Designing mobile application messages to impact route choice: A survey and simulation study

Crowd congestion is a common issue at train stations around major sports events, and puts passengers at risk and lowers service quality. Guiding arriving fans along less traveled routes may alleviate congestion. Smartphone apps provide a medium to deliver route suggestions but the messages they provide are pivotal to adherence. We explore how message design affects pedestrians' willingness to follow route instructions. We present an online survey conducted with two groups: football fans, and students and faculty associates. We vary the presence of top down views of the route choices at train station Münchner Freiheit in Munich, real-time information on congestion, and appeals to team spirit. We compute a distribution of route choices that suggests that congestion may be reduced with the right combination of message components for each target group. We then use a computer simulation to investigate the congestion situation. Our results suggest that lowest congestion is achieved when people base their decisions on real-time information. The social identity approach is highlighted in our study as having a possible influence on message design. Moreover, it indicates that the implementation of such apps in real-life applications can improve safety. Our methodology can be applied to other scenarios to test the suitability of apps and message designs.

Agent-based simulation of collective cooperation: from experiment to model

Simulation models of pedestrian dynamics have become an invaluable tool for evacuation planning. Typically, crowds are assumed to stream unidirectionally towards a safe area. Simulated agents avoid collisions through mechanisms that belong to each individual, such as being repelled from each other by imaginary forces. But classic locomotion models fail when collective cooperation is called for, notably when an agent, say a first-aid attendant, needs to forge a path through a densely packed group. We present a controlled experiment to observe what happens when humans pass through a dense static crowd. We formulate and test hypotheses on salient phenomena. We discuss our observations in a psychological framework. We derive a model that incorporates: agents’ perception and cognitive processing of a situation that needs cooperation; selection from a portfolio of behaviours, such as being cooperative; and a suitable action, such as swapping places. Agents’ ability to successfully get through a dense crowd emerges as an effect of the psychological model.

Walking on stairs: Experiment and model

An increasing global population forces urban planners to construct buildings and infrastructure that is extremely deep and high. Elevators and escalators serve skyscrapers and tunnels, but in an emergency people still have to walk on stairs. Computer simulations can mitigate risks of escape situations. For these situations, pedestrian locomotion models need to match reality well. Motion on stairs, however, is not nearly as well understood as motion in the plane. Publications are scarce and some are contradictory. As a result, movement on stairs is usually modeled by slowing down pedestrians by a fixed factor. But is this justified? And what happens at intermediate landings? This contribution aims to clarify inconclusive results of previous research and provide new information to directly incorporate empirical results into a parsimonious computer model. The algorithms are freely available through an open-source framework. After outlining the shortcomings of existing approaches, we present three experiments, from which we derive requirements for the computer model. Reenacting computer experiments shows the extent to which our model meets our observations. We conclude with an applied example, simulating an evacuation of Germany's famous Neuschwanstein Castle.

Arthroscintigraphy in Suspected Rotator Cuff Rupture

Aim: In order to evaluate the diagnostic efficiency of arthroscintigraphy in suspected rotator cuff ruptures this new imaging procedure was performed 20 times in 17 patients with clinical signs of a rotator cuff lesion. The scintigraphic results were compared with sonography (n = 20), contrast arthrography (n = 20) and arthroscopy (n = 10) of the shoulder joint. Methods: After performing a standard bone scintigraphy with intravenous application of 300 MBq 99m-Tc-methylene diphosphonate (MDP) for landmarking of the shoulder region arthroscintigraphy was performed after an intraarticular injection of 99m-Tc microcolloid (ALBURES 400 μCi/5 ml). The application was performed either in direct combination with contrast arthrography (n = 10) or ultrasound conducted mixed with a local anesthetic (n = 10). Findings at arthroscopical surgery (n = 10) were used as the gold standard. Results: In case of complete rotator cuff rupture (n = 5), arthroscintigraphy and radiographic arthrography were identical in 5/5. In one patient with advanced degenerative alterations of the shoulder joint radiographic arthrography incorrectly showed a complete rupture which was not seen by arthroscintigraphy and endoscopy. In 3 patients with incomplete rupture, 2/3 results were consistant. A difference was seen in one patient with a rotator cuff, that has been already revised in the past and that suffered of capsulitis and calcification. Conclusion: Arthroscintigraphy is a sensitive technique for detection of rotator cuff ruptures. Because of the lower viscosity of the active compound, small ruptures can be easily detected, offering additional value over radiographic arthrography and ultrasound, especially for evaluation of incomplete cuff ruptures.

How cognitive heuristics can explain social interactions in spatial movement

The movement of pedestrian crowds is a paradigmatic example of collective motion. The precise nature of individual-level behaviours underlying crowd movements has been subject to a lively debate. Here, we propose that pedestrians follow simple heuristics rooted in cognitive psychology, such as 'stop if another step would lead to a collision' or 'follow the person in front'. In other words, our paradigm explicitly models individual-level behaviour as a series of discrete decisions. We show that our cognitive heuristics produce realistic emergent crowd phenomena, such as lane formation and queuing behaviour. Based on our results, we suggest that pedestrians follow different cognitive heuristics that are selected depending on the context. This differs from the widely used approach of capturing changes in behaviour via model parameters and leads to testable hypotheses on changes in crowd behaviour for different motivation levels. For example, we expect that rushed individuals more often evade to the side and thus display distinct emergent queue formations in front of a bottleneck. Our heuristics can be ranked according to the cognitive effort that is required to follow them. Therefore, our model establishes a direct link between behavioural responses and cognitive effort and thus facilitates a novel perspective on collective behaviour.

Parsimony versus Reductionism: How Can Crowd Psychology be Introduced into Computer Simulation?

Computer simulations are increasingly being used to monitor and predict the movement behavior of crowds. This can enhance crowd safety at large events and transport hubs, and increase efficiency such as capacity utilization in public transport systems. However, the models used are mainly based on video observations, not an understanding of human decision making. Theories of crowd psychology can elucidate the factors underpinning collective behavior in human crowds. Yet, in contrast to psychology, computer science must rely upon mathematical formulations in order to implement algorithms and keep models manageable. Here, we address the problems and possible solutions encountered when incorporating social psychological theories of collective behavior in computer modeling. We identify that one primary issue is retaining parsimony in a model while avoiding reductionism by excluding necessary aspects of crowd psychology, such as the behavior of groups. We propose cognitive heuristics as a potential avenue to create a parsimonious model that incorporates core concepts of collective behavior derived from empirical research in crowd psychology.

Gradient navigation model for pedestrian dynamics

We present a microscopic ordinary differential equation (ODE)-based model for pedestrian dynamics: the gradient navigation model. The model uses a superposition of gradients of distance functions to directly change the direction of the velocity vector. The velocity is then integrated to obtain the location. The approach differs fundamentally from force-based models needing only three equations to derive the ODE system, as opposed to four in, e.g., the social force model. Also, as a result, pedestrians are no longer subject to inertia. Several other advantages ensue: Model-induced oscillations are avoided completely since no actual forces are present. The derivatives in the equations of motion are smooth and therefore allow the use of fast and accurate high-order numerical integrators. At the same time, the existence and uniqueness of the solution to the ODE system follow almost directly from the smoothness properties. In addition, we introduce a method to calibrate parameters by theoretical arguments based on empirically validated assumptions rather than by numerical tests. These parameters, combined with the accurate integration, yield simulation results with no collisions of pedestrians. Several empirically observed system phenomena emerge without the need to recalibrate the parameter set for each scenario: obstacle avoidance, lane formation, stop-and-go waves, and congestion at bottlenecks. The density evolution in the latter is shown to be quantitatively close to controlled experiments. Likewise, we observe a dependence of the crowd velocity on the local density that compares well with benchmark fundamental diagrams.

Predicting pedestrian flow: a methodology and a proof of concept based on real-life data

Building a reliable predictive model of pedestrian motion is very challenging: Ideally, such models should be based on observations made in both controlled experiments and in real-world environments. De facto, models are rarely based on real-world observations due to the lack of available data; instead, they are largely based on intuition and, at best, literature values and laboratory experiments. Such an approach is insufficient for reliable simulations of complex real-life scenarios: For instance, our analysis of pedestrian motion under natural conditions at a major German railway station reveals that the values for free-flow velocities and the flow-density relationship differ significantly from widely used literature values. It is thus necessary to calibrate and validate the model against relevant real-life data to make it capable of reproducing and predicting real-life scenarios. In this work we aim at constructing such realistic pedestrian stream simulation. Based on the analysis of real-life data, we present a methodology that identifies key parameters and interdependencies that enable us to properly calibrate the model. The success of the approach is demonstrated for a benchmark model, a cellular automaton. We show that the proposed approach significantly improves the reliability of the simulation and hence the potential prediction accuracy. The simulation is validated by comparing the local density evolution of the measured data to that of the simulated data. We find that for our model the most sensitive parameters are: the source-target distribution of the pedestrian trajectories, the schedule of pedestrian appearances in the scenario and the mean free-flow velocity. Our results emphasize the need for real-life data extraction and analysis to enable predictive simulations.

Avoiding numerical pitfalls in social force models

The social force model of Helbing and Molnár is one of the best known approaches to simulate pedestrian motion, a collective phenomenon with nonlinear dynamics. It is based on the idea that the Newtonian laws of motion mostly carry over to pedestrian motion so that human trajectories can be computed by solving a set of ordinary differential equations for velocity and acceleration. The beauty and simplicity of this ansatz are strong reasons for its wide spread. However, the numerical implementation is not without pitfalls. Oscillations, collisions, and instabilities occur even for very small step sizes. Classic solution ideas from molecular dynamics do not apply to the problem because the system is not Hamiltonian despite its source of inspiration. Looking at the model through the eyes of a mathematician, however, we realize that the right hand side of the differential equation is nondifferentiable and even discontinuous at critical locations. This produces undesirable behavior in the exact solution and, at best, severe loss of accuracy in efficient numerical schemes even in short range simulations. We suggest a very simple mollified version of the social force model that conserves the desired dynamic properties of the original many-body system but elegantly and cost efficiently resolves several of the issues concerning stability and numerical resolution.

Natural discretization of pedestrian movement in continuous space

Is there a way to describe pedestrian movement with simple rules, as in a cellular automaton, but without being restricted to a cellular grid? Inspired by the natural stepwise movement of humans, we develop a model that uses local discretization on a circle around virtual pedestrians. This allows for movement in arbitrary directions, only limited by the chosen optimization algorithm and numerical resolution. The radii of the circles correspond to the step lengths of pedestrians and thus are model parameters, which must be derived from empirical observation. Therefore, we conducted a controlled experiment, collected empirical data for step lengths in relation with different speeds, and used the findings in our model. We complement the model with a simple calibration algorithm that allows reproducing known density-velocity relations, which constitutes a proof of concept. Further validation of the model is achieved by reenacting an evacuation scenario from experimental research. The simulated egress times match the values reported for the experiment very well. A new normalized measure for space occupancy serves to visualize the results.

[Revision arthroplasty of the hip: modularity of neck and metaphyseal components]

BACKGROUND

Modular parts in femoral components used for hip arthroplasty are reported to be predilection sites for mechanical failure. The possible benefit of their use is therefore controversial.

PATIENTS AND METHOD

We report the outcome of 97 revision hip arthroplasties using a non-cemented femoral component with a modular metaphyseal part and an interchangeable neck (Profemur). The femoral defects treated included Paprosky types I-III. The average follow-up was 5 years (range 3-10 years).

DISCUSSION

No mechanical failure of the modular parts and taper connections has been observed so far. The percentage of patients with a balanced leg length increased from 32% preoperative to 65% postoperative. The mean leg length discrepancy could be reduced from 1.4 cm preoperative to 0.5 cm postoperative. A total of 5 re-revisions were required, including 2 cases of infection. The cumulative survival of the implants due to aseptic loosening was 96.5%.

CONCLUSION

Because of the achieved results the use of the modular stem investigated in this study can be classified as safe and effective for revision hip arthroplasty. The interchangeable neck proved to be a useful completion of the revision system.

Prevalence of mastitis pathogens and their resistance against antimicrobial agents in dairy cows in Brandenburg, Germany

The primary objective of this study was to determine management practices concerning mastitis in Brandenburg, Germany, the prevalence of mastitis pathogens in dairy cows, and their resistance to selected antimicrobial agents. A further objective was to study the potential effect of parity and stage of lactation on the resistance of Staphylococcus aureus isolates against ampicillin. Milk samples for microbiological culture were collected from 4 groups of clinically healthy cows (first lactation, >1 lactation, >50 d in milk, and >250 d in milk; 8 cows/group) in 80 dairy herds. Resistance of gram-positive pathogens against 6 antimicrobial agents was tested using the broth microdilution method. Mastitis pathogens were isolated from 26.4% of the milk samples. Coagulase-negative staphylococci (CNS, 9.1% of quarters) and Corynebacterium bovis (7.3%) were the pathogens most frequently isolated. Among the major pathogens, Staph. aureus (5.7%) and Streptococcus uberis (1.0%) had the highest prevalence. Streptococcus agalactiae was isolated in samples from 29% of the herds. Although the prevalence of most pathogens was higher in older cows, the prevalence of CNS was higher in primiparous cows. Results of the mastitis control questionnaire showed that cows with clinical mastitis were transferred to a sick cow pen in 70% of the herds. Cephalosporins were the drug of first choice for treatment of clinical mastitis cases followed by fixed combinations of antimicrobial agents, beta-lactamase-resistant penicillins, and penicillin. Most farmers treated cows 3 to 4 times per case. Cloxacillin, alone or in combination, and penicillin were most often used for dry-cow therapy. Antimicrobial resistance of the pathogens was within the range of other reports. Resistance of Staph. aureus to ampicillin increased significantly during the first lactation. Further research is required to determine the factors that lead to the selection of Staph. aureus strains that are resistant to ampicillin during the first lactation.

Factors Associated with High Milk Test Day Somatic Cell Counts in Large Dairy Herds in Brandenburg. II. Milking Practices

The objective of this study was to examine the influences of different milking practices on cow udder health in 80 large dairy herds (range 100-1100 cows) in Brandenburg, Germany. Milking practices were evaluated during one complete milking using a standardized data capture form. The somatic cell count (SCC) of all lactating cows on each farm was determined monthly by the local milk recording association 'Landeskontrollverband Brandenburg'. Factor analysis was used to investigate the relationship between the different aspects of the milking practices. The components extracted by the factor analysis were examined for their influence on the SCC of the current month (CMSCC) and the year before the visit (YASCC) using univariate analysis of variance. Three components were extracted from the milking practices. 'Reasonable use of water' was significantly related to CMSCC (P = 0.019) and YASCC (P = 0.003). It included information on the use of a hose to clean udders before milking, cleaning of the floor between groups and use of water to clean teats. 'Attention of the milkers' was also significantly associated with CMSCC (P = 0.012) and YASCC (P = 0.014). It included information on the accuracy of mastitis detection by foremilk screening and the regular use of post-milking teat and cluster disinfection. The component 'preparation routines' (method of udder cleaning and forestripping) did not significantly influence CMSCC and YASCC. These results indicate that excessive use of water in the parlour during milking time is harmful to udder health and that the consistency of procedures in the milking parlour presents significant room for improvement in large dairy herds in Brandenburg.

Factors Associated with High Milk Test Day Somatic Cell Counts in Large Dairy Herds in Brandenburg. I: Housing Conditions

The aim of this study was to examine influences of housing conditions on the udder health in 80 German dairy herds with a herd size between 100 and 1100 cows. Data were collected using a standardized questionnaire for the farm manager and a farm visit using a standardized data capture form on hygiene and management. The somatic cell counts of all lactating cows on each farm were collected monthly by the local dairy herd improvement association and analysed to assess udder health status. Factor analysis was used to analyse the variables describing the environmental hygiene. The values derived for the extracted components were classified into good, moderate and poor. The association of the categories was then analysed for their influence on log somatic cell count of the current month (CMSCC) and the year before the farm visit (YASCC) by a one-way anova. In comparison to other housing systems, free stalls with cubicles had the lowest geometric mean somatic cell count. Three components were derived from the factor analysis. Of those, acceptance of the cubicles by the cows and barn hygiene were determined as components influencing the CMSCC and YASCC significantly, while the association of hygiene of the milking parlour with somatic cell counts was only significant for YASCC. The results of the study show that the cow comfort and housing hygiene have a substantial impact on milk quality and should therefore become the focus of further research on the farm management practices.

The Nottingham health profile-experiences after hip revision arthroplasty

INTRODUCTION

Considering patients after hip revision arthroplasty postoperative quality controls allows an evaluation of the individual implant situation as well as the achieved postoperative quality of life. With regard to a possible loss of data reliable statements about the used implant system with special consideration to the implant survival rate could not be received. In this connection standardized self-assessment questionnaires like the Nottingham Health Profile (NHP) are in the centre of interest. The main focus of this study was to demonstrate a correlation between the Nottingham Health Profile and the Merle d'Aubigne (MDA) Score.

PATIENTS AND METHODS

Fifty-one patients after femoral stem revision were re-examined. All patients received a written appointment for an ambulatory re-examination together with the NHP 4 weeks before. The clinical evaluation was carried out by using the MDA Score. Correlations between the NHP and the MDA were calculated.

RESULTS

Overall the data of 39 patients could be evaluated completely. Three patients (5.9%) did not appear to the ambulatory re-examination, four patients (7.8%) deceased in the meantime. With further five patients (9.8%) the NHP questionnaire could not be rated due to an incorrect treatment. The mean follow-up after revision was 5.8 years. Correlations between the category 'Pain' NHP/MDA as well as to the combination of the NHP-categories 'Pain' + 'Physical Mobility' and the total MDA-Score could be demonstrated.

CONCLUSION

Out of our personal experiences the use of the NHP makes an individual follow-up evaluation after revision hip arthroplasty possible. Patient-referred changes can lead to direct re-examinations. Correlation coherences between the NHP and the MDA could be demonstrated equivalent to already published results. In what way a survival rate analysis of an implant by using the NHP is possible could not be answered clearly. It has to be included that wrong answered questionnaires lead to an additional drop-out rate beneath the lost to follow-up rate.

Chronic bacterial osteomyelitis: prospective comparison of (18)F-FDG imaging with a dual-head coincidence camera and (111)In-labelled autologous leucocyte scintigraphy

Indium-111-labelled white blood cells ((111)In-WBCs) are currently considered the tracer of choice in the diagnostic work-up of suspected active chronic osteomyelitis (COM). Previous studies in a limited number of patients, performed with dedicated PET systems, have shown that [(18)F]2'-deoxy-2-fluoro- D-glucose (FDG) imaging may offer at least similar diagnostic accuracy. The aim of this prospective study was to compare FDG imaging with a dual-head coincidence camera (DHCC) and (111)In-WBC imaging in patients with suspected COM. Thirty consecutive non-diabetic patients with possible COM underwent combined skeletal scintigraphy (30/30 patients), (111)In-WBC imaging (28/30 patients) and FDG-PET with a DHCC (30/30 patients). During diagnostic work-up, COM was proven in 11/36 regions of suspected skeletal infection and subsequently excluded in 25/36 regions. In addition, soft tissue infection was present in five patients and septic arthritis in three. (111)In-WBC imaging in 28 patients was true positive in 2/11 regions with proven COM and true negative in 21/23 regions without further evidence of COM. False-positive results occurred in two regions and false-negative results in nine regions suspected for COM. Most of the false-negative results (7/9) occurred in the central skeleton. If the analysis was restricted to the 18 regions with available histology ( n=17) or culture ( n=1), (111)In-WBC imaging was true positive in 2/18 regions, true negative in 8/18 regions, false negative in 7/18 regions and false positive in 1/18 regions. FDG-DHCC imaging was true positive in 11/11 regions with proven COM and true negative in 23/25 regions without further evidence of COM. False-positive results occurred in two regions. If the analysis was restricted to the 19 regions with available histology ( n=18) or culture ( n=1), FDG-DHCC imaging was true positive in 9/9 regions with proven COM and true negative in 10/10 regions without further evidence of COM. It is concluded that FDG-DHCC imaging is superior to (111)In-WBC scintigraphy in the diagnosis of COM in the central skeleton and therefore should be considered the method of choice for this indication. This seems to hold true for peripheral lesions as well, but in our series the number of cases with proven infection was too small to permit a final conclusion.

Alterations of INK4a(p16-p14ARF)/INK4b(p15) expression and telomerase activation in meningioma progression

Dysregulation of cell cycle progression and telomerase activation have been implicated in malignant tumor progression as well as in the evasion of senescence and immortalization. We have investigated expression of the cell cycle control and tumor suppressor genes INK4a(p16-p14ARF), INK4b(p15-p10) and RB, and their relation to telomerase activation during malignant meningioma progression. 7/26 (27%) benign, 3/12 (25%) atypical but 4/7 (57%) anaplastic tumors lacked both, p16 and p15 protein expression. 14/39 (36%) benign and atypical but 5/7 (71%) anaplastic meningiomas contained no p14ARF mRNA. 2/46 (4%) tumors failed to express pRB. We observed frequent differential loss of expression of the alternatively spliced INK4a tumor suppressors p16 and p14ARF. Exclusive expression of the alternative INK4b transcript p10 possibly at the expense of p15 and therefore resulting in loss of p15 tumor suppressor activity was noted in two meningiomas. We have previously described telomerase activity or expression of the telomerase catalytic subunit hTERT in this meningioma series. Telomerase activation was detected in 10/27 (37%) benign, but 18/19 (95%) non-benign meningiomas. We observed no significant overall correlation between loss of INK4a/INK4b expression and telomerase activation. In conclusion, our results suggest a greater role for losses of INK4a/INK4b gene products in meningioma formation and malignant progression than previously thought. Inactivation of p16/p15- and pl4ARF-dependent pathways possibly in conjunction with telomerase activation might be critical steps for a meningioma cell towards escape from senescence, that is, immortalization.

Tissue response and osteoinduction of human bone grafts in vivo

Freeze-dried human bone allograft is used clinically as an adjunct to autologous bone graft. When freeze-dried human bone allograft is demineralized, the allograft is osteoinductive, since it causes bone to form heterotopically. Both types of allograft are also used alone, such as in spinal fusions, critical size defects, and periodontal therapy. The purpose of this study was to determine the effect of demineralization on the osteoinductive potential of human bone grafts obtained from two different groups of patients. One group consisted of six patients younger than 42 years of age, while the other group consisted of six patients who were older than 70 years of age. The harvested material was lyophilized and divided into two portions, one of which was used directly while the other was demineralized. Osteoinductive ability was established using an in vivo assay for heterotopic bone formation. Activity in these bone grafts was compared with a batch of commercially prepared demineralized, freeze-dried human bone grafts that had been previously shown to be active and another batch that had been shown to display low ('inactive') osteoinductive ability. A bone induction score was determined for each group of grafts based on the number and size of any ossicles formed. In addition, the area of new bone formation and area of residual particles were determined histomorphometrically. Tissue response to the bone grafts varied with donor age and whether the samples had been demineralized or not. Only demineralized, freeze-dried bone graft from patients younger than 42 years of age was osteoinductive; all other batches displayed little or no osteoinductive activity. In the demineralized, freeze-dried bone from donors younger than 42 years of age, the bone induction score and new bone area were significantly higher than in the other batches of bone graft, and the area of residual particles was reduced. Both demineralized and nondemineralized bone graft from patients older than 70 years of age were encapsulated in dense, fibrous connective tissue. These results may help explain the observed differences in clinical outcome when demineralized, freeze-dried bone graft or nondemineralized, freeze-dried bone graft from different donors is used in bone regeneration applications.

Alternative splicing of the p15 cdk inhibitor in glioblastoma multiforme

Thirty-four to fifty-six percent of malignant gliomas harbor homozygous co-deletions of the INK4a(p16-p14ARF) and INK4b(p15) tumor suppressor genes. Recently, an alternatively spliced form of p15 has been cloned and termed p10 based on the presumed molecular weight of the protein. In this study, we have investigated the role of p10 expression in human glioblastomas. Both, wild-type p15 and p10 were detected in three of nine glioblastoma cell lines. Sixteen of twenty-nine (55%) glioblastoma tumor samples contained INK4b transcripts, but only nine (31%) tumors expressed p15 protein. Three p15 protein-negative tumors expressed only p10 mRNA. Preferential expression of p10 was not due to splice site mutations. Strong suppression of tumorigenicity was seen in four glioblastoma cell lines after transfection with p15 but not with p10. Loss of p15 protein expression was almost always accompanied by loss of p16 expression. p1 6/p15-negative tumors commonly lacked p14ARF expression. These results suggest that differential splicing of the INK4b gene may result in the expression of p10 at the expense of p15, which would lead to loss of p15-mediated growth suppression. This novel mechanism of loss of p15 might complement alterations of the INK4a tumor suppressor gene in some glioblastomas, resulting in combined loss of p16, p15 and p14ARF.

Intracellular measurement of polyethylene particles. A histomorphometric study

A histological and histomorphometric study was carried out on pseudo-capsules retrieved from patients during revision surgery of cementless total hip replacement. Polyethylene loading and areal polyethylene particle size in different cells of the reticuloendothelial cell line were determined within the tissue by histomorphometry. In the reticuloendothelial cell line, foreign-body giant cells are considered to be the result of confluence of mononuclear macrophages caused by large particles or other unknown stimuli. The aim of this study was to investigate whether polyethylene particle size and polyethylene loading are different in mononuclear macrophages and foreign-body giant cells. The specimens were examined under the light-optical microscope with plain and polarized light. The polyethylene loading of 329 macrophages (mononuclear), 81 small foreign-body giant cells (2-5 visible nuclei), and 103 large foreign-body giant cells (6 or more visible nuclei) was determined and the intracellular polyethylene particle size analyzed by histomorphometry. The mean polyethylene loading was 13 +/- 8 microm2, 25 +/- 16 microm2, and 49 +/- 42 microm2, respectively. This difference was statistically significant (Student's t-test, P < 0.05). The mean polyethylene particle size was 2.34 +/- 3.2 microm2, 3.02 +/- 3.46 microm2, and 4.70 +/- 11.25 microm2, respectively. This difference was statistically significant between macrophages and large foreign-body giant cells (t-test, P < 0.05). The findings of this light-optical study show that the mean intracellular polyethylene particle size is greater in foreign-body giant cells. In addition, absolute polyethylene loading tends to be higher in foreign-body giant cells than in mononuclear macrophages.

Effect of polymer molecular weight and addition of calcium stearate on response of MG63 osteoblast-like cells to UHMWPE particles

Periprosthetic osteolysis and implant loosening is associated with the presence of ultrahigh molecular weight polyethylene (UHMWPE) wear debris particles. Osteoblast phenotypic expression in vitro is affected by UHMWPE particles, suggesting that bone formation may also be affected by wear debris. Here we tested the hypothesis that the response of osteoblasts to UHMWPE can be modified by changes in UHMWPE particle chemistry. We used four different commercially available preparations of GUR UHMWPE particles to determine if chemical composition (+/- Ca-stearate) or polymer molecular weight (3.1-4.2 million or 5.4-6.5 million g/mol) modulates osteoblast response. Particles were characterized by size distribution, morphology, and number of particles added to the culture medium. They had an average equivalent circle diameter ranging from 0.46-1.26 microm. MG63 cell response was assessed by measuring cell number, cellular and cell layer alkaline phosphatase, and prostaglandin E2 (PGE2) production. There were dose-dependent effects of the particles on cell response. Cell number and PGE, production were increased, while alkaline phosphatase specific activity was decreased. In addition, there was a marked difference between cultures treated with particles containing Ca-stearate and as a function of polymer molecular weight. Particles of higher molecular weight caused a greater stimulation of proliferation and inhibition of alkaline phosphatase than particles of lower molecular weight. The presence of Castearate exerted a more pronounced depression of osteoblast phenotype as well as a significantly greater increase in PGE2 release by the cells. The present study shows that chemical composition and polymer molecular weight of UHMWPE are capable of modulating osteoblast response to particles. The results suggest that osteoblast differentiation is inhibited by UHMWPE particles, whereas cell proliferation and PGE2 production are stimulated. This may have direct effects on osteoblasts and bone formation, but also paracrine effects on cells of the monocytic lineage inducing bone resorption and promoting inflammation which may lead to aseptic loosening. The present results suggest that the cellular events in aseptic loosening may be modulated or even accelerated by changes in the composition of the UHMWPE used to fabricate implants.

Human osteoblast-like cells phagocytose metal particles and express the macrophage marker CD68 in vitro

Periprosthetic osteolysis is a major cause of aseptic loosening in artificial joint replacement. It is assumed to occur in conjunction with the activation of macrophages. We have shown in vitro that human osteoblast-like cells, isolated from bone specimens obtained from patients undergoing hip replacement, phagocytose fine particles of titanium alloy (TiAlV). The human osteoblast-like cells were identified immunocytochemically by the presence of bone-specific alkaline phosphatase (BAP). With increasing duration of culture, a variable number of the osteoblastic cells became positive for the macrophage marker CD68, independent of the phagocytosis of particles, with a fine granular cytoplasmic staining which was coexpressed with BAP as revealed by immunodoublestaining. The metal particles were not toxic to the osteoblastic cells since even in culture for up to four weeks massively laden cells were vital and had a characteristic morphology. Cells of the human osteosarcoma cell line (HOS 58) were also able to phagocytose metal particles but had only a low expression of the CD68 antigen. Fluorescence-activated cell scanning confirmed our immunocytochemical results. Additionally, the cells were found to be negative for the major histocompatibility complex-II (MHC-II) which is a marker for macrophages and other antigen-presenting cells. Negative results of histochemical tests for tartrate-resistant acid phosphatase excluded the contamination by osteoclasts or macrophages in culture. Our observations suggest that the osteoblast can either change to a phagocytosing cell or that the phagocytosis is an underestimated property of the osteoblast. The detection of the CD68 antigen is insufficient to prove the monocytic lineage. In order to discriminate between macrophages and osteoblasts additional markers should be used. To our knowledge, this is the first demonstration of cells of an osteoblastic origin which have acquired a mixed phenotype of both osteoblasts and macrophages.

Phagocytosis of wear debris by osteoblasts affects differentiation and local factor production in a manner dependent on particle composition

Wear debris is considered to be one of the main factors responsible for aseptic loosening of orthopaedic endoprostheses. Whereas the response of cells in the monocytic lineage to foreign materials has been extensively studied, little is known about cells at the bone formation site. In the present study, we examined the hypothesis that the response of osteoblasts to wear debris depends on the chemical composition of the particles. We produced particles from commercially pure titanium (cpTi), Ti-6Al-4V (Ti-A), and cobalt-chrome (CoCr) and obtained ultrahigh molecular weight polyethylene (UHMWPE; GUR 4150) particles from a commercial source. The equivalent circle diameters of the particles were comparable: 1.0 +/- 0.96 microm for UHMWPE; 0.84 +/- 0.12 microm for cpTi; 1.35 +/- 0.09 microm for Ti-A, and 1.21 +/- 0.16 microm for CoCr. Confluent primary human osteoblasts and MG63 osteoblast-like cells were incubated in the presence of particles for 24 h. Harvested cultures were examined by transmission electron microscopy to determine if the cells had phagocytosed the particles. Particles were found intracellularly, primarily in the cytosol, in both the primary osteoblasts and MG63 cells. The chemical composition of the particles inside the cells was confirmed by energy-dispersive X-ray analysis. Morphologically, both cell types had extensive ruffled cell membranes, less-developed endoplasmic reticulum, swollen mitochondria, and vacuolic inclusions compared with untreated cells. CpTi, Ti-A, and CoCr particles were also added to cultures of MG63 cells to assess their effect on proliferation (cell number) and differentiation (alkaline phosphatase activity), and PGE2 production. All three types of particles had effects on the cells. The effect on cell number was dependent on the chemical composition of the particles; Ti-A and CoCr caused a dose-dependent increase, while cpTi particles had a biphasic effect with a maximal increase in cell number observed at the 1:10 dilution. Alkaline phosphatase specific activity was also affected and cpTi was more inhibitory than Ti-A or CoCr. PGE2 production was increased by all particles, but the magnitude of the effect was particle-dependent: CoCr > cpTi > Ti-A. This study demonstrates clearly that human osteoblast-like cells and MG63 cells can phagocytose small UHMWPE, CoCr, Ti-A, and cpTi particles. Phagocytosis of the particles is correlated with changes in morphology, and analysis of MG63 response shows that cell proliferation, differentiation, and prostanoid production are affected. This may have negative effects on bone formation adjacent to an orthopaedic implant and may initiate or contribute to the cellular events that cause aseptic loosening by inhibiting bone formation. The effects on alkaline phosphatase and PGE2 release are dependent on the chemical composition of the particles, suggesting that both the type and concentration of wear debris at an implant site may be important in determining clinical outcome.

Functional evidence for a role of combined CDKN2A (p16-p14(ARF))/CDKN2B (p15) gene inactivation in malignant gliomas

Homozygous chromosome 9p deletions in gliomas commonly include the CDKN2A and CDKN2B genes, which code for the structurally highly homologous cdk inhibitors/tumor suppressors p16 and p15, respectively. Alternative splicing of the CDKN2A gene results in the expression of p14(ARF). Interestingly, not only p16 and p15, but also the structurally unrelated p14(ARF) appear to function as negative cell cycle regulators. Concerted inactivation of p16, p15 and p14(ARF) could be demonstrated in seven of nine glioblastoma cell lines. Strong suppression of tumorigenicity after transfection with p16 and p15 alone or in combination was seen in cell lines containing neither endogenous p16 nor p15 but functional pRB. Significantly weaker growth suppression was observed in tumors either retaining expression of both p16 and p15 or p15 only. p14(ARF) proved to be a potent tumor suppressor in the presence of wild-type p53, while mutant p53 substantially reduced growth inhibition by p14(ARF). No differences between p16 and p15 effects could be observed, suggesting a largely overlapping function of p16 and p15. To facilitate further research into p16/p15 effects, three cell lines with conditional, tetracycline-controlled p16 expression were established. Reversible growth suppression mediated by p16 was observed in these models. Combined inactivation of CDKN2A and CDKN2B, i.e., loss of both p16 and p15 as well as p14(ARF), results in disruption of two major growth control pathways involving pRB and p53 in malignant gliomas. Therefore, homozygous co-deletions of CDKN2A and CDKN2B rather than mutations targeting individual transcripts are frequently selected for in these tumors.

[Fractures of the distal radius. Changing therapeutic strategies]

Fractures of the distal radius represent one of the most common fractures and do have high social-economic relevance. For treatment they need practicable classification and therapeutic standards. The demand for stable osteosynthesis of A3-, B2-B3 and C1-C2-fractures is connected to dorsal or volar internal fixation with plate and practical autogenous cancellous bone grafting, even for the elder patient. The isolated external fixation with K-wires represent special situation. Supply of implants and biodegradable materials will support this development.

[Surgical treatment of congenital clavicular pseudarthrosis]

INTRODUCTION

Congenital pseudarthrosis of the clavicle is an extremely rare disease of unknown histogenesis. The method of treatment is still discussed controversely.

CASES

Two cases of a congenital pseudarthrosis of the right clavicle were presented, revealing the typical clinical, radiologic and histopathologic features. Surgical treatment was performed at the age of 4 and 7 years, consisting of a partial resection of the bony ends of both segments of the clavicle, partial excision of the dense fibrous tissue lying within the defective area in the middle third of the clavicles by forming a continuous sleeve for interposing autogeneous spongiosa from the iliac crest and internal fixation with a Kirschner wire. Both cases showed a successful solid bone union in X-ray controls after 8 weeks.

CONCLUSIONS

According to the histopathological findings we assume an abnormal ineffective chondral instead of an endesmal ossification resulting from a damage during embryogenesis as the underlying pathogenetic mechanism of congenital pseudarthrosis of the clavicle. Since chondral ossification proves to be ineffective also after birth, spontaneous bony union cannot be expected. Therefore, reconstructive surgery is the treatment of choice.

Endoscopy of the femoral canal in revision arthroplasty of the hip.A new method for improving the operative technique and analysis of implant failure

Femoral endoscopy using a special endoscope was performed in 28 revision arthroplasties with the aim of improving the operative technique and to analyze implant failure. Before clinical application, the method was used to analyze the implant bed in clinically and radiographically well-fixed prostheses in autopsy cases without implant failure. Initially, it was performed on 4 experimental implantations of newly designed revision devices into cadaver femurs to obtain additional information concerning the design rationale of implants and instruments for revision surgery. During revision surgery, the new endoscope showed that controlled removal of the cement and granulomatous tissue was possible while avoiding cortical windows or transfemoral approaches. Under visual control, preparation of the new implant bed was less hazardous and more efficient, resulting in good preservation of bone stock and reduced exposure to X-rays. Analysis of the implant bed in failed hip endoprostheses revealed cracks or fractures of the cement mantle in 21 of 23 cemented components. There were two different types of cracks: longitudinal and transverse, which were mostly connected and invisible to X-ray analysis. Cement defects, thin cement mantles, or the proximal border of the cement mantle were found to be places where cracks originated. Granulomatous tissue was noted to protrude into the cement fissures and cracks. In autopsy cases, cement cracks were also found in clinically asymptomatic and radiographically well-fixed prostheses. These cracks were observed to be mainly oriented in the longitudinal direction, similar to those seen in the revision cases. Early signs of debonding became obvious even without lesions in the cement mantle. In experimental implantations of newly designed stems, the efficacy of the different instruments and the fit of the implant could be evaluated by endoscopic control inside the intramedullary canal. Further, it was possible to directly visualize the shape and condition of the primary implant bed after removal of the implant. Femoral endoscopy improved the surgical technique in revision arthroplasty. In addition, it is a very useful tool for the analysis of the implant bed in clinical and autopsy cases as well as in experimental implantations.

Degradation of and intraosseous reactions to biodegradable poly-L-lactide screws: a study in minipigs

In 20 minipigs an osteotomy of the lumbar spine was done at L3 and fixed with resorbable implants (plate and screws) made of poly-L-lactide. For 24 months postoperatively the cancellous bone surrounding the screws was examined histologically. Specimens from the body of lumbar spine L2 and L4, carrying the screws, were fixed in a series of ethanol immersions and then embedded in methylmethacrylate. Longitudinal and transverse sections were cut with a microtome at 4-5 microns and stained by the Masson-Goldner and Giemsa method for light microscopy. Our investigation confirmed a long degradation period of poly-L-lactide and little inflammatory reaction within the bone during the whole period of observation. For poly-L-lactide the degradation time exceeded the longest follow-up time in this study, 24 months. Polymorphonuclear granulocytes and mononuclear round cells were scarce in all follow-up groups. Osteolytic changes or the emergence of seroma was not observed. Textured bone was evident early close to a thin fibrous capsule surrounding the screws. The remodelling of the bone close to the screws ensues by the formation of osteons.

Unsuccessful surgical treatment of hip dislocation in congenital sensory neuropathy with anhidrosis. A case report

A six-year-old girl with congenital sensory neuropathy with anhidrosis (CSNA) presented with bilateral hip dysplasia and subluxation on the right side. Conservative treatment of the hips by closed reduction and a plaster cast was unsuccessful. When aged seven years the patient had an intertrochanteric varus rotation osteotomy on the right side, but subluxation was again evident after five months. A Salter-type pelvic osteotomy was carried out followed by immobilisation, but one year later subluxation was present in the right hip and dislocation in the left. At the age of nine years, the right femoral head resembled a Charcot joint, although walking ability was preserved. In patients with CSNA, surgery may not always be advisable.

Arthroscintigraphy in suspected rotator cuff rupture

AIM

In order to evaluate the diagnostic efficiency of arthroscintigraphy in suspected rotator cuff ruptures this new imaging procedure was performed 20 times in 17 patients with clinical signs of a rotator cuff lesion. The scintigraphic results were compared with sonography (n = 20), contrast arthrography (n = 20) and arthroscopy (n = 10) of the shoulder joint.

METHODS

After performing a standard bone scintigraphy with intravenous application of 300 MBq 99m-Tc-methylene diphosphonate (MDP) for landmarking of the shoulder region arthroscintigraphy was performed after an intraarticular injection of 99m-Tc microcolloid (ALBU-RES 400 MicroCi/5 ml). The application was performed either in direct combination with contrast arthrography (n = 10) or ultrasound conducted mixed with a local anesthetic (n = 10). Findings at arthroscopical surgery (n = 10) were used as the gold standard.

RESULTS

In case of complete rotator cuff rupture (n = 5), arthroscintigraphy and radiographic arthrography were identical in 5/5. In one patient with advanced degenerative alterations of the shoulder joint radiographic arthrography incorrectly showed a complete rupture which was not seen by arthroscintigraphy and endoscopy. In 3 patients with incomplete rupture, 2/3 results were consistent. A difference was seen in one patient with a rotator cuff, that has been already revised in the past and that suffered of capsulitis and calcification.

CONCLUSION

Arthroscintigraphy is a sensitive technique for detection of rotator cuff ruptures. Because of the lower viscosity of the active compound, small ruptures can be easily detected, offering additional value over radiographic arthrography and ultrasound, especially for evaluation of incomplete cuff ruptures.

Centralization of the femoral component in cemented hip arthroplasty using guided stem insertion

In order to improve the positioning of the stem within the femur, to centralize it within the cement and to achieve a complete and homogeneous cement mantle, a new hip endoprosthesis with guided stem insertion was developed. The femoral component has a longitudinal channel that takes up a guidewire which directs it during insertion into the centre. The guidewire is attached to the cement stopper which is positioned in the marrow cavity before applying the bone cement. The first 100 endoprostheses of this type with an observation period of at least 6 years were assessed radiologically and clinically. The clinical evaluation according to the hip scores of Merle d'Aubigne and Harris revealed a marked improvement between preoperative and postoperative values for all criteria. On radiological assessment 94% of the stems had a neutral position within the femur; 98% of the stems were found to be ideally centred within the cement distally, 80% distally and proximally; 74% of the cement cuffs had a complete and homogeneous cement layer between 2 and 5 mm medially and laterally, while 25% had partially a dimension of more than 5 mm, predominantly proximally. In only 3 cases was one part of the cement mantle found to be less than 2 mm. The radiological follow-up was also documented according to the delineated zones of Gruen. It revealed zonal radiolucent lines in 15 cases, combined in 11 cases with reactive lines, never extending up to 4 zones out of 14. Five prostheses had subsided moderately between 2 and 3 mm, and only one 8 mm. None of these radiological signs was associated with clinical symptoms. There were five cement fractures. Two stems were symptomatic, radiologically loose and revised. Beside these two cases of aseptic loosening there was one septic case, so that in total 97% of the implants are still functioning well.

An oblong revision cup for large acetabular defects: design rationale and two- to seven-year follow-up

Loosening and migration of acetabular components often lead to extensive bony defects with an elongated, oval acetabular cavity. In these cases standard implants will not reestablish and maintain sufficient stability without leaving bone defects or using massive bone grafts or excess cement and additional metal rings or shells, disadvantages that are overcome by using an oblong revision cup without cement. The titanium shell is available in different sizes, is screwed to the autochthonous acetabular bone and houses an oblong polyethylene inlay, designed to reestablish the normal anatomic hip center. Of 109 consecutive revision cups, 102, implanted for American Academy of Orthopaedic Surgeons (AAOS) defects types I-IV, were followed up clinically and radiologically for 2 to 7 years (mean, 3.6 years). Primary stability was achieved in all cases. In 40% no bone grafting was necessary at all. The radiological follow-up revealed good remodeling of the surrounding bone and osseointegration of the implants. Zonal radiolucent lines, always smaller than 2 mm, were seen in 18 cases, only once completely and in only 5 cases partially progressing. Six cups migrated slightly (< or =2 mm), two moderately (3-5 mm), all without clinical symptoms, and two more than 5 mm. Migration and radiolucencies were mainly seen in patients with allografts and major defects, which indicates that bone ingrowth appears more unlikely in such cases. Few asymptomatic cases showed zonal sclerotic lines. There were two aseptic loosenings, one in a case with pelvic discontinuity, the other in a patient with severe rheumatoid arthritis following two previous revisions. Survivorship analysis based on implant removal because of aseptic loosening as the endpoint shows a cumulative success rate of 98.1% at 8 years.

Crevice corrosion of cemented titanium alloy stems in total hip replacements

Twenty-eight cemented Müller straight femoral stems of titanium forged alloys were mainly revised for causing pain in the patient. The pain pattern differed from aseptic loosening and pain recurred only 14.5 months on average after implantation. The character of pain was dull, permanent, and increased at rest. Some patients reported pain relief while walking. Revisions were performed on average 25.5 months after primary implantation. Data from medical records, radiographs, histology of tissues taken at revision surgery, intraoperative pH measurements, examination of retrieved stems and bone cement fragments were gathered. In the radiographs debonding was visible only in 3 cases; a spindle shaped thickening of the femora occurred 9 months on average after recurrence of pain. After a further 11 months (average), scalloping osteolyses appeared. Abraded particles like metallic titanium alloy, titanium corrosion products, polymethylmethacrylate, xray contrast medium, and polyethylene were detected. Metallic particles dominated in the joint capsule whereas more corrosion products impregnated the cement to bone interface. The distal surfaces of the stems were corroded at a higher rate, whereas the proximal regions more often were subject to abrasion. Measurements of the pH of the corroded stems revealed values of high acidity. Recurrence of pain and subperiosteal apposition of bone are due to diffusion of acid; subsequent scalloping osteolyses develop due to particle induced foreign body granulomas. The mechanism of crevice corrosion of cemented titanium based alloys does not seem applicable to cobalt and iron based implant alloys. Titanium alloys can no longer be recommended for cementation, but are as safe as ever for anchorage without cement.

Wear behavior and histopathology of classic cemented metal on metal hip endoprostheses

The authors reviewed their collection of retrieved all metal hip joints (9 McKee-Farrar, 7 Müller, and 3 Huggler type prostheses) and tissues from the joint capsules and implant beds. The amount of wear was measured, and the total volume was calculated. The tissues were analyzed by atomic absorption spectral analysis or inductively coupled plasma mass spectrometry and examined by light and scanning electron microscopy. The size of particles was measured with a texture analysis system. The articulating surfaces showed many delicate scratches which represent normal wear. The calculated annual wear averaged approximately 5 mm3 per year, which is low compared with polyethylene. The cellular reaction to metal wear particles was regarded as mild. The cellular reaction to scattered and worn bone cement was always more pronounced than to metallic debris. Scanning electron microscopy confirmed the irregular shapes and mostly submicron size of the metal particles. The analytically detected metal content of the periarticular tissue was relatively low and in accordance with the wear measurements from the articulating surfaces. The excess of chromium in the tissues is discussed in the light of the elimination of cobalt as well as the relation between elements representing either corrosion products or elements still bound in wear particles.

Glial alpha 2-receptors probably inhibit the high-affinity uptake of noradrenaline into astrocytes in the rat brain in vivo

The effect of alpha 2-receptor blockage on the extraneuronal turnover of noradrenaline (NA) has been studied in the intact rat brain. Tropolone and yohimbine, along with reserpine or desmethylimipramine, were given 30 min after intracerebroventricular injection of [7-3H]NA, i.e. after the tracer had been stored or inactivated. Tropolone given alone did not change the fractions of 3H-activity recovered as [3H]NA from hypothalamus, septum, striatum and pons-medulla, but in the presence of yohimbine improved the [3H]NA recovery in all areas except pons-medulla. The maximum effect was seen in the hypothalamus of reserpine-treated rats. Since the alpha 2-autoreceptors were blocked, the increased [3H]NA recovery does not reflect a down-regulated neuronal NA turnover. Instead it seems to show that a fraction greater than normal of neuronally released NA had been taken up into astrocytes and remained unmetabolized if catechol-O-methyltransferase was inactive. It is assumed that yohimbine enabled the protective tropolone effect by blocking astrocytic alpha 2-receptors that otherwise, either by itself or by antagonizing beta-receptor-induced hyperpolarization or cAMP formation, had impaired parameters that stimulate the high-affinity NA Uptake 1 of astrocytes (e.g. membrane potential, Na+,K(+)-ATPase) or control the gap junction permeability in the glial syncytium.

Clinical value of combined contrast and radionuclide arthrography in suspected loosening of hip prostheses

Combined contrast and radionuclide arthrography was performed in 71 cemented, non-cemented and hybrid hip arthroplasties for diagnosis of component loosening. In 31 cases, either one or two prosthesis components were clearly loose upon clinical and radiological diagnosis, with subsequent intraoperative confirmation. The other 40 cases had doubtful component loosening, with discrepancy between clinical and radiological findings, and were investigated for clarification. Contrast and radionuclide arthrograms were compared with sequential plain radiographs and their ability to indicate component loosening was evaluated. The combined contrast and radionuclide arthrograms proved in 90.9% of the cases whether a loose component existed as confirmed by intraoperative findings. They had a high sensitivity, specificity and predictive accuracy for both the acetabular and the femoral component. Sensitivity and predictive accuracy were remarkably precise in comparison to those of plain radiographs on the acetabular side. In nearly all patients with contradictory clinical and radiological findings, conclusive diagnosis was possible on the basis of the contrast and radionuclide arthrograms. Coinciding positive results in both contrast and radionuclide arthrograms were verified in each operated case. The combination of contrast and radionuclide arthrography is an useful method to diagnose doubtful loosening of hip arthroplasty components, especially in addition to routine sequential plain radiographs.

Time course of the metabolite patterns of intraventricularly injected [3H]noradrenaline in rat brain regions

In the hypothalamus, septum, pons with medulla, and hippocampus regions of rat brain, the level of radioactivity of [3H]noradrenaline and of five of its metabolites were determined up to 6 h after intraventricular injection of the tritiated amine. The following main results were found: In anterior hypothalamus and septum, the [3H]noradrenaline level declined in two phases. Similar turnover curves were obtained for the primary deaminated metabolites, with almost the same final half-lives as for [3H]noradrenaline. The level of the initial methylation product, normetanephrine, also showed a biphasic decline, which did not correspond to that of [3H]noradrenaline but rather was faster throughout the experiment. The final metabolites (i.e., the glycol sulfates) reached maximal levels in hypothalamus and septum earlier than in other regions. Thereafter, their levels declined with almost similar rates in all areas tested, but always faster than the [3H]noradrenaline level. The following conclusions were drawn: In areas rich in catecholaminergic nerve terminals, there seems to be a site, in addition to the vesicular storage pool, that accumulates exogenous noradrenaline and then releases it with relatively short half-lives. The contents of primary deaminated metabolites followed the turnover of [3H]noradrenaline at both sites. Exogenous [3H]noradrenaline seems to be methylated at two extraneuronal sites, which are distinguished by the rates of subsequent deamination. The size of the pool of slowly deaminated [3H]normetanephrine that is formed immediately after [3H]noradrenaline injection determined the apparent turnover of this product throughout the experiment and, thus, like the final metabolites, reflects for several hours the initial degradation of the unstored [3H]noradrenaline, rather than the metabolism of the stored amine.(ABSTRACT TRUNCATED AT 250 WORDS)

Isolated aplasia of the flexor pollicis longus: a case report

A case of isolated aplasia of the flexor pollicis longus is reported. Function was supplied by a two-stage transfer of the superficialis tendon of the ring finger.

On the metabolism of [3H]noradrenaline in different compartments of rat brain with respect to the role of catechol-O-methyltransferase

Rats were pretreated with either reserpine or desmethylimipramine, either alone or in combination with tropolone. At either 10 min or 1 h after the intraventricular injection of [3H]noradrenaline, in several brain regions the complete metabolic patterns were determined: normetanephrine; the glycol metabolites (methylated and nonmethylated) and their sulfate conjugates; and the acidic metabolites (methylated and non-methylated). A reserpine-induced increase in the turnover of [3H]noradrenaline caused a transient increase of the catechol glycol followed by elevated levels of the two glycol sulfates. The stimulated [3H]noradrenaline turnover if achieved by desmethylimipramine caused a transient increase of normetanephrine and initially lowered values of catechol glycols (both free and sulfated), which were followed by elevated levels. Drug-pretreated rats compensated for the inhibition of catechol-O-methyl-transferase by tropolone in different ways: Reserpine caused an early increase of the catechol glycol beyond the measurements in other treatment groups, whereas desmethylimipramine increased the nonmethylated carboxylic acid and glycol sulfates rather slowly to levels beyond those of other groups. The results support the existence of two compartments with a fast metabolism (an intraneuronal monoamine oxidase compartment and an extraneuronal catechol-O-methyltransferase compartment). In addition, there seems to exist another extra-neuronal space with a slow, monoamine oxidase-dependent noradrenaline turnover.

On the recovery of [3H]noradrenaline from different metabolic compartments of rat brain with respect to the role of catechol-O-methyltransferase

Rats were treated with reserpine, desmethyl-imipramine, or carrier, either alone or in combination with tropolone. Either 10 min (t1) or 1 h (t2) after intraventricular injection of [3H]noradrenaline, they were decapitated. The total 3H activity and the recovery of [3H]noradrenaline were determined in tissue extracts from various brain regions. Maximum total 3H activity was measured at t1 in all tropolone-treated rats; the mean sum of these results served as an estimate of the initial tissue concentration of [3H]noradrenaline. At t1, 40-50% of the sum of [3H]noradrenaline and its metabolites was recovered unchanged in normal rats; reserpine and DMI reduced the recovery to 18-27%. In all groups, the decline of [3H]noradrenaline was retarded after t1. Inhibition of catechol-O-methyltransferase by tropolone caused consistently elevated [3H]noradrenaline levels, but did not affect the metabolic rate after t1 when compared with similarly pretreated, but tropolone-free rats. Thus, if catechol-O-methyltransferase was inhibited during the injection of [3H]noradrenaline, a higher percentage of the amine had been taken up into spaces with a slow noradrenaline turnover. The maximum increase was seen when the neuronal uptake1 was inhibited by desmethylimipramine. This supported the hypothesis that an additional extraneuronal space exists, in addition to the known intraneuronal and extraneuronal compartments, which has a slow noradrenaline turnover. The tropolone effect on the noradrenaline recovery possibly shows that there might be a saturable "methylating system," similar to that described for the periphery, in which catechol-O-methyltransferase is linked to the extraneuronal uptake2.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of 2-substituted oestrogens in vivo on the metabolism of noradrenaline in rat brain

The effects of oestradiol-17 beta, 2-hydroxyoestradiol-17 beta and 2-methoxyoestradiol-17 beta on the metabolism of [3H]noradrenaline were studied in various brain regions of ovariectomized in rats in vivo. Under the experimental conditions chosen, oestradiol-17 beta had no effect on the metabolic pattern of noradrenaline. After pre-treatment of ovariectomized rats with 2-hydroxyoestradiol-17 beta, the formation of methylate metabolites of noradrenaline (normetanephrine and 3-methoxy-4-hydroxyphenylglycol sulphate) was reduced, whereas that of non-methylated products (3,4-dihydroxymandelic acid and 3,4-dihydroxyphenylglycol sulphate) was increased. The inhibition of methylation was most pronounced in posterior hypothalamus and less significant in anterior hypothalamus and thalamus. Pre-treatment with 2-methoxyoestradiol-17 beta yielded inconsistent results. From the findings described here it may be concluded that 2-hydroxyoestradiol-17 beta, as previously shown in vitro, also affects the metabolism of noradrenaline in vivo by directly interacting with the catechol-O-methyltransferase. It is suggested that this metabolic effect may be responsible - at least to some extent - for the inhibitory effect of 2-hydroxyoestradiol-17 beta on LH secretion.

[Effect of anaesthesia on the metabolism of noradrenaline in rat brain (author's transl)]

A specific and sensitive method is described for the separation and determination of metabolites of radioactively labelled noradrenaline in very small amounts of brain tissue. This method gives reproducible results, it allows the direct determination of all major metabolites of noradrenaline from the same extract, and is suitable for quantitating a large number of samples in relatively short time. This method was used to investigate how the half-life (turnover) and the metabolism of noradrenaline in rat brain may be influenced by anaesthesia with nembutal. It was found that both the half-life time as well as the metabolism of noradrenaline are reduced during nembutal anaesthesia; in addition, the release of metabolites of noradrenaline into the blood is delayed. When studying the metabolism of neurotransmitters, it has to be considered that nembutal-narcosis influences the metabolic pattern of noradrenaline as well as its temporal changes.

Effect of oestradiol-17 beta on the metabolism of noradrenaline in brain slices of ovariectomized rats

Ovariectomized rats received a single injection of 10 microgram oestradiol-17 beta 3-benzoate; 90 min or 19 h after injection, slices of various brain areas were prepared and incubated with tritiated noradrenaline for 30 min. Methylated and non-methylated metabolites of tritiated noradrenaline were determined after chromatographic separation. Nineteen h after administration of oestradiol-17 beta 3-benzoate, the formation of normetanephrine, 3-methoxy 4-hydroxy phenylglycol and 3-methoxy 4-hydroxy mandelic acid was decreased (P less than 0.05) in hypothalamic tissue, whereas that of 3,4-dihydroxy mandelic acid was increased (P less than 0.001). In thalamus tissue a decrease or normetanephrine (P less than 0.005) and an increase of 3,4-dihydroxy mandelic acid (P less than 0.001) were also observed. No conclusive results were obtained with hypophyseal tissue. The present findings suggest that oestrogens reduce the methylation of noradrenaline, probably through a competitive inhibition of the catechol-O-methyl-transferase by 2-hydroxylated oestrogens.