be used for assessing changes in body composition at group level.

Macronutrient-specific effect of FTO rs9939609 in response to a 10-week randomized hypo-energetic diet among obese Europeans.

BACKGROUND: The A risk allele of rs9939609 of the fat mass- and obesity-associated gene (FTO) increases body fat mass. OBJECTIVE: To examine whether FTO rs9939609 affects obese individuals' response to a high-fat, low-carbohydrate (CHO) (HF) or low-fat, high-CHO (LF), hypo-energetic diet and whether the effect of the FTO variant depends on dietary fat and CHO content. DESIGN: In a 10-week, European, multi-centre dietary intervention study 771 obese women and men were randomized to either LF (20-25% of energy (%E) from fat, 60-65%E from CHO) or HF (40-45%E from fat, 40-45%E from CHO), hypo-energetic diet (measured resting metabolic rate multiplied by 1.3-600 kcal day(-1)). Body weight, fat mass (FM), fat-free mass (FFM), waist circumference (WC), resting energy expenditure (REE), fasting fat oxidation as % of REE (FatOx), insulin release (HOMA-beta) and a surrogate measure of insulin resistance (HOMA-IR) were measured at baseline and after the intervention. In all, 764 individuals were genotyped for FTO rs9939609. RESULTS: For A-allele carriers the drop-out rate was higher on HF than LF diet (in AT, P=0.002; in AT/AA combined, P=0.003). Among those individuals completing the intervention, we found no effect of FTO rs9939609 genotype on Deltaweight, DeltaFM, DeltaFFM, DeltaWC or DeltaFatOx. However, participants with TT had a smaller reduction in REE on LF than on HF diet (75 kcal/24 h; interaction: P=0.0055). These individuals also showed the greatest reduction in HOMA-beta and HOMA-IR (interaction: P=0.0083 and P=0.047). CONCLUSION: The FTO rs9939609 may interact with the macronutrient composition in weight loss diets in various ways; carriers of the A allele on LF diet appear to have a lower risk for drop out, and TT individuals have a smaller decrease in REE and greater decrease in HOMA-beta and HOMA-IR on LF than on HF diet.

Circulating levels of osteopontin, osteoprotegerin, total soluble receptor activator of nuclear factor-kappa B ligand, and high-sensitivity C-reactive protein in patients with active rheumatoid arthritis randomized to etanercept alone or in combination with methotrexate.

OBJECTIVE: To determine whether circulating levels of osteopontin (OPN), osteoprotegerin (OPG), total soluble receptor activator of nuclear factor-kappa B ligand (total sRANKL), and high-sensitivity C-reactive protein (hsCRP) change in patients with rheumatoid arthritis (RA) during immunosuppressive therapy. METHODS: Twenty-five active RA patients were randomized to treatment with either etanercept alone or in combination with methotrexate (MTX). The treatment response after 16 weeks was assessed using the European League Against Rheumatism (EULAR) response criteria. Blood samples were taken before the start of and every fourth week during the study. OPN, OPG, and total sRANKL were measured by enzyme-linked immunosorbent assays (ELISAs) and hsCRP by highly sensitive turbidometry. RESULTS: At baseline, OPN and hsCRP were significantly (p<0.001) elevated compared to healthy persons. Compared to baseline only hsCRP levels decreased significantly (p<0.05 to p<0.001) in the EULAR responders through the study. OPN remained significantly (p<0.05) elevated at 16 weeks in patients with a low disease activity score (DAS< or =3.2). Total sRANKL increased significantly (p<0.05) from baseline to week 12. No statistically significant changes were observed in the non-responders. CONCLUSION: Active RA patients showed increased circulating levels of hsCRP and OPN, but only hsCRP decreased during etanercept therapy. Our findings suggest that OPN, OPG, total sRANKL, and hsCRP reflect different aspects of the inflammatory process in RA.

IVIG treatment for progressive stroke in the primary antiphospholipid antibody syndrome.

A 32-year old woman with antiphospholipid antibody syndrome (APS) developed severe thrombocytopenia, elevated liver enzymes and progressive cerebral thrombosis a few days after preterm delivery by caesarean section. Her condition deteriorated despite treatment with low dose aspirin, anticoagulation by heparin and iv glucocorticoid administration. Intravenous immunoglobulin (IVIG) on three consecutive days was followed by rapid resolution of her neurological impairment and increasing platelets counts. The temporal association between IVIG and reversal of both neurological impairment and platelet number strongly indicates a specific effect of IVIG administration in this condition. It is proposed that IVIG therapy is considered as a therapeutic option in APS patients with progressive cerebral infarction despite optimal use of anticoagulant and immunomodulating agents.

Comparison of HIG scintigraphy and bloodpool scintigraphy using HDP in arthritic joint disease.

AIM: Because of a similar tracer accumulation, we assumed to get the same information about synovitis in arthritic joint disease with HIG scintigraphy and bloodpool scintigraphy using HDP. Therefore, we compared retrospectively 23 patients. METHODS: In HIG scintigraphy, synovitis was diagnosed according to increasing activity from early to late image. In bloodpool scintigraphy according to an increased activity in comparison to the surrounding tissues. RESULTS: In 694 joints comparison of both scintigraphic modalities was possible, resulting in a 2 x 2 kappa coefficient of 0.93 or 0.97 by using late-phase bone scintigraphy as an anatomical marker. For intra- and interobserver agreement, 2 x 2 kappa coefficients of 0.93 and 0.88 in HIG scintigraphy, respectively 0.96 and 0.90 in blood-pool scintigraphy were calculated. CONCLUSION: This study shows an excellent agreement in the visualization of synovitis by HIG and bloodpool scintigraphy. Because of its higher objectivity and lower cost, investigation of synovitis should be performed by bloodpool scintigraphy.

Safety and tolerability of metoprolol OROS in hypertension treatment.

One hundred twenty-six patients with mild to moderate hypertension responsive to beta-adrenergic blocking agents--alone or in combination with other antihypertensive drugs--entered this open-label, multicenter study designed to evaluate the safety and tolerability of metoprolol OROS (metoprolol fumarate). Metoprolol OROS was given once daily for 14 weeks in doses ranging from 100 to 600 mg. Satisfactory blood pressure control was achieved by 85% of the patients at doses between 100 and 400 mg. Mean diastolic blood pressure was maintained at or below 90 mm Hg. Adverse reactions were experienced by 29% of the patients; most of these reactions were mild or moderate, and none was unexpected for treatment with a beta-blocker. Only three patients withdrew because of adverse reactions. The results of this study indicate that metoprolol OROS given once daily is safe and well tolerated.