Development of somatosensory-evoked potentials in foetal sheep: effects of betamethasone.

AIM: Antenatal glucocorticoids are used to accelerate foetal lung maturation in babies threatened with premature labour. We examined the influence of glucocorticoids on functional and structural maturation of the central somatosensory pathway in foetal sheep. Somatosensory-evoked potentials (SEP) reflect processing of somatosensory stimuli. SEP latencies are determined by afferent stimuli transmission while SEP amplitudes reveal cerebral processing. METHODS: After chronic instrumentation of foetal sheep, mothers received saline (n = 9) or three courses of betamethasone (human equivalent dose of 2 × 110 µg kg-1 betamethasone i.m. 24 h apart, n = 12) at 0.7, 0.75 and 0.8 of gestational age. Trigeminal SEP were evoked prior to, 4 and 24 h after each injection and at 0.8 of gestational age before brains were histologically processed. RESULTS: Somatosensory-evoked potentials were already detectable at 0.7 of gestation age. The early and late responses N20 and N200 were the only reproducible peaks over the entire study period. With advancing gestational age, SEP latencies decreased but amplitudes remained unchanged. Acutely, betamethasone did not affect SEP latencies and amplitudes 4 and 24 h following administration. Chronically, betamethasone delayed developmental decrease in the N200 but not N20 latency by 2 weeks without affecting amplitudes. In parallel, betamethasone decreased subcortical white matter myelination but did not affect network formation and synaptic density in the somatosensory cortex. CONCLUSION: Somatosensory stimuli are already processed by the foetal cerebral cortex at the beginning of the third trimester. Subsequent developmental decrease in SEP latencies suggests ongoing maturation of afferent sensory transmission. Antenatal glucocorticoids affect structural and functional development of the somatosensory system with specific effects at subcortical level.

Dysautonomia in prodromal α-synucleinopathy: peripheral versus central autonomic degeneration.

BACKGROUND AND PURPOSE: There is an urgent need for early predictive markers for the course of disease in prodromal α-synucleinopathies such as idiopathic rapid eye movement (REM) sleep behaviour disorder. Autonomic cardiac/vascular dysfunction is a prominent feature in advanced α-synucleinopathies, but its diagnostic value as an early neurodegenerative marker remains unclear. The latter may be complicated since synuclein-mediated neurodegeneration may involve central and peripheral components of the autonomic nervous system. METHODS: The diagnostic value of autonomic symptoms and central and peripheral autonomic markers of blood pressure and heart rate regulation were prospectively evaluated in 20 subjects with idiopathic REM sleep behaviour disorder and 20 age-matched healthy controls. RESULTS: Although subjects with REM sleep behaviour disorder showed no clinical autonomic symptoms, blood pressure (P ≤ 0.035) and heart rate response (P ≤ 0.065) were slightly diminished during orthostatic challenge. Autonomic dysregulation was distinctively reflected in lower resting heart rate (all components, P ≤ 0.05) and blood pressure variability (low frequency component, P ≤ 0.024) indicating peripheral cardiac/vascular denervation. In contrast, baroreflex sensitivity and central cardiac autonomic outflow (sympathovagal balance) were well preserved indicating intact central autonomic regulation. Heart rate variability [very low frequency component, receiver operating characteristic (ROC) area under the curve (AUC) 0.80, P ≤ 0.001] and blood pressure variability (low frequency component ROC AUC 0.73, P ≤ 0.01) but not baroreflex sensitivity and sympathovagal balance showed an excellent diagnostic accuracy in identifying subjects with REM sleep behaviour disorder and healthy controls. CONCLUSIONS: Cardiac/vascular dysfunction in prodromal α-synucleinopathy arises from peripheral rather than from central autonomic degeneration. Autonomic indices encoded in heart rate and blood pressure variability are precise functional markers of early synuclein-mediated neurodegeneration.

Preclinical animal study and clinical trail of modified extraoral craniofacial implants.

We report on our experience using a new endosseous implant designed to provide sufficient retention to various types of facial prostheses. In a preclinical animal experiment implants (N=12, 4 x 3.5 mm) were placed in the frontal calvarial region of nine adult pigs. The animals were sacrificed at 2, 4 and 8 weeks to evaluate the implant incorporation microradiographically. The clinical outcome and patient satisfaction of implant-retained prostheses were evaluated in a group of 10 patients with facial defects by using clinical assessment and standardized questionnaires for patients and relatives. In the prospective clinical study 33 identical modified implants for extraoral anchorage were placed for the fixation of various prostheses in the midfacial (eye, nose) and ear regions in the course of a clinical trial and observed over a follow-up period of 34 months. The bone-implant contact in the animal experiment reached 31% (+/-2) at 2 weeks, 39% (+/-1) after 4 weeks and 51% (+/-5) at 8 weeks. In the clinical trial, no implants were lost and all implants remained osseointegrated as confirmed clinically and radiographically, providing a stable prosthetic restoration. The analysis of the questionnaire indicates an improvement of the quality of life of patients with respect to aesthetic and psychological well-being. The results demonstrate that extraoral implants not only achieve sufficient osseointegration but also show good clinical handling and easy fixation possibilities for prosthetic anchorage.

Effect of betaTCP filled polyetheretherketone on osteoblast cell proliferation in vitro.

Non-resorbable thermoplastic polymers have become more important for reconstructive surgery due to their excellent chemical and physical properties. Polyetheretherketone-beta-tricalcium phosphate (betaTCP-PEEK) composites were developed as alternative materials for load-bearing applications. This study presents the effect of polyetheretherketone (PEEK) specimens incorporated with 5, 10, 20 and 40 wt% beta-tricalcium phosphate (betaTCP) and processed by injection molding on cultivated osteoblast cells. Normal human osteoblast (NHOst) cells were seeded onto polymer discs to evaluate cell viability and proliferation after 24, 72 and 120 h of cultivation by employing the WST-1 assay. Standard tissue culture plastic was used as a control. The osteoblast cells were found to be viable in all PEEK groups, while the cell proliferation was progressively inhibited due to the incorporated beta-tricalcium phosphate. BetaTCP-PEEK showed concentration independent decrease of cell proliferation compared to the unfilled PEEK and the control group. In summary, this study confirms the non-toxic nature of pure PEEK, whereas this could not definitely be verified for betaTCP-PEEK as a composite material in chosen concentrations of beta-tricalcium phosphate in vitro.

Expression of bone matrix proteins during de novo bone formation using a bovine collagen and platelet-rich plasma (prp)--an immunohistochemical analysis.

This animal study (domestic pig) examined the bone formation after filling defined defects with autogenous bone or a collagen lyophilisat in combination with Platelet-rich-plasma (PRP) by evaluating bone matrix proteins. Six groups, both materials with and without PRP in two concentrations (+ 1, + 2) were compared to untreated bone by means of immunohistochemistry at 2, 4, 12 and 26 weeks. BMP-2 expression was increased at 2 weeks in the collagen + 1 group and after 4 weeks in the collagen + 1 and + 2 group. Collagen-I expression was increased at 2 weeks in all collagen groups. After 4 weeks raised levels were observed after adding the higher concentrated PRP to bone and the collagen material. Osteocalcin expression was enhanced at 2 weeks in all collagen groups and the autogenous bone + PRP1 group, after 4 weeks in the bone and collagen + 2 groups. At 12 weeks higher values were observed after adding higher concentrated PRP to bone. Osteonectin and especially osteopontin were confirmed to be effective markers of early bone formation in all specimens. The described setting allows to combine established techniques (microradiography, light microscopy) with approaches to explore the underlying biology (immunohistochemistry) on the same specimen.

[Central giant cell granuloma and osteitis fibrosa cystica of hyperparathyroidism. A challenge in differential diagnosis of patients with osteolytic jawbone lesions and a history of cancer]. / Riesenzellgranulom und Osteitis fibrosa cystica bei Hyperparathyreoidismus. Differenzialdiagnose bei Osteolysen der Maxilla und bekannter maligner Grunderkrankung.

BACKGROUND: Giant cell lesions of the bone present similar histological features. The differential diagnosis comprises central giant cell granuloma, giant cell tumor of bone, and osteitis fibrosa cystica (brown tumor) in combination with hyperparathyroidism. Since these lesions may mimic metastatic bone disease in patients with a history of cancer, a malignant process has to be considered. Since the treatment and prognosis of these entities-benign versus malignant osteolytic bone processes-differ greatly, definitive differential diagnosis is of utmost importance. CASE REPORT: Two patients presenting with osteolytic lesions of the maxilla are reported here. In both cases a history of cancer (breast and prostate) suggested bone spreading of these malignant tumors. The clinical and histological findings were similar in both patients. One lesion was diagnosed as central giant cell granuloma, the other was found to be brown tumour in osteitis fibrosa cystica as an initial manifestation of hyperparathyroidism. DISCUSSION: The presented cases demonstrate the difficulties in establishing the correct diagnosis of patients found to have osteolytic lesions of the jawbones which is critical for the appropriate management of these patients. The article discusses the different entities of osteolytic lesions of the jawbones and the necessary diagnostic and therapeutic approach.

[Patients with oral squamous cell carcinoma. Long-term survival and evaluation of quality of life-initial results obtained with two treatment protocols in a prospective study]. / Plattenepithelkarzinome der Mundhöhle. Uberlebenswahrscheinlichkeit und Lebensqualität-Erste Ergebnisse von 2 Behandlungsstrategien.

INTRODUCTION: In patients with oral cancer the treatment has a strong impact on the quality of life. In recent years different therapeutic concepts have been developed, which include preoperative simultaneous 'neoadjuvant' radiochemotherapy (RCT) and one-stage surgery with tumour ablation and reconstruction. Consideration of long-term survival rates yields substantial evidence that mixed-modality treatment including neoadjuvant RCT is superior to adjuvant therapy concepts based on a surgical approach with postoperative radiation. PATIENTS AND METHODS: In this nonrandomised longitudinal prospective study quality of life was evaluated in two groups made up of a total of 53 patients with squamous cell carcinoma of the oral cavity, 26 of whom underwent neoadjuvant radiochemotherapy with subsequent surgical resection while the remaining 27 received surgical treatment first and then postoperative radiotherapy. The quality-of-life core questionnaire (QLQ C-30) and the head and neck cancer module (H&N 35) of the European Organisation for Research and Treatment of Cancer (EORTC) were used. Long-term survival was estimated according to the Kaplan-Meier test. RESULTS: Postoperatively both groups showed a marked reduction in quality of life, especially in restricted chewing, swallowing and speaking. One year later their quality of life had improved substantially, though without quite reaching the preoperative quality-of-life scores. Both groups showed specific impairments in the symptom scales. With adjustment for the fact that the patients were not randomised, long-term survival was 78% in the neoadjuvant treatment group and 50% in the adjuvant treatment group. CONCLUSION: Temporary limitations in the quality of life can be expected after tumour treatment of the kinds presented here for oral cancer. Neoadjuvant therapy concept is more aggressive and might result in longer disease-free survival. The primary goal should be eradication of the tumour. Nevertheless preservation or reconstruction of a maximum of function is essential for a high level of quality of life. Combined-modality treatments seem to be superior to any kind of monotherapy and should therefore be preferred.

[Experimental pilot study on surface activation of implants with liposomal vectors]. / Experimentelle Untersuchung zur Oberflächenaktivierung von Implantaten durch liposomale Vektoren-eine Pilotstudie.

BACKGROUND: Surface coating with mitogenic or morphogenic proteins can improve the healing of bone adjacent to implants and increase the bone-implant interface. Clinical surveys have shown liposome-mediated gene transfer to be a promising and safe new therapeutic method. The aim of our study was to evaluate an experimental model of new approaches for topical treatment of the implant surface and of periimplant defects by using DNA liposomes encoding for BMP-2 (bone morphogenetic protein). MATERIAL AND METHODS: A total of 27 implants (3.5 x 14 mm) were placed in critically sized defects of the frontal skull bone of adult pigs (n=3). The bottom of the implant was placed in the base of the defect which guaranteed primary stability, whereas the superior part of the implant (10 mm) represented an implant in a defect area. Liposomes containing DNA encoding for BMP-2 and GFP (green fluorescence protein) were used. In a first trial GFP-DNA liposomes on a collagen matrix were directly applied to the periimplant defect. In a second stage, the surface of the implants was encoded with BMP-2 DNA liposomes. Subsequently, these implants were inserted in the manner described. The resulting bone samples were prepared for immunohistochemical staining. Staining for GFP was performed in the area of the defect and for BMP-2 on the bone-implant interface. RESULTS: Immunohistochemical staining on day 3 postoperatively revealed an increased GFP expression in the periimplant defect. Therefore, the effectiveness of the liposomal vector was verified for the chosen animal model. On the surface of the implants encoded with BMP-2 DNA liposomes an increased BMP-2 expression was found. Thus, the liposomal vector system was validated also for BMP-2 DNA transfer in the chosen animal model. Further, the established system allows a sustainable and delayed release of BMP-2 in the area of the bone-implant interface. CONCLUSIONS: As a result of the study we were able to collect data concerning the influence of implant surface conditioning on the bone-implant interface and on therapeutically relevant options for the treatment of periimplant defects. These approaches are currently being evaluated in a long-term study.

De novo bone formation using bovine collagen and platelet-rich plasma.

In order to regenerate critical-size bone defects, a variety of bone substitutes is used in addition to autogenous bone. The regenerative capacity of these bone substitutes is usually compared to the efficacy of autogenous bone known as the "golden standard". Different cytokines influence the regeneration process because of their morphogenic or mitogenic properties. Platelet-rich plasma (PRP), a platelet concentrate, is characterised by having a positive effect on wound healing, reducing bone graft resorption and increasing the density of bone transplants. This experiment was commenced with a view to studying the osseous defect regeneration after placing various combinations of "filler materials" in experimentally created defects in the forehead of adult pigs. Regeneration by means of grafted autogenous bone (Group 1) or a bovine collagen based medical device (Group 4) alone and combined with PRP in two concentrations (Groups 2, 3, 5 and 6) was evaluated by means of microradiography and light microscopy after 2, 4 and 12 weeks. The microradiographic and light microscopic findings showed that autogenous bone in combination with PRP (Groups 2 and 3) had a significant accelerating effect on early bone regeneration (2 weeks). This effect was not evident when PRP was added to the bovine collagen (Groups 5 and 6). When using the collagen alone, significantly higher mineralisation values were achieved after 2 and 4 weeks than when using autogenous bone alone. After a 12-week observation period, the existing differences between the healing processes in the various groups were more or less levelled out. In summary, the results of the study indicate that clinically autogenous bone, as expected, is the ideal defect filler. Combining autogenous bone with PRP did not provide significantly better results. The findings in the groups treated with bovine collagen indicate that its local application mimics the effect of autogenous bone and amplifies bone regeneration when comparing with the control defect.

Degradation characteristics of alpha and beta tri-calcium-phosphate (TCP) in minipigs.

In seven Goettingen minipigs 3.5--4.7-ml cancellous bone defects were created in the area of the tibial head on both sides. The defects were filled with alpha-TCP or beta-TCP (tricalciumphosphate). ITI implants (Straumann, Freiburg, Germany) of 3.2 x 12-mm length were inserted into the underlying ceramic substitutes. Two additional pigs were used as control. Within the periods of observation (4, 16, 20, 28, 46, 68, and 86 weeks) fluorescent dyes were applied. Nondecalcified thin-sliced sections were examined by means of light and fluorescence microscopy. In addition microangiography and microradiography were performed. Bony regeneration occurred basally and on the sides of the defect according the angiogenetic reossification pattern. Resorption was due to a hydrolytic and cellular degradation process. After 46 weeks histomorphological evaluation showed an incomplete osseointegration of the simultaneously implanted dental implants. The bone contact surface ratio was lower than 25%. After 86 weeks 95--97% of both alpha- and beta-TCP were resorbed. Ceramic residuals stayed within the newly formed trabeculae thus resisting further degradation until remodeling occurred. Both alpha- and beta-TCP show a comparable degradation process. At the 86-week postoperative point only small residuals of the ceramic can be found. These residuals stay within the newly formed trabeculae, which show a functional orientation. In comparison control defects showed only sparse reossification. The beta-TCP material shows an accelerated degradation mode and has an optimal reactivity with the surrounding tissues. According to the results of this animal experiment both materials can be classified as bone-rebuilding materials.

Differences in immune cell invasion into the cerebrospinal fluid and brain parenchyma during cerebral infusion of interleukin-1beta.

Cytokine-mediated inflammatory cell recruitment into the brain is a critical step in the response to diverse insults, including infection, trauma, and stroke. Hence, continous intra-cerebroventricular infusion of interleukin (IL)-1beta leads to an impressive cell invasion into the cerebrospinal fluid, as well as the brain parenchyma. Neither tumor necrosis factor-alpha nor IL-6 induced any significant cell invasion at all. However, the diverse immune cells (granulocytes, monocytes/macrophages) showed a different time course of invasion. Moreover, there was an association between the number of infiltrating immune cells and the infused IL-1 concentration. By analyzing intra-brain immune events, we demonstrated a time- and dose-dependent induction of intercellular adhesion molecule (ICAM)-1, whereas there were no differences for P-selectin, vascular cell adhesion molecule (VCAM)-1, and monocyte-chemotractant protein (MCP)-1, comparing vehicle and IL-1-infused animals. In conclusion, we assume IL-1beta to be a key cytokine for the granulocyte and monocyte recruitment into the central nervous system after various insults. However, granulocytes anticipate monocyte invasion.

Stereoselective synthesis of chiral pinene[5,6]bipyridine ligands and their coordination chemistry.

The C(2)-symmetric chiral pinene[5,6]bipyridine V (Chart 1) was synthesized according to a procedure published by our group recently (Kolp, B.; Abeln, D.; Stoeckli-Evans, H.; Zelewsky, A. v. Eur. J. Inorg. Chem. 2001, 1207). A series of stereoselectively alkylated derivatives (Va-Vo) (Table 1) was prepared. The solid-state structures of the compounds Vc and Vk were determined by single-crystal X-ray diffraction, where both compounds show a transoid conformation of the bipyridine unit and proved to be alkylated stereoselectively from the sterically less hindered side of the pinene moiety. The X-ray structure of the cobalt complex 4 shows the metal ion to be tetrahedrally coordinated by one chiral bipyridine V and two chloride ligands. If 2 equiv of ligand V was used, 2:1 complexes were obtained with Cu(I), Ag(I), and Co(II) ions.

Comparison of simulation and experiments of different closed-loop strategies for functional electrical stimulation: experiments in paraplegics.

Open-loop and closed-loop stimulation of the knee extensors for the control of the knee joint angle and torque were tested as a potential basis for more complex functional electrical stimulation (FES) systems to be used in human locomotion. The output of the biomechanical simulation model described previously was compared with stimulation experiments in patients with complete thoracic spinal cord injury. Good correspondence between simulation and experiments was obtained under both isometric conditions and conditions with a freely swinging shank. For closed-loop control, a simple proportional integral derivative (PID) controller yielded sufficient performance only under isometric conditions, especially if combined with (linear) feedforward. Because of additional nonlinearities of musculotendon and body segmental dynamics, more complex strategies have to be applied to the control of unconstrained movements. To compensate for these nonlinearities, an inverse model was derived from the direct biomechanical model. This inverse model had satisfactory agreement between the measured knee angle and the desired trajectory already under open-loop conditions. A combination of the inverse model in the feedforward part of the control loop and a PID controller provided robust and precise control of the knee angle. Further improvement may be achieved by including elements of spasticity into the simulation model and by controlling both agonistic and antagonistic muscles.