Hydrodynamic interactions between squirmers near walls: far-field dynamics and near-field cluster stability.

Confinement increases contacts between microswimmers in dilute suspensions and affects their interactions. In particular, boundaries have been shown experimentally to lead to the formation of clusters that would not occur in bulk fluids. To what extent does hydrodynamics govern these boundary-driven encounters between microswimmers? We consider theoretically the symmetric boundary-mediated encounters of model microswimmers under gravity through far-field interaction of a pair of weak squirmers, as well as the lubrication interactions occurring after contact between two or more squirmers. In the far field, the orientation of microswimmers is controlled by the wall and the squirming parameter. The presence of a second swimmer influences the orientation of the original squirmer, but for weak squirmers, most of the interaction occurs after contact. We thus analyse next the near-field reorientation of circular groups of squirmers. We show that a large number of swimmers and the presence of gravity can stabilize clusters of pullers, while the opposite is true for pushers; to be stable, clusters of pushers thus need to be governed by other interactions (e.g. phoretic). This simplified approach to the phenomenon of active clustering enables us to highlight the hydrodynamic contribution, which can be hard to isolate in experimental realizations.

[Treatment and Recidivism of Patients Convicted for Homicide After Release From a Forensic Psychiatry for Addiction Treatment]. / Behandlung und Rückfälligkeit bei entlassenen Tötungsdelinquenten aus der Forensischen Psychiatrie nach §â€Š64 StGB.

The forensic clinic for addiction treatment in Rostock is a forensic institution for patients who committed crimes under the influence of psychotropic substances. Regardless of the severity of the offence, patients receive different kinds of treatment depending on the therapy program. Criminal recidivism can be seen as one of the most important factors to validate success in treatment. Due to this purpose, an extensive recidivism study including all former patients from 2001 to 2012 was conducted at our clinic. The criminal court records as well as clinic-intern databases of 38 patients for whom homicide is the offence of referral and 38 patients with nonviolent crimes were analyzed for this study. The general recidivism rate for homicide delinquents was 47.7 %, but only 21 % of the examined patients were convicted to a new prison sentence. 7 homicide patients and 8 of the nonviolent group didn't finish the therapy successfully. Alcohol dependency was more common among the homicide patients. In addition, the average IQ was significantly lower than the comparison group. Compared to the nonviolent patients, homicide delinquents also got registered with a greater proportion of violent crimes during their criminal career.

[Value of fall-risk tests for patients with rheumatoid arthritis]. / Wertigkeit von Sturzrisikotests bei Patienten mit rheumatoider Arthritis.

The aim of the study was to quickly and efficiently determine the risk of falling in patients with rheumatoid arthritis over the age of 46 with established methods, to discover parameters which influence the risk of falling and fractures. The study group consisted of 67 patients (median age 69±7.4 years, duration of disease <10 years 71%).With the help of the present data on fractures the performance of the chair-rising (CR) test, the timed up-and-go (TUG) test and the tandem stand (TS) test plus determination of the average daily and cumulative glucocorticoid (GC) dosage, it was possible to detect parameters which influence the risk of falling and fractures.Higher age (>60 years), overweight, deficits in muscle strength in the lower extremities and very low GC dosage (≤5 mg) were found to be associated with an increased risk of falling, which is accompanied by an increased risk of fractures.

[Are hospital administrative data suitable for external quality assurance? Comparison of quality indicators based on separate statutory data collections (BQS) and hospital administrative data]. / Krankenhaus-Routinedaten zur externen Qualitätssicherung? Vergleich von Qualitätsindikatoren anhand der Daten der gesetzlichen externen Qualitätssicherung (BQS) und Routinedaten.

BACKGROUND: German hospitals are obliged legally to provide clinical data for external comparative quality assurance. Data rely on administrative data and just as on additional data collections for this purpose only. They are used to identify defined quality indicators (so-called BQS data). The Agency for Healthcare Research and Quality (AHRQ) also developed quality indicators that rely on hospital administrative data to evaluate the quality of inpatient care. METHODS: Six selected quality indicators were computed by both methods. 2007 data from the nationwide external quality assurance program were analyzed and compared to quality information derived from a 2007 10 % nationwide sample of administrative hospital data. RESULTS: Regarding the indicators "Obstetric trauma", "Mortality of community acquired pneumonia", "Postoperative deep vein thrombosis" and "Postoperative pulmonary embolism" rates are significantly higher in hospital administrative data than in BQS data (p < 0.01). Inversely, rates of the indicator "Decubitus ulcer" are significantly lower (p < 0.001). CONCLUSION: Possible causes for the results might be divergent motivations for data collection or restrictions in data collection. It remains unclear which method properly reflects the true status. Selected indicators (e. g. obstetric trauma), however, are suitable to be substituted by hospital administrative data.

Influence of gravity on a granular Maxwell's demon experiment.

In the usual description of the granular Maxwell's demon experiment, where phase separation occurs due to an instability in the densities, the control parameter scales linearly with gravity. In this paper we investigate this scaling experimentally using the properties of diamagnetic particles in strong magnetic-field gradients to reduce and even balance gravitation. We find that phase separation occurs even at vanishingly small gravitational accelerations as is predicted by other theories. This is due to the fact that granular samples tend to form clusters as a result of the inelasticity of the particle collisions. Combining the heat balance of the driven granular gas with the cooling rate and thus the appearance of clustering, we are able to describe the crossover between the limiting cases.

Experimental investigation of the freely cooling granular gas.

We investigate the dynamics of the freely cooling granular gas. For this purpose we diamagnetically levitate the grains providing a terrestrial milligravity environment. At early times we find good agreement with Haff's law, where the time scale for particle collisions can be determined from independent measurements. At late times, clustering of particles occurs. This can be included in a Haff-like description taking into account the decreasing number of free particles. At very late times, only a single particle determines the dynamics, which is again described by a version of Haff's law. With this a good description of the data is possible over the whole time range.

Characterisation of tumour vasculature in mouse brain by USPIO contrast-enhanced MRI.

To enhance the success rate of antiangiogenic therapies in the clinic, it is crucial to identify parameters for tumour angiogenesis that can predict response to these therapies. In brain tumours, one such parameter is vascular leakage, which is a response to tumour-derived vascular endothelial growth factor-A and can be measured by Gadolinium-DTPA (Gd-DTPA)-enhanced magnetic resonance imaging (MRI). However, as vascular permeability and angiogenesis are not strictly coupled, tumour blood volume may be another potentially important parameter. In this study, contrast-enhanced MR imaging was performed in three orthotopic mouse models for human brain tumours (angiogenic melanoma metastases and E34 and U87 human glioma xenografts) using both Gd-DTPA to detect vascular leakage and ultrasmall iron oxide particles (USPIO) to measure blood volume. Pixel-by-pixel maps of the enhancement in the transverse relaxation rates (Delta R(2) and Delta R(2)(*)) after injection of USPIO provided an index proportional to the blood volume of the microvasculature and macrovasculature, respectively, for each tumour. The melanoma metastases were characterised by a blood volume and vessel leakage higher than both glioma xenografts. The U87 glioblastoma xenografts displayed higher permeability and blood volume in the rim than in the core. The E34 glioma xenografts were characterised by a relatively high blood volume, accompanied by only a moderate blood-brain barrier disruption. Delineation of the tumour was best assessed on post-USPIO gradient-echo images. These findings suggest that contrast-enhanced MR imaging using USPIOs and, in particular, Delta R(2) and Delta R(2)(*) quantitation, provides important additional information about tumour vasculature.

Three-dimensional reconstruction of tumor microvasculature: simultaneous visualization of multiple components in paraffin-embedded tissue.

Three-dimensional (3D) visualization of microscopic structures may provide useful information about the exact 3D configuration, and offers a useful tool to examine the spatial relationship between different components in tissues. A promising field for 3D investigation is the microvascular architecture in normal and pathological tissue, especially because pathological angiogenesis plays a key role in tumor growth and metastasis formation. This paper describes an improved method for 3D reconstruction of microvessels and other microscopic structures in transmitted light microscopy. Serial tissue sections were stained for the endothelial marker CD34 to highlight microvessels and corresponding images were selected and aligned. Alignment of stored images was further improved by automated non-rigid image registration, and automated segmentation of microvessels was performed. Using this technique, 3D reconstructions were produced of the vasculature of the normal brain. Also, to illustrate the complexity of tumor vasculature, 3D reconstructions of two brain tumors were performed: a hemangioblastoma and a glioblastoma multiforme. The possibility of multiple component visualization was shown in a 3D reconstruction of endothelium and pericytes of normal cerebellar cortex and a hemangioblastoma using alternate staining for CD34 and alpha-smooth muscle actin in serial sections, and of a GBM using immunohistochemical double staining. In conclusion, the described 3D reconstruction procedure provides a promising tool for simultaneous visualization of microscopic structures.

Coronary artery stenting in cardiac allograft vascular disease.

Cardiac allograft vascular disease is characterized by diffuse and multifocal heterogeneous myointimal hyperplasia with or without vascular remodeling. Catheter-based interventions are indicated in selected patients. This study documents our experience with percutaneous transluminal coronary angioplasty and coronary stents (n = 48) in a group of 27 patients 5.7 +/- 2.9 years after heart transplantation. Early and intermediate results were controlled by angiography and intravascular ultrasound. Conventional percutaneous transluminal coronary angioplasty resulted in a mild and mostly inadequate gain in luminal dimensions (lumen area: 3.17 +/- 0.92 mm2 to 3.70 +/- 1.21 mm2; minimal lumen diameter: 1.84 +/- 0.23 mm to 2.04 +/- 0.36 mm). Coronary stenting led to a further improvement of luminal gain (lumen area: 3.70 +/- 1.21 mm2 to 5.86 +/- 1.76 mm2; minimal lumen diameter: 2.04 +/- 0.36 mm to 2.53 +/- 0.38 mm). These results were stabilized by application of aspirin and ticlopidine only. There were no stent thromboses or bleeding complications, and early hospital discharge of the patients was possible. At follow-up (mean follow-up period 7.72 +/- 5.45 months (range 0.50 to 23.13 months) all patients were clinically event free. In six of 24 stented vessels (25%) in 16 patients, significant restenosis (>50%) was found by intravascular ultrasound (n = 20) or by angiography (n = 4) 6 months after stent placement. We conclude that in eligible cardiac allograft vascular disease lesions primary stenting may be the method of choice. However, further evaluation of the modalities of stent application and different stent designs with respect to long-term survival is necessary.

The extent of peritubular CD14 staining in renal allografts as an independent immunohistological marker for acute rejection.

Previously, we demonstrated that in acute interstitial rejection, immunohistological staining of renal allograft biopsies with the CD14 mAb WT14, reacting with human monocytes/macrophages, shows a characteristic peritubular increase of positive cells. To test the diagnostic value of this CD14 positivity, we compared, in 154 unselected renal allograft biopsies, the extent of peritubular WT14 staining with (a) the original histological diagnosis, made with knowledge of clinical data, (b) the retrospectively and blindly scored histological diagnosis according to the criteria of the Banff classification, and (c) the eventual clinical diagnosis, which included evaluation of the response to therapy. The extent of peritubular WT14 positivity, blindly scored on cryostat sections of the frozen part of the biopsies, correlated positively with the probability of acute rejection (AR). When using a cutoff of 70% WT14 positivity for the diagnosis of AR, as extracted from a receiver operating characteristic curve, the WT14 diagnosis had a positive predictive value of 91% and a negative predictive value of 56%, compared with the original histological diagnosis. Compared with the Banff diagnosis of AR (grade I-III), these values were 95% and 47%, and compared with the clinical diagnosis, 84% and 63%, respectively. The WT14 diagnosis essentially corrected the original histological diagnosis in 7 cases, and was consistent with the eventual diagnosis in 5 equivocal cases. We conclude that the extent of peritubular CD14 positivity can be used as a marker for AR and can serve as a valuable additional criterion for AR in the histological examination of renal allograft biopsies.

When to treat varicocele?

In order to find criteria that might prognosticate the outcome of varicocele treatment, we studied 48 patients with unilateral or bilateral varicocele. Examinations prior to therapy included GnRH test and determination of alpha-glucosidase in addition to normal sperm analysis. The morphological analysis was performed according to the Düsseldorf classification. Thirty-five of the 48 patients underwent varicocele sclerosing, 13 patients received no therapy. Ten normozoospermic donors served as control. At 6-7 months after sclerosing, the aforementioned parameters were checked in all patients. Almost all of the untreated patients had pathological GnRH tests initially and on control, and sperm parameters had deteriorated. In the treated group, 75% had pathological GnRH tests initially. Of these, 70% improved, particularly sperm morphology with reduction of hyperelongated forms, and 30% had GnRH tests returned to normal. However, improved sperm parameters were also observed in 75% of patients who had normal GnRH tests initially. The improvement of sperm parameters was not associated with significant changes in alpha-glucosidase (normal initial values). According to these results, the GnRH test does not seem to be an important prognostic parameter for the outcome of varicocele therapy. However, patients with pathological values should be treated. Determination of alpha-glucosidase as an epididymal marker is no decisive criterion either. The most significant improvement was observed in patients with increased occurrence of hyperelongated spermatozoa.

Detection of interstitial increase in macrophages, characteristic of acute interstitial rejection, in routinely processed renal allograft biopsies using the monoclonal antibody KP1.

Acute interstitial rejection (AIR) of renal allografts is accompanied by a characteristic peritubular increase in macrophages, which can be identified with the CD14 monoclonal antibody (mAb) WT14 in cryostat sections. Since frozen tissue is not always available, we tested whether this increase can also be demonstrated in Bouin-fixed, paraffin-embedded biopsies, using the CD68 antimacrophage mAb KP1, which can also be applied to paraffin sections. Sections of 16 biopsies with AIR and 11 controls were stained with KP1. In 25 of the 27 biopsies, macrophages were strongly positive for KP1. Two AIR biopsies were completely negative, probably due to prolonged fixation. In the remaining 14 AIR biopsies, the number of KP1-positive cells was significantly higher than in the controls [1184 +/- 410 per mm2 (mean +/- SD) vs 112 +/- 126 per mm2]. We conclude that, especially in cases in which frozen tissue is not available, the demonstration of increased numbers of monocytes/macrophages with mAb KP1 can be a helpful adjunct in the histological diagnosis of AIR in routinely processed renal biopsies.

Tetrazolium [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] reduction by mycoplasmas.

We investigated 22 mycoplasma and acholeplasma species for their ability to reduce tetrazolium salts by using the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. The test results were evaluated visually, as well as spectrophotometrically, by using an enzyme-linked immunosorbent assay reader. Our results were very similar to the results obtained when the tetrazolium salt reduction assay described by Aluotto et al. was used. However, the MTT reduction assay appeared to be better because it is faster, more objective and sensitive, easier to evaluate, and less expensive; in addition, it allows quantitative determinations. By using regression analysis a linear correlation between formazan production and the number of colony-forming units was demonstrated for all of the species investigated, indicating that the MTT assay can also be used for growth, toxicity, or chemosensitivity tests for the mycoplasma species that are capable of reducing tetrazolium salts.

Immunocytology of urinary sediments as a method of differentiating acute rejection from other causes of declining renal graft function.

We have previously reported that during acute rejection of renal allografts T lymphocytosis and increased HLA-DR expression on tubular epithelial cells can be demonstrated in urinary sediments by incubating cytospin preparations with monoclonal antibodies against T cells and HLA-DR antigen in an indirect alkaline phosphatase technique. We now tested whether immunocytological analysis of urinary sediments can be used to differentiate acute rejection from other causes of declining graft function. For this we retrospectively selected, from a series of urinary samples that were taken either at random or as part of a longitudinal study in unselected graft recipients, those specimens that were taken at the time of increasing creatinine levels, and compared the original immunocytological diagnosis, made without knowledge of clinical data, with the final clinical one. In 44 of 74 evaluable cases an immunocytological diagnosis of rejection was made, which in 37 patients was consistent with the eventual clinical diagnosis. In 28 of 30 cases the diagnosis no rejection proved to be correct. This indicates a sensitivity of 95% and a specificity of 80% for the immunocytological diagnosis of rejection. Of 38 patients who underwent a renal core biopsy, the immunocytological diagnosis was consistent with the histological diagnosis in 36 cases (31 rejections, 5 no rejections). In this subgroup the sensitivity of the immunocytology was 97% and the specificity 83%. We conclude that immunocytological examination of urinary sediments in renal allograft recipients can be a valuable new tool in discriminating acute interstitial rejection from other causes of deteriorating graft function.

Variable expression of Ia antigens on the vascular endothelium of mouse skin allografts.

Ia antigens are membrane-bound glycoproteins that play a part in antigen recognition and subsequent cell-cell interactions in the immune response. In the mouse they are coded for by the I region of the major histocompatibility complex H-2 and have been demonstrated on B lymphocytes, monocytes, activated T cells, macrophages and dendritic cells, including Langerhans cells. Ia-like antigens have also been detected on the vascular endothelium in man and on epidermal keratinocytes in rats but expression on the latter cells was induced by a graft-versus-host reaction or by contact hypersensitivity. In the mouse, previous studies have suggested that Ia antigens in skin are restricted to epidermal Langerhans cells and it was thought that these were the targets for Ia-dependent rejection of skin allografts. The results presented here show that Ia antigens in mouse allografts are also present on the vascular endothelium but their expression is variable and dependent on the immunological status of the recipient. These findings suggest that vascular endothelial cells can act as targets in Ia-incompatible skin allograft rejection.