Endoskopische Knochentransplantation an der Wirbels�ule

The application of autogenous bone grafts represents the golden standard for reconstruction of the load-bearing anterior column in the thoracolumbar spine. However, the osseous integration of the implanted grafts is demanding and delayed union or pseudarthrosis may occur. There are no standardized data available yet indicating the further course in such cases. The aim of this study was to evaluate the incorporation of endoscopically applied grafts and to develop therapeutic strategies for delayed or non-fusions. Twenty patients suffering from unstable injuries of the thoracolumbar spine were studied in a prospective clinical trial. After primary dorsal stabilization, the anterior column was thoracoscopically reconstructed with an autogenous iliac crest graft and a fixed-angle implant (MACS). The osseous integration of the bone grafts was detected by MSCT 1 year postoperatively. Complete integration of the transplanted bone grafts was observed in only 65% of the cases. In 25% partial integration was detected and in two cases a fracture of the transplanted iliac crest graft occurred. Despite the incomplete integration of the bone grafts, the further course without surgical intervention revealed no clinical or radiological evidence of a concomitant implant loosening or a relevant secondary loss of correction. Similar to the open technique, endoscopic reconstruction of the anterior column with autogenous bone grafts may lead to disadvantageous results concerning the integration and healing of the applied bone grafts. Decision making in such cases depends on the individual clinical and radiological findings (i.e., evidence of implant loosening and concomitant loss of correction).

Factors influencing the quality of life after burst fractures of the thoracolumbar transition

INTRODUCTION

Dorsal stabilisation has represented the standard procedure for the treatment of burst fractures of the thoracolumbar spine for a long time, but in the last few years the combined dorsoventral stabilisation has gained in significance due to its higher mechanical stability. However, there are no data yet available indicating whether the patients benefit from the combined operation with regard to their postoperative quality of life and what the advantages are in comparison with the dorsal procedures. Therefore, the question was researched in the framework of a matched-pairs analysis of patients suffering from an unstable fracture of the thoracolumbar transition.

MATERIALS AND METHODS

From a consecutive series of patients treated in our clinic between 1995 and 2000, 10 patients with combined and 10 patients with a purely dorsal stabilisation were selected and included in the study. Their quality of life was summed up in retrospect with the SF-36 questionnaire. The X-rays were analysed, and the Cobb angle as well as the sagittal index were calculated. Only patients with burst fractures of the thoracolumbar transition without accompanying co-morbidity and neurological deficits were included in the study. Both of the treated groups were matched with regard to sex, age and radiological patterns of injury.

RESULTS

Patients who had undergone only a dorsal stabilisation showed a significant loss of correction according to the sagittal index at the time of the examination (0.88+/-0.02 postoperative vs 0.77+/-0.03 at 4 years postoperatively, p=0.01). In the group of patients treated with the combined therapy, there was no statistically relevant loss of correction with regard to the sagittal vertebral profile. The SF-36 questionnaire showed a reduced quality of life in both groups compared with an age-referenced norm population, especially concerning the parameters of bodily health. No statistically relevant difference was observed between the two groups. Further, there was no statistically relevant association between the parameters of the SF-36 and the clinical and radiological data. After performing several regression analyses it could be shown that the patient's mental health is a strong predictor of the postoperative vitality (r=0.803, p<0.01). However, none of the remaining parameters was able to predict the postoperative quality of life.

CONCLUSION

The patients in this study showed a reduced quality of life, independent of the method of surgical treatment. Although better radiological results could be seen for the combined procedure, regarding the postoperative quality of life no advantage could be proved compared with the dorsally stabilized patients. Furthermore, there was no relation between the radiological results and the quality of life parameters. Therefore, it can be assumed that the injury itself seems to be the main cause of the decreased quality of life after a burst fracture of the thoracolumbar transition.

The role of angiogenesis in a murine tibial model of distraction osteogenesis

Distraction osteogenesis (DO) is one of the most dramatic in vivo applications of mechanical stimulation as a means of inducing bone regeneration. A simple and reproducible murine model of tibia distraction osteogenesis was developed using a monolateral fixator. Bone formation was assessed histologically over a 35-day time course. The steady state expression of a broad family of angiogenesis-associated genes was assessed by microarray hybridization analyses over the same time course, while the immediate gene response that was induced during each cycle of distraction was assessed at 30 min and 8 h after the first and last rounds of activation of the fixator. Distraction osteogenesis promoted new bone formation primarily through an intramembranous process with maximal osteogenesis during the active distraction period. Histological analysis also showed that dense cortical bone continued to be formed, during the consolidation phase, for 2 weeks after distraction ended. The analysis of steady state mRNA expression levels over the time course of DO showed that VEGF-A and neuropilin, an alternate receptor for VEGF-A, both angiopoietin (Ang) 1 and 2 factors, and the Ang receptor Tie2 were the critical angiogenic factors during DO. A key transcriptional regulator of many of the angiogenic factors, hypoxia-induced factor1alpha (Hif-1a), the FGF binding protein pleiotropin/OSF1, and multiple MMP(s), were also induced during the active distraction period. Examination of the expression of angiogenic factors that were induced after each cycle of activation, demonstrated that Hif-1a, Nrp1, and VEGF-A were all cyclically induced after each increment of distraction. These results suggest that these factors are early mediators that are produced by distraction and contribute toward the processes that promote bone formation. These experiments represent the first step in defining the molecular mechanisms that regulate skeletal regeneration and the functional relationship between angiogenesis and osteogenesis during distraction osteogenesis.

Biomechanical analysis of anterior cervical spine plate fixation systems with unicortical and bicortical screw purchase

Anterior plate fixation with unicortical screw purchase does not involve the risk of posterior cortex penetration and possible injuries of the spinal cord. However, there are very few biomechanical data about the immediate stability of non-locking plate fixation with unicortical or bicortical screw placement. The aim of the present study was to evaluate the immediate biomechanical properties in terms of flexibility of a non-locking anterior plate system with 4.5-mm screw fixation and unicortical or bicortical screw purchase applied to a single destabilized cervical spine motion segment. Using fresh cadaveric cervical spine specimens C3-C7, multidirectional flexibility was measured at the level C4-C5 before and after destabilization and fixation with an anterior plate with either unicortical or bicortical screw purchase. The results showed that fixed cervical spine segments with anterior plate and bicortical screw purchase were more rigid than intact specimens in all modes of testing. The difference was statistically significant for flexion and extension ( P<0.001). Plate fixation with unicortical screw purchase had statistically significant decreased ranges of motion compared to the intact specimen only in extension. Neither unicortical nor bicortical screw purchase decreased the range of motion significantly in axial rotation compared to the intact specimens. This in vitro study documented that neither unicortical nor bicortical screw purchase with non-locking plate fixation can increase stability in all modes of testing, in axial rotation in particular. Direct comparison between the group with uni- and that with bicortical screw fixation did not reveal significant differences, and therefore no advantage was shown for either type of screw fixation. Therefore, we demonstrated that both uni- and bicortical screw purchase with non-locking plate fixation can decrease immediate flexibility of the tested motion segment, with better results for bicortical purchase. No significant differences were found comparing the two groups of screw fixation. These data suggest that unicortical screw fixation can be used for anterior plate fixation with a comparable immediate stability to bicortical screw fixation.

Expression of angiogenic factors during distraction osteogenesis

Distraction osteogenesis is a unique and effective way to treat limb length inequality resulting from congenital and posttraumatic skeletal defects. However, despite its widespread clinical use, the cellular and molecular mechanisms by which this surgical treatment promotes new bone formation are not well understood. Previous studies in distraction osteogenesis have noted increased blood flow and vessel formation within the zone of distraction. These observations suggest that distraction osteogenesis may be driven in part by an angiogenic process. Using immunohistological analysis, the expression of two different angiogenic factors (VEGF and bFGF) was shown to localize at the leading edge of the distraction gap, where nascent osteogenesis was occurring. These cells were spatially adjacent to new vessels that were identified by staining for factor VIII. Microarray analysis detected maximal mRNA expression for a wide variety of angiogenic factors including angiopoietin 1 and 2, both Tie receptors, VEGF-A and -D, VEGFR2, and neuropilin 1. Expression of these factors was found to be maximal during the phase of active distraction. Expression of mRNA for extracellular matrix proteins and BMPs was also maximal during this period. A comparison between the patterns of gene expression in fracture healing and distraction osteogenesis revealed similarities; however, the expression of a number of genes showed selective expression in these two types of bone healing. These data suggest that bone formation during distraction osteogenesis is accompanied by the robust induction of factors associated with angiogenesis and support further investigations to elucidate the mechanisms by which angiogenic events promote bone repair and regeneration.

Tumor necrosis factor α activation of the apoptotic cascade in murine articular chondrocytes is associated with the induction of metalloproteinases and specific pro-resorptive factors

OBJECTIVE

Tumor necrosis factor alpha (TNFalpha) blockade provides substantive reduction of the symptoms of rheumatoid arthritis (RA). While the biologic actions of TNFalpha have been well characterized in immune and synovial cells, which are known to be major contributors to the progression of cartilage destruction in RA, the current studies were designed to assess the direct effects of TNFalpha on chondrocytes.

METHODS

We examined the expression of several groupings of messenger RNA (mRNA) that define key biologic pathways that have previously been associated with either the general actions of TNFalpha or cartilage destruction, in murine articular chondrocytes isolated from wild-type mice and TNFalpha receptor-null (p55/p75(-/-)) mice.

RESULTS

TNFalpha induced the expression of multiple mRNA that facilitate apoptosis and lead to apoptosis-induced cell death. The induction of apoptosis was accompanied by the increased expression of several factors involved in the regulation of skeletal tissue proteolysis and resorption. Quantitative increases from 2-fold to >10-fold were seen for inducible nitric oxide synthase, matrix metalloproteinase 3, macrophage colony-stimulating factor, and osteoprotegerin mRNA expression. The dependence of the induction of these mRNA on TNFalpha was confirmed by comparison with the effects of TNFalpha on chondrocytes isolated from receptor-null mice.

CONCLUSION

These findings demonstrate that TNFalpha alters the expression of a complex array of genes within murine chondrocytes that contribute to the destruction of joint surfaces, independent of its actions on synovial and immune cells. Further studies are needed to clarify the biologic actions of TNFalpha in human cartilage cells.

[Investigation of the health-related quality of life after a dorso ventral stabilization of the thoracolumbar junction]

OBJECTIVE

Combined dorsoventral stabilization provides superior mechanical stability in the operative treatment of thoracolumbar spine fractures. Currently, there are no data available reflecting the quality of life in trauma patients following the combined procedure. The aim of this investigation was to study the health-related quality of life after dorsoventral stabilization of the thoracolumbar junction using the SF-36 Health Survey.

METHODS

In order to assess the quality of life, 30 patients from a consecutive series with unstable fractures of the thoracolumbar junction were investigated in a clinical study. After posterior stabilization with an internal fixator (USS, Synthes),anterior arthrodesis was performed subsequently by autogenous iliac bone grafting in combination with osteosynthesis (MACS, Aesculap; VentroFix, Synthes). The quality of life was investigated 2 years after surgery. Additionally, plain X-rays were obtained and the degree of kyphotic deformation was measured.

RESULTS

The evaluation of the data obtained from the SF-36 revealed a reduced quality of life, especially regarding the "physical functioning index", the "bodily pain index", and the "emotional functioning index". Of the patients, 42% still suffered from moderate to severe pain. Measurement of the Cobb angle showed a slight loss of correction without occurrence of a relevant kyphotic deformity. Our statistical analyses did not show any correlation between the data obtained from the SF-36 and the clinical results. Especially there was no correlation between the "bodily pain index" and the Cobb angle ( r=0.112, Spearman's rank order correlation).

CONCLUSION

The patients studied here showed a reduced quality of life 2 years after dorsoventral stabilization of the thoracolumbar junction predominantly resulting in long-term pain symptoms. As these findings could not be related to the radiological results (i.e., the occurrence of a kyphotic deformation), other factors such as injury of the motion segment of the spine and the major surgical procedure have to be considered as the main reasons for the reduced quality of life. In summary, it can be concluded that the SF-36 is a suitable tool for the investigation of the postoperative outcome following dorsoventral stabilization of the thoracolumbar junction in trauma patients.

[Treatment of metaphyseal bone defects after fractures of the distal radius. Medium-term results using a calcium-phosphate cement (BIOBON)]

PROBLEM

Since 1998 the calcium-phosphate cement BIOBON has been an established tool for the operative treatment of metaphyseal bone defects. No data are currently available in the literature on the clinical results of employing BIOBON:

METHODS

For the evaluation of the mediumterm outcome in the therapy of metaphyseal bone defects after distal radial fractures, we examined 29 patients in a retrospective study. These patients with unstable radial fractures were treated between 1998 and 2001 with BIOBON and additional osteosynthesis.

RESULTS

We performed a clinical and radiological examination of 20 patients (69.0%) after an average period of 18.35 months (9-40 months). In all patients parts of the bone replacement material were still visible radiologically. The average outcome using the Gartland and Werley score was 7.5 points (2-21) and therefore a good result.

CONCLUSION

Calcium-phosphate cements represent a good alternative to autogenous bone transplantation, especially in elderly patients.

Visuelle Vorstellungsfähigkeit, Bewegungsvorstellung und mentales Rotieren bei Morbus Parkinson

Zusammenfassung: In dieser Studie wurden Parkinson-Patienten (n = 54) und eine Kontrollgruppe (n = 54) mit dem Mental Rotation Test (MRT), weiteren Verfahren zur visuellen Informationsverarbeitung und zur Bewegungsvorstellung untersucht. Die Kontrollgruppe weist im MRT signifikant mehr richtige Lösungen auf als die Patienten. Besonders ausgeprägt ist dieser Effekt bei den älteren Probanden. Ferner gibt es einen Geschlechtseffekt zugunsten der Männer. Die Patienten mit niedrigen MRT-Leistungen haben ein höheres Alter und einen höheren Wert in der Unified Parkinson's Disease Rating Scale (UPDRS), einer umfassenden Einschätzungsskala zur Schwere der Parkinson-Symptomatik. Die volle Manifestation der bilateralen Schädigung wirkt sich beim mentalen Rotieren besonders leistungsmindernd aus. Die Selbsteinschätzung zur visuellen Leistungsfähigkeit ist bei den Parkinson-Patienten unabhängig von ihrer tatsächlichen Leistungsfähigkeit. Die Befunde zeigen einen deutlichen Zusammenhang zwischen Schwere der Erkrankung und der Fähigkeit zum mentalen Rotieren. Damit bietet sich die mentale Rotationsleistung als einer von mehreren diagnostischen Indikatoren an. In Pfadanalysen wurde deutlich, dass die Parkinson-Patienten wahrscheinlich keine mentale Rotation durchführen, sondern auf visuelle Ersatzstrategien in Form von Abgleichungsprozessen zurückgreifen. Ein Training im Bereich des räumlichen Visualisierens (mentales Rotieren) wird empfohlen.

Girls' spatial abilities: charting the contributions of experiences and attitudes in different academic groups

BACKGROUND

Gender-related differences in spatial abilities favouring males are well established but have also generated a great deal of controversy. Cross-cultural research, meta-analyses and training studies could show the influence of socio-cultural and experiential factors on spatial-test performance. However, little is known about how experiences and gender-role stereotypes mediate performance differences in this area.

AIM

The relationship between specific experiences (spatial activities, computer experience), achievement-related attitudes, and spatial abilities, i.e., mental-rotation ability was investigated with males and females in different academic subgroups.

SAMPLE

The sample comprised 112 female and 71 male undergraduates, majoring in arts, humanities and social sciences, sports, psychology and computational visualistics.

METHODS

A redrawn version of the Vandenberg and Kuse Mental Rotations Test (MRT) was administered and the participants completed a questionnaire about their spatial activities, computer experience, self-ratings regarding everyday spatial abilities, and attitudes towards mathematics and physics.

RESULTS

Mental Rotations Test performance was mainly affected by academic programme and gender, but the effect size of gender differences varied. It was largest with students majoring in arts, humanities and social sciences and smallest with those majoring in computational visualistics. Data analyses revealed statistically significant correlations with spatial activities and computer experience only for females. The relationship between test performance and scales of achievement-related self-concept also depended on gender.

CONCLUSIONS

Compared to males, females' spatial abilities are extremely vulnerable to and thus modifiable through attitudinal and experiential factors. This has considerable consequences for intervention programmes that could help to overcome the gender gap in spatial abilities.

Allgemeine und domänenspezifische kognitive Leistungen

In dieser Studie wurde das Verhältnis von allgemeinen und domänenspezifischen kognitiven Leistungen bei Schülergruppen in unterschiedlichen Schultypen untersucht. Theoretische Auffassungen gehen einerseits davon aus, dass die allgemeine Intelligenz domänenspezifische Leistungen (mathematische oder fremdsprachliche) determiniert, andererseits wird die Position vertreten, dass domänenspezifische Leistungen mehr von speziellen Fähigkeiten bestimmt werden. Die Stichprobe bildeten zehn- bis elfjährige Schülerinnen und Schüler fünfter Klassen aus mathematisch bzw. sprachlich orientierten Gymnasien (Versuchsgruppe) sowie aus der Förderstufe einer Sekundarschule (Kontrollgruppe). Die beiden gymnasialen Subgruppen gleichen sich in den Intelligenztestleistungen und liegen mehr als eine Standardabweichung über den Leistungen der Kontrollgruppe. Es wurden domänenspezifische Variablen gefunden, die zwischen den beiden gymnasialen Gruppen gut diskriminieren. Faktorenanalytisch konnte ein mathematisch-räumlicher und ein fremdsprachlicher Faktor ermittelt werden.

[Long-term outcomes after using porous hydroxyapatite ceramics (Endobon) for surgical management of fractures of the head of the tibia]

Endobon is a porous hydroxyapatite ceramic which has been used as a bone replacement substitute since 1989. Currently there are no data available reflecting long-term effects of Endobon in human bone grafting. In order to assess such effects 35 patients with fractures of the proximal tibia were studied retrospectively over a period up to 91 months. The metaphyseal defects were filled by Endobon and fractures were stabilized by internal plate fixation subsequently. A secondary loss of reduction due to mechanical failure of the bone replacement material did not occur even after removal of metal implants. No histological signs of resorption or degradation could be found 18 months after application. Our data show that Endobon provides good mechanical properties during a long term follow-up and can be recommended as a suitable therapeutic option versus cancellous bone graft.

Nasal and paranasal sinus carcinoma: are we making progress? A series of 220 patients and a systematic review

BACKGROUND

The authors reviewed treatment results in patients with nasal and paranasal sinus carcinoma from a large retrospective cohort and conducted a systematic literature review.

METHODS

Two hundred twenty patients who were treated between 1975 and 1994 with a minimum follow-up of 4 years were reviewed retrospectively. A systematic review of published articles on patients with malignancies of the nasal and paranasal sinuses during the preceding 40 years was performed.

RESULTS

The 5-year survival rate was 40%, and the local control rate was 59%. The 5-year actuarial survival rate was 63%, and the local control rate was 57%. Factors that were associated statistically with a worse prognosis, with results expressed as 5-year actuarial specific survival rates, included the following: 1) histology, with rates of 79% for patients with glandular carcinoma, 78% for patients with adenocarcinoma, 60% for patients with squamous cell carcinoma, and 40% for patients with undifferentiated carcinoma; 2) T classification, with rates of 91%, 64%, 72%, and 49% for patients with T1, T2, T3, and T4 tumors, respectively; 3) localization, with rates of 77% for patients with tumors of the nasal cavity, 62% for patients with tumors of the maxillary sinus, and 48% for patients with tumors of the ethmoid sinus; 4) treatment, with rates of 79% for patients who underwent surgery alone, 66% for patients who were treated with a combination of surgery and radiation, and 57% for patients who were treated exclusively with radiotherapy. Local extension factors that were associated with a worse prognosis included extension to the pterygomaxillary fossa, extension to the frontal and sphenoid sinuses, the erosion of the cribriform plate, and invasion of the dura. In the presence of an intraorbital invasion, enucleation was associated with better survival. In multivariate analysis, tumor histology, extension to the pterygomaxillary fossa, and invasion of the dura remained significant. Systematic review data demonstrated a progressive improvement of results for patients with squamous cell and glandular carcinoma, maxillary and ethmoid sinus primary tumors, and most treatment modalities.

CONCLUSIONS

Progress in outcome for patients with nasal and paranasal carcinoma has been made during the last 40 years. These data may be used to make baseline comparisons for evaluating newer treatment strategies.

Endoscopic neck dissection in human cadavers

OBJECTIVE

To evaluate the feasibility and efficacy of endoscopic neck dissection (END) in human cadavers.

STUDY DESIGN

Experimental self-controlled study.

METHODS

END on five human cadavers through three openings: one for the camera, one for the dissecting instrument, and one for a grasping one. The tissue specimens removed were divided into traditional neck groups (I to V). After the completion of END, open neck dissection was performed using standard surgical techniques and the remaining tissue within each neck group was retrieved. The important neck structures (carotid artery, internal jugular vein, cranial nerves X, XI, and XII, phrenic nerve) were evaluated for lesions. A pathologist evaluated each specimen, without knowing its exact origin in terms of neck group or side, and type of surgical technique used. For each specimen, the number of retrieved lymph nodes and their anatomic integrity was analyzed.

RESULTS

Ten neck dissections were performed on 5 cadavers, without any major difficulty. An injury of the internal jugular vein occurred twice and once the phrenic nerve was cut. Little tissue was usually left for open surgical dissection. The average number of retrieved lymph nodes by endoscopy was 4.9 +/- 2.7 (mean +/- standard deviation). Completion open neck dissection retrieved an additional 0.5 +/- 0.5 lymph nodes. Efficacy of END was 92 +/- 10%. The majority of retrieved lymph nodes were intact but exhibited important postmortem autolysis artifacts.

CONCLUSIONS

Endoscopic neck dissection is possible in human cadavers and is free of lesions to major structures. The majority of neck lymph nodes can be removed endoscopically.

Treatment of Alzheimer's disease with clioquinol

As heavy metal ions may be implicated in the formation of senile plaques in Alzheimer-afflicted brains, treatment with clioquinol was tested in 20 patients with Alzheimer's disease. Clioquinol is a chelator that crosses the blood-brain barrier and has greater affinity for zinc and copper ions than for calcium and magnesium ions. Treatment was given for 21 days at doses of 20 mg/day to 10 patients and 80 mg/day to another 10 patients. The study was blind to the dosages but included no controls. Cerebrospinal fluid (CSF) investigations revealed a significant increase at day 7 and a decrease at day 21 in Tau protein and growth-associated protein (GAP43). These proteins are increased in Alzheimer's disease and considered as rather stable markers. The initial increase may indicate a temporary cytotoxicity to the brain and/or an increased release into the CSF from stores in the tissue, possibly from senile plaques where the proteins are accumulated. The levels of CSF-Tau protein correlated positively and significantly with the serum levels of copper and also with the serum copper/zinc ratio. Clinical ratings showed slight improvement after 3 weeks treatment with clioquinol in this open study.

Giant lateral electrostriction in ferroelectric liquid-crystalline elastomers

Mechanisms for converting electrical energy into mechanical energy are essential for the design of nanoscale transducers, sensors, actuators, motors, pumps, artificial muscles, and medical microrobots. Nanometre-scale actuation has to date been mainly achieved by using the (linear) piezoelectric effect in certain classes of crystals (for example, quartz), and 'smart' ceramics such as lead zirconate titanate. But the strains achievable in these materials are small--less than 0.1 per cent--so several alternative materials and approaches have been considered. These include grafted polyglutamates (which have a performance comparable to quartz), silicone elastomers (passive material--the constriction results from the Coulomb attraction of the capacitor electrodes between which the material is sandwiched) and carbon nanotubes (which are slow). High and fast strains of up to 4 per cent within an electric field of 150 MV x m(-1) have been achieved by electrostriction (this means that the strain is proportional to the square of the applied electric field) in an electron-irradiated poly(vinylidene fluoride-trifluoroethylene) copolymer. Here we report a material that shows a further increase in electrostriction by two orders of magnitude: ultrathin (less than 100 nanometres) ferroelectric liquid-crystalline elastomer films that exhibit 4 per cent strain at only 1.5 MV x m(-1). This giant electrostriction was obtained by combining the properties of ferroelectric liquid crystals with those of a polymer network. We expect that these results, which can be completely understood on a molecular level, will open new perspectives for applications.

Multiple forms of glycoproteins in the secretory product of the bovine subcommissural organ--an ancient glial structure

The glial subcommissural organ (SCO) is a conserved structure of the vertebrate brain that secretes a glycoprotein-rich product into both the extracellular matrix and the cerebrospinal fluid of the third ventricle that forms Reissner's fibre (RF). In order to identify specific secretory proteins of the subcommissural organ, a panel of antigen- and epitope-specific monoclonal antibodies was raised against bovine RF to study the distribution of epitopes in Western blots of bovine RF. Six groups of epitopes that were specific for SCO secretion were distinguished on the basis of their phylogenetic conservation and their different grades of resistance against chemical denaturation. The monoclonal antibody aRFME 4 recognised a carbohydrate-containing epitope that was strongly conserved in vertebrates and unique for SCO secretion. All epitopes showed essentially the same distribution pattern over 15 bovine RF glycoprotein fractions of different molecular masses in immunoblots indicating that the different RF fractions are closely related. They may represent multiple forms of SCO spondin.

Specificity of parotid sialendoscopy

OBJECTIVE

To present our initial experience with sialendoscopy of the parotid duct.

STUDY DESIGN

METHODS

Diagnostic and interventional sialendoscopy procedures were performed in 79 and 55 cases, respectively. Diagnostic sialendoscopy was used to classify ductal lesions into sialolithiasis, stenosis, sialodochitis, and polyps. Interventional sialendoscopy was used to treat these disorders. The type of endoscope used, the type of sialolithiasis fragmentation and/or extraction device used, the total number of procedures, the type of anesthesia, and the number and size of the sialoliths removed were the dependent variables. The outcome variable was the endoscopic clearing of the ductal tree and resolution of symptoms.

RESULTS

Diagnostic sialendoscopy was possible in all cases, with an average duration of 26+/-14 minutes and no complications. Interventional sialendoscopy was successful in 85% of cases, with an average duration of 73+/-43 minutes (+/- standard deviation). Multiple procedures were performed in 45% of cases, general anesthesia was used in 24%, and parotidectomy in 2%. Multiple sialoliths were found in 58% of ducts and associated with more procedures under general anesthesia and longer operations. The average size of sialoliths was 3.2+/-1.3 mm; larger stones were associated with more procedures under general anesthesia, longer and multiple procedures, use of fragmentation, and sialendoscopy failures. Sialolithiasis fragmentation was required in 10% of cases, with a success rate of 70%. Semirigid sialendoscopes performed better than flexible ones. Complications were mostly minor but were encountered in 12% of cases.

CONCLUSIONS

Diagnostic sialendoscopy is a new technique for evaluating salivary duct disease, a technique which is associated with low morbidity. Interventional sialendoscopy allows the extraction of sialoliths in most patients, preventing open gland excision.

Biologically and chemically optimized composites of carbonated apatite and polyglycolide as bone substitution materials

We report on the development and characterization of a new composite material consisting of amorphous carbonated apatite, Ca(5)(PO(4), CO(3))(3)(OH), and microstructured poly(hydroxyacetic acid), polyglycolide (PGA). This material is able to keep the pH of a surrounding solution within the physiological range (7.2-7.6). This was achieved by chemical fine-tuning of the counterplay between the acidic degradation of the polyester and the basic dissolution of calcium phosphate. Microporous samples with pore sizes of <1 microm and compact samples were prepared. The biological behavior was assayed in vitro by long-term osteoblast culture. Morphological and biochemical analyses of cell differentiation revealed excellent biocompatibility, leading to cell attachment, collagen and osteocalcin expression, and mineral deposition. This material could be of use as a biodegradable bone substitution material and as a scaffold for tissue engineering.

Retrograde theory in sialolithiasis formation

Sialolithiasis is a relatively frequent occurrence; however, cases of sialolithiasis originating around a "foreign body" nidus are rare. We describe a patient with submandibular sialolithiasis organized around a vegetal nidus and discuss the etiology of the case.