Causality Between the Amplitude and Frequency of Cardiac Oscillations

Using an information-theoretic approach, causality between the systolic amplitude in blood pressure and the frequency of the heart beat was analyzed. Blood pressure and ECG were noninvasively recorded in young, healthy subjects. Three successive measurements were performed: during spontaneous breathing and during paced respiration—at frequencies both higher and lower than that of spontaneous respiration. We demonstrate that the amplitude and frequency of the cardiac rhythm are synchronized for most of the time. The synchronization is stronger during paced respiration at a frequency lower than that of spontaneous breathing. Episodes where the cardiac frequency was driven by the systolic pressure were also detected during slow, paced respiration.     

Induction of primary anti-viral cytotoxic T cells by in vitro stimulation with short synthetic peptide and interleukin-7.

The present study investigated whether a short synthetic peptide NPP, with a modified sequence (147-158 R156-) derived from influenza A virus nucleoprotein with high affinity for Kd major histocompatibility complex class I molecules, could induce primary influenza virus-specific cytotoxic T (Tc) cells in vitro. Naive BALB/c (H-2d) splenocytes did not respond to the stimulation with only NPP with the generation of effector Tc cells specific for influenza A virus-infected target cells in vitro. However, they were able to do so if cultured with NPP in the presence of IL-7. IL-7 activity in this system differed significantly from IL-2 activity in the specificity of the effect. The use of exogenous IL-2, instead of IL-7, with NPP resulted in the induction of lytic cells that lysed both influenza virus-infected and uninfected syngeneic target cells. These results suggest that IL-7 is a potent regulatory cytokine in the antigen-specific activation of resting naive Tc cell precursors and may provide the necessary conditions for the induction of human primary Tc cells in vitro.     

High-performance liquid chromatographic determination of p-aminohippuric acid and iothalamate in human serum and urine: comparison of two sample preparation methods

A high-performance liquid chromatography method applied to determine p-aminohippuric acid (PAH) and iothalamate (IOT) in serum and urine samples of patients was evaluated according to recovery, reproducibility and linearity utilizing narrow-bore columns. The mobile phase consisted of 0.15 M sodium dihydrogenphosphate with 1.2 mM tetrabutylammonium sulphate, the pH was adjusted to pH 4.6, acetonitrile was added to a final ratio of 95:5 (v/v), the flow-rate was set at 0.3 ml/min. The separation was achieved on a ODS Hypersil column (200 x 2.1 mm I.D.). The UV detector was set at 254 nm. PAH and IOT are used for evaluation of kidney function [effective renal plasma flow (ERPF) and glomerular filtration rate (GFR)]). Under the described chromatographic conditions two sample preparation techniques, ultrafiltration and acetonitrile precipitation were compared. The results demonstrate the accuracy of both methods in evaluation of ERPF and GFR. Due to its cost-effectiveness we recommend the acetonitrile precipitation method in clinical routine.     

Japanese encephalitis virus glycoproteins

Mature Japanese encephalitis (JE) virus, or N-form virus, contained three structural proteins: V-1, V-2, and V-3. The large membrane protein V-3 was glycosylated, whereas both V-1 (the small membrane protein) and V-2 (the nucleocapsid protein) were not. Intracellular (I-form), immature virions from infected chick embryo cells did not contain V-1 but a larger protein NV-2, which was glycosylated. T-form virions, released by LLC-MK₂ cells incubated with tris(hydroxymethyl)amino-methane (Tris), also contained the glycoprotein NV-2 instead of the nonglycosylated and smaller V-1. We therefore concluded that JE contained two structural membrane glycoproteins, at least one of which is modified during morphogenesis. The NV-2 polypeptide was heterogeneous, and slight differences in electrophoretic mobility were detected among the NV-2 polypeptide peaks from glucosamine-labeled I-form and T-form virions, glucosamine-labeled cell extracts, and amino acid-labeled cell extracts. The significance of these differences is not clear, but they may indicate that NV-2 is composed of several proteins of similar molecular weight. By analyzing extracts of infected cells labeled with glucosamine or amino acids, we tentatively classified the intracellular polypeptide NV-3 as a virus-specified nonstructural glycoprotein; this polypeptide may be a proteolytic fragment of V-3. The virus-specified polypeptides NV-5, NV-4, and NV-1 were classified as nonglycosylated, nonstructural proteins.     

Detection of lignin biopolymer- and vitamin E-stimulated reduction of DNA strand breaks in H2O2- and MNNG-treated mammalian cells by the comet assay

In this study the possible protective effects of water-soluble sulfur-free lignin biopolymer and vitamin E (alpha-tocopherol) on DNA in human VH10 cells and hamster V79 cells exposed to H2O2 and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were investigated. The level of DNA damage (DNA strand breaks) was measured using single-cell gel electrophoresis, i.e., comet assay. Lignin biopolymer and vitamin E exhibited a protective effect against the overall DNA damage induced after H2O2 treatment. If H2O2-treated human cells were incubated for 90 minutes to ligate frank breaks of DNA, two lesion-specific enzymes, endonuclease III and formamidopyrimidine DNA glycosylase (FPG), significantly increased the level of DNA strand breaks originating from oxidized pyrimidines and purines. Preincubation of cells with lignin or vitamin E reduced mainly the level of oxidized pyrimidines. Reduction of oxidized purines was less evident. In addition, lignin biopolymer exhibited a protective effect against MNNG-induced DNA damage, whereas vitamin E exhibited a protective effect only against H2O2-induced DNA damage. These findings suggest that the antioxidant nature of lignin biopolymer enables a reduction of the level of frank breaks and of oxidized DNA bases in H2O2-treated cells, and its adsorptive capacity enables binding of nitroso compounds and reduction of alkylation in MNNG-treated cells.     

Lamina propria of sex cords in human fetal testis: an immunohistological and stereological study

Testicular peritubular cells are located in the lamina propria of seminiferous tubules. These cells, significantly contributing to the basal membrane of seminiferous epithelium, have been studied in a number of species. However, there is a lack of data on the development of the lamina propria in the human testis. The aim of our survey was to investigate the characteristics of the lamina propria and, in particular, peritubular cells in the fetal human testes by immunohistological and stereological methods. Therefore, testes (14–39 weeks of gestation, n=45) were dissected and fixed in a 4% buffered paraformaldehyde solution. Several pieces of each testis were embedded in paraffin and processed for immunohistochemical and stereological analysis. All investigated testes have shown sex cords in the process of development and differentiation. Morphologically, peritubular cells in the lamina propria can be divided into two types: fibroblast-like (FL) and myoid-like (ML) type (cells which much resemble mature myoid cells). By immunohistochemistry, both FL and ML cells are found to be strongly positive for the intermediate filament desmin, but negative for -smooth actin. While FL cells intensively express Ki-67 demonstrating proliferative activity, ML cells are found to be negative. The basement membrane of sex cords as well as the blood vessels of the interstitium show strong positivity to collagen IV and laminin. Concerning the correlation between the appearance of the investigated antigens with the gestational age, all antigens have been expressed (in the manner described above) already in the 14th week of gestation. The stereological analysis of the number (Nv) and volume (Vv) of peritubular cells indicates a pulsatile development of these cells in the lamina propria of the human fetal testis. While the stereological variables determined for FL cells show a gradual decrease, the same variables determined for ML cells demonstrate a successive increase. It appears that the lamina propria of the fetal human testes shares many of the properties previously discovered in rodents.     

Evaluation of Sediments from the River Drava and Their Potential for Further Use in the Building Sector

Sedimentation is a naturally occurring process of allowing particles in water bodies to settle out of the suspension under a gravity effect. In this study, the sediments of the Drava River were fully investigated to determine the heavy metal concentrations along the river and their potential reuse in the construction sector. Naturally dehydrated sediments from the Drava River were tested as an additive for the production of fired bricks. The dredged sediments were used as a substitute for natural brick clay in amounts up to 50% by weight, and it was confirmed that up to 20% by weight of the added sediment could be used directly in the process without critically affecting performance. Finally, the naturally dehydrated sediments were also evaluated for their use as a filling material in the construction of levees. The natural moisture content of the dehydrated sediment was too high for it to be used without additives, so quicklime was added as an inorganic binder. The test results showed an improvement in the geotechnical properties of the material to such an extent that it is suitable as a filling material for levees.     

Endovascular Treatment of Thoracic Dissection

Background: Surgical residents used to work many hours. The European working time directive (EWTD) 2003/88/EG was created to protect young doctors from working too many hours. EWTD was implemented in Belgium on February 1st 2011. A decrease in working hours and improvement of surgical education was expected. Methods: Every resident was requested by the Faculty of Medicine to answer an ACC (Activities Coaching Context) questionnaire about his/her teaching hospital. The answers of surgical residents in all teaching hospitals, during the academic years before, during and after the implementation of the EWTD were used. Statistical analysis was performed with SPSS 20.

Results: Since implementation we noted a significant decrease in mean daily working time (MDWT) (p < 0,001). However, this MDWT stayed significantly longer in university hospitals (UH), even after implementation of EWTD (p = 0,024). Non-medical administrative workload (AW) did not change significantly (p = 0,531), but medical AW increased significantly after implementation (p = 0,050). Non-medical and medical AW were significantly higher in UH after implementation (p = 0,002 and p < 0,001). The opportunity to practice skills and also the perception of a good balance between working and learning did not change significantly after implementation (p = 0,200 and p = 0,819), but both were scored significantly better in non-UH (p < 0,001 and p = 0,052) regardless implementation of EWTD. Conclusions: Since implementation of EWTD there is a significant decrease in MDWT. However, AW has not decreased and is higher in UH. The main challenge for future surgical education will be to reduce AW in order to give surgical residents enough opportunities to practice their surgical skills without prolonging training time.