A hydrodynamic interaction between bubbles and gas supply system during gas bubble departures in liquids: an experimental study.

In the present paper, the hydrodynamic interactions between bubbles and the gas supply system to a needle were experimentally investigated. In experimental investigations in one of the needles, the air volume flow rate was constant, and in the neighbouring needle, it was changed. In the paper, the methods of data analysis: wavelet decomposition, and FFT were used. It was shown that the hydrodynamic interaction becomes stronger with the increase in air volume flow rate supply to the needle. The occurrence of hydrodynamic interaction modifies bubble growth time slightly, but it significantly modifies the bubble waiting time. In the case when the liquid penetration into the needle is repeatable, then the percentage disturbances in bubble growth time and bubble waiting time are close to each other. Moreover, it can be concluded that synchronized or alternative bubble departures from twin neighbouring needles (occurring due to hydrodynamic interaction) are possible by modifying the bubble waiting time. The modification of hydrodynamic interaction between bubbles, the bubbles themselves, and gas supply systems can be used to control the bubble departure process.

[Promotion of next generation urologists-Construct urology of the future]. / Förderung des urologischen Nachwuchses ­ Urologie der Zukunft gestalten.

In view of the growing demand for urological care and the simultaneous demographic change, the need for urologists in Germany is increasing. Therefore, young professionals are urgently needed to ensure urological care in the future. This objective can be achieved by fascinating medical students for urology and by implementing satisfactory residency programs in clinical departments and outpatient offices. Perspectives and possible career paths should be shown to junior colleagues at an early stage. Structured research funding is needed to reconcile academic with clinical work. The German Society for Residents in Urology (GeSRU) offers young urologists a platform for networking, for representation of interests as well as for education and training.

[Experiencing continuing education-experience of future urologists]. / Weiterbildung erlebt ­ Erfahrung des urologischen Nachwuchses.

Structured residency programmes within dedicated associations of hospitals, practices and medical care centres offer the opportunity to improve the quality of training and to increase the attractiveness of urology through fixed rotations of doctors in continued training. The implementation of such programmes is guided by the framework conditions of the respective location. Possible rotations range from andrology to paediatric urology and uro-gynaecology to interdisciplinary uro-oncology. An outpatient training period also offers the chance for a change of perspective and supports career orientation. Rotations in the interdisciplinary intermediate care unit offer the opportunity to become familiar with the care of complex disease processes, including the differential diagnostic assessment of abdominal diseases, which is important in urology. In summary, the diversity of urological training available can enable junior urologists to receive more individualised and targeted training by promoting multilayered, intersectoral as well as interprofessional training.

Mitochondrial membrane potential and reactive oxygen species in liquid stored and cryopreserved turkey (Meleagris gallopavo) spermatozoa.

The extensive use of artificial insemination in turkeys has led to the development of in vitro semen storage. However, fertility rates from liquid stored and frozen/thawed turkey semen are still unsatisfactory. The aim of the study was to assess spermatozoa viability, mitochondrial membrane potential (MMP), and reactive oxygen species production (ROS) in liquid stored and cryopreserved turkey semen with the use of flow cytometry. Moreover, motility and adenosine triphosphate (ATP) content in sperm were monitored at the same time to link flow cytometry data with sperm movement and energetics. Liquid storage led to a decrease in sperm motility (80.6 vs. 55.6%, for fresh and stored for 48 h), live sperm with an intact MMP (59.9 vs. 30.5% for fresh and stored for 48 h), and a 20-fold decrease in ATP content after 24 h of storage. A 3-fold increase in ROS+ sperm was observed after 48 h of storage (9.3 vs. 26.8% for fresh and stored for 48 h). Semen equilibration before cryopreservation affected only ATP content. However, freezing/thawing led to a dramatic decrease in all of the studied semen quality parameters. A 5-fold decrease in live sperm with intact MMP (59.8 vs. 11.9%) and a 7-fold increase in sperm ROS+ (10.8 vs. 74.4%) were recorded between fresh and frozen/thawed semen. The results strongly suggested that a significant loss of MMP and a disturbance in sperm ATP production during semen storage can be the main reason for the decline in sperm motility. The disturbance of mitochondria activity during storage seems to be associated with the increase in oxidative stress in turkey semen. Turkey sperm mitochondria also appear to be very sensitive to cryodamage. Diminished energy production in turkey spermatozoa, visible as the low percentage of sperm with an intact MMP and low level of ATP after freezing/thawing, which is associated with high ROS generation, could be responsible for the low fertilizing ability of cryopreserved turkey semen.

Echocardiographic assessment of right ventricle adaptation to endurance training in young rowers - speckle tracking echocardiography.

The aim of this study was to determine the relationship between the degree of cardiorespiratory fitness and the function of the right ventricle (RV). 117 rowers, age 17.5±1.5 years. All subjects underwent cardiopulmonary exercise. Standard echocardiography and 2D speckle tracking echocardiography with evaluation of longitudinal strain in each segment of the RV (basal - RVLS-B; mid - RVLS-M, apical - RVLS-A) and global RV free-wall strain (RVLS-G) were performed. RVLS-B values were lower compared to the RVLS-M (-25.8±4.4 vs -29.3±3.5; p<0.001) and RVLS-A values (-25.8±4.4 vs -26.2±3.4; p=0.85). Correlations between VO2max and RVLS were observed in men: RVLS-G strain (r = 0.43; p <0.001); RVLS-B (r = 0.30; p = 0.02); RVLS-M (r = 0.38; p = 0.02). A similar relationship was not observed in the group of women. The strongest predictors corresponding to a change in global and basal strain were VO2max and training time: RVLS-G (VO2max: ß = 0.18, p = 0.003; training time: ß = -0.39; p = 0.02) and RVLS-B (VO2max: ß = 0.23; p = 0.0001 training time: ß = -1.16; p = 0.0001). The global and regional reduction of RV systolic function positively correlates with the level of fitness, and this relationship is observed already in young athletes. The character of the relationship between RV deformation parameters and the variables that determine the physical performance depend on gender. The dependencies apply to the proximal fragment of the RV inflow tract, which may be a response to the type of flow during exercise in endurance athletes.

Respiration response imaging for real-time detection of microbial function at the single-cell level.

The ability to detect specific functions of uncultured microbial cells in complex natural communities remains one of the most difficult tasks of environmental microbiology. Here we present respiration response imaging (RRI) as a novel fluorescence microscopy-based approach for the identification of microbial function, such as the ability to use C(1) substrates, at a single-cell level. We demonstrate that RRI could be used for the investigation of heterogeneity of a single microbial population or for functional profiling of microbial cells from complex environmental communities, such as freshwater lake sediment.

Elevating tensor rank increases anisotropy in brain areas associated with intra-voxel orientational heterogeneity (IVOH): a generalised DTI (GDTI) study.

Rank-2 tensors are unable to represent multi-modal diffusion associated with intra-voxel orientational heterogeneity (IVOH), which occurs where axons are incoherently oriented, such as where bundles intersect or diverge. Under this condition, they are oblate or spheroidally shaped, resulting in artefactually low anisotropy, potentially masking reduced axonal density, myelinisation and integrity. Higher rank tensors can represent multi-modal diffusion, and suitable metrics such as generalised anisotropy (GA) and scaled entropy (SE) have been introduced. The effect of tensor rank was studied through simulations, and analysing high angular resolution diffusion imaging (HARDI) data from two volunteers, fit with rank-2, rank-4 and rank-6 tensors. The variation of GA and SE as a function of rank was investigated through difference maps and region of interest (ROI)-based comparisons. Results were correlated with orientation distribution functions (ODF) reconstructed with q-ball, and with colour-maps of the principal and second eigenvectors. Simulations revealed that rank-4 tensors are able to represent multi-modal diffusion, and that increasing rank further has a minor effect on measurements. IVOH was detected in subcortical regions of the corona radiata, along the superior longitudinal fasciculus, in the radiations of the genu of the corpus callosum, in peritrigonal white matter and along the inferior fronto-occipital and longitudinal fascicula. In these regions, elevating tensor rank increased anisotropy. This was also true for the corpus callosum, cingulum and anterior limb of the internal capsule, where increasing tensor rank resulted in patterns that, although mono-modal, were more anisotropic. In these regions the second eigenvector was coherently oriented. As rank-4 tensors have only 15 distinct elements, they can be determined without acquiring a large number of directions. By removing artefactual underestimation of anisotropy, their use may increase the sensitivity to pathological change.

The "open" and "closed" structures of the type-C inorganic pyrophosphatases from Bacillus subtilis and Streptococcus gordonii.

Recently, a new class of soluble inorganic pyrophosphatase (type-C PPase) has been described that is not homologous in amino acid sequence or kinetic properties to the well-studied PPases (types A and B) found in many organisms from bacteria to humans and thought to be essential to the cell. Structural studies of the type-C PPases from Streptococcus gordonii and Bacillus subtilis reveal a homodimeric structure, with each polypeptide folding into two domains joined by a flexible hinge. The active site, formed at the interface between the N and C-terminal domains, binds two manganese ions approximately 3.6 A apart in a conformation resembling binuclear metal centres found in other hydrolytic enzymes. An activated water molecule bridging the two metal ions is likely poised for nucleophilic attack of the substrate. Importantly, the S. gordonii and B. subtilis enzymes have crystallised in strikingly different conformations. In both subunits of the S. gordonii crystal structure (1.5 A resolution) the C-terminal domain is positioned such that the active site is occluded, with a sulphate ion bound in the active site. In contrast, in the B. subtilis structure (3.0 A resolution) the C-terminal domain is rotated by about 90 degrees, leaving the active site wide open and accessible for substrate binding.

Local experience in the diagnosis of avascular necrosis of the femoral head in adults using magnetic resonance.

We analyzed MRI results from 36 patients referred for testing to assess the degree of advancement of non-traumatic avascular necrosis (AVN) of the femoral head in adults (24 cases) or for diagnosis in difficult cases (12 cases). 32 patients were found to have AVN of the femoral head with various degree of advancement, mostly stages III and IV. In three cases the MRI did not show any pathology within the hip joint, and in one case the MRI picture was consistent with a metastatic lesion. This suggests that the value of the MRI as a sensitive diagnostic tool in the early diagnosis of AVN in adults is underestimated.

Human papillomavirus and host variables as predictors of clinical course in patients with juvenile-onset recurrent respiratory papillomatosis.

This study provides the first systematic evaluation of papillomavirus type and viral mutation occurring during the course of juvenile-onset recurrent respiratory papillomatosis. One hundred ninety-nine consecutive papillomas excised from 47 children between 1981 and 1996 at The New Children's Hospital in Sydney, Australia, were tested for human papillomavirus (HPV) DNA by PCR. PCR products from the viral upstream regulatory region (URR) enhancer were sequenced, and variation was related to clinical variables. Forty-four of the 47 children had HPV-induced papillomas, with type 11 accounting for 24 (55%) and type 6 accounting for 19 (43%); one (2%) was positive for either type 6 or 11. Overall, 183 (98%) of the 186 samples with amplifiable DNA were HPV positive. There was no change in HPV type over time and no statistically significant association between HPV type and disease aggressiveness. One novel, large-scale URR duplication was identified in an HPV type 11 isolate in the last of a series of six papillomas examined and the first from the bronchus. However, the duplication was not found in HPV type 11 isolates from the associated pulmonary carcinoma and its metastases in other organs. Three of 14 URR point mutations coincided with transcription factor binding sites, but there were no obvious associations with clinical course. Chi-square and multiple linear regression analyses of clinicopathological variables revealed early age at diagnosis (less than 4 years) as an independent predictor of aggressive disease (P < 0.001). A bimodal distribution of the age at diagnosis was noted, with peaks at 2 and 11 years of age.

Phenotyping methods in epidemiological analysis of epidemic Staphylococcus aureus strains.

One hundred and fifty hospital Staphylococcus aureus strains isolated on Polish hospitals during an outbreaks were used to evaluate usefulness of S. aureus phenotyping methods. According to the expression of resistance to methicillin (a marker of resistance to all beta-lactam antibiotics) all strains were classified as homogeneously of heterogeneously resistant to methicillin (methicillin resistant S. aureus--MRSA) and as susceptible to this antibiotic (methicillin-susceptible S. aureus--MSSA). All strains were analysed according to the resistance patterns to fifteen antistaphylococcal drugs, results of crystal violet test, phage patterns and results of biochemical fingerprinting by PhenePlate (PhP) System (BioSys inova). All MSSA analysed were resistant to penicillin and 22% to tetracycline, and only occasionally resistant to other antimicrobials. They showed sensitive to phages of all international and additional lytic groups. Heterogeneous MRSA were widely susceptible to almost all antimicrobials except tetracycline and were lysed by phages of Ist, IIIrd international groups and additional phages. All these strains produced penicillinases. Homogeneous MRSA were multi-drug resistant and were not typable by phages of Ist and IInd lytic groups and weakly typable by phages of IIIrd and additional groups. PhP Systems divided all used strains into 13 common (with two dominating) and 50 single strain PhP-types. The combination of various phenotyping methods may be useful in epidemiological investigation of hospitals.

[Analysis of selected prognostic factors in patients with ruptured cerebral aneurysms operated-on in the early period]. / Analiza wybranych czynników prognostycznych u chorych z peknietym tetniakiem mózgu operowanych we wczesnym okresie.

An analysis of certain clinical and laboratory findings of 80 patients with ruptured intracranial aneurysms was done. All of them underwent an operation in acute stage. The following prognostic factors were analysed: age of patient, sex, number of previous subarachnoid hemorrhages (SAH), clinical status according to the Hunt-Hess scale, CT finding according to Fisher scale, location and number of aneurysms, time of operation, Nimodipine treatment, body temperature, serum sodium level, white blood count just before operation, mean blood pressure, coexistence of heart and kidney disease. A special computer programme was used to analyse the value of the above factors on follow-up and the final results of the ruptured intracranial aneurysms treated surgically in acute stage.

Thy-1 antigen is specific to ganglion cells in chicks.

The cellular localization of Thy-1 in the chick retina was investigated by selectively destroying certain populations of neurons with toxins. In control retinae four weeks after intravitreal injection of vehicle, there was strong immunoreactivity for Thy-1 in the nerve fibre layer, ganglion cell layer and inner plexiform layer. By contrast, 4 weeks after intraocular injection with 1.25 nmol of colchicine, virtually all ganglion cells had been destroyed, but most amacrine cells remained. Very little Thy-1 immunoreactivity was evident in these retinae. Four weeks after intraocular injection of 2 mumol of N-methyl-D-aspartic acid (NMDA), a large proportion of amacrine cells had been destroyed, but most ganglion cells remained. In these retinae Thy-1 immunoreactivity was present in the nerve fibre, ganglion cell and inner plexiform layers, in the latter with greater intensity than in controls. We conclude that in chicks the Thy-1 antigen is principally, if not exclusively restricted to ganglion cells.

Thy-1 expression in the retinotectal system of the chick.

Previous investigations into the occurrence of Thy-1 in the chick retina have not clearly defined when the antigen first appears and have not adequately described its expression during the relatively early phases of retinal ontogeny. We have investigated these issues, using improved immunohistochemical procedures and show that Thy-1 is associated with the retinal ganglion cells from the time they begin to differentiate by extending their axonal projections. In addition, we have found that its expression reflects the growth of the optic fibre layer and the elaboration of the ganglion cell dendritic processes into the inner plexiform layer. For the first time we describe the appearance and the developmental expression of Thy-1 in the chick tectum. We have found that Thy-1 is associated with retinal axons from the time of their arrival at the tectum and that its expression reflects the elaboration of the stratum opticum. Within the tectum proper Thy-1 appears first in 3 distinct layers all of which are plexiform in nature. By the time that tectal histogenesis is essentially complete the antigen is expressed by all the layers of the tectum. The implications of these findings are discussed in terms of the development of the individual tissues and with respect to the elaboration of the retinotectal pathway.

The developmental appearance of Thy-1 in the avian cerebellum.

The cellular localization of the Thy-1 antigen during development of the chick cerebellum has been investigated using a monoclonal antibody SB1-20.11. Improved cellular morphology and retention of both membrane and intracellular antigenicity was achieved by the immunohistochemical labelling of polyester wax sections using an indirect peroxidase visualization protocol. A parallel histological investigation was carried out using a modified silver staining procedure based on that of Bodian. Immunoreactivity was found throughout development in the soma and dendritic tree of the Purkinje cell, in the internal granular layer, white matter and elements of the deep cerebellar nuclei. The antigen's expression closely correlates to the morphological maturation of Purkinje cell population. Furthermore, it appears to reflect the formation of glomeruli and the basket cell interaction with the Purkinje cell. An association of Thy-1 with climbing fibres, as reported previously in rodent species, cannot be unambiguously shown in the chick because of the high levels of Thy-1 expressed throughout development on the Purkinje cell dendrites in the molecular layer. The spatial and temporal pattern of expression in the chick cerebellum suggests that Thy-1 contributes to the definition of synaptic fields.