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Rationale and Objectives: Although the gold standard in predicting future progression from clinically isolated syndrome (CIS) to clinically definite multiple sclerosis (CDMS) consists in the McDonald criteria, efforts are being made to employ various advanced MRI techniques for predicting clinical progression. This study's main aim was to evaluate the predictive power of diffusion tensor imaging (DTI) of the brain and brain volumetry to distinguish between patients having CIS with future progression to CDMS from those without progression during the following 2 years and to compare those parameters with conventional MRI evaluation., Materials and Methods: All participants underwent an MRI scan of the brain. DTI and volumetric data were processed and various parameters were compared between the study groups., Results: We found significant differences between the subgroups of patients differing by future progression to CDMS in most of those DTI and volumetric parameters measured. Fractional anisotropy of water diffusion proved to be the strongest predictor of clinical conversion among all parameters evaluated, demonstrating also higher specificity compared to evaluation of conventional MRI images according to McDonald criteria., Conclusion: Conclusion: Our results provide evidence that the evaluation of DTI parameters together with brain volumetry in patients with early-stage CIS may be useful in predicting conversion to CDMS within the following 2 years of the disease course., (Copyright © 2021 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.)

Although the role of high-risk human papillomaviruses (hrHPVs) as etiological agents in cancer development has been intensively studied during the last decades, there is still the necessity of understanding the impact of the HPV E6 and E7 oncogenes on host cells, ultimately leading to malignant transformation. Here, we used newly established immortalized human keratinocytes with a well-defined HPV16 E6E7 expression cassette to get a more complete and less biased overview of global changes induced by HPV16 by employing transcriptome sequencing (RNA-Seq) and stable isotope labeling by amino acids in cell culture (SILAC). This is the first study combining transcriptome and proteome data to characterize the impact of HPV oncogenes in human keratinocytes in comparison with their virus-negative counterparts. To enhance the informative value and accuracy of the RNA-Seq data, four different bioinformatic workflows were used. We identified potential novel upstream regulators (e.g., CNOT7, SPDEF, MITF, and PAX5) controlling distinct clusters of genes within the HPV-host cell network as well as distinct factors (e.g., CPPED1, LCP1, and TAGLN) with essential functions in cancer. Validated results in this study were compared to data sets from The Cancer Genome Atlas (TCGA), demonstrating that several identified factors were also differentially expressed in cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC) and HPV-positive head and neck squamous cell carcinomas (HNSCs). This highly integrative approach allows the identification of novel HPV-induced cellular changes that are also reflected in cancer patients, providing a promising omics data set for future studies in both basic and translational research. IMPORTANCE Human papillomavirus (HPV)-associated cancers still remain a big health problem, especially in developing countries, despite the availability of prophylactic vaccines. Although HPV oncogenes have been intensively investigated for decades, a study applying recent advances in RNA-Seq and quantitative proteomic approaches to a precancerous model system with well-defined HPV oncogene expression alongside HPV-negative parental cells has been missing until now. Here, combined omics analyses reveal global changes caused by the viral oncogenes in a less biased way and allow the identification of novel factors and key cellular networks potentially promoting malignant transformation. In addition, this system also provides a basis for mechanistic research on novel key factors regulated by HPV oncogenes, especially those that are confirmed in vivo in cervical cancer as well as in head and neck cancer patient samples from TCGA data sets., (Copyright © 2019 Yang et al.)

The adenylate cyclase toxin (CyaA) of the whooping cough agent Bordetella pertussis subverts immune functions of host myeloid cells expressing the α M β 2 integrin (CD11b/CD18, CR3 or Mac-1). CyaA delivers into cytosol of cells an extremely catalytically active adenylyl cyclase enzyme, which disrupts the innate and adaptive immune functions of phagocytes through unregulated production of the key signaling molecule cAMP. We have used phosphoproteomics to analyze cAMP signaling of CyaA in murine bone marrow-derived dendritic cells. CyaA action resulted in alterations of phosphorylation state of a number of proteins that regulate actin cytoskeleton homeostasis, including Mena, Talin-1 and VASP. CyaA action repressed mTOR signaling through activation of mTORC1 inhibitors TSC2 and PRAS40 and altered phosphorylation of multiple chromatin remodelers, including the class II histone deacetylase HDAC5. CyaA toxin action further elicited inhibitory phosphorylation of SIK family kinases involved in modulation of immune response and provoked dephosphorylation of the transcriptional coactivator CRTC3, indicating that CyaA-promoted nuclear translocation of CRTC3 may account for CyaA-induced IL-10 production. These findings document the complexity of subversive physiological manipulation of myeloid phagocytes by the CyaA toxin, serving in immune evasion of the pertussis agent.

The success of pathogens depends on their ability to circumvent immune defences. Francisella tularensis is one of the most infectious bacteria known. The remarkable virulence of Francisella is believed to be due to its capacity to evade or subvert the immune system, but how remains obscure. Here, we show that Francisella triggers but concomitantly inhibits the Toll-like receptor, RIG-I-like receptor, and cytoplasmic DNA pathways. Francisella subverts these pathways at least in part by inhibiting K63-linked polyubiquitination and assembly of TRAF6 and TRAF3 complexes that control the transcriptional responses of pattern recognition receptors. We show that this mode of inhibition requires a functional type VI secretion system and/or the presence of live bacteria in the cytoplasm. The ability of Francisella to enter the cytosol while simultaneously inhibiting multiple pattern recognition receptor pathways may account for the notable capacity of this bacterium to invade and proliferate in the host without evoking a self-limiting innate immune response., (© 2017 John Wiley & Sons Ltd.)

The initiation of T-cell signaling is critically dependent on the function of the member of Src family tyrosine kinases, Lck. Upon T-cell antigen receptor (TCR) triggering, Lck kinase activity induces the nucleation of signal-transducing hubs that regulate the formation of complex signaling network and cytoskeletal rearrangement. In addition, the delivery of Lck function requires rapid and targeted membrane redistribution, but the mechanism underpinning this process is largely unknown. To gain insight into this process, we considered previously described proteins that could assist in this process via their capacity to interact with kinases and regulate their intracellular translocations. An adaptor protein, receptor for activated C kinase 1 (RACK1), was chosen as a viable option, and its capacity to bind Lck and aid the process of activation-induced redistribution of Lck was assessed. Our microscopic observation showed that T-cell activation induces a rapid, concomitant, and transient co-redistribution of Lck and RACK1 into the forming immunological synapse. Consistent with this observation, the formation of transient RACK1-Lck complexes were detectable in primary CD4 + T-cells with their maximum levels peaking 10 s after TCR-CD4 co-aggregation. Moreover, RACK1 preferentially binds to a pool of kinase active pY394 Lck , which co-purifies with high molecular weight cellular fractions. The formation of RACK1-Lck complexes depends on functional SH2 and SH3 domains of Lck and includes several other signaling and cytoskeletal elements that transiently bind the complex. Notably, the F-actin-crosslinking protein, α-actinin-1, binds to RACK1 only in the presence of kinase active Lck suggesting that the formation of RACK1-pY394 Lck -α-actinin-1 complex serves as a signal module coupling actin cytoskeleton bundling with productive TCR/CD4 triggering. In addition, the treatment of CD4 + T-cells with nocodazole, which disrupts the microtubular network, also blocked the formation of RACK1-Lck complexes. Importantly, activation-induced Lck redistribution was diminished in primary CD4 + T-cells by an adenoviral-mediated knockdown of RACK1. These results demonstrate that in T cells, RACK1, as an essential component of the multiprotein complex which upon TCR engagement, links the binding of kinase active Lck to elements of the cytoskeletal network and affects the subcellular redistribution of Lck.

Background: Amyloidosis is a disease characterized by deposits of abnormal protein known as amyloid in various organs and tissues. It can be classified into systemic or localized forms, the latter of which is less frequent. Deposition of amyloidogenic monoclonal light chains leads to the most common type of this disease called light-chain (AL) amyloidosis. (18)F-FDG positron emission tomography/ computed tomography hybrid imaging (FDG-PET/ CT) demonstrates tracer uptake usually in all patients with localized amyloidosis as opposed to the systemic form., Case: Herein, we present a case of an otherwise healthy 56-year-old women diagnosed with a nasal polyp on the right side. The biopsy results were consistent with amyloidosis. FDG-PET/ CT imaging revealed a pathological, metabolically active lesion measuring 11 × 9 mm with a maximum standardized uptake value (SUV(max)) of 3.47. No other distant pathological changes were identified. After a radical resection, the patient has been regularly followed-up with clinical and imaging methods (MRI, FDG-PET/ CT), both of which repeatedly showed normal findings with disease-free survival of 27 months. Thus, FDG-PET/ CT imaging plays an important role not only for obtaining the right diagnosis but also in the follow-up of patients after surgical resection. In accordance with the literature, this case report confirms that FDG-PET/ CT imaging holds promise as an auxiliary method for distinguishing between localized and systemic forms of amyloidosis.

Outer membrane vesicles secreted by gram-negative bacteria play an important role in bacterial physiology as well as in virulence and host-pathogen interaction. Isolated vesicles of some bacteria have also been studied for their immunomodulatory potential in the vaccine development. However, the production of vesicles in sufficient amount, purity and reproducibility remains a critical challenge for subsequent analyses in most bacteria. In the present review methods of production, isolation, purification and quantification of outer membrane vesicles are summarized and discussed., (Copyright © 2014 Elsevier GmbH. All rights reserved.)

Purpose of the Study: The aim of this prospective study was to evaluate clinical and radiographic results in the patients who underwent L5-S1 fixation using the technique of percutaneous lumbar interbody fusion (AxiaLIF)., Material: The study comprised 23 patients, 11 women and 12 men, who ranged from age of 21 to 63 years, with an average of 48.2 years. In all patients surgical posterior stabilisation involving the L5-S1 segment had previously been done. The initial indications for surgery were L5-S1 spondylolisthesis in 20 and L5-S1 spondylosis and stenosis in three patients., Methods: The AxiaLIF technique for L5-S1 fixation was indicated in overweight patients and in those after repeated abdominal or retroperitoneal surgery. A suitable position and shape of the sacrum or lumbosacral junction was another criterion. The patients were evaluated between 26 and 56 months (average, 40.4 months) after primary surgery and, on the basis of CT and radiographic findings, bone union and lumbosacral junction stability were assessed. The clinical outcome was investigated using the ODI and VAS systems and the results were statistically analysed by the Wilcoxon test for paired samples with statistical significance set at a level of 0.05., Results: The average VAS value was 6.6 before surgery and, after surgery, 5.2 at three months, 4.2 at six months, 3.1 at one year, 2.9 at two years and 2.1 at three years (n=18). At two post-operative years, improvement in the VAS value by 56.1% was recorded. The average pre-operative ODI value was 25.1; the post-operative values were 17.0 at six months, 12.3 at one year, 10.6 at two years and 8.2 at three years (n=18). At two years after surgery the ODI value improved by 57.8%. To the question concerning their willingness to undergo, with acquired experience, surgery for the same diagnosis, 21 patients (91.3%) gave an affirmative answer. Neither screw breakage nor neurovascular damage or rectal injury was found. CT scans showed complete interbody bone fusion in 22 of the 23 patients (95.6%), In one patient the finding was not clear. Also, posterolateral fusion was achieved in all but one patients (95.6%). A stable L5-S1 segment was found in all patients at all follow-up intervals. The improvement in both VAS and ODI values was statistically significant., Discussion: In addition to indications usual in degenerative disc disease, overweight patients, those who had repeated trans- or retroperitoneal surgery in the L5-S1 region or who underwent long posterior fixation to stabilise the caudal margin of instrumentation are indicated for the AxiaLIF procedure. The clinical results of our study are in agreement with the conclusions of other studies and are similar to the outcomes of surgery using other types of fusion or dynamic stabilisation for this diagnosis. The high rate of fusion in our group is affected by use of a rigid transpedicular fixator together with posterolateral arthrodesis. On the other hand, no negative effects of only synthetic bone applied to interbody space were recorded., Conclusions: The percutaneous axial pre-sacral approach to the L5-S1 interbody space with application of a double-treaded screw is another option for the management of this much strained segment. The technique is useful particularly when contraindications for conventional surgical procedures are present in patients with anatomical anomalies, in overweight patients or in those who have had repeated surgery in the region. Clinical outcomes and the success rate for L5-S1 bone fusion are comparable with conventional techniques. Complications are rare but their treatment is difficult.

Purpose of the Study: Injuries to the upper cervical spine in children are rare and account for 0.6 to 9.5% of all cervical spine injuries. We present a detailed analysis of the children and adolescents with unstable upper cervical spine injuries treated at our spinal centre., Material: During 16 years of follow-up, unstable injury to the upper cervical spine was recorded in 23 children and adolescents. Two patients (8.7%) were treated conservatively and 21 (91.3%) underwent surgery. The patients were allocated by age to three groups: 0-9 year, 10-14 year and 15-18 year categories. Twenty patients were seen at the final clinical and radiographic follow-up. One patient died at 62 months after surgery and two patients unfit for transport were evaluated on the basis of mailed interviews. The interval between injury and final evaluation ranged from 6 to 137 months, with an average of 53.4 months., Methods: The patients treated conservatively first wore a Philadelphia collar, then a custom-made brace, and eventually a soft Schanze cervical collar to finish the healing process. Application of a halo vest was considered a surgical procedure and was used only in very small children. In unstable odontoid fractures, direct osteosynthesis with two cannulated titanium screws was performed from the anterior approach in older children while, in small children, transoral or submandibular retropharyngeal decompression to treat spinal stenosis caused by bone fragments was carried out and a halo vest was applied. Hangman's fractures were treated by anterior cervical discectomy, fusion with bone graft and anterior plate fixation. The other types of unstable fractures were managed from the posterior approach by occipitocervical fixation, atlantoaxial fixation or instrumented fusion extended caudally. The patients characteristics included gender, age, mechanism of injury, type of injury, neurological findings, type of therapy or surgery, complications and treatment outcome. Neurological status was evaluated using the Frankel classification., Results: The patient group comprised 14 boys (60.9%) and nine girls (39.1%), which gave a gender ratio of 3 : 2. The age of patients at injury ranged from 2 to 18 years, with an average of 11 years and 6 months. The most frequent injuries included rotational or vertical atlantoaxial dislocation in eight (34.8%) and odontoid fractures in seven (30.4%) patients; atlas fracture was recorded in three (13.0%) and hangman's fracture also in three (13.0%) patients; occipitocervical displacement was found in one (4.3%) and complex atlantoaxial fracture also in one patient (4.3%). At the time of injury, 17 patients (73.9%) had no neurological deficit (Frankel grade E), three had Frankel grade A (one paraplegic with a concomitant T5 spinal cord injury) and three had Frankel grade D neurological deficits. Of the six patients with neurological deficit, two showed improvement by one or two Frankel grades. The method of dorsal atlantoaxial fixation was used in eight patients (Magerl fixation in 2 and Harms method in 6). Direct osteosynthesis of an odontoid fracture was performed in four patients, halo fixation was applied in four, C2-C3 discectomy with tricortical bone grafting and plating was carried out in three, occipitocervical fixation was used in three patients, and direct atlas osteosynthesis, simple decompression and simple non-instrumented dorsal spondylodesis each was performed in one patient. Neither intra-operative complications nor post-operative complications related to the surgical technique were recorded. Osteoarthritis or bone non-union, as late post-operative complications, were found in two patients. All other patients showed bone healing by first intention in the desired extent. Superficial or deep wound infections were not recorded., Discussion: In the first age category, the number of boys and girls with injuries to the upper cervical spine was equal while, in the third one, the boys outnumbered the girls more than twice. Of the 23 patients, 91.3% were surgically treated; the anterior approach was used in approximately one third of the patients and the posterior approach in the rest of them. The high number of surgical interventions is due to the fact that the most serious paediatric spinal injuries are referred to our centre., Conclusions: 1. Injuries to the upper cervical spine are most frequently found in the youngest children and in adolescents who, however, frequently have injury also to the lower cervical spine. 2. Neurological deficit is relatively frequent but has a better prognosis than in adults. The youngest children with mild deficits have the best prognosis. 3. The mortality rate in young children with upper cervical spine injuries is evidently high, mostly due to associated head, chest and abdomen trauma 4. Therapy, particularly in small children, is strictly individual.

Purpose of the Study: Atlantoaxial osteoarthritis (AAOA) is a clinical syndrome with signs distinctly different from those of degenerative sub - axial spine disease. Its diagnosis may long be delayed, partly because of insufficient knowledge and partly due to difficulties in interpreting both anteroposterior and lateral radiographs. The aim of this prospective study was to evaluate the first 27 AAOA patients treated at our department., Material: From 2001 we performed atlantoaxial fixation with fusion in a total of 29 patients with painful arthritis of the atlanto axial complex. The 27 patients treated before the end of 2010 were enrolled in the study and analysed in detail. This group included 13 women and 14 men aged between 35 and 72 years, with an average age of 53.5 years. In all patients atlanto - axial fixation was performed using the polyaxial screw-rod system according to Harms., Methods: The patients were followed up at 6 and 12 weeks, 6 and 12 months and then once a year after surgery. X-ray examinations were done at the same intervals as clinical examinations; functional radiographs were made at 12 to 14 weeks after surgery. The definitive analysis of the group was made in the range of 4 to 59 months (average, 25.7 months) after the primary operation. Patients' subjective evaluation was based on NPDI and VAS scores and a question of whether the patient would undergo the surgery again. Objective evaluation included clinical outcomes - pain and neurological findings; radiographic results - stability and healing of C1-C2 fusion; and complications during surgery and in early and late postoperative periods. As intra-operative complications were regarded those associated with the surgical approach, nerve injury and vertebral artery injury. Early post-operative complications included poor wound healing and changes in the patient's neurological status, late complications included instrumentation failure and infection. Patients' clinical status (NPDI, VAS) was statistically evaluated using the one-way ANOVA., Results: The mean VAS score was pre-operatively 7.0 and post-operatively 5.6 at 3 months, 5.0 at 6 months, 5.1 at 1 year; 3.9 at 2 years and 4.0 at 3 years. The mean NPDI value was pre-operatively 39.6 and post-operatively 38.7 at 3 months, 36.0 at 6 months, 34.5 at 1 year, 34.3 at 2 years and 33.1 at 3 years. The question of willingness to undergo the same operation again was answered in the affirmative by 21 patients (77.8%), in the negative by five (18.5%) and one patient did not know (3.7%). Complete bone fusion, as assessed by radiography or CT scanning, was achieved in 26 out of 27 patients (96.3%). In one patient the result was ambiguous but, at 3 months as well as the next follow-ups, C1-C2 complex stability was found., Discussion: All patients in our group underwent a unified system of clinical, radiological, CT and MRI examination. In the decision-making process, emphasis was placed on a correlation of clinical findings with CT scanning results. All patients were operated on from the posterior approach using the Harms method, and radiological outcomes were similar to those of Grob et al. who used the Magerl's technique of C1-C2 fixation. The VAS and NPDI scores demonstrated significant improvement as early as 3 post-operative months, with still further improvement in the following period. The stable clinical status of the patients was achieved at 2 years after surgery. From the practical standpoint we were interested in an answer to the question of whether the patients would be willing to undergo the procedure again. Almost 80% of affirmative answers testified to the correct choice of treatment. The values found corresponded to those reported by Grob at al., Conclusions: Patients with painful osteoarthritis refractory to conservative treatment will benefit from atlantoaxial fixation and fusion. For the patient, restricted cervical rotation is acceptable in return for pain relief. From the surgical point of view, the risk of complications associated with the operative technique did not exceed a tolerable rate.

We present the case of a patient, aged 4 years and 10 months, with metatropic dysplasia. The baby had repeated apnoeic episodes, bradycardia and cardiac arrests and was diagnosed with foramen magnum stenosis and atlantodental dislocation. The episodes were markedly associated with neck movements. Considering this clinical presentation, we performed laminectomy of the atlas, foramen magnum enlargement and decompression followed by dorsal C0-C2 stabilisa - tion with allogeneic bone chips. After the operation, apnoeic episodes did not recur.

Purpose of the Study: Spinal cord concussion is characterised as fully reversible, temporary inhibition of conductive function due to trauma, without signs of structural changes. Although neurological deficit is usually related to the severity of spinal injury, this is different in spinal cord concussion. The aim of this retrospective study was to evaluate a group of 24 patients with spinal cord concussion, to design a diagnostic algorithm and propose an effective therapy with a good prognosis for the patients., Material: We reviewed clinical records of 9 768 patients hospitalised at the Department of Spinal Surgery, University Hospital in Motol, from September 2002 till December 2010, and of 457 patients treated at other departments of the Hospital between January 2008 and December 2010; this was a total of 10 225 patients. The data were retrospectively analysed and only the patients with a clear history of trauma and subsequent conservative therapy were selected to comprise a group characterised by the generally known criteria of spinal cord concussion: (1) spinal injury with immediate neurological deficit of varying degree; (2) neurological deficit corresponding to the level of spinal injury; (3) recovery of neurological function within 72 hours of injury; (4) no morphological evidence of injury to the spinal structures obtained by imaging methods. This group comprised 24 patients., Methods: The patients were followed up from 6 to 95 months, with a mean of 46 months and a median of 48 months, at intervals of 6 and 12 weeks and 6 and 12 months after injury, and then every following year. The recorded information included the patient's age at the time of injury, their gender, the mechanism of injury, reports on alcohol consumption, the first detected neurological deficit, its development immediately after injury, during the hospital stay and at follow-ups in the out-patient department, methylprednisolone administration according to the National Acute Spinal Cord Injury Study (NASCIS) 2, and findings of imaging methods, particularly MRI., Results: Our group consisted of 22 men (91.7%) and two women (8.3%), with an average age of 29 years; the average age was 30 years in men and 18.5 years in women. Seven patients (29.2%) were younger than 18 years, with an average of 16.14 years; the remaining 17 patients (70.8%) were older than 18 years, with an average of 34.35 years. The major mechanisms of injury included falls from a height in 10 patients (41.7%) and injury due to alcohol consumption in five patients (20.1%). Clinical findings involved lesions of the medullary cone in 12 (50.0%), cervical spinal cord in seven (29.2%) and thoracic spinal cord in five (20.8%) patients. Motor function deficit was present in all patients, of whom 10 (41.2%) showed a complete loss of motor function. Impaired sensory function was found in 21 (87.5%) patients. One patient had perianal and genital sensory deficit and one (4.2%) had urinary retention. Neither radiograms nor CT scans showed traumatic changes in any of the patients; MRI findings free of any traumatic spinal changes were recorded in 21 patients (87.5%). One patient had oedema of the T5 and T8 vertebral bodies. No complications were recorded. All patients experienced rapid resolution of neurological deficit, which occurred within 6 hours of injury in two (8.4%), within 12 hours in two (8.4%), within 24 hours in 12 (50.0%) and within 48 hours in six (25.0%) patients, and later than 48 hours after injury in two patients (8.4%). However, recovery always occurred within 72 hours of injury., Discussion: A good prognosis for patients with this injury is supported by our findings, because all patients experienced rapid resolution of neurological deficit within 72 hours of injury. This result is in agreement with the relevant international studies reporting no serious complications associated with spinal trauma. There are no clear recommendations for administration of high doses of methylprednisolone according to the NASCIS system., Conclusions: Spinal cord concussion is not a frequent injury; in our study, it accounted for 3.54% of the patients with trauma histories out of the total number of 678 patients, or for 2.40% out of 997 injured spinal levels. The first steps should be the same as in any other injury to the spinal cord. An early examination of the patient with imaging methods including MRI is of primary importance. At present administration of methylprednisolone according to the NASCIS system is disputable. The patient diagnosed with spinal cord concussion has a good prognosis, with rehabilitation as the main therapeutic approach.

Purpose of the Study: To present the results of an independent prospective monocentric study of patients with ProDisc-C Total Disc Replacement (CTDR) followed up for 4 years, and to analyse the most frequent late complications, in particular heterotopic ossification., Material: In the period from October 2004 to May 2006, a total of 61 patients underwent ProDisc-C CTDR involving one or two segments at the Department of Spinal Surgery, University Hospital in Motol. This study included 39 patients who were followed up for at least 4 years. With the exception of one patient operated on two segments, the patients were treated by ProDisc-C CTDR at one level., Methods: In the study, only the surgical procedure recommended by the implant manufacturer (Synthes, USA) was used and all operations were performed by a team with the same leading surgeon. Clinical assessment. The patients were examined before surgery, immediately after it and at 6 and 12 weeks and 6, 12, 24 and 48 months post-operatively. At each follow-up, responses to the questionnaire were obtained, and the patients' health status was evaluated on the basis of Neck Disability Index (NDI) and Visual Analogue Score (VAS) values for cervical spine and radicular pain, the use of analgesics and personal satisfaction Radiographic assessment. Pre- and post-operative radiographs were taken in antero-posterior and lateral projection, and flexion, extension and lateral bending films were obtained The height of the intervertebral disc space at the affected level was measured and range of motion in flexion and extension was evaluated together with the adjacent levels. In addition, subsidence, loosening, failure or displacement of the implant was assessed, as well as the presence of heterotopic ossification. The results were statistically analysed using Student's t-test., Results: The clinical results at 1, 2 and 4 years of follow-up were as follows: NDI values, 44.9 pre-operatively, 26.1, 25.8 and 25.1 post-operatively, improvement by 44.1% after 4 years; VAS for cervical spine pain, 5.8 pre-operatively, 3.0, 2.7 and 2.7 postoperatively, improvement after 4 years by 53.7%; VAS for radicular pain, 6.3 pre-operatively, 2.9, 2.9 and 2.7 postoperatively, improvement by 57.1% after 4 years. The radiographic findings showed the average intervertebral disc space height of 3.2 mm at the affected level before and 7.4 mm after surgery, with no significant change in the following period. The average range of disc motion at the affected level was 4.2 degrees before and 11.1 degrees after surgery, with 11.4 degrees at 4 years of follow-up. During that period, heterotopic ossification was recorded in 10 (25%) treated discs, with five of them (12.5%) classified as grade III or IV. Spontaneous fusion across the disc replacement level was found in three cases (7.5%). Two patients (5%) developed kyphosis at the affected disc level. The statistical analysis showed a significant difference between the pre-operative VAS values and those at 6 post-operative weeks for both cervical spine and radicular pain (t = 4.4 and t = 5.3, respectively; p < 0.05). No significant difference in VAS values was found between 6 weeks and 3 months after surgery for either condition (t = 1.69 and t = 0.3; p > 0.05). Changes in VAS values in the following period were minimal and non-significant. The differences in NDI values before surgery and at 6 weeks after it, and between 6 weeks and 3 months post-operatively were significant (t = 11, p < 0.05 and t = 3.8, p < 0.05, respectively). In the following period, changes in the values were minimal and non-significant., Discussion: Short-term studies on various types of cervical disc replacement have been optimistic and reported good clinical results and few complications. However, with longer follow-ups there has been an increasing incidence of heterotopic ossification as the most frequent late complication. Although the number of patients diagnosed with it is growing, heterotopic ossification influences the patient's clinical problems only little. What are its causes and how to prevent it are questions to be fully answered yet, Conclusions: Heterotopic ossification is the most frequent late complication of total disc replacement. Many factors may be responsible for its development and therefore its prevention is not clear. The correct indication and appropriate surgical technique are most often recommended, and are considered also by the authors to be most important. Restricted motion at the treated segment/s has no significant effect on the patient's clinical status.

Purpose of the Study: The development of a cervical kyphotic deformity can be associated with a degenerative disease, trauma, tumour, developmental anomaly and also a surgical procedure. Post-operative kyphosis can develop after both the anterior and posterior surgical approaches. The deformity can also result from systemic diseases, such as ankylosing spondylitis or rheumatoid arthritis. The aim of the study was to make the clinical and radiographic evaluation of a group of patients with kyphotic deformity treated at our department., Material: Between May 2005 and April 2010, a total of 102 patients underwent correction of cervical kyphosis at our department. (Center for Spinal Surgery). Of them, 90 patients with complete medical records and post-operative periods longer than 6 months were included in this study. There were 36 men and 54 women ranging in age from 13 to 90 years and with an average of 56.7 years. In six patients cervical kyphosis was caused by an inveterate injury, in 71 by degenerative disease, in six it developed in association with rheumatoid arthritis, and in seven patients it was due to previous surgery. Patients with acute trauma, tumour, infectious disease or congenital anomaly were not included., Methods: All patients were examined before surgery by radiography in antero-posterior and lateral projection, including flexion- extension bending films, and by CT scanning of ultrathin cross-sections with sagittal, frontal and recently also 3D reconstructions. Magnetic resonance imaging in three planes was also performed. On the basis of the results and clinical examination, the operative strategy was planned. Surgery was carried out from the anterior or the posterior approach, or the combined approach was used. Three-stage surgery was performed in one patient. The surgical outcome was assessed using the Nurick score and Neck Disability Index (NDI), the Visual Analogue Scale (VAS) was used to evaluate pain intensity or paraesthesia. Statistical analysis was done using the Chi-square test and paired t-test., Results: The average NDI value was 25.5 before surgery and 14.3 and 14.9 at one and two years after surgery, respectively. Compared with the pre-operative state, improvement or no changes were recorded in 89.7 % of the patients; transient deterioration occurred in 10.3 %. Improvements found were as follows: by one degree in 46.2 % of the patients, by two degrees in 18 %, by three degrees in 5.1 % and by five degrees in 2.6 % of the patients. The condition remained unchanged in 18 % of the patients. The average outcome was an improvement by one degree. The average pre-operative Nurick score was 0.7; an average post-operative value of 0.6 was recorded at both one and two years of follow-up. The average VAS value for neck and radicular pain was 5.7 pre-operatively, and 2.5 and 2.7 at one and two post-operative years, respectively. Out of 90 patients, complete bone union was achieved at 6 months after surgery in 88 patients (97.8 %). The average pre-operative value for the cervical curvature index (Ishihara) was -13.7; the average pre-operative cervical kyphosis was -14.4 degrees, ranging from -2.2 to -44.0 degrees. After surgery, the average Ishihara index was +15.3 and the average lordosis was +13.5 degrees, with a range of -16.0 to + 37.4 degrees., Discussion: A single/isolated anterior approach can be used for fixed deformities without ankylosing spondylitis. It allows for decompression of the anterior pathology and for correction of cervical kyphosis with use of instrumentation and structural graft. A combined ventral-dorsal approach is appropriate in fixed deformities or deformities involving the cervico-thoracic junction. The main principle of correction is to lengthen the cervical spinal column in the front and to shorten it at the back by anterior decompression with or without instrumentation and by subsequent posterior stabilisation. An isolated/single dorsal correction can be used in the case of successful correction by traction or specific head positioning on the table without anterior nerve compression. In severe fixed deformities such as Bekhterev's disease, the chin can be so close to the chest as to interfere with eating and breathing. The deformity most often develops at the cervico-thoracic junction and requires treatment by osteotomy., Conclusions: The results of the study showed a marked improvement in the patients' quality of life after kyphosis correction, improved neurological status and an improved posture seen on radiograms of the cervical spine. The study also revealed a higher number of potential complications associated, in particular, with corrective osteotomy. The best results were achieved with the combined surgical approach; however, the choice of a surgical method was independent of the patient's clinical status.

Percutaneous vertebroplasty is a minimally invasive surgical technique involving transpedicular injection of polymethylmetacrylate into the vertebral body. The aim of this procedure is to enhance the mechanical strength of a pathologically changed vertebra. Currently, the method is most often used for painful osteoporotic vertebral fractures, aggressive haemangiomas, necrotic lesions and spinal tumours, particularly the metastatic ones. Although this method is less invasive, relatively straight-forward and effective, there may be complications. The authors present the case of a 70-year-old woman who, on the second day after surgery, developed a rare symptomatic pulmonary polymethylmetacrylate embolism after per- cutaneous vertebroplasty performed for osteoporotic fractures of the lumbar spine.

In this case study, three patients are presented who had incomplete cauda equina syndrome following elective lumbar spine surgery for degenerative disease. In all patients, the neurological symptoms developed due to post-operative arachnoiditis. Its aetiology, pathogenesis and diagnostics are discussed, as well as the methods of prevention and therapy which are still limited and often not beyond experimentation.

Purpose of the Study: Occipitocervical fixation and spondylodesis is indicated in various cases of occipitocervical instability. The aim of this retrospective study was to evaluate the results of occipitocervical fixation at our institutions., Material: Between 1997 and 2007, a total of 57 patients underwent occipitocervical fixation (OC) there were 25 men and 32 women, from four to 77 years of age, with an average of 58.7 years. The patients were allocated to two groups according to the method of OC fixation used: tying wires or cables (group 1) screw-rod or screw-plate systems (group 2). Indications for OC fixation included trauma in 15, rheumatoid arthritis (RA) in 28, destruction due to psoriasis in one, tumour in eight, and congenital anomalies of the cervico-cranial junction in five patients. In five patients with tumour, OC fixation was completed with a transoral or transmandibular procedure. The C0-T 1 or C0-T 2 segments were fixed in 22 patients, C0-C2 segments in 14, C0-C3 segments in six, C0-C4 segments in two, C0-C5 segments in eight and C0-C6 segments in five patients., Methods: In atlanto-occipital dislocation, comminuted fractures of the ;atlas or similar injuries, C0-C1-C2 segments were fused in congenital anomaly, the C0-to-lower cervical spine was fixed, with C1 being avoided. The RA patients were treated by fixation of the C0 to T1 or T2 segments. The atlas was fixed by the screw method of Goel, the C2 joint by that of Judet, or stable fusion of the two vertebrae was carried out by the Magerl transarticular technique. For the middle and lower cervical spine, lateral mass screw fixation by the Magerl method was used, and from C7 caudally the vertebrae were fixed transpedicularly. Occasionally, in small children in particular, a Ransford frame fixed with wires or cables was used. In principle, an extent of fixation as small as possible was employed. The patients were evaluated at a final follow-up ranging between 12 and 132 months after the primary surgery (average, 42.7 months). Indications for surgery and the method and extent of instrumentation were recorded. The evaluation included pain and neurological deficit assessment, radiographic evidence of the stability of fixation and bone union and intra-operative and early and late post-operative complications., Results: Of the 57 patients, bone fusion was the objective of surgery in 52. Further five patients died of associated injuries or serious medical complications shortly after the operation. Of the remaining 47, bone union was achieved in 44 patients (93.6%). Pseudoarthrosis developed in three patients who, however, because of a higher age and minimal complaints did not require revision surgery. In terms of bone union, there was no difference between a short (C0-C2) and a long (C0-CX or C-T) fixation. No differences among fixation materials were found. The differences in percent bone union after spondylodesis between the tying-wire and screw-rod fixation systems were not statistically significant (p > 0.05). In the patients treated for RA, psoriasis or congenital anomaly, the Nurick scale score significantly improved at 2 years after surgery (p < 0.05). In comparison with the others, the RA patients had a significantly higher number of complications (p < 0.05). The patients treated for tumour showed a significant difference between the pre- and post-operative VAS values (p < 0.05)., Discussion: Of the patients with RA, psoriasis or congenital anomaly, 57.6% showed post-operative improvement in the Nurick scale score by 1-2 but never more than by 2. A decrease in pain intensity and neurological findings was recorded in 88.2% of the patients. This is in agreement with the results published in the international literature. In the patients treated for trauma, a high proportion (53.3%) had neurological deficit, which is unusually high for craniocervical injuries. This can be explained by the fact that OC fixation is used only in the most serious injuries. Of five patients with neurological deficit of Frankel grade A or B, three died and two required mechanical ventilation. Less serious neurological findings of Frankel grade C or D in three patients improved to a normal condition., Conclusions: Rigid OC fixation is a very effective method for the treatment of craniocervical junction instability. The currently used implants allow us to achieve high stability and efficiency of bone union. Regardless of the instrumentation used, fusion is achieved in more than 90%, and clinical improvement in more than 80% of the patients.

PURPOSE OF THE STUDY To evaluate retrospectively a group of patients with hyperextension injury to the cervical spine who were treated at the Department of Spinal Surgery of the University Hospital in Motol, Prague, between 2003 and 2006. MATERIAL The group comprised 22 patients, 17 men (77 %) and five women (23 %) in the age range of 35 to 81 years, with an average of 59.5 years. All patients had, in association with the injury, neurological deficit of varying degree. METHODS All patients underwent X-ray and magnetic resonance imaging examination and received methylprednisolone according to the National Acute Spinal Cord Injury Study (NASCIS) 2 trial. Eleven patients had urgent surgery within 24 hours of injury; eight patients were operated on within an interval of 3 days to 2 months because of the seriousness of their state and multiple morbidity; and three patients were treated conservatively. Neurological deficit in terms of upper- and lower-limb mobility was evaluated by the American Spinal Injury Association (ASIA) motor score. The values obtained for the urgently operated patients and for those operated on after a time interval were compared by Wilcoxons two-sample test. The other aspects evaluated included trauma aetiology, level of spinal cord injury, manner of treatment, and intra-operative and post-operative complications. RESULTS The most frequent cause of injury was a low-height fall (13 patients; 59 %); car accidents ranked second (9 patients; 41 %). In five patients (22.7 %) ebriety was found. Eighteen patients had no skeletal injury (81.8 %). Four patients (18.2 %). Four patients (18.2 %) suffered fractures of articular or spinous processes, but the anterior column skeleton was intact in all. The segment most frequently affected by myopathy was C3-C4, then C4-C5 and C5-C6. Decompression was carried out to the extent of myopathy; and in the adjacent segments only if significant stenosis was present. In both subgroups of surgically treated patients (urgent and delayed management), comparisons of the ASIA scores at the time of injury and at one-year follow-up showed no significat improvement in post-operative mobility, as evaluated by Wilcoxons two-sample test at a level of significance a = 5 %. No intra-operative or post-operative complications, except for early death, were recorded. In all patients the wound healed by first intention and no loosening of instrumentation was foud on follow-ups at the out-patient departments. DISCUSSION Although the greatest narrowing of the spinal canal due to spondylosis occurs at the C5-C6 segment, the C4-C5 segment sustained most injuries. Although some relevant papers report no significant difference in improved neurological deficit between patients treated surgically and those undergoing conservative therapy, we prefer surgical management, in most of the cases from the anterior approach, which allows us to remove dorsal osteophytes and perform careful decompression to prevent damage to nerve structures and to preserve those which are still intact. There was no significant difference in the outcome between urgent and delayed trauma management, which is unusual amongst other injuries associated with neurological lesions and this indicates that the timing of surgery must be strictly individual and should be carried out at a time when operative benefit outweighs operative burden. The surgical treatment used should, in the first place, lead to early recuperation and rehabilitation. CONCLUSIONS Hyperextension injuries of the cervical spine are usually associated with serious neurological deficit. A correct algorithm of examination will result in good treatment outcomes. However, these injuries require a therapy that is long-lasting and difficult, with a need for cooperation of anaesthesiologists, spinal surgeons, physical therapists and, last but not least, psychologists. Key words: cervical spine, hyperextension injury, spondylosis, myelopathy.

Purpose of the Study: To present the results of an independent mono-centric prospective study on patients with a mobile ProDisc-C implant. This cervical artificial disc replacement (CADR), which is one of the options for avoiding cervical spine fusion, was evaluated during two-years follow-up., Material: A total of 61 patients underwent CADR with a ProDisc-C in one or two segments at the Department of Spinal Surgery of the University Hospital in Motol, Prague, in the period from October 2004 to May 2006. Of these, 39 were included in the study and followed up for 2 years at least. Except for one patient, one segment was replaced in all patients., Methods: The surgical procedure recommended by the manufacturer (Synthes, USA) was used throughout the study. Clinical evaluation. Each patient was examined before and immediately after surgery, and followed up at 6 and 12 weeks, and 6, 12 and 24 months. At each follow-up the patient answered the questionnaire which included the Neck Disability Index (NDI) and Visual Analoque Scale (VAS) assessment for neck and radicular pain, analgesic use and the patient's satisfaction. Radiographic examination. Radiographs were taken in antero-posterior and lateral projection, and on bending films in flexion, extension and lateral flexion on both sides. The height of the intervertebral space of the involved segment and motion of the replaced and adjacent discs in flexion and extension were measured. The radiographs were examined for potential sinking, loosening, failure or migration of the implant. Statistical evaluation. The results were statistically analysed using Student's t-test., Results: Clinical outcome. The NDI evaluation showed that the mean value of the index improved from 44.9 pre-operatively to 26.1 and 25.9 at 1 and 2 years of follow-up, respectively, i.e. by 42.5 % in two years. The mean VAS score for neck pain changed from 5.8 pre-operatively to 3.0 and 2.7 at post-operative years 1 and 2, respectively, which is an improvement by 53.7 % in two years. The mean VAS score for radicular pain improved from 6.3 to 2.9 and 2.8 at the same intervals, which is an improvement by 53.9 % in two years. Radiographic findings. The mean height of the affected intervertebral space was 3.2 mm before and 7.4 mm after surgery and it did not change significantly thereafter. The mean range of motion at the involved segment was 4.1 degrees before and 11.1 degrees after surgery. Statistical evaluation. In assessment of both neck and radicular pain, the difference between the mean VAS score pre-operatively and that 6 weeks post-operatively was significant (t=4.4 and t=5.3, respectively; p<0.05). The difference in mean VAS scores between 6 weeks and 3 months post-operatively was not significant (t=1.69 and t=0.3, respectively; p>0.05). At the next follow-ups the mean VAS scores changed only minimally and the differences were not significant. The difference between the mean NDI before and that at 6 weeks after surgery was significant (t=11; p<0.05) and significant was also the difference between 6 weeks and 3 months after surgery (t=3.8; p<0.05). After that changes were minimal and were not significant., Discussion: Currently, mobile implants are in the focus of interest amongst spinal specialists, their materials and shapes, primary implant stability, the centre of rotation, indications for replacement and correct operative techniques being discussed. The situation appears similar to that of 20 years ago when large joint replacement was being introduced, and it is the future that will show the right development., Conclusions: This two-year prospective study on patients with CADR shows very good and promising outcomes. It is evident that the implant increases the range of motion at the treated segment and reduces degenerative changes in the adjacent intervertebral spaces. On the other hand, CADR is associated with complications such as artificial disc kyphosis and heterotropic ossifications. An unequivocal requirement for a correct indication and a faultless operative technique was the conclusion drawn from a detailed analysis.

Purpose of the Study: Surgical treatment is preferred in our department in all patients with type II and type III dens fractures, regardless of their age, with the exception of non-displaced or completely reduced fractures in young patients. The aim of this study was to evaluate patients over 65 years of age treated by direct osteosynthesis of the dens or posterior atlanto-axial fixation and spondylodesis., Material: In the years 2001 to 2005, 28 patients aged 65 years and older were surgically treated for dens fracture. This included 13 men and 15 women between 65 and 90 years of age, with an average of 77.4 years. According to the treatment, i.e., direct dens osteosynthesis (1) or C1-C2 posterior fixation (2), two groups were evaluated, and two categories were considered by age, i.e., 65 to 74 years (8 patients) and 75 years and older (20 patients). In 23 patients, an isolated fracture of the dens was present and, in five patients, injury was part of a complex C1-C2 fracture. A Frankel grade D neurological deficit was found in three patients., Methods: In all patients, surgical treatment by direct osteosynthesis of the dens from the anterior approach, using two cannulated screws, was preferred as the method of choice. However, in the case of distinct osteoporosis, fragmented fracture of the dens base or tear of the ligamentum transversum atlantis, we used the Harms method of posterior fusion with polyaxial screw fixation as the primary treatment, or the Magerl transarticular fixation completed with the Gallie technique from the dorsal approach. The patients were followed up at 3, 6 and 12 weeks, at 6 and 12 months, and then at one-year intervals. X-ray and clinical examinations were made at the regular follow-ups and functional radiographs were taken at 12 months following the surgery. The whole group was evaluated in the range of 18 to 84 months (average, 37.3 months). Neurological deficit was assessed on the basis of the Frankel classification. The results were analysed using the Chi-square test., Results: Of 20 patients still living at the time of this evaluation, 11 underwent direct osteosynthesis and nine were treated by posterior instrumented spondylodesis. In group 1, pseudoarthrosis of the dens or fibrous callus developed in one patient (9.1 %) and a line of fracture was evident in one patient of group 2 (11.1 %), which was not significant (p<0.05). However, a statistically significant difference in mortality was found when the two age categories were compared (p>0.05), with 0 % in the younger and 40 % in the older category. The overall mortality within 6 weeks of injury was 28.6 %. Mortality in group 1 and group 2 was 21.4 % and 35.7 %, respectively; this difference was not statistically significant (p<0.05)., Discussion: We use conservative treatment only in the patients who are able to stand up and move soon after injury. If this is not feasible, we prefer surgical treatment with the same aim achieved as soon as possible without rigid external fixation. In this study, surgery was associated with an acceptable number of minor complications due to poor bone quality or health state of the patient. The higher mortality in the higher age category was obviously related to generally poorer health of these patients., Conclusion: Surgical treatment can significantly improve the quality of life in elderly patients who have suffered a fracture of the dens. The surgical technique should be chosen to take bone quality, degenerative changes of the spine and overall health of the patient into consideration. Mortality after surgery is not related to the technique selected but to patient's age. Elderly patients with neurological deficit usually die due to co-morbidity, regardless of the therapy used.

Purpose of the Study: To evaluate a group of 11 patients with L5 burst fractures treated by L4-S1 posterior instrumented spinal fusion without reconstruction of the anterior column., Material: The group included seven men and four women aged between 14 and 66 years (average, 37.5 years), followed for 12 to 36 months (average, 18 months). Ten patients were treated by posterior instrumented spinal fusion at the L4-S1 level, and one with an associated injury to L3 underwent L2-L4-S1 posterior instrumented spinal fusion. The spinal column was inspected in eight patients in whom neurological symptoms or significant stenosis were present., Methods: On admission, the evaluation of post-traumatic radiographs included measurements of the angle between the L4 lower and the S1 upper end-plates, the angle between the upper and lower end-plates of L5 and height of the anterior and posterior rims of the L5 vertebral body. CT scans were assessed for a relative narrowing of the spinal canal. The patient's neurological status was also evaluated. At 3, 6, 12, 24 and 36 months of follow-up, radiographs, neurological findings and subjective complaints were assessed., Results: On comparison of pre-operative values with those 3 months after surgery, the differences were on average 3.6 degrees for L4-S1 lordosis, 2.5 degrees for the angle between the upper and lower end-plates of L5, and 1 mm for the height of the anterior rim; there was no difference in posterior rim height. Eight patients had the same values at the latest as at 3- month follow-up. Three patients with broken screws showed the loss of L4-S1 lordosis by 4 to 13 degrees (average, 9 degrees). Neither the angle between the upper and lower end-plates of L5, nor vertebral body height were changed. The narrowing of the spinal canal by vertebral body fragments ranged from 0 to 60 % (average, 35 %) of canal space. On admission, neurological findings were normal in two patients and involved nerve root syndrome in five patients. In four patients it was not possible to assess their neurological status. At he latest follow-up, ten patients were free from peripheral neurological lesions, one still had lumbar radicular syndrome, two patients reported mild or moderate lumbosacral pain and seven patients were without complaints. Subjective complaints could not be assessed in two patients because of their mental state. An early post-operative complication included wound dehiscence in one patient (9 %) and, in three patients, broken screws in S1 were recorded as late complications., Discussion: Only a few references referring to a relatively low number of patients with L burst fractures treated by surgery were found in the literature. Most of the authors report limitations of reduction and good clinical outcomes. CONCLUSIONS The posterior instrumented spinal fusion of L5 alone is sufficient for the treatment of most L5 burst fractures. Early removal of the fixator is indicated in active patients. Often good clinical outcomes are in contradiction with radiological findings. The possibilities of spinal canal decompression by ligamentotaxis at this level of injury are limited. When significant spinal stenosis is present, laminectomy or hemilaminectomy is necessary to achieve decompression of the spinal canal.

Spinal cord injury results in a permanent neurological deficit due to tissue damage. Such a lesion is a barrier for "communication" between the brain and peripheral tissues, effectors as well as receptors. One of the primary goals of tissue engineering is to bridge the spinal cord injury and re-establish the damaged connections. Hydrogels are biocompatible implants used in spinal cord injury repair. They can create a permissive environment and bridge the lesion cavities by providing a scaffold for the regeneration of neurons and their axons, glia and other tissue elements. The advantage of using artificial materials is the possibility to modify their physical and chemical properties in order to develop the best implant suitable for spinal cord injury repair. As a result, several types of hydrogels have been tested in experimental studies so far. We review our work that has been done during the last 5 years with various types of hydrogels and their applications in experimental spinal cord injury repair.

Purpose of the Study: Although great advances have been made in both radiological diagnosis and antibiotic therapy of microbial infections, the treatment of spinal infections remains a major clinical challenge. Many of the patients affected are referred to spinal units with long delays. The general population is ageing and the number of immunocompromised patients, as well as the number of operative procedures for spinal disorders are increasing. The aim of our study was to evaluate the clinical presentations of spinal infections, options for their diagnosis, indications for treatment and their risk factors and the results of surgery., Material and Methods: The group of 112 patients evaluated after the treatment of spinal infection comprised 63 men and 49 women at an average age of 59.4 years (range, 17 to 84). The average follow-up was 3.2 years (range, 6 months to 8 years). Of these, 82 patients had primary hematogenous infection, 29 had post-operative infection,and one had an infected gun shot wound. Thirty-six patients showed neurological deficit and six were paraplegic. The diagnostic methods included FBC, CRP and EST tests, examination of blood cultures, aspirates and biopsy samples from the infected site, bone scintigraphy, MRI and CT scanning. Indications for surgery included an infection not responding to conservative treatment,with existing or impending spinal instability, and with or without neurological deficit. The surgical management involved transpedicular drainage of the abscess, wound debridement from the posterior approach and instrumented spondylodesis. Surgery which included spinal decompression with radical excision of infected tissue was augmented with posterolateral instrumented fusion and/or anterior stabilization, as indicated., Results: Of the 112 patients treated, seven died of uncontrollable sepsis after surgery; the remaining 105 were followed up. Another four patients died of causes unrelated to the spinal problem treated within 12 months. All patients recovered except for two in whom the infection persisted, but 13 required more than one surgical procedure. One patient with CSF leakage failed to heal after five interventions. The most frequently isolated infectious agents were Staphylococus aureus, Staphylococus epidermidis and E. coli. Of the 33 patients with neurological deficit, 24 improved by one or two Frankel grades. The neurological status of six paraplegic patients did not improve, but their functional findings did after stabilization of the spine. Clinical evaluation showed 47 (44.7 %) very good, 40 (38 %) good, eight (7.6 %) unchanged and 10 (9.5 %) poor outcomes., Conclusion: Early diagnosis is a prerequisite for good treatment outcomes. Clinical examination, results of laboratory tests, and scintigraphy and MRI findings play the key role. When progressing osteolysis is suspected, a CT scan is necessary. Debridement should be as radical as possible, but always in compliance with the patient's health state. At an advanced stage of disease, spinal stabilization is important because it allows us to remove infected tissue. Intravenous and then oral antibiotic therapy at 2 to 4 and 6 to 12 weeks of follow-up is mandatory. The management of spinal infections is a complex process requiring good multidisciplinary cooperation.

Purpose of the Study: Cervical spine injuries in young adults are usually caused by high-energy trauma. However, a typical injury to the cervical spine can also occur in older patients, in whom it is often associated with the presence of osteoporosis and relatively low-energy trauma, similarly to distal radial or proximal femoral fractures, or fractures of the thoracolumbar spine. The aim of this study was to evaluate a group of elderly patients with cervical spine injuries treated at our department., Material: In the period from 2001 to 2005, 66 patients older than 65 years were treated for cervical spine injury at the Department of Spinal Surgery of the Motol University Hospital in Prague. Of these, the 53 patients treated surgically, and followed up longer than 6 months after surgery, were evaluated in detail in this retrospective study. They included 30 men and 23 women at an average age of 75.5 years (range, 65-92 years)., Methods: Conservative therapy was used to treat stable injuries to both the upper and the lower spine that were without risk of the development of secondary instability or deformity and that were not associated with neurological deficit. Surgery was performed in primary unstable injuries of the upper and lower spine or in injuries involving the risk of secondary instability or deformity, and also in all injuries associated with neurological deficit, when the patient's health state allowed for it. The final retrospective evaluation was made at 6 to 78 (average, 31.3) months after the primary operation. The evaluation included trauma etiology, type and level of injury, neurological findings, kind of treatment, complications and outcome., Results: In our group, 56 % of the patients were men, injury occurred due to a fall in 66 % and the upper cervical spine was affected in 60 % of the patients. Most of the upper cervical spine injuries happened to the patients over 75 years, and included fractures of the dens and complex atlantoaxial fractures. Neurological deficit was found in 37.7 % of the patients treated surgically, but only 7.5 % had a deficit classified as Frankel grade A or B. Of the 13 patients treated conservatively and the 53 patients treated surgically, two (15.4 %) and 15 (28.3 %) died, respectively., Discussion: The results of our study are in agreement with the relevant international literature data. Conservative treatment is used only in the patients in whom early mobilization, including standing and walking, is possible. In other patients, surgical treatment is preferred with the aim to achieve early mobilization without rigid external fixators, if possible. Surgery is carried out predominantly in patients with more serious injuries; therefore, mortality in our patients was nearly twice as high after surgery as after conservative treatment. Some surgical procedures were accompanied by minor complications usually associated with poor bone quality or poor health in general. Old patients with serious neurological deficit usually die of co-existent diseases regardless of the therapy used., Conclusions: In patients older than 65 years, injuries to the upper cervical spine are usually caused by low-energy trauma. In this age category, neurological deficit is found more often than in younger patients and is typically manifested as a central cord syndrome.

According to the available sources, no case of total spondylectomy of C2 with preservation of roots, preservation of vertebral arteries and a short fixation without occipitocervical fusion has been so far described in the literature. We decided to perform a radical surgery in a man, now 27 y. o., with solitary metastasis of thyroid adenocarcinoma. In the first step, we applied the posterior surgical approach. The patient was placed prone on a standard operating table with a support of head fixed by adhesive plaster, with the upper cervical spine slightly bent forward. We made a mid-line incision, extending from the external occipital protuberance to the C7 spinous process, controlled bleeding and exposed the C0-C4 section. Subsequently, the entire posterior epistropheus was resected, including most of the pedicles and the entire articular processes for C2-C3 articulation. Both the C2 roots were preserved, however, we had to control quite a profuse bleeding from the venous plexus around the left root. During dissection, the dural sac was damaged in the region of the attachment of the left root, which was treated by suture and covered with Tissucol fibrin sealant. Screws 4.0 mm thick, were inserted into the lateral masses of the atlas after Harms and 4.0mm screws into the C3 and C4 articular processes. On both sides, the screws were connected with 3.2 mm rods, and a transverse stabilizer was then applied to fix the two sides together. Cancellous bone grafts were harvested from the iliac crest and a massive posterolateral and posterior fusion of C1-C4 was performed. The second operation was performed after 21 days. Transoral transmandible approach without tongue splitting was applied. The patient was placed supine on a standard operating table with a support of neck, the head was fixed by adhesive plaster and slightly bent back, and tracheostomy was inserted. An arched incision through the middle of the red lip was made, extending 2 cm straight caudally and arching across the chin and neck, in the midline. On the caudal end we made a transverse inverted T incision. Subsequently, we exposed and osteotomised the mandible using the midline Z-type incision. In order to identify the space between the anterior arch of C1 and the C4 vertebral body, the Synframe retractor was inserted with one blade opening the mouth by pressure on the upper teeth and two blades pressing the tongue caudally. Then an inverted U incision through the mucosa of pharynx was made to identify paravertebral muscles. Caspar retractor was used to separate the muscles and expose C1-C3 laterally, including transversal processes with vertebral arteries. No pathological changes were manifested on the skeleton. First we removed the middle portion of the C2 vertebral body where we did not find any tumour, only sclerotic remodelling. Subsequently, we reamed the lower middle portion of the anterior arch of C1, extracted the dens and cut off the alar ligaments and the apical ligament of dens. The entire dens was then removed. Then we continued on the right side, in the intact part and extracted part of C2 in the region of the atlantoaxial joint, including the rest of the pedicle, and the anterior portion of the transversal process up to the vertebral artery. The posterior part of the transversal process was carefully rotated around the artery and also removed. All parts were extremely hard, sclerotic. The same procedure was followed on the left side where we found a 7 x 10 mm gelatinous greyish tumour in the lateral part of C2 below the atlantoaxial joint. Other parts were again sclerotic. Liquorrhea appeared again from dissection around the C2 root on the left side, the source of which we could not clearly identify. We filled the site of the probable hole with Tissucol fibrin sealant. Between the notch in the lower part of the anterior arch of C1 and the upper end plate of the C3 vertebral body we seated a shaped SynMesh cage with sharp edges providing a very good fixation. No additional fixation was needed. Again we harvested cancellous bone grafts from the iliac crest and placed them on the sides of the cage and at the front between the anterior arch of the atlas and the C3 vertebral body. Subsequently, the muscles were approximated and the mucous tissue of the pharynx repaired. The mandible was fixed by two Miniplate System plates and supported by a dental plate. Total spondylectomy of C2 with preservation of vertebral arteries and roots stabilized only by a short fixation is an extreme surgical procedure suitable only for exceptional cases of young patients with a good bone quality. With regard to potential complications it is of vital importance to consider carefully such operation and consult the proposed therapy with the patient.

Purpose of the Study: The authors present a group of patients treated for pelvic fractures in a period of 6 years and they evaluate radiographic findings and clinical outcomes following surgical management of type B and type C fractures., Material and Methods: Between July 1998 and June 2004, a total of 271 patients with pelvic fractures, 162 men and 109 women (average age, 42 years; range, 15 to 93 years) were hospitalized at the authors' departments. Of these, 141 patients were operated on (94 men, 47 women; average age, 37 years; range, 15 to 72 years) and 130 were treated conservatively (average age, 47 years; range, 15 to 93 years). The clinical outcome assessment in patients with type B and type C fractures treated surgically was based on the Majeed scoring system, and the radiographs were evaluated as described by Matta and Tornetta., Results: In 85 % of the patients, pelvic fractures were due to a high-energy trauma caused by traffic accidents in 63 % (pedestrian injury, 30 %; injury of the driver or passenger, 28 %; motorcycle injury, 5 %), by falls from heights in 20 % (occupational injury, 10 %; suicidal attempt, 10 %) and by other causes in 2 %. Sports accidents, usually due to a low-energy trauma, accounted for 8 % of the injuries (falls from a bicycle, violent kicks) and ordinary falls of elderly persons for 7 %. Type A injury was in 56 patients (21 %), type B in 103 patients (38 %) and type C in 112 patients (41 %). In 27 % of the patients, pelvic ring injury was part of a multiple trauma, in 58 % it was a combined injury and in 15 % it presented as a single trauma. Primary neurological deficit was found in nine patients (9 %) with type B fracture and in 20 patients (18 %) with type C fracture; this difference was statistically significant (p = 0.005). Urogenital injury was co-existent with type B fracture in 12 patients (12 %) and with type C fracture in 15 patients (13 %); the difference was not significant (p = 0.734). In seven patients (3 %), the injury involved an open fracture. Thirty-three patients (12 %) died during hospitalization. The difference in death rate between the patients with type C and those with type B fractures was significant (p = 0.021). Excellent and good clinical outcomes were achieved in 83 % and 70 % of the patients with type B and type C fractures, respectively. The difference was not significant (p = 0.236). Radiographs showed excellent reduction in 83 % of type B fractures and in 61 % of type C fractures; the difference was not significant (p = 0.271). Intra-operative complications were recorded in 22 %, early post-operative ones in 13 % and late complications in 11 % of the patients., Discussion: The significant difference in primary neurological deficit between the patients with type C fractures and those with type B fractures was attributed to more severe injury and vertical dislocation of the posterior segment in type C fractures. On the other hand, the fact that urogenital involvement was not significantly higher in type C fractures can be explained by an equal presence of anterior segment injury in both type B and type C fractures. The significantly higher number of deaths in patients with type C fractures, as compared with those with type B fractures, was related more to severe injuries of other organ systems in polytraumatized patients than to injuries of the pelvis itself, although severe injury to the posterior segment in type C fractures can result in massive bleeding into the retroperitoneum., Conclusions: An active approach to the treatment of patients with unstable pelvic fractures, which is based on the correct diagnosis, comprehensive multi-disciplinary care, urgent primary stabilization and early definitive fixation by internal osteosynthesis, offers a prospect of survival and a good functional outcome for the patient. However, a high proportion of lasting sequelae due to altered biomechanics of the pelvic ring, and irreversible injuries to neural structures and the urogenital system may lessen good results achieved by a demanding surgical procedure on the skeleton.

Purpose of the Study: Spinal injuries in children are rare and account for a low proportion of all childhood injuries. Due to anatomical and biomechanical properties of the growing spine, there are great differences between spinal injury in childhood and adulthood. Because of higher mobility and elasticity of the spine and a lower body mass in children, spinal injuries are not frequent and represent only 2 to 5 % of all spinal injuries. In this retrospective study, the effectiveness of conservative and surgical treatment of injured spines in children is evaluated in a 10-year period., Material: All patients from birth to the completed 18th year of age treated in our departments between 1996 and 2005 were included in this study. The patients, evaluated in three age categories (0-9, 10-14, 15-18), were allocated to two groups according to the method of treatment used (conservative or surgical). The information on patients treated conservatively was drawn from medical records; the surgically treated patients were invited for a check-up., Methods: We used conservative treatment in patients with stable spinal injury who had no neurological deficit and in patients with neurological deficit but without apparent injury to the skeleton. Surgery was indicated in patients with unstable spinal injury and in those with neurological deficit and apparent injury to the skeletal structures. Injuries to the cervical spine were treated conservatively using a Philadelphia collar or a halo-vest in more serious cases. For treatment of injury to the thoracolumbar spine, the Magnuson method was preferred, together with rest in bed until subsidence of acute pain, followed by application of a vest and active rehabilitation to strengthen postural muscles. When surgery was used, the procedure was selected on a strictly individual basis in patients under 12; in older patients it was carried out according to the adult treatment protocol., Results: During 1996 through 2005, we treated a total of 15 646 patients with injury to the skeleton, aged 0 to 18 years. The spine was affected in 571 cases, which is 3.6 %. We used conservative treatment in 528 (92.5 %) and surgery in 43 (7.5 %) children. The period between surgery and evaluation ranged from 6 to 120 months (average, 46.3 months) in the patients treated conservatively, and from 6 to 66 months (average, 27 months) in the surgically treated patients. The group of patients treated conservatively consisted of 292 boys (55. 3 %) and 236 girls (44.7 %); of these 219 (41.5 %) were in the 0-9 year category, 251 (47.5 %) were between 10 and 14 years and 58 (11 %) were 15 to 18 years old. The average age in this group was 10.2 years. The most frequent cause of injury was a fall (277; 52.2 %), then sports activity or games (86; 16.3 %), car accidents (34; 6.4 %) and diving accidents (30; 5.7 %). Pedestrians were injured on 25 occasions (4.7 %) and other causes of injury were recorded in 76 patients (14.4 %). In all age categories, injury to the thoracic spine was most frequent (340; 64.4 %). Three and more vertebrae were injured (multi-segment injury) in 124 patients (23.5 %). The thoracolumbar spine was affected in 22 patients (4.2 %), and lumbar vertebrae were injured in 28 patients (5.3 %). Injury to the cervical spine, both upper and lower, was least frequent, including four (0.8 %) and 10 (1.9 %) patients, respectively. None of the patients in this group showed neurological deficit. The surgically treated group included 29 (67.4 %) boys and 14 (32.6 %) girls; two (4.7 %) children were between 0 and 9 years, nine (20.9 %) between 10 and 14 years, and 32 (74.7 %) between 15 and 18 years, with an average of 15.1 years for the whole group. The frequent causes of injury were car accidents and falls in 21 (48.8 %) and 14 (32.6 %) children, respectively. Other causes were infrequent. The upper cervical spine was operated on in five (11.6 %), lower cervical spine in eight (18.6 %), thoracic spine in 13 (30.2 %), thoracolumbar spine in five (11.6 %) and lumbar vertebrae in 12 (27.9 %) patients. Thirty-six (83.7 %) patients had fractures, five had dislocated fractures (11.6 %) and two (4.7 %) had a dislocation. Of the 43 children in this group, neurological deficit was recorded in nine (20.9 %); this included a complete spinal cord lesion, an incomplete spinal cord lesion and a nerve root lesion in three, five and one patient, respectively., Discussion: The results of this study confirm, in the majority of aspects, the conclusions of previously published papers. In some of the characteristics described above, however, our results are different, which can be explained by some specific features of care for injured children in the Czech Republic., Conclusions: Childhood spinal injuries account for only 2 to 5 % of all spinal injuries and for 3.6 % of all skeletal injuries in children. Particularly at the age of 11 to 12 years, they differ significantly from spinal injuries in adults and therefore require different therapeutic approaches. The cervical spine is affected most often in younger children, while the thoracolumbar spine in older children. Multi-segment injuries are typical in the childhood spine, particularly in smaller children. Typically, children show SCIWORA and a more rapid improvement of neurological deficit than adults. Conservative treatment is preferred; surgery before 12 years of age is strictly individual, while after 12 years therapy is similar to that used in adults.

The patient, a 52-year-old male foreign citizen working as a construction worker, was attacked by his coworker who had fired a drive stud, 70 mm long, with reverse hooks from a powered gun at him; the stud pierced the worker's spine at the scapular level. The patient was taken to the nearest surgical ward. On the basis of clinical presentation and X-ray of the thoracic spine, the diagnosis of penetrating injury to the spinal column at the 7th thoracic vertebra level was made. Subsequently, the patient was admitted to the intensive care unit of our department. On admission the patients showed slight paresis of the right lower extremity and hypesthesia of the right thigh, but no other neurological deficit. After preoperative examination, the patient was operated on within six hours of the injury. Intraoperatively, a 3-mm-thick stud, piercing the T7 vertebral arch, was found on the left side, lateral to the T7 spinous process. After partial resection of the arch around the stud, the spinal canal was inspected. The stud passed paramedially on the right side through the dura mater and the centre of the spinal cord into the body of the 7th thoracic vertebra. The stud was gently removed. Subsequently, some sanguineous liquor appeared. The dura mater was sutured and the wound was closed layer by layer. The postoperative period was uneventful, and the patient was allowed to stand up on day 2. The drain was removed on day 4. Healing by first intention took place. At 6 weeks after surgery slight neurological deficit still remained. Key words: spinal penetrating injury, spinal gunshot injury.

Purpose of the Study: The anterior approach to the thoracic and lumbar spine is used with increasing frequency for various indications. With the advent of prosthetic intervertebral disc replacement, its use has become even more frequent and has often been associated with serious complications. The aim of this study was to evaluate vascular complications in patients who underwent anterior spinal surgery of the thoracic and lumbar spine., Material: We performed a total of 531 operations of the thoracolumbar spine from the anterior approach. In 12 cases, after exposure of the body of the first or second thoracic vertebrae, we employed the Smith-Robinson technique to expose the cervical spine. We used sternotomy in six, posterolateral thoracotomy in 209, the pararectal retroperitoneal approach in 239, anterolateral lumbotomy in 58 and the transperitoneal approach in seven patients. The aim of surgery was somatectomy in 190 patients and discectomy in 341 patients. Sternotomy and transperitoneal approaches were carried out by a thoracic or vascular surgeon and all the other procedures were done by the first author. The indications for spinal surgery included an accident in 171, tumor in 56, spondylodiscitis in 43 and a degenerative disease in 261 patients., Methods: All patients indicated for anterior spinal surgery were examined by conventional radiography in two projections, and this was completed by CT sagittal and frontal reconstructions of the affected region. Most patients also underwent MR imaging. The Smith-Robinson approach was used for exposure of T1 or T2. Sternotomy was indicated for treatment of T2-T4 and also T1 in the patients with a short, thick neck. Access to T3-L1 was gained by posterolateral thoracotomy, in most cases performed as a minimally invasive transpleural procedure. For access to the lumbar spine we usually used the retropleural approach from a pararectal incision or lumbotomy. We preferred the pararectal retroperitoneal approach in L2-S1 degenerative disease, L5 fractures, and L5-S1 spondylodiscitis. We carried out lumbotomy in patients with trauma, tumors and L1-L4 spondylodiscitis. The transperitoneal approach from lower middle laparotomy was used only in tumors at L5 or L4. For treatment of trauma and degenerative disease of the lumbar spine we preferred less invasive procedures, and for tumors and spondylodiscitis we used more extensive exposure because of the difficult terrain. The patients were followed up for 2 to 96 months (average, 31.4 months) after anterior spinal surgery., Results: In 12 patients treated by the Smith-Robinson procedure and in six patients undergoing sternotomy, neither early nor late signs of any injury to major blood vessels or internal organs were recorded. The 209 patients with posterolateral thoracotomy were also free from any signs of vascular injury, but trauma to the thoracic duct was recorded in one case. We found injury to major blood vessels in three patients in the group treated by the pararectal retroperitoneal procedure. In the total of 531 anterior spinal surgery procedures this accounts for 0.56 %; of the 304 lumbar operations and 239 pararectal retroperitoneal operations it is 0.99 % and 1.26 %, respectively. In one patient the vascular injury was associated with trauma to the ureter., Discussion: In our group of 531 patients we found a higher risk of vascular injury when the L4-L5 segment was treated, when less invasive surgery was used or when spinal anatomy was altered due to tumor or spondylodiscitis. All the complications were recorded in the first 250 patients. It should be emphasized that, because in five patients, the planned anterior spondylodesis would have been associated with high risk due to altered anatomy of the bifurcation of the aorta, these patients were treated by dorsal instrumented spondylodesis. We also avoided the anterior approach for revision spinal surgery and used the posterior approach instead. Vascular complications were treated in cooperation with a vascular or cardiac surgeon. In the most serious case, if a sophisticated cardiosurgical technique had not been immediately available, the patient would probably have died., Conclusions: The technique of anterior approach is safe only in the hands of experienced spinal surgeons with long experience. In institutions where anterior spinal surgery is not a routine method it is advisable to involve a vascular or cardiac surgeon. However, the most important point is to know when not to operate.

Francisella tularensis is a highly virulent intracellular pathogen responsible for tularemia. This bacterium is capable of infecting many mammalian species and various cell types, but little is known about the mechanisms of survival and interactions with host cells. We examined the number of infected host cells, cytotoxicity and the role of apoptosis or necrosis in infection-induced cell death. Our results demonstrate that F. tularensis LVS induces apoptosis of infected macrophages within 10 h. At later time points we were also able to detect a dramatic increase in the proportion of necrotic macrophages. We investigated the signalling pathways involved in infection-induced cell death by analysing three mitogen-activated protein kinase (MAPK) pathways that are known to be activated by LPS stimulation; p42/p44 MAPK (Erk1/2), transcription factor c-Jun and p38 MAPK. We identified post-translational activation of both p42 MAPK and p44 MAPK by phosphorylation at threonine and tyrosine residues after infection. Furthermore, treatment of infected cells with MEK1/2 inhibitors abrogated phosphorylation of p42/p44 MAPK and inhibited macrophage apoptosis and necrosis after infection. In contrast, phosphorylation and kinase activity of p38 MAPK was significantly lower in F. tularensis-infected cells, and inhibition of p38 MAPK activity induced apoptosis in uninfected cells. When we monitored JNK-dependent phosphorylation of the transcription factor c-Jun, we did not observe any reactivity with either SAPK/JNK or phospho-SAPK/JNK antibodies at any time point. In conclusion, we demonstrate that F. tularensis LVS infection induces macrophage apoptosis. This process requires activation of the p42/p44 MAPK pathway and is associated with reduced p38 MAPK activity, indicating that infection-induced cell death can be caused by perturbation of these two signalling pathways.

Analyses of the protein expression profiles of irradiated cells may be beneficial for identification of new biomolecules of radiation-induced cell damage. Therefore, in this study we exploited the proteomic approach to identify proteins whose expression is significantly altered in gamma-irradiated human T-lymphocyte leukemia cells. MOLT-4 cells were irradiated with 7.5 Gy and the cell lysates were collected at different times after irradiation (2, 5 and 12 h). The proteins were separated by two-dimensional electrophoresis and quantified using an image evaluation system. Proteins exhibiting significant radiation-induced alterations in abundance were identified by peptide mass fingerprinting. We identified 14 proteins that were either up- or down-regulated. Cellular levels of four of the proteins (Rho GDP dissociation inhibitor 1 and 2, Ran binding protein 1, serine/threonine protein kinase PAK2) were further analyzed by two-dimensional immunoblotting to confirm the data obtained from proteome analysis. All identified proteins were classified according to their cellular function, including their participation in biochemical and signaling pathways. Taken together, our results suggest the feasibility of the proteome method for monitoring of cellular radiation responses.

Exposure of human leukaemia MOLT-4 cells to ionizing irradiation led to apoptosis, which was detected by flow cytometric analysis and degradation of the nuclear lamina. The multiple signalling pathways triggered by either membrane or DNA damage play a critical role in radiation-induced apoptosis. The response to DNA damage is typically associated with the p53 protein accumulation. In this study, we proved that the transcriptionally active p53 variant occurs in the MOLT-4 cells and its abundance alteration is triggered in the gamma-irradiated cell population concomitantly with phosphorylation at both the serine-392 and serine-15 residues. The p21 upregulation followed the p53 phosphorylation process in irradiated MOLT-4 cells.

In this study we examined the protein expression profiles in X-irradiated L929 cells to get insight into how mammalian cells respond to radiation-induced cell damage. L929 cells were irradiated with the dose of 6 Gy and cell lysates were collected at different time intervals (20 min, 12, 24, 36, 48 and 72 h). The extracted proteins were separated by 2-DE and quantified using computerized image analysis. Proteins exhibiting significant abundance alterations when comparing irradiated to unirradiated cells were identified by mass spectrometry. Using the proteomics approach we detected 47 proteins that exhibited a significant radiation-induced increase or decrease in the course of 72 h. From this group of spots 28 proteins were identified by mass spectrometry and of these 24 proteins exhibited minimally 2-fold differences in mean abundance values in comparison to controls. The identified proteins represent diverse sets of proteins participating either in protective and reparative cell responses or in induction of apoptosis and oncogenesis. The results document that proteomics is a useful method for unravelling the molecular mechanisms involved in cell reaction to ionizing radiation.

The oncoprotein v-Myb induces myeloid leukemia and its cellular counterpart c-Myb is involved in the regulation of hematopoiesis. Although intensively studied, their precise subcellular localization is not known. In order to expand our knowledge in this respect, we used an artificial system overexpressing these proteins. We investigated the subcellular localization of Myb proteins in cultured non-synchronized insect cells transfected with recombinant baculoviruses overexpressing either v-myb oncogene or c-myb proto-oncogene. The cell expressing Myb proteins underwent extensive nuclear changes and exhibited distinct nuclear structures resembling nucleoli. The bulk of v-Myb and c-Myb proteins accumulated in such nucleolus-like structures which, according to the nucleolar nomenclature, we classified to three types: compact of enlarged size (type I), large ring-shaped (type II) and with nucleolonemas (type III). We investigated these structures for the presence of important nucleolar macromolecules in order to establish whether they were compatible with the function in the production of ribosomes. Strikingly, our results indicated that the different forms of these structures did not represent genuine nucleoli. They rather reflected progressive changes, induced by the virus infection and high expression of v-myb genes, accompanied by the formation of these prominent nucleolus-like structures highly enriched in Myb protein. Gradual changes in number of individual nucleolus-like forms during infection, increasing amount of Myb protein and DNA localized in them together with decreasing amount of RNA and their different interaction with viral particles indicate that the nucleolus-like structure of type I is a precursor of the type II and finally of the type III.

Nuclear speckles (speckles) represent a distinct nuclear compartment within the interchromatin space and are enriched in splicing factors. In a previous study (Melcák et al., 2001), it has been shown that the pre-spliceosomal assembly on microinjected splicing-competent precursor mRNA takes place in the speckles, and it has been suggested that the targeting of RNA into speckes consists of two interdependent steps, namely the diffusion process, followed by the energy-dependent translocation of RNA into the speckles. In the present study, we confirm the existence of these two steps and show that this latter translocation is ATP dependent.