The influence of thyroid function and bone turnover on lipoprotein profile in young physically active men with different insulin sensitivity.

Physical activity induces changes in the endocrine system. Previous data indicated that changes in insulin secretion and the tissue response to this hormone are very important for energy metabolism. It is believed that they are accompanied by changes in lipid metabolism, but factors contributing to this process are still disputed. The aim of this study was to assess interactions among insulin sensitivity, thyroid function, a bone turnover marker and serum lipid profile in young physically active men. Eighty-seven physical education students, aged 18-23 years, participated in the study. We measured serum levels of glucose, lipids, insulin, thyroid-stimulating hormone (TSH), osteocalcin and anthropometric parameters. Insulin sensitivity was determined using homeostatic model assessment for insulin resistance (HOMA-IR). The median value of HOMA-IR (1.344) was used to divide the study population into Group A (above the median) and Group B (below the median). Men from both groups did not differ in anthropometric parameters or in daily physical activity. Triglycerides (TG), total cholesterol (TC) and high-density lipoprotein cholesterol (HDL-C) levels were higher in Group A (P < 0.05). TSH and osteocalcin levels were similar in males with different HOMA-IR. Multiple regression analysis for TSH and osteocalcin showed that in Group A these hormones had no effect on plasma lipoproteins. However, in Group B they significantly determined the variation of plasma TC and low-density lipoprotein cholesterol (LDL-C) levels (in about 28% and 29%, respectively). We concluded that TSH and osteocalcin are involved in determination of a more healthy lipid profile at a certain level of insulin sensitivity.

Reactive oxygen species production in the early and later stage of chronic ventilatory hypoxia.

Pulmonary hypertension resulting from chronic hypoxia is at least partly caused by the increased production of reactive oxygen species (ROS). The goal of the presented study was to investigate the dynamics and the site of production of ROS during chronic hypoxia. In our study Wistar rats were kept for 1, 4 and 21 days in an isobaric hypoxic chamber (F(iO2)=0.1), while controls stayed in normoxia. We compared NO production in expired air, plasma and perfusate drained from isolated rat lungs and measured superoxide concentration in the perfusate. We also detected the presence of superoxide products (hydrogen peroxide and peroxynitrite) and the level of ROS-induced damage expressed as the concentration of lipid peroxydation end products. We found that the production and release of ROS and NO during early phase of chronic hypoxia has specific timing and differs in various compartments, suggesting the crucial role of ROS interaction for development of hypoxic pulmonary hypertension.

Pulse pileup statistics for energy discriminating photon counting x-ray detectors.

PURPOSE: Energy discriminating photon counting x-ray detectors can be subject to a wide range of flux rates if applied in clinical settings. Even when the incident rate is a small fraction of the detector's maximum periodic rate No, pulse pileup leads to count rate losses and spectral distortion. Although the deterministic effects can be corrected, the detrimental effect of pileup on image noise is not well understood and may limit the performance of photon counting systems. Therefore, the authors devise a method to determine the detector count statistics and imaging performance. METHODS: The detector count statistics are derived analytically for an idealized pileup model with delta pulses of a nonparalyzable detector. These statistics are then used to compute the performance (e.g., contrast-to-noise ratio) for both single material and material decomposition contrast detection tasks via the Cramdr-Rao lower bound (CRLB) as a function of the detector input count rate. With more realistic unipolar and bipolar pulse pileup models of a nonparalyzable detector, the imaging task performance is determined by Monte Carlo simulations and also approximated by a multinomial method based solely on the mean detected output spectrum. Photon counting performance at different count rates is compared with ideal energy integration, which is unaffected by count rate. RESULTS: The authors found that an ideal photon counting detector with perfect energy resolution outperforms energy integration for our contrast detection tasks, but when the input count rate exceeds 20% N0, many of these benefits disappear. The benefit with iodine contrast falls rapidly with increased count rate while water contrast is not as sensitive to count rates. The performance with a delta pulse model is overoptimistic when compared to the more realistic bipolar pulse model. The multinomial approximation predicts imaging performance very close to the prediction from Monte Carlo simulations. The monoenergetic image with maximum contrast-to-noise ratio from dual energy imaging with ideal photon counting is only slightly better than with dual kVp energy integration, and with a bipolar pulse model, energy integration outperforms photon counting for this particular metric because of the count rate losses. However, the material resolving capability of photon counting can be superior to energy integration with dual kVp even in the presence of pileup because of the energy information available to photon counting. CONCLUSIONS: A computationally efficient multinomial approximation of the count statistics that is based on the mean output spectrum can accurately predict imaging performance. This enables photon counting system designers to directly relate the effect of pileup to its impact on imaging statistics and how to best take advantage of the benefits of energy discriminating photon counting detectors, such as material separation with spectral imaging.

[Disodium cromoglycate--mast cell degranulation blocker in the process of tissue remodelation]. / Kromoglykát sodný--blokátor degranulace zírných bunek v procesu tkánové remodelace.

Disodium cromoglycate (DSCG) is a compound commonly used in the treatment of allergic diseases. The effect of DSCG is due to its ability to stabilize the mast cell membrane and to prevent release of histamine and inflammatory mediators. Mast cells are also an abundant source of tissue metalloproteinases, serine proteases and growth factors, which play an important role in the processes of the tissue remodeling. In this view the DSCG is a substance which allows us to study the mechanisms of the pulmonary vascular bed remodeling in the experimental animals exposed to chronic hypoxia and in a phase of the recovery from hypoxia.

Oxidative stress in the lung tissue--sources of reactive oxygen species and antioxidant defence.

Reactive oxygen species are oxygen-based molecules readily reacting with various compounds. It is already known that they play significant role in many physiological as well as pathological body processes. The aim of our review is to briefly summarize our knowledge of possible ROS sources in the lung tissue.

Lung transplantation for cystic fibrosis: immune system and autoimmunity.

BACKGROUND: In the current study we focused on changes in the immune parameters of patients with CF after lung transplantation (Tx), with particular emphasis on the interaction of the immune system, infection, the autoimmune phenomenon observed in some CF patients, and immunosuppression. MATERIAL AND METHODS: Seven transplant patients with CF were investigated, 3 men and 4 women; the average age at Tx was 24.2 years (20.2-32.3). The parameters of both humoral immunity (immunoglobulins, complement, CRP, antinuclear and antineutrophil cytoplasmic antibodies) and cellular immunity (T and B lymphocytes, NK cells) were traced. RESULTS: We observed marked initial hyperimmunoglobulinemia, with a sharp drop in immunoglobulin levels within 1 month after Tx. Positivity for antineutrophil cytoplasmic antibodies (ANCA) was found in 3 patients before Tx. A strong ANCA positivity persisted 2 months after Tx despite deep introductory immunosuppression. In one patient ANCA positivity, after a transient negative result at months 2 and 12 after Tx, reappeared one year after Tx. The Burkholderia cepacia infections found in 2 patients proved to be lethal. CONCLUSIONS: In our series of CF lung transplant recipients, we found Burkholderia cepacia infection to be a risk factor. The robust appearance of autoantibodies and their persistent positivity for many months despite deep immunosuppression is a remarkable feature observed in some CF patients.