Influence of hepatitis C virus infection and high virus serum load on biliary complications in liver transplantation

BACKGROUND

Biliary complications (BCs) and recurrent hepatitis C virus (HCV) infection are among the major causes of morbidity and graft loss following liver transplantation. The influence of HCV on BCs has not been definitely clarified.

PATIENTS AND METHODS

We performed a retrospective cohort study to analyze risk factors and outcome of post orthotopic liver transplantation (OLT) BCs in 352 liver transplant recipients over 12 years in Munich, Germany (n = 84 with HCV; living donor and re-OLT were excluded). BCs diagnosed with imaging techniques and abnormal liver enzyme pattern, requiring an intervention, were considered.

RESULTS

In a multivariate analysis, HCV serostatus and a high pre-and post-surgery HCV RNA serum load were independent risk factors for anastomotic strictures. HCV positivity and BCs alone did not alter graft loss. HCV-positive patients with BCs, however, had a significantly worse graft outcome (P = 0.02). Non-anastomotic strictures, bile leaks, and the number of interventions needed to treat bile leaks led to worse graft outcome in all patients.

CONCLUSION

HCV positivity and a high HCV RNA serum load were risk factors for anastomotic strictures. BCs and HCV had an additive effect on graft loss.

Chronic treatment with a novel γ-secretase modulator, JNJ-40418677, inhibits amyloid plaque formation in a mouse model of Alzheimer's disease

BACKGROUND AND PURPOSE

γ-Secretase modulators represent a promising therapeutic approach for Alzheimer's disease (AD) because they selectively decrease amyloid β 42 (Aβ42), a particularly neurotoxic Aβ species that accumulates in plaques in the brains of patients with AD. In the present study, we describe the in vitro and in vivo pharmacological properties of a potent novel γ-secretase modulator, 2-(S)-(3,5-bis(4-(trifluoromethyl)phenyl)phenyl)-4-methylpentanoic acid (JNJ-40418677).

EXPERIMENTAL APPROACH

The potency and selectivity of JNJ-40418677 for Aβ reduction was investigated in human neuroblastoma cells, rat primary neurones and after treatment with single oral doses in non-transgenic mouse brains. To evaluate the effect of JNJ-40418677 on plaque formation, Tg2576 mice were treated from 6 until 13 months of age via the diet.

KEY RESULTS

JNJ-40418677 selectively reduced Aβ42 secretion in human neuroblastoma cells and rat primary neurones, but it did not inhibit Notch processing or formation of other amyloid precursor protein cleavage products. Oral treatment of non-transgenic mice with JNJ-40418677 resulted in an excellent brain penetration of the compound and a dose- and time-dependent decrease of brain Aβ42 levels. Chronic treatment of Tg2576 mice with JNJ-40418677 reduced brain Aβ levels, the area occupied by plaques and plaque number in a dose-dependent manner compared with transgenic vehicle-treated mice.

CONCLUSIONS AND IMPLICATIONS

JNJ-40418677 selectively decreased Aβ42 production, showed an excellent brain penetration after oral administration in mice and lowered brain Aβ burden in Tg2576 mice after chronic treatment. JNJ-40418677 therefore warrants further investigation as a potentially effective disease-modifying therapy for AD.

The subfornical organ: a central nervous system site for actions of circulating leptin

Adipose tissue plays a critical role in energy homeostasis, secreting adipokines that control feeding, thermogenesis, and neuroendocrine function. Leptin is the prototypic adipokine that acts centrally to signal long-term energy balance. While hypothalamic and brain stem nuclei are well-established sites of action of leptin, we tested the hypothesis that leptin signaling occurs in the subfornical organ (SFO). The SFO is a circumventricular organ (CVO) that lacks the normal blood-brain barrier, is an important site in central autonomic regulation, and has been suggested to have a role in modulating peripheral signals indicating energy status. We report here the presence of mRNA for the signaling form of the leptin receptor in SFO and leptin receptor localization by immunohistochemistry within this CVO. Central administration of leptin resulted in phosphorylation of STAT3 in neurons of SFO. Whole cell current-clamp recordings from dissociated SFO neurons demonstrated that leptin (10 nM) influenced the excitability of 64% (46/72) of SFO neurons. Leptin was found to depolarize the majority of responsive neurons with a mean change in membrane potential of 7.3 +/- 0.6 mV (39% of all SFO neurons), while the remaining cells that responded to leptin hyperpolarized (-6.9 +/- 0.7 mV, 25% of all SFO neurons). Similar depolarizing and hyperpolarizing effects of leptin were observed in recordings from acutely prepared SFO slice preparations. Leptin was found to influence the same population of SFO neurons influenced by amylin as three of four cells tested for the effects of bath application of both amylin and leptin depolarized to both peptides. These observations identify the SFO as a possible central nervous system location, with direct access to the peripheral circulation, at which leptin may act to influence hypothalamic control of energy homeostasis.

Proteomics-based strategies in kinase drug discovery

Studies of drug action classically assess biochemical activity in settings which typically contain the isolated target only. Recent technical advances in mass spectrometry-based analysis of proteins have enabled the quantitative analysis of sub-proteomes and entire proteomes, thus initiating a departure from the traditional single gene--single protein--single target paradigm. Here, we review chemical proteomics-based experimental strategies in kinase drug discovery to analyse quantitatively the interaction of small molecule compounds or drugs with a defined sub-proteome containing hundreds of protein kinases and related proteins. One novel approach is based on 'Kinobeads'--an affinity resin comprised of a cocktail of immobilized broad spectrum kinase inhibitors--to monitor quantitatively the differential binding of kinases and related nucleotide-binding proteins in the presence and absence of varying concentrations of a lead compound or drug of interest. Differential binding is detected by high throughput and sensitive mass spectroscopy techniques utilizing isobaric tagging reagents (iTRAQ), yielding quantitative and detailed target binding profiles. The method can be applied to the screening of compound libraries and to selectivity profiling of lead compounds directly against their endogenously expressed targets in a range of cell types and tissue lysates. In addition, the method can be used to map drug-induced changes in the phosphorylation state of the captured sub-proteome, enabling the analysis of signalling pathways downstream of target kinases.

Indikation, Biomechanik und Frühergebnisse des künstlichen Bandscheibenersatzes

AIM

Judgment of factors concerning the indication for the implantation of an artificial disc endoprosthesis, the rating of this operation and biomechanical considerations.

METHOD

Presentation of the indication and the value of a new operative concept in comparison to a so-called dynamic stabilization procedure (Dynesys' method). Indications for the operation are: unsuccessful, orthopedic conservative treatment for > 6 months, segmental pain, age < 45 years, evidence of an MRI demonstrable mono- or bisegmental disc degeneration with or without disc prolabation, exclusion of psychogenic disease and positive preoperative, diagnostic measures such as facet joint infiltration and discography.

RESULTS

In an earlier investigation the efficacy of the Link method was demonstrated as shown by the reduction of the analgesic use, the angle of the lumbar lordosis (L1-S1) increased from 35.6 degrees to 42.6 degrees (20.2 %), the segmental angle from 19 degrees to 30 degrees (57.5 %). The new investigation using the Aesculap endoprosthesis resulted in a change of the angle of lumbar lordosis from 35.4 degrees to 45.4 degrees (25.4 %) and a change of the segmental angle from 17.3 degrees to 29.1 degrees (57.6 %). This method is a real endoprosthetic instrumentation in the field of spinal surgery.

CONCLUSION

In younger patients with mono- or bisegmental disc degeneration there is an indication for the implantation of a disc endoprosthesis. A facet joint arthrosis and an age over 45 years are contraindications for the operation. The indication in patients with a classic failed back surgery syndrome is still unclear, the improvement of the instrumentation and a further adaptation of the systems to the known biomechanics of the lumbar spine are mandatory as is an intensive discussion of the operative procedure in the case of revision operations. The Dynesys method, with the inherent danger of segmental kyphozitation, a published, significant revision quota combined with a reduction of motility, does not fulfill this criterion.

Calcium-dependent maintenance of agrin-induced postsynaptic specializations

Although much progress has been made in understanding synapse formation, little is known about the mechanisms underlying synaptic maintenance and loss. The formation of agrin-induced AChR clusters on cultured myotubes requires both activation of the receptor tyrosine kinase MuSK and intracellular calcium fluxes. Here, we provide evidence that such AChR clusters are maintained by agrin/MuSK-induced intracellular calcium fluxes. Clamping intracellular calcium fluxes after AChR clusters have formed leads to rapid MuSK and AChR tyrosine dephosphorylation and cluster dispersal, even in the continued presence of agrin. Both the dephosphorylation and the dispersal are inhibited by the tyrosine phosphatase inhibitor pervanadate. In contrast, clamping intracellular calcium at the time of initial agrin stimulation has no effect on agrin-induced MuSK or AChR phosphorylation, but blocks AChR cluster formation. These findings suggest an avenue by which postsynaptic stability can be regulated by modification of intracellular signaling pathways that are distinct from those used during synapse formation.

[Disc replacement with the SB Charité endoposthesis - experience, preliminary results and comments after 35 prospectively performed operations]

Aim of this prospective study was an investigation concerning the indication for the implantation of an artificial disc endoprosthesis and the rating of this operation.

METHOD

35 patients with 11 bi- and 24 monosegmental implanted disc endoprosthesis were observed over an average follow-up of 14.7 months. Indications for the operation were: unsuccessful, orthopedic conservative treatment > 6 months, segmental pain, age < 45 years, evidence of a radiologic (MRI) demonstrable mono- or bisegmental disc degeneration with or without disc prolabation, exclusion of psychogenic disease and positive preoperative, diagnostic measures.

RESULTS

The average stay in the hospital was 16.8 days (preoperative: 4.3 days), the average operation time 85.5 minutes, the average blood loss was 125 ccm. 23 patients were operated in L 5 / S 1, 20 in L 4 / 5 and 2 in L 3 / 4. NSAR was given in 33 patients preoperatively, opiates in 2 further patients, postoperatively NSAR was necessary in 5 patients, opiates in 2 patients. The preoperative angle of lordosis (L 1 - S 1, n = 25) was changed from 35.6 degrees to 42.6 degrees (20,2 %), the segmental angle from 19 degrees to 30 degrees (57.5 %).

CONCLUSION

The implantation of the artificial disc was followed by a good pain relief in patients suffering from a mono- or bisegmental disc degeneration. In patients with a facett joint arthrosis and elderly patients > 45 years this method cannot be used, the indication in patients with failed back surgery syndrome cannot be estimated yet. Improvements of the instrumentation and the discussion in the case of revisional operations are mandatory.

[Principles of surgical treatment of upper thoracic and cervicothoracic kyphosis]

Idiopathic upper thoracic and cervicothoracic kyphoses are rare. More frequently they are the consequence of spinal instability as in neurofibromatosis (von Recklinghausen's disease), after laminectomies, in tumors, congenital disorders, spondylodiscitis, and fractures. Neurologic problems with severe pareses complicate these deformities. Anterior bone loss (fracture, tumor, spondylodiscitis), posterior instability (post-laminectomy kyphosis) or a combination of both are responsible for the deformity. The operative treatment of the anatomically unfavorable localization requires great experience in spinal surgery; the procedures often are salvage surgeries. In the absence of a successful conservative treatment, early posterior/anterior or anterior/posterior reconstruction of the sagittal profile with primary stable implants is necessary to minimize the risk of renewed surgery. Transplantation of stable bone grafts such as the fibula is a precondition for postoperative treatment without external support. The indication is restrictive in the presence of malignant primary and secondary tumors with poor prognosis. Restitution of existing neurologic deficits is unpredictable.

[Kyphotic deformation in fractures of the thoracic and lumbar spine]

Kyphosis is the typical deformity of untreated spine fractures. In the majority of all injuries, destruction of the anterior part of the spine occurs. Biomechanical aspects require reconstruction of the anterior column. In 112 patients with a traumatic fracture of the thoracolumbar spine, a loss of correction in the sagittal plane exceeded the intraoperative correction. The cause of deterioration was in the main part the destruction of the intervertebral disk. The results of different surgical techniques are reviewed and discussed based on the literature. The dorsal instrumentation with or without autogenous bone grafting is not sufficient for spinal stabilization and kyphosis is the result. The golden standard for prevention of kyphosis is the combined approach with anterior cortical bone graft and posterior transpedicular screwing. In the case of anterior cage implantation, the risk of graft failure can be avoided. With anterior minimally invasive approaches, traumatization can be reduced by using the same biomechanical principles. In the case of a type A fracture with intact posterior elements, use of an anterior primary stable implant with bone graft represents an alternative method.

[Necessary steps for implementing the Australian DRG system]

The introduction of the DRG-System will be followed by severe changes in the German hospitals. From the view of today departments or hospitals are threatened by closing if they do not deal with the new rules. A common implementation of this system by all participants of the health system is necessary before the introduction at 1.1.2003. Only this will guarantee an adequate presentation of the different defaults in the future because the conditions of the implementation of the system are not qualified yet. The hospitals are forced to prepare the introduction of the DRG-System, however. Only the Arrangement of an extensive documentation of all diagnoses and all conservative and operation methods together with a cost--cutting administration will be consequently followed by a financial healthy situation. The most important points to be emphasized are the medical documentation, the controlling, the improvement of the processes and the computer assisted documentation. By an intensive information concerning all further resources the involvement of the employees of the hospital is a necessary part for the success of the introduction.

[Function of back extensor muscles in upright standing position and during sitting with identical back posture--an electromyography study]

PROBLEM

There is a controversial discussion about the loading of the spine by the force of the extending muscles of the back in upright sitting with the back curved as in upright standing. Experimental studies investigating this issue are still lacking.

METHODS

In the study presented in this paper we measured in 30 subjects the activity of the extending back muscles both in a natural upright standing posture and in sitting with identical posture of the back as recommended in some back training programs. To this end we recorded the electromyographical surface activity of the back muscles at four levels of the spine in both postures. The EMG activities were intraindividually normalized with reference to the respective activity recorded at maximum voluntary isometric contraction (MVC).

RESULTS

At three of the four levels of the spine examined, the group averages of the EMG activity in sitting were significantly higher than in standing (p < 0.001). The maximum activity enhancement evaluated was 48% at Th12. The force of the lower back muscles in sitting with a posture of the back as in natural upright standing could be estimated to be at least greater than 30% of the force at MVC.

CONCLUSION

The force needed to enforce in sitting a posture of the back identical to the posture at natural standing entails lower back muscle fatigue in a few minutes. The results of our study agree with recent experimental findings about an increased loading of the spine in lordotic sitting.

Nitric oxide synthase (NOS-1) coclustered with agrin-induced AChR-specializations on cultured skeletal myotubes

Previously we reported that neuronal nitric oxide synthase type-1 (NOS-1) is expressed in skeletal myotubes in vitro. In the present paper we sought to determine whether agrin-induced membrane specializations known to include the nicotinic acetylcholine receptor (AChR) on cultured myotubes may also contain NOS-1 and related molecules. After treatment with various agrin constructs containing the full C-terminally AChR-clustering domain (fragments N2, N4), but not with fragment C2 (truncated), NOS-1 expressed in the cytosol of mouse C2C12 skeletal myotubes coclustered with AChR, 43K rapsyn, MuSK, and the dystrophin/utrophin glycoprotein-complex (DUGC). Agrin-induced specializations also included coaggregates of N-methyl-d-aspartic acid (NMDA)-receptor, alpha-sodium (NaCh), or Shaker-type K+ channel (KCh)/PSD-95 complexes, and NOS-1. We conclude that agrin is crucial for recruitment of preassembled multimolecular membrane clusters, including AChR, NMDAR, and ion channels linked to NOS-1. Coassembly of NOS-1 to postsynaptic molecules may reflect site-specific NO-signaling pathways in neuromuscular junction formation and functions.

[Criteria for treatment of idiopathic scoliosis between 40 degrees and 50 degrees. Surgical vs. conservative therapy]

The treatment of idiopathic scoliosis over 40 degrees (Cobb) during the growth period is under discussion concerning the indication for conservative or surgical treatment. Curve progression depends on the degree of the frontal and sagittal deformity, vertebral rotation, rigidity of the curve, the skeletal age, the age and sex of the patient, the familial frequency of scoliosis and the location of the curve. In scoliosis over 40 degrees progression is fast and the possibilities for successful conservative brace treatment are reduced during the growth period. Progression occurs more frequently in thoracic and double major scolioses, especially in young patients (Risser sign 0 and 1). Predictive factors of a successful brace treatment are the correction of scoliosis and rotation; deterioration of both during the brace treatment leads to poor results. Evaluating the flexibility of the sagittal profile is important, as is primary correction of 30-50% in the brace during the 3 months. Operative correction of small primary curves reduces the fusion length, operation time, and blood loss and is followed by a reduction in loading on the adjacent vertebral segments in comparison to the long fusions necessary in more structural and double major scolioses. So far it is not possible to make an equivalent judgment of the frequency of the "crankshaft" phenomenon and the treatment necessary in young patients (Rissersign 0 and 1) treated by dorsal instrumentation alone, but temporary brace treatment may be considered in those cases.

[Scoliosis and hip flexion contracture in Duchenne muscular dystrophy]

Spinal deformity is common in muscular dystrophy and usually occurs after loss of walking ability. Unlike in idiopathic and other scoliosis forms, there seems to be no side preference of the convexity. Aim of the study was to analyse, if there is any relation between incidence and extent of walking ability, lower limb contractures and development of scoliosis.

METHODS

In a retrospective study, 45 patients with Duchenne muscular dystrophy who underwent surgery were analysed, concerning walking ability, contractures of lower extremities and scoliosis.

RESULTS

1: No scoliosis was observed in ambulatory patients. 2: 96% of the wheelchair bound patients suffered from scoliosis. 3: 96% of the scoliosis patients had hip flexion or abduction contractures. 4: In 12 of 15 cases with side-different contractures, scoliosis tended to the side with the greater contracture.

CONCLUSIONS

The influence of hip contracture and pelvic obliquity on scoliosis is discussed controversially. Concerning muscular dystrophy, there seems to be a positive correlation between convexity and hip contracture. If this is a causal relation or if there is a faster progression of structural alteration of the muscles on one side has to be further investigated.

Orthopedic and neurosurgical treatment of severe kyphosis in myelomeningocele

Kyphosis in myelomeningocele is characterized by a complex pattern of problems during development and therapy. On the one hand, decompensation of upright posture leads to loss of sitting ability and social integration; on the other hand, accompanying malformations and trophic alterations threaten the physical integrity and performance. Neurologic function, cerebrospinal fluid (CSF) circulation, skeletal deformity and the urinary transport system need to be kept in mind and need to be treated with cooperation between the different specialties. Especially during serious surgical interventions such as spinal surgery, neither the nervous system nor the kidneys must be ignored. Sixteen patients underwent kyphectomy in the Orthopedic Department of the University of Mainz between 1993 and 1997, all of them supervised by the Neurosurgical Department. In 13 cases, transversal myelotomy was performed. No insufficiency of CSF circulation was seen; neither were there any CSF fistulae. Particular problems arose from the skin and soft tissue above the gibbus, the lack of muscles and the regeneration deficiency caused by trophic disorders. Therefore, a significantly higher complication rate was found than with other correctional operations.

Shock-wave therapy for tennis and golfer's elbow--1 year follow-up

Thirty patients with chronic medial epicondylitis were treated with low-energy shock waves. They received 500 impulses of 0.08 mJ/mm2 three times at weekly intervals. At 1 year follow-up examinations were performed. According to the Verhaar criteria, only seven patients reached excellent or good results. In eight cases a fair outcome was recorded, and in 14 patients the outcome was poor. Only six patients were satisfied with the treatment. The average relief of pain was 32%. These data were significantly worse than for identically treated patients with chronic tennis elbow. Thus, the question arises as to whether extracorporal shock-wave therapy is indicated in medial epicondylitis.

Operative treatment of spondylodiscitis--what is the most effective approach?

In a study the results recorded in 34 surgically treated patients with specific or unspecific spondylodiscitis after dorsoventral one-stage instrumentation with CDI and anterior grafting (group 1) were compared with those obtained in a group of 38 patients treated with anterior CDH instrumentation in combination with anterior grafting (group 2). The mean observation periods were 48.4 (19-82) months in group 1 and 29.0 (8-54) months in group 2. In both groups the infection healed after fusion without a secondary operation. In group 1 the mean values for blood loss, operating time, length of hospital stay and fusion length (3.5 segments) were significant higher than those in group 2; in particular, the fusion length was shorter (1.3 segments) in group 2. Only 8 patients in group 1 were treated with postoperative external support. The mean preoperative segmental angle of 18.2 degrees (group 1) was corrected by a mean of 11.9 degrees, and the reposition loss during follow-up amounted to an average of 2.7 degrees. Group 2 showed a mean preoperative segmental deformity angle of 13.4 degrees, which was corrected by 11.6 degrees, and the loss of reposition was 2.9 degrees on average. Even in florid spondylodiscitis a short-range anterior fusion of the affected spinal segment can be performed with a primary stable implant, avoiding a second operation without an increased risk of infection-related dislocation. In the authors' own experience a secondary dorsal operation can be avoided except in the case segment L-5/S-1, the fast mobilization without external support allows a up-to-date treatment in this severe spinal disease.

Shoulder function after extracorporal shock wave therapy for calcific tendinitis

We report a controlled, prospective study that explored the effect of extracorporal shock waves of low- versus high-energy density in patients with chronic shoulder pain and calcific tendinitis. We assigned at random 100 patients who had had calcific tendinitis for more than 12 months to 2 groups to receive shock wave therapy either of a low- or high-energy density. Group 1 received 1500 impulses of 0.06 mJ/mm2, whereas group 2 received 1500 impulses of 0.28 mJ/mm2. Unlike group 1, in which the shock wave application could be performed without local anesthesia, all patients in group 2 required brachial plexus anesthesia. The patients were reviewed at 6 and 24 weeks. Partial or complete disintegration of the calcareous deposit was observed in 50% of the patients in group 1 and 64% of the patients in group 2 (P < .01). According to the Constant score, ratings increased from 48 to 71 points in group 1 (P < .001) and from 53 to 88 in group 2 (P < .001) (out of a total possible 100 points), the end values of both groups differing significantly (P < .01). After 24 weeks, 52% of the patients in group 1 rated the results of treatment as good or excellent, compared with 68% in group 2 (P < .01). No improvement was reported by 24% versus 10%, respectively, at the 24-week follow-up.

[Results of extracorporeal shock-wave application in lateral elbow tendopathy]

AIM

This review article focuses on a possible pain-alleviating effect of shock-wave application in persistent lateral epicondylopathy of the elbow and compares the effects with data on other non-operative and operative procedures.

METHODS

Patients who suffered from chronic tennis elbow for more than 12 months and were therefore referred for a surgical procedure were assigned at random to two groups of low-energy shock-wave therapy. Group I received a total of 3000 (3 x 1000) impulses of 0.08 mJ/mm(2), while group II (control group) received a total of 30 (3 x 10) impulses of 0.08 mJ/mm(2). Follow-up examinations were carried out after 3, 6, and 24 and 52 weeks.

RESULTS

There was a significant improvement of pain and function in group I, with a good or excellent outcome in 52% of cases compared to 6% in group II at the last evaluation.

CONCLUSION

Extracorporeal shock-wave application has a dose-dependent pain-relieving effect on chronic tendopathy of the lateral elbow.

Tyrosine phosphorylation of the muscle-specific kinase is exclusively induced by acetylcholine receptor-aggregating agrin fragments

During formation of the neuromuscular junction, the basal membrane protein agrin initiates the aggregation of acetylcholine receptors (AChR) on the surface of myotubes. A muscle-specific kinase (MuSK) becomes phosphorylated upon incubation with agrin, although it does not bind to agrin on its own. Utilizing MuSK-specific antibodies, we demonstrate that the ability of different splicing variants and truncation fragments of agrin to trigger MuSK phosphorylation and AChR aggregation are correlated. Only agrin forms which are potent inducers of AChR-clustering are able to trigger the phosphorylation of MuSK. Picomolar concentrations of agrin are already sufficient to induce MuSK phosphorylation. Similar amounts are necessary for the aggregation of AChRs as well as their phosphorylation on a tyrosine residue. The complete overlap of specificities for MuSK phosphorylation and AChR aggregation suggests that only binding of agrin to a MuSK-containing receptor complex is responsible for the initiation of AChR aggregation. In contrast, interactions of agrin with binding proteins on the muscle surface harbouring different specificities such as alpha-dystroglycan do not seem to be necessary for this process.

Formation of postsynaptic-like membranes during differentiation of embryonic stem cells in vitro

To analyze the formation of neuromuscular junctions, mouse pluripotent embryonic stem (ES) cells were differentiated via embryoid bodies into skeletal muscle and neuronal cells. The developmentally controlled expression of skeletal muscle-specific genes coding for myf5, myogenin, myoD and myf6, alpha 1 subunit of the L-type calcium channel, cell adhesion molecule M-cadherin, and neuron-specific genes encoding the 68-, 160-, and 200-kDa neurofilament proteins, synaptic vesicle protein synaptophysin, brain-specific proteoglycan neurocan, and microtubule-associated protein tau was demonstrated by RT-PCR analysis. In addition, genes specifically expressed at neuromuscular junctions, the gamma- and epsilon-subunits of the nicotinic acetylcholine receptor (AChR) and the extracellular matrix protein S-laminin, were found. At the terminal differentiation stage characterized by the formation of multinucleated spontaneously contracting myotubes, the myogenic regulatory gene myf6 and the AChR epsilon-subunit gene, both specifically expressed in mature adult skeletal muscle, were found to be coexpressed. Only the terminally differentiated myotubes showed a clustering of nicotinic acetylcholine receptors (AChR) and a colocalization with agrin and synaptophysin. The formation of AChRs was also demonstrated on a functional level by using the patch clamp technique. Taken together, our results showed that during ES cell differentiation in vitro neuron- and muscle-specific genes are expressed in a developmentally controlled manner, resulting in the formation of postsynaptic-like membranes. Thus, the embryonic stem cell differentiation model will be helpful for studying cellular interactions at neuromuscular junctions by "loss of function" analysis in vitro.

Dimerization of the muscle-specific kinase induces tyrosine phosphorylation of acetylcholine receptors and their aggregation on the surface of myotubes

During development of the neuromuscular junction, neuronal splice variants of agrin initiate the aggregation of acetylcholine receptors on the myotube surface. The muscle-specific kinase is thought to be part of an agrin receptor complex, although the recombinant protein does not bind agrin with high affinity. To specify its function, we induced phosphorylation and activation of this kinase in the absence of agrin by incubating myotubes with antibodies directed against its N-terminal sequence. Antibody-induced dimerization of the muscle-specific kinase but not treatment with Fab fragments was sufficient to trigger two key events of early postsynaptic development: acetylcholine receptors accumulated into aggregates, and their beta-subunits became phosphorylated on tyrosine residues. Heparin partially inhibited receptor aggregation induced by both agrin and anti-muscle-specific kinase antibodies. In contrast, it did not affect kinase or acetylcholine receptor phosphorylation. These data indicate that agrin induces postsynaptic differentiation by dimerizing the muscle-specific kinase. They also suggest that activation of the kinase domain can account for only part of agrin's effects. Dimerization of this molecule appears to activate an additional signal, most likely by organizing a scaffold for other postsynaptic proteins.

Invasion of human cartilage by cultured multicellular spheroids of rheumatoid synovial cells--a novel in vitro model system for rheumatoid arthritis

OBJECTIVE

A new 3-dimensional cell culture system was established to examine the invasion of rheumatoid synovial cells into cartilage.

METHODS

Synovial cells from 20 patients with rheumatoid arthritis (RA) and 15 patients with osteoarthritis (OA) were co-cultured as multicellular spheroids with cartilage fragments.

RESULTS

After 4 weeks the rheumatoid spheroids eroded the cartilage. The destruction of cartilage was supported by a high expression level of cathepsin D and matrix metalloproteinases. In contrast, the OA tissue showed attachment to the cartilage only.

CONCLUSION

Our results indicate that spheroid/cartilage co-cultures seem to be a suitable in vitro model for the study of destructive cellular mechanisms that occur in RA.

Gait analysis in idiopathic scoliosis before and after surgery: a comparison of the pre- and postoperative muscle activation pattern

In a prospective experimental study the level gait activity scores of the iliocostalis lumborum, glutaeus medius, tensor fasciae latae, vastus lateralis and peronaeus longus muscles of both body sides were examined by computerized electromyography in 23 patients with idiopathic scoliosis before and after CD instrumentation. The pre- and postoperative findings were examined as to asymmetric patterns in muscle requisition during gait and the respective changes induced by the spinal correction. These results were compared with the corresponding results obtained in healthy subjects in two independent sessions with identical experimental conditions. A muscle activity asymmetry coefficient was defined to quantify the degree of left/right muscle activation asymmetry observed. Postoperatively a statistically significant reduction (P < 0.05) of a preoperatively strongly increased activity was found in the lumbar muscles of the convex side of double major scolioses as well as in the glutaeus medius and tensor fascia lata muscles of the concave side of thoracic curvatures. Both the casuistic and statistical analysis of the results of our study support the hypothesis that activity asymmetries observed in the paravertebral musculature in idiopathic scoliosis patients are the result of the scoliotic body deformities, with consequent asymmetries in the biomechanical force patterns of body postures and body motions, rather than an aetiological factor of scoliotic curvatures.

Preoperative estimation of screw fixation strength in vertebral bodies

STUDY DESIGN

Bone mineral density and bone cross-sectional area of human cadaveric vertebral bodies were investigated radiologically and histologically, respectively. After ventral instrumentation with ventral derotation spondylodesis screws, axial pullout force was measured and compared with radiologic and histologic data.

OBJECTIVES

To elucidate how well ventral derotation spondylodesis screw fixation strength can be estimated before surgery by specified applications of dual-energy x-ray absorptiometry, quantitative computed tomography, T2*-relaxation time in magnetic resonance imaging, and histomorphometry.

SUMMARY OF BACKGROUND DATA

It is postulated that bone quality plays a crucial role in initial strength of the instrumented spine. Bone quality is even more important in anterior fixation because of the prevalence of spongy bone in the vertebral body.

METHODS

Bone mineral density of human cadaveric lumbar-vertebral bodies was assessed by dual-energy x-ray absorptiometry and quantitative computed tomography (cancellous and cortical bone separately). Cancellous bone was also characterized by T2*-relaxation time, measured by magnetic resonance imaging and histomorphometric study. Vertebral bodies were instrumented ventrally with VDS screws, and screw axial pullout force was measured and correlated with each of the nonmechanical measures. Patients with manifest osteoporosis, osteomalacia and tumors were excluded. For statistical analysis, the Mann-Whitney rank sum test was used with a significance value of P < 0.05.

RESULTS

The highest correlation with pullout force was for density of cancellous bone determined by quantitative computed tomography (r = 0.72; P < 0.001), immediately followed that determined by dual-energy x-ray absorptiometry (r = 0.70; P < 0.001). Results of measurement of T2*-relaxation time and those of histomorphometric study correlated moderately (r = 0.55; r = 0.50), whereas cortical bone density determined by quantitative computed tomography showed negligible correlation (r = 0.2).

CONCLUSIONS

The absorptiometric techniques, quantitative computed tomographic scan of cancellous bone and dual-energy x-ray absorptiometric study, provide more accurate readings for preoperative estimation of initial VDS screw fixation strength than do the other methods studied.

[Extracorporeal shockwave therapy in epicondylitis humeri ulnaris or radialis--a prospective, controlled, comparative study]

AIM OF THE STUDY

Has extracorporal shockwave therapy in chronic golfer's elbow comparable results as in tennis elbow?

METHOD

30 patients for extracorporal shockwave therapy who suffered from chronic medial epicondylitis (group I) and 30 patients with persistent tennis elbow (group II) received 500 impulses of 0.08 mJ/mm2 three times at weekly intervals. The final follow-up examination was done after 24 weeks.

RESULTS

Significant differences in relief of pain and improvement of function were observed in favour of group II. Good or excellent outcome was found in only 27% for the epicondylitis humeri ulnaris, but in 60% for epicondylitis humeri radialis.

CONCLUSION

The indication for extracorporeal shock-wave therapy in medial epicondylitis must be questioned.

Application of extracorporeal shock-waves in the treatment of pseudarthrosis of the lower extremity. Preliminary results

Between January 1991 and January 1996, pseudarthroses of the legs were treated prospectively in 48 patients by application of high-energy extracorporeal shock waves with an experimental device. The mean duration of pseudarthrosis was 12 months. On average, 2.4 surgical interventions had previously been performed. A total of 3000 impulses with an energy density of 0.6 mJ/mm2 was applied to the pseudarthrosis. Bony union was achieved in 60.4% of our patients after an average of 3.4 months. Failures were found especially in the atrophic types of pseudarthrosis as well as in congenital bone disorders like fibrous dysplasia or osteogenesis imperfecta. No serious complications were observed. Even after numerous surgical interventions high-energy extracorporeal shock-wave therapy showed a fair success rate. A higher success rate of this non-invasive method for the treatment of bony non-unions may be expected by applying strict selection criteria.

[Extracorporeal shockwave treatment of delayed bone healing. A critical assessment]

Since the late 1980s, experiments have been performed to influence physiologic and disturbed healing of bone. However, the mainly negative results of animal studies, cannot be applied to the human nonunion situation as long as there is no adequate animal pseudarthrosis model. Prospective clinical studies in various centres have resulted in success rates of more than 50%, although the majority of patients had been treated repeatedly and ineffectively with the gold standard of re-osteosynthesis and grafting. Since the mechanisms are not yet understood, only such desperate conditions are an indication for the application of high-energy extracorporal shock waves.

[Extracorporeal shockwave therapy in orthopedics. Positive results in tennis elbow and tendinosis calcarea of the shoulder]

Since the beginning of the 1990s scientific investigations on the use of extracorporeal shock wave therapy (ESWT) in the field of orthopedics have been carried out at the Orthopedic Department of the University of Mainz. Prospective studies demonstrated beneficial effects in chronic lateral humeral epicondylitis (tennis elbow), and in calcifying tendinitis of the shoulder in more than 50% of the cases. Additional indications for which positive results of prospective studies have been published during the past 2 years are plantar calcaneodynea and pseudoarthrosis. On the basis of the results achieved, it may be concluded that, for specific indications, extracorporeal shock wave therapy may now be taken out of the clinical testing stage and introduced into routine practice.

Heparin inhibits acetylcholine receptor aggregation at two distinct steps in the agrin-induced pathway

Muscle cells depend on motoneurons for the initiation of postsynaptic differentiation during early development of the neuromuscular junction. Motoneurons secrete specific isoforms of the extracellular matrix protein agrin which trigger the aggregation of acetylcholine receptors (AChRs) on the muscle surface. Both motoneuron- and agrin-induced AChR aggregation are inhibited by heparin. Here we show that this inhibition is due to two separate and distinguishable mechanisms. At high concentrations, heparin directly binds to agrin isoforms which contain the peptide KSRK, resulting in a virtually complete inhibition of AChR clustering. Heparin and other polyanions do not bind to agrin splicing variants without KSRK insert. Isoforms containing or lacking the KSRK insert have a high potency to induce AChR aggregation in the presence of an activating eight-amino-acid insert. This activity is inhibited by low concentrations of heparin even in the absence of any binding of heparin to agrin. Therefore, this second type of inhibition is due to the interaction of heparin with a downstream component of the agrin-induced clustering pathway. Binding of heparin to this yet unidentified component substantially decreases, but does not completely abolish AChR aggregation. The inhibition is particularly strong on myotubes which have not completely matured in culture.

[Fractures after total knee joint endoprosthesis. Results of treatment with various stabilizing methods]

In 20 patients with a fracture of femur or tibia 5.2 years after arthroplasty of knee the results of the operative treatment are presented. The results show that especially bone damaging diseases as rheumatoid arthritis, osteoporosis and the loosening of the endoprosthesis are favorable for the fracture during the follow-up. The conclusion of the investigation shows that in younger patients the external fixation by plates and screws is the preferential treatment, in elderly people or comminuted fracture an internal fixation, also in combination with an additional osteosynthesis, allows a fast mobilization. The number of observed complications is higher than in primary knee arthroplasty, the full weight bearing 1st delayed. The rate of further operations and unsatisfactory results is also higher being affected by the high mean age of the operated patients (73.4 years). The possible use of a total femur implant must be discussed critically because only an individual production can avoid further damage of the parts of the joint that were not concerned by the fracture.

[High-energy extracorporeal shock-wave therapy (ESWT) in the treatment of pseudarthrosis]

PROBLEM

The success rate of high-energy extracorporal shock wave therapy in the treatment of non-unions in comparison to the "golden standard" surgery is still unclear.

METHOD

In a prospective study, 3000 impulses with an energy density of 0.6 mJ/mm2 were applied with an experimental device to the pseudarthrosis in 52 patients.

RESULTS

The mean duration of pseudarthrosis was 13 months. A mean of 2.5 surgical interventions had already been performed. Bony union was achieved in 52% of our patients after an average of 3.3 months. Failures especially were found in the atrophic type of pseudarthrosis as well as in congenital bone disorders like fibrous dysplasia or osteogenesis imperfecta. No serious complications were observed.

CONCLUSIONS

Even after numerous surgical interventions high-energy extracorporal shock wave therapy as a noninvasive method for the treatment of bony non-unions showed a fair success rate. A higher success rate can be expected by strict selection criteria.

[Extracorporeal shock-wave therapy. Experimental basis, clinical application]

The purpose of our studies was to investigate experimentally the dose-dependent effects of extracorporeal shock waves on tendon and bone and to unveil therapeutic possibilities in tendinopathies and pseudarthroses. In animal experiments, both positive and negative influences were exerted by shock waves, depending on the initial situation and on the power of the applied shock waves. In prospective clinical trials positive effects were found in the treatment of persistent tennis elbow, plantar fasciitis, calcifying tendinitis, and pseudarthrosis. Our data show that extracorporeal shock waves may provide analgesic, resorptive and osteo-inductive reactions with nearly no side effects. However, the high cost of apparatus and staff prevents a routine application. Extracorporeal shock waves thus remain a last alternative before the indication is made for an operative procedure.

Primary stable anterior instrumentation or dorsoventral spondylodesis in spondylodiscitis? Results of a comparative study

The operative results of 23 patients with a specific or unspecific spondylodiscitis were documented over 2 years after the focus of the inflammation had been eradicated, bone chip had been interposed and a CDH instrumentation had been performed by an anterior approach only. These outcomes were compared with the results of 32 patients in whom the focus had been removed and the defect had been filled with bone graft from an anterior approach, followed by stabilisation with CD instrumentation through an additional dorsal approach. In the cases where CDH instrumentation was applied, the range of fusion averaged 1.3 segments. This was clearly less extensive than in dorsoventral stabilisation, in which on average 3.5 segments were fused. In 47 of 55 cases mobilisation was achieved without orthesis. Eight months after the operations bony fusion could be observed radiologically in all patients. The mean preoperative kyphotic angle of the affected segments was 14.4 degrees, compared to 4 degrees after the operation. The mean loss of reposition was measured to be about 2.7 degrees in both groups. Average operation time and blood loss were about 50% higher in the patients treated dorsoventrally. We conclude that even in the case of florid spondylodiscitis, a short-range anterior fusion of the affected spinal segment may be performed by use of a stable-angle implant without an increased risk of infection-related loosening.

[Significance of exact lateral roentgen documentation in Meyerding's grading of spondylolistheses]

The treatment of spondylolisthesis-in particular the indication of operation-is based on clinical symptoms as well as radiological criteria. For radiological techniques, the lateral profile, especially in function tests, is of importance. As a basic requirement the grade of Meyerding should be evaluated on x-ray in the exact lateral profile. We have observed, that even a slight rotation of the spine leads to misjudging of the real degree of vertebral dislocation. In 30 patients with spondylolisthesis of the lumbar spine the x-rays, made in exact lateral position, were compared with x-rays in 10 degrees rotation of the spine. On the average we measured an increase of vertebral dislocation of 3-4 mm. The increase was independent of the grade of Meyerding or the level of spondylolisthesis. The results could be verified by a spine of a human corpse.

ANALGESIC EFFECT OF EXTRACORPOREAL SHOCK-WAVE THERAPY ON CHRONIC TENNIS ELBOW

We report a controlled, prospective study to investigate the effect of treatment by low-energy extracorporeal shock waves on pain in tennis elbow. We assigned at random 100 patients who had had symptoms for more than 12 months to two groups to receive low-energy shock-wave therapy. Group I received a total of 3000 impulses of 0.08 mJ/mm2 and group II, the control group, 30 impulses.

The patients were reviewed after 3, 6 and 24 weeks. There was significant alleviation of pain and improvement of function after treatment in group I in which there was a good or excellent outcome in 48% and an acceptable result in 42% at the final review, compared with 6% and 24%, respectively, in group II.