Electron beam-based functionalization of polymer membranes.

A new electron beam-based approach for the direct functionalization of polyethersulfone, polyvinylidene fluoride, polysulfone as well as polyacrylonitrile membranes in a one-step procedure is presented. Aqueous solutions of functional molecules were immobilized on the membrane surface by electron beam treatment. The resulting membranes show significantly increased flux and water wettability accompanied by decreased protein adsorption. Stability tests demonstrated the permanence of the modification. This new method neither requires any preceding surface functionalization nor the use of catalysts/photoinitiators or other toxic reagents. In addition, it avoids the synthesis of hydrophilic monomers/polymers, thus avoiding additional synthetic and purification steps as well as the use of organic solvents.

The laser-pointer assisted angle reproduction test for evaluation of proprioceptive shoulder function in patients with instability.

INTRODUCTION: Over the last decade, proprioceptive function gained increasing attention in joint disorders such as instability of the shoulder. Common tests for evaluation of proprioception are limited by their complexity and high technical demands. Thus, they are hardly applicable during daily routine. Our hypothesis was that the simplified "laser-pointer assisted angle reproduction test" (LP-ART) presented here allows for clinically feasible assessment of proprioceptive shoulder function. METHODS: Active angle reproduction capability as an aspect of sensorimotor function was evaluated with the new method in patients with shoulder instability (n = 24) and healthy controls (n = 24). 15 patients had traumatic, 9 non-traumatic anterior instability (6 bilateral), 17 were treated surgically, 13 non-operatively. Tests were performed in flexion and abduction in different angles (55°, 90°, 125°) in randomized order. RESULTS: Angle reproduction capability was worst below shoulder level (55°) in all groups. Best results were achieved at shoulder level (90°). Healthy controls showed overall better results than patients with instability. Patients after surgical stabilization had better results in 55° and 90° abduction compared to instability patients before surgery. CONCLUSIONS: The new LP-ART presented here is a technically simple, yet effective instrument for evaluation of the proprioceptive function of the shoulder. In contrast to former test setups it is feasible in daily routine. Compared to healthy controls, patients with unstable shoulder joints show significant proprioceptive disorders that can be quantified by the LP-ART.

Transport spectroscopy of non-equilibrium many-particle spin states in self-assembled quantum dots.

Self-assembled quantum dots (QDs) are prominent candidates for solid-state quantum information processing. For these systems, great progress has been made in addressing spin states by optical means. In this study, we introduce an all-electrical measurement technique to prepare and detect non-equilibrium many-particle spin states in an ensemble of self-assembled QDs at liquid helium temperature. The excitation spectra of the one- (QD hydrogen), two- (QD helium) and three- (QD lithium) electron configuration are shown and compared with calculations using the exact diagonalization method. An exchange splitting of 10 meV between the excited triplet and singlet spin states is observed in the QD helium spectrum. These experiments are a starting point for an all-electrical control of electron spin states in self-assembled QDs above liquid helium temperature.

[Arthroscopic versus open anterior shoulder stabilization. A systematic validation]. / Arthroskopische vs. offene ventrale Schulterstabilisierung. Eine Wertung.

The treatment of traumatic anterior glenohumeral instability has been a topic of debate over the last couple of decades. However, a consensus exists regarding the necessity of an individualized treatment plan based on the type and degree of instability and the patient's functional demands. Various open and arthroscopic techniques are among the currently used surgical procedures. Open reconstruction of the capsulolabral complex had been considered the treatment of choice for many years, but the latest results for arthroscopic anterior shoulder stabilization demonstrate its increasing use. The current literature suggests that with the introduction of suture anchors, it is possible to mirror the principles of open anterior shoulder stabilization and thus combine the general advantages of arthroscopic surgery with a low recurrence rate.

Controlled fabrication of patterned lateral porous alumina membranes.

Confined lateral alumina templates are fabricated with different pore sizes by changing the acid electrolyte and the anodization voltage. The control of the number of pore rows down to one dimension is also achieved, by controlling the thickness of the starting aluminum film as well as the anodization voltage. We observe that the mechanism of pore formation in the lateral regime is very similar to that in the classical vertical situation.

Density control of electrodeposited Ni nanoparticles/nanowires inside porous anodic alumina templates by an exponential anodization voltage decrease.

Porous alumina templates have been fabricated by applying an exponential voltage decrease at the end of the anodization process. The time constant η of the exponential voltage function has been used to control the average thickness and the thickness distribution of the barrier layer at the bottom of the pores of the alumina structure. Depending on the η value, the thickness distribution of the barrier layer can be made very uniform or highly scattered, which allows us to subsequently fine tune the electrodeposition yield of nickel nanoparticles/nanowires at low voltage. As an illustration, the pore filling percentage with Ni has been varied, in a totally reproducible manner, between ∼3 and 100%. Combined with the ability to vary the pore diameter and repetition step over ∼2 orders of magnitude (by varying the anodization voltage and electrolyte type), the control of the pore filling percentage with metal particles/nanowires could bring novel approaches for the organization of nano-objects.

[Shoulder arthroplasty: biomechanics and design]. / Schulterendoprothetik - Biomechanik und Design.

Shoulder arthroplasty is becoming increasingly important in orthopaedic surgery. Continuous development of the implants means that the modern endoprostheses make it possible to recreate the original anatomy with a high degree of accuracy. This is of decisive importance in the long-term restoration of physiological patterns of movement and achievement of pain relief. The modern shoulder arthroplasties allow adjustment of the important parameters: ante-/retroversion, inclination and offset to fit the individual anatomy of the proximal humerus. Fixation is the most important factor for the glenoid component; reduced bone stock can make this difficult. Cemented components are still the gold standard. For young patients surface replacement arthroplasty can be a good alternative treatment for early stages of osteoarthritis. In cuff tear arthropathy reverse prostheses can be used. Reversing the anatomical relationship between glenoid and humerus leads to medialisation and lowering of the center of rotation, which in turn leads to increased tension on the deltoid muscle. Because of the high complication rate this operation should be performed only by experienced shoulder surgeons.

[The influence of reduced bone density on primary stability of cementless femoral stems. A biomechanical in vitro study]. / Der Einfluss der Knochendichte auf die Primärstabilität von zementfreien Femurschaftprothesen--Eine biomechanische In-vitro-Studie.

OBJECTIVE: The aim of the present in vitro study is to examine the influence of bone density on the primary stability of cementless femoral stems in nine pairs of human cadaveric femurs. METHOD: The human proximal femurs were evaluated with regard to their bone density by dual-energy X-ray absorptiometry. Two pairs of human cadaveric femurs had an osteoporotic and two pairs an osteopenic bone stock. After implantation of the cementless femoral stems, the prostheses were loaded in a physiological position. Subsidence, rotation and interface motion of the stems were measured with load cycles up to 2000 Newton. RESULTS: There was no significant correlation between the bone density of the proximal femur and the primary stability of the femoral stem in subsidence (p=0.23) and rotation (p=0.79). Reduced bone density in the osteoporotic and osteopenic human femora did not increase the interface motion at the proximal or distal part of the prosthesis (p>0.05). CONCLUSION: The initial stability of cementless femoral stems was not influenced by the bone density, at least in this biomechanical in vitro study. Thus, theoretical conditions exist that allow secondary osseointegration of femoral stems also in cases of reduced bone density.

[Lumbar spinal stenosis]. / Lumbale Spinalkanalstenose.

Lumbal spinal stenosis is gaining more and more clinical relevance because of changing population structure and increasing demand on lifequality in the elderly. Current treatment recommendations are based on clinical experience, expert opinions and single studies rather than on proven evidence. The radiologic degree of stenosis does not correlate with the patients' clinical situation. It is not the main factor indicating surgery but rather the typical history and spinal claudication. Symptomatic patients with light to moderate complaints should undergo multimodal conservative treatment. Epidural injections, delordosating physiotherapy and medication are useful. In patients with severe symptomatic stenosis surgery is indicated after a conservative treatment of 3 months. Relevant pareses or a cauda equina syndrome are absolute indications for surgery. The general aim is to decompress sufficiently while maintaining or restoring segmental stability. A laminectomy is not necessarily required. In patients with accompanying degenerative Meyerding grade I-II spondylolisthesis or instability in functional radiographs, fusion or dynamic stabilisation are recommended in addition to decompression, depending on the patient's age and activity level.

Raman and near-infrared spectroscopy for quantification of fat composition in a complex food model system.

Raman and near-infrared (NIR) spectroscopy have been evaluated for determining fatty acid composition and contents of main constituents in a complex food model system. A model system consisting of 70 different mixtures of protein, water, and oil blends was developed in order to create a rough chemical imitation of typical fish and meat samples, showing variation both in fatty acid composition and in contents of main constituents. The model samples as well as the pure oil mixtures were measured using Raman and NIR techniques. Partial least squares regression was utilized for prediction, and fatty acid features were expressed in terms of the iodine value and as contents of saturated, monounsaturated, and polyunsaturated fatty acids. Raman spectroscopy provided the best results for predicting iodine values of the model samples, giving validated estimation errors accounting for 2.8% of the total iodine value range. Both techniques provided good results for predicting the content of saturated, monounsaturated, and polyunsaturated fatty acids in the model samples, yielding validated estimation errors in the range of 2.4-6.1% of the total range of fatty acid content. Prediction results for determining fatty acid features of the pure oil mixtures were similar for the two techniques. NIR was clearly the best technique for modeling content of main constituents in the model samples.

Spectroscopic imaging of protein crystals in crystallization drops.

Automatic imaging and scoring of crystallization drops is an essential step in high-throughput crystallography. Presently, white-light images of crystallization drops are acquired robotically and the images are analyzed and scored using pattern recognition algorithms. However, the scoring part remains unreliable as crystals and microcrystals are not always recognized by existing feature-extraction and recognition algorithms. We propose a fundamental shift in crystal monitoring through spectroscopic imaging of crystallization drops. This method converts the problem of automatic crystal detection from one of pattern recognition into one of intensity (concentration) analysis. The latter can be more robust and reliable.

Neuronal regeneration after application of radiofrequency energy to collagenous tissue is affected by limb immobilization: an in vivo animal study.

Despite widespread use of radiofrequency (RF)-shrinkage, there have been no studies on the influence of RF-energy on neural elements of collagenous tissue. The purpose of this study was to examine the effect of RF-shrinkage on neural structures of capsuloligamentous tissue and the recovery of neural elements under different postoperative treatment protocols. One patellar tendon of 46 New-Zealand-White rabbits was shrunk. Six rabbits were sacrificed immediately postoperative. Twenty rabbits were not immobilized, 10 were immobilized for 3 and 10 were immobilized for 6 weeks. A monoclonal antibody, specific against a neurofilament protein, was used to detect nerves and neural structures. Staining pattern of nerve fibres was significantly altered immediately postoperative. After 3 weeks the number of nerve fibres and bundles decreased significantly in immobilized and non-immobilized limbs. The loss of nerve fibres was significantly less in immobilized limbs. At 6 weeks the number of neural elements in immobilized limbs increased to the level of untreated control tissue. In non-immobilized limbs we found no recovery of neural elements 9 weeks postoperatively. At this time the number of nerve fibres and bundles was still significantly less compared to the untreated control limbs. RF-shrinkage causes significant alteration of neural elements. Under immobilization nerve fibres and bundles reach the level of normal untreated tissue. Careful rehabilitation is important after RF-shrinkage. Not only for biomechanical reasons, but also to allow the neural elements to recover, thermally modified tissue should be protected from normal physiologic loads.

Immobilisation after radiofrequency-induced shrinkage of tendon. A histological study in rabbits.

Despite widespread use of radiofrequency (RF) shrinkage, there have been no animal studies on the effects of post-operative immobilisation on the histological properties of the shrunken tissue. We have therefore examined the role of post-operative immobilisation after RF shrinkage with special emphasis on the histological properties of collagenous tissue. One patellar tendon of 66 New Zealand White rabbits was shrunk. Six rabbits were killed immediately after the operation. Twenty rabbits were not immobilised, 20 were immobilised for three weeks and 20 for six weeks. Fibroblasts, collagen and vascular quality and density were evaluated on sections, stained by haematoxylin and eosin. Nine weeks after operation the histological properties were inferior to those of the contralateral control tendons. Shrunk tendons did not return to normal at any time after operation irrespective of whether the animals had been immobilised or not. All the parameters improved significantly between zero and three weeks after operation. Immobilised tendons tended to have a better and faster recovery. Careful rehabilitation is imperative after RF shrinkage. Immobilisation aids recovery of the histological properties. Our findings in this animal model support a period of immobilisation of more than three weeks.

SLAP: design software for optimization of fluorescence analysis systems.

Initial results of a comprehensive design software that optimizes parameters for fluorescence analysis of a user-defined fluorophore are presented. SLAP (spectral LED aggregation program) automatically selects configurations of LEDs that, in a fluorescence analysis system, maximize the emission signal (useful output) as a function of the excitation signal (interference), optics, photodetection modality, and sample characteristics. Initial results draw on an extensive database of blue, blue-green, green and purple LEDs characterized across a range of nominal and overdrive operating conditions. Overdrive conditions enable spectral shifts of the LED excitation bands to enhance the overall flexibility of SLAP optimization. Representative results show a 70.1% improvement in collected signal for GFPuv fluorophores when compared to conventional LED-based fluorescence operated under nominal operating conditions.

[Final results after operative treatment of shoulder joint infections]. / Endergebnis nach operativer Behandlung von Schultergelenksinfekten.

PURPOSE: In a consecutive case series the results of operative treatment of patients with shoulder joint infections following rotator cuff surgery, endoscopic subacromial decompression or subacromial injection were studied. PATIENTS AND METHODS: Between 1990 and 2001 26 patients developed a postoperative infection. 24 patients were available for a mean follow-up of 4.3 (1-12) years. The mean age of the study group was 59.8 (28-84) years. Patients were divided into three groups. Group I consisted of 9 patients with infection after rotator cuff repair, group II consisted of 4 patients with infection after endoscopic subacromial decompression and there were 11 patients in group III with an infection that developed following subacromial injection. Patient evaluation was done according to the Constant and ASES Scores, the SF-36 and a visual analogue scale (VAS) for postoperative pain and satisfaction. RESULTS: The mean postoperative Constant Score was 68.6 pts (SD 25.1) in group I, 84.6 pts (SD 10.4) in group II and 75.6 pts (SD 25.1) in group III. The mean ASES-Score was 65.6 pts (SD 30.0) in group I, 69.8 pts (23.6) in group II and 78.5 pts (SD 25.7) in group III. The SF-36 showed for the summarized physical scale 37.3 pts (SD 12.6) in the first, 39.8 pts (SD 5.8) in the second and 37.7 pts (SD 12.4) in the third group and for the summarized psychometric scale 40.4 pts (SD 2.7) in the first, 44.3 pts. (SD 10.8) in the second and 45.7 pts. (SD 10.1) in the third group. For the VAS for pain, group I had 4.3, group II 4.0 and group III 2.5 pts Patient satisfaction showed similar results with 6.4 pts in the first, 6.5 pts in the second and 6.8 pts in the third group. CONCLUSION: Considering the functional results of operative revision, infection of the shoulder joint following rotator cuff surgery, endoscopic subacromial decompression or subacromial injection is a rare but severe complication.

[Selective pre- intra- and postoperative bile duct diagnosis--an efficient and low complication regimen within the scope of laparoscopic cholecystectomy. Early and late results of a prospective study]. / Selektive prä- intra- und postoperative Gallengangdiagnostik--Ein effizientes und komplikationsarmes Regime im Rahmen der laparoskopischen Cholecystektomie. Früh- und Spätergebnisse einer prospektiven Studie.

INTRODUCTION: The discussion of diagnostic pre- and intraoperative procedures of the common bile duct (CBD) for laparoscopic cholecystectomy is still open. METHODS: Results of a prospective study of 4000 laparoscopic cholecystectomies were evaluated, adhering to the concept of selective common bile duct examination. In 1999 an inquiry was performed on 1197 patients an average of 38.7 months postoperatively to judge this concept. RESULTS: Three hundred and nineteen patients (8%) examined preoperatively by ERC revealing a CBD stone in 126 cases. The morbidity of this procedure was 3.1%. In 0.18% a lesion of the common bile duct was documented following laparoscopic cholecysTectomy. A intraoperative cholangiography was performed in 67 patients (1.7%) because of unclear anatomy or to exclude a CBD stone. Perioperatively a CBD stone was found in 0.5% of cases. Additionally, in 0.3% the same problem occurred in the long-term follow-up, so that the risk for unknown CBD stones following the selective diagnostic concept is 0.8%. CONCLUSION: The concept of selective diagnostic procedures of the common bile duct shows a low morbidity with sufficient efficiency in avoiding CBD stones as well as duct lesions. Therefore it is recommended for routine use in laparoscopic cholecystectomy.

Development of a positive pressure driven micro-fabricated liquid chromatographic analyzer through rapid-prototyping with poly(dimethylsiloxane) Optimizing chromatographic efficiency with sub-nanoliter injections.

A rapid and low-cost means of developing a working prototype for a positive-displacement driven open tubular liquid chromatography (OTLC) analyzer is demonstrated. A novel flow programming and injection strategy was developed and implemented using soft lithography, and evaluated in terms of chromatographic band broadening and efficiency. A separation of two food dyes served as the model sample system. Sample and mobile phase flowed continuously by positive displacement through the OTLC analyzer. Rectangular channels, of dimensions 10 mum deep by 100 mum wide, were micro-fabricated in poly-dimethylsiloxane (PDMS), with the separation portion 6.6 cm long. Using a novel flow programming method, in contrast to electroosmotic flow, sample injection volumes from 0.5 to 10 nl were made in real-time. Band broadening increased substantially for injection volumes over 1 nl. Although underivatized PDMS proved to be a sub-optimal stationary phase, plate heights, H, of 12 mum were experimentally achieved for an unretained analyte with the rectangular channel resulting in a reduced plate height, h, of 1.2. Chromatographic efficiency of the unretained analyte followed the model of an OTLC system limited by mass-transfer in the mobile phase. Flow rates from 6 nl min(-1) up to 200 nl min(-1) were tested, and van Deemter plots confirmed plate heights were optimum at 6 nl min(-1) over the tested flow rate range. Thus, the best separation efficiency, N of 5500 for the 6.6 cm length separation channel, was achieved at the minimum flow rate through the column of 6 nl min(-1), or 3 ml year(-1). This analyzer is a low-cost sampling and chemical analysis tool that is intended to complement micro-fabricated electrophoretic and related separation devices.

A Raman waveguide detector for liquid chromatography.

A novel real-time liquid core Raman waveguide detector designed for liquid chromatographic applications is described. The Raman waveguide detector provides enhanced selectivity over typical high-performance liquid chromatography (HPLC) detectors. The waveguide detector also greatly improves the sensitivity of a typical Raman measurement without resorting to surface enhancement or resonance approaches and is compatible with the typical peak width volumes eluted by microbore and minibore HPLC (packed 1-2-mm-i.d. columns). Detection limit enhancements of over 1000-fold have been achieved for the measurement of alcohols in the aqueous phase with the Raman cell utilizing liquid core waveguide technology. The liquid core waveguides demonstrated in this study were constructed using Teflon AF 2400 tubing with a refractive index of 1.29. The low refractive index of the polymer material allowed HPLC separations with Raman detection to be performed with an aqueous mobile phase. A calibration curve for aqueous solutions of 2-propanol was generated and a limit of detection (LOD) of 2 ppm was determined. The Raman waveguide detector is demonstrated for the HPLC analysis of alcohol test mixtures, with LODs in the low-ppm range at the detector. By coupling the temporal separation achieved by HPLC with the vibrational information gleaned from Raman detection, an information-rich multivariate data matrix is obtained that can be deconvoluted to provide chemical speciation even when the HPLC resolution is poor. In this paper, we will discuss the physical and optical design of the Raman waveguide detector and the demonstration of the detector for HPLC detection.

[Endoscopic hernia repair within the scope of a total management concept]. / Endoskopische Hernienreparation im Rahmen eines Gesamtkonzeptes.

From 1991 until 1998 there were 1832 hernioplasties in 1696 patients. Endoscopic procedures as there were the Trans Abdominal Hernioplasty (TAPP) and the Totaly Extraperitoneal Hernioplasty (TEP) are increasing as the Lichtenstein procedure. This is in opposite to the Shouldice operation. Endoscopic treatment is highly accepted and the results are as good as with other operations. The analysis of our patients shows that there is an indication for all the different procedures. We clame to use the optimal operation for each individual patient depending on clear criteria. Principally there are still the Shouldice operation without a net for the youngers and the Lichtenstein operation in local anaesthesia for elder and risk patients recommended. All others, especially those with bilateral and recurrent hernia profit from endoscopic procedures. Advantages and disadvantages for TAPP and TEP are demonstrated.

Incidence and time course of cardiovascular side effects during spinal anesthesia after prophylactic administration of intravenous fluids or vasoconstrictors.

UNLABELLED: We studied the time course of arterial hypotension and/or bradycardia requiring treatment during spinal anesthesia and compared the efficacy of i.v. fluid or vasoconstrictor administration for the prevention of these side effects. Patients (n = 1066) were randomly allocated to either a volume group (lactated Ringer's solution 15 mL/kg within 15 min before spinal anesthesia), a dihydroergotamine group (10 microg/kg i.m. 15 min before anesthesia), or a placebo group. All patients breathed O2-enriched air during spinal anesthesia (4 mL of plain 0.5% bupivacaine). With the placebo, there were side effects (mean incidence 22.9%) for up to 45 min after the start of anesthesia. Dihydroergotamine reduced the incidence of side effects, preferentially the late ones, more (mean incidence 11.8%) than fluid administration (mean incidence 16.9%), which was effective only during the first 15 min of anesthesia. Both heart rate and arterial pressure decreased within 15 min before the manifestation of symptoms. In a subgroup of patients, the incidence of side effects (8%) was greatly reduced by the intraoperative application of both sedatives and opioids. We conclude that cardiovascular side effects may occur at any time during spinal anesthesia. Fluid administration reduced the incidence of early events, but dihydroergotamine the late events. IMPLICATIONS: Cardiovascular side effects requiring treatment occurred at any time during spinal anesthesia in our placebo-controlled study, regardless of the prophylactic regimen (fluid infusions versus dihydroergotamine).