[Nonspecific craniovertebral spondylitis]. / Nespetsificheskie spondility kraniovertebral'noi oblasti.

OBJECTIVE: To analyze surgical strategy for nonspecific spondylitis of the craniovertebral region (CVR) taking into account clinical features and morphological signs of disease. MATERIAL AND METHODS: Eight patients with nonspecific spondylitis of CVR underwent surgery (4 women and 4 men aged 31-75 years). Three patients had pain syndrome, 5 ones - conduction disorders. Combined interventions were performed in 5 patients with neurological disorders. Of these, 3 patients underwent transoral decompression with subsequent occipitospondylodesis. In other cases, stages of surgical treatment were reverse. Four patients underwent simultaneous interventions, 1 patient - with 7-day interval. Patients with pain syndrome underwent occipitospondylodesis. RESULTS: In all patients, postoperative VAS score of pain syndrome decreased by 5-7 points (mean 5.5). Among 5 patients with conduction symptoms, regression of neurological disorders 1 year after surgery was achieved in 2 cases, and complete recovery was observed in 3 patients (Frankel E). In all cases, examination confirmed relief of inflammatory process and no compression of the spinal cord and medulla oblongata. One patient had a dehiscence of the wound edges of posterior pharyngeal wall, and another one had implant fracture in 3 years after surgery. CONCLUSION: Active surgical approach is reasonable for nonspecific spondylitis of CVR. Craniocervical fixation eliminates pain and risk of neurological complications following atlantoaxial instability. Conduction disorders require simultaneous transoral decompression and occipitospondylodesis in patients with nonspecific purulent craniovertebral lesions. Impaired head tilt complicates transoral stage. In this regard, it is more rational to carry out craniocervical fixation at the last stage.

[Total resection of aggressive hemangioma of thoracic spine: case report and literature review]. / Total'noe udalenie agressivnoi gemangiomy grudnogo otdela pozvonochnika (klinicheskoe nablyudenie i obzor literatury).

The authors report total resection of aggressive hemangioma of Th7 vertebra in a patient with severe conduction disorders in the lower extremities. Total Th7 spondylectomy (Tomita procedure) was performed. This method provided simultaneous en bloc resection of the vertebra and tumor via the same approach, eliminate spinal cord compression and perform stable circular fusion. Postoperative follow-up period was 6 months. Neurological disorders were evaluated using the Frankel scale, pain syndrome - visual analogue scale, muscle strength - MRC scale. Pain syndrome and motor disorders in the lower extremities regressed in 6 months after surgery. CT confirmed spinal fusion without signs of continued tumor growth. Literature data on surgical treatment of aggressive hemangiomas are reviewed.

[Skip corpectomy in surgical treatment of cervical spondylotic myelopathy]. / Metod «skip corpectomy¼ pri khirurgicheskom lechenii tservikal'noi spondilogennoi mielopatii.

OBJECTIVE: To evaluate the effectiveness and safety of skip corpectomy in surgical treatment of cervical spondylotic myelopathy. MATERIAL AND METHODS: The study included 7 patients with cervical myelopathy following extended cervical spine stenosis. All patients underwent skip corpectomy. Clinical examination included degree of neurological disorders according to the modified scale of the Japanese Orthopedic Association (JOA) with assessment of recovery rate and Nurick score, as well as VAS score of pain syndrome. Verification of diagnosis was based on the data of spondylography, magnetic resonance and computed tomography. The indications for surgical treatment were conduction disorders and their spondylotic genesis confirmed by neuroimaging methods. RESULTS. VAS: Score of pain syndrome decreased by 2-4 points (mean 3.1) in long-term postoperative period. The JOA, Nurick scores and recovery rate (mean 42.5%) demonstrated significant improvement of neurological status in all patients. In all cases, the follow-up examination confirmed adequate decompression and spinal fusion. CONCLUSION: Skip corpectomy provides adequate spinal cord decompression in case of extended cervical spine stenosis and minimizes the risk of complications typical for multilevel corpectomy. Recovery rate indicates the effectiveness of this method in surgical treatment of cervical myelopathy caused by multilevel stenosis. However, further studies on sufficient clinical material are needed.

[En-bloc resection of giant neuroma of thoracic spine via transthoracic extrapleural access: a case report and literature review]. / Blok-rezektsiya gigantskoi nevrinomy grudnogo otdela pozvonochnika s ispol'zovaniem transtorakal'nogo ekstraplevral'nogo dostupa: redkoe klinicheskoe nablyudenie i obzor literatury.

The authors describe surgical treatment of a patient with giant neuroma of thoracic spine. The patient underwent en-bloc resection of tumor via transthoracic extrapleural access. Technical nuances of surgery and operational capabilities of transthoracic extrapleural access for resection of neurogenic tumors of posterior mediastinum are demonstrated. Capabilities of transthoracic extrapleural access are comparable to thoracotomy. The first experience of transthoracic extrapleural access showed its effectiveness in resection of giant neuromas of thoracic spine. Indisputable advantage of this access is less surgical injury compared to thoracotomy. A brief literature review is presented.

[Successful surgical treatment of patient with cervical myelopathy due to ossification of the posterior longitudinal ligament: a rare clinical observation and literature review]. / Uspeshnoe khirurgicheskoe lechenie patsienta s tservikal'noi mielopatiei na fone ossifikatsii zadnei prodol'noi svyazki: redkoe klinicheskoe nablyudenie i obzor literatury.

The authors describe the result of combined surgical treatment of a patient with symptomatic multiple-level cervical spine stenosis following ossification of posterior longitudinal ligament. The first stage included decompressive laminectomy and cervical spine fusion using a screw. At the second stage, CIV-CV-CVI-CVII corporectomy with total resection of the ossified posterior longitudinal ligament and CIII-ThI corporodesis with a bone autograft were carried out. This approach was valuable to minimize the risk of iatrogenic damage to the spinal cord, eliminate long spinal stenosis and perform circular fusion of the cervical spine. These measures led to regression of cervical myelopathy symptoms. A brief review is presented.

Infrared luminescence in bismuth-doped AgCl crystals.

Experimental and computer-modeling studies of the spectral properties of crystalline AgCl doped with metal bismuth or bismuth chloride are performed. The broad near-IR luminescence band in the 0.8-1.2 µm range with time dependence described by two exponential components corresponding to the lifetimes of 1.5 and 10.3 µs is excited mainly by 0.39-0.44 µm radiation. Computer modeling of probable Bi-related centers in the AgCl lattice is performed. On the basis of experimental and calculation data, a conclusion is drawn that IR luminescence can be caused by Bi+ ion centers substituted for Ag+ ions.

Near-infrared luminescence in TlCl:Bi crystal.

Experimental and theoretical studies of spectral properties of crystalline TlCl:Bi are performed. Two broad near-infrared luminescence bands with a lifetime of about 0.25 ms are observed: a strong band near 1.18 µm excited by 0.40, 0.45, 0.70, and 0.80 µm radiation and a weak band at ≳1.5 µm excited by 0.40 and 0.45 µm radiation. Computer modeling of Bi-related centers in TlCl lattice suggests that a Bi(+)…VCl(Cl)(-) center (Bi(+) in Tl site and a negatively charged Cl vacancy in the nearest anion site) is most likely responsible for the IR luminescence.

Insertion of polydeoxyadenosine-rich sequences into an intergenic region increases transcription in Chlamydomonas reinhardtii chloroplasts.

In this study, chloroplast transformation in Chlamydomonas reinhardtii was used to insert a tract of polydeoxyadenosine, which is known to influence DNA structure and transcription in other systems, between the 3' end of the atpB gene, encoding the beta-subunit of the chloroplast ATP synthase, and a downstream chimeric gene, aadA, encoding antibiotic resistance. Run-on transcription and RNA analyses revealed that in cells containing (dA)40 and (dAAAGGG)8, aadA was transcribed at a higher rate, and its RNA accumulated to a relatively high level. It is concluded that poly(dA/dT) can function in the chloroplast as a transcription enhancer element. Therefore, the insertion of poly(dA/dT) sequence into the intergenic region of a multicistronic transcription unit may modulate gene expression at the transcriptional level.

Preferential degradation of polyadenylated and polyuridinylated RNAs by the bacterial exoribonuclease polynucleotide phosphorylase.

Polyadenylation of mRNA has been shown to target the RNA molecule for rapid exonucleolytic degradation in bacteria. To elucidate the molecular mechanism governing this effect, we determined whether the Escherichia coli exoribonuclease polynucleotide phosphorylase (PNPase) preferably degrades polyadenylated RNA. When separately incubated with each molecule, isolated PNPase degraded polyadenylated and non-polyadenylated RNAs at similar rates. However, when the two molecules were mixed together, the polyadenylated RNA was degraded, whereas the non-polyadenylated RNA was stabilized. The same phenomenon was observed with polyuridinylated RNA. The poly(A) tail has to be located at the 3' end of the RNA, as the addition of several other nucleotides at the 3' end prevented competition for polyadenylated RNA. In RNA-binding experiments, E. coli PNPase bound to poly(A) and poly(U) sequences with much higher affinity than to poly(C) and poly(G). This high binding affinity defines poly(A) and poly(U) RNAs as preferential substrates for this enzyme. The high affinity of PNPase for polyadenylated RNA molecules may be part of the molecular mechanism by which polyadenylated RNA is preferentially degraded in bacterial cells.

The mechanism of preferential degradation of polyadenylated RNA in the chloroplast. The exoribonuclease 100RNP/polynucleotide phosphorylase displays high binding affinity for poly(A) sequence.

Polyadenylation of mRNA in the chloroplast has recently been shown to target the RNA molecule for rapid exonucleolytic degradation. A model has been suggested in which the degradation of chloroplast mRNA is initiated by endonucleolytic cleavage(s) followed by the addition of poly(A)-rich sequences and rapid exonucleolytic degradation. When in vitro transcribed RNAs were incubated with chloroplast protein extract, competition between polyadenylated and non-polyadenylated RNAs for degradation resulted in the rapid degradation of the polyadenylated molecules and stabilization of their non-polyadenylated counterparts. To elucidate the molecular mechanism governing this effect, we determined whether the chloroplast exoribonuclease 100RNP/polynucleotide phosphorylase (PNPase) preferably degrades polyadenylated RNA. When separately incubated with each molecule, isolated 100RNP/PNPase degraded polyadenylated and non-polyadenylated RNAs at the same rate. However, when both molecules were mixed together, the polyadenylated RNA was degraded, whereas the non-polyadenylated RNA was stabilized. In RNA binding experiments, 100RNP/PNPase bound the poly(A) sequence with much higher affinity than other RNA molecules, thereby defining the poly(A)-rich RNA as a preferential substrate for the enzyme. 100RNP/PNPase may therefore be involved in a mechanism in which post-transcriptional addition of poly(A)-rich sequence targets the chloroplast RNA for rapid exonucleolytic degradation.

Addition of destabilizing poly (A)-rich sequences to endonuclease cleavage sites during the degradation of chloroplast mRNA.

In this work, we report the posttranscriptional addition of poly(A)-rich sequences to mRNA in chloroplasts of higher plants. Several sites in the coding region and the mature end of spinach chloroplast psbA mRNA, which encodes the D1 protein of photosystem II, are detected as polyadenylylated sites. In eukaryotic cells, the addition of multiple adenosine residues to the 3' end of nuclear RNA plays a key role in generating functional mRNAs and in regulating mRNA degradation. In bacteria, the adenylation of several RNAs greatly accelerates their decay. The poly(A) moiety in the chloroplast, in contrast to that in eukaryotic nuclear encoded and bacterial RNAs, is not a ribohomopolymer of adenosine residues, but clusters of adenosines bounded mostly by guanosines and rarely by cytidines and uridines; it may be as long as several hundred nucleotides. Further analysis of the initial steps of chloroplast psbA mRNA decay revealed specific endonuclease cleavage sites that perfectly matched the sites where poly(A)-rich sequences were added. Our results suggest a mechanism for the degradation of psbA mRNA in which endonucleolytic cleavages are followed by the addition of poly(A)-rich sequences to the upstream cleavage products, which target these RNAs for rapid decay.

Phosphorylation of a chloroplast RNA-binding protein changes its affinity to RNA.

An RNA-binding protein of 28 kDa (28RNP) was previously isolated from spinach chloroplasts and found to be required for 3' end-processing of chloroplast mRNAs. The amino acid sequence of 28RNP revealed two approximately 80 amino-acid RNA-binding domains, as well as an acidic- and glycine-rich amino terminal domain. Upon analysis of the RNA-binding properties of the 'native' 28RNP in comparison to the recombinant bacterial expressed protein, differences were detected in the affinity to some chloroplastic 3' end RNAs. It was suggested that post-translational modification can modulate the affinity of the 28RNP in the chloroplast to different RNAs. In order to determine if phosphorylation accounts for this post-translational modification, we examined if the 28RNP is a phosphoprotein and if it can serve as a substrate for protein kinases. It was found that the 28RNP was phosphorylated when intact chloroplasts were metabolically labeled with [32P] orthophosphate, and that recombinant 28RNP served as an excellent substrate in vitro for protein kinase isolated from spinach chloroplasts or recombinant alpha subunit of maize casein kinase II. The 28RNP was apparently phosphorylated at one site located in the acidic domain at the N-terminus of the protein. Site-directed mutagenesis of the serines in that region revealed that the phosphorylation of the protein was eliminated when serine number 22 from the N-terminus was changed to tryptophan. RNA-binding analysis of the phosphorylated 28RNP revealed that the affinity of the phosphorylated protein was reduced approximately 3-4-fold in comparison to the non-phosphorylated protein. Therefore, phosphorylation of the 28RNP modulates its affinity to RNA and may play a significant role in its biological function in the chloroplast.

RNA-Binding Characteristics of a Ribonucleoprotein from Spinach Chloroplast.

A chloroplast (nuclear-encoded) RNA-binding protein (28RNP) was previously purified from spinach (Spinacia oleracea). This 28RNP was found to be the major RNA-binding protein co-purified during the isolation scheme of 3[prime] end RNA-processing activity of several chloroplastic genes. To learn more about the possible involvement of 28RNP in the 3[prime] end RNA-processing event, we investigated the RNA-binding properties and the location of the protein in the chloroplast. We found that recombinant Escherichia coliexpressed 28RNP binds with apparently the same affinity to every chloroplastic 3[prime] end RNA that was analyzed, as well as to RNAs derived from the 5[prime] end or the coding region of some chloroplastic genes. Differences in the RNA-binding affinities for some chloroplastic 3[prime] end RNAs were observed when the recombinant 28RNP was compared with the "native" 28RNP in the chloroplast-soluble protein extract. In addition, we found that the 28RNP is not associated with either thylakoid-bound or soluble polysomes in which a great portion of the chloroplast rRNA and mRNA are localized. These results suggest that the native 28RNP binds specifically to certain RNA molecules in the chloroplast in which other components (possibly proteins) and/or posttranslational modifications are involved in determining RNA-binding specificity of the 28RNP.

RNA-binding activities of the different domains of a spinach chloroplast ribonucleoprotein.

An RNA-binding protein of 28 kD (28RNP) has been previously isolated from spinach chloroplasts and was found to be required for 3' end processing of chloroplast mRNAs. The amino acid sequence of 28RNP revealed two approximately 80 amino-acid RNA-binding domains, as well as an acidic and glycine-rich amino terminal domain. Each domain by itself, as well as in combination with other domains, was expressed in bacterial cells and the polypeptides were purified to homogeneity. We have investigated the RNA-binding properties of the different structural domains using UV-crosslinking, saturation binding and competition between the different domains on RNA-binding. It was found that the acidic domain does not bind RNA, but that each of the RNA-binding domains, expressed either individually or together, do bind RNA, although with differing affinities. When either the first or second RNA-binding domain was coupled to the acidic domain, the affinity for RNA was greatly reduced. However, the acidic domain has a positive effect on the binding of the full-length protein to RNA, because the mature protein binds RNA with a better affinity than the truncated protein which lacks the acidic domain. In addition, it was found that a stretch of two or three G residues is enough to mediate binding of the 28RNP, whereas four U residues were insufficient. The implications of the RNA-binding properties of 28RNP to its possible function in the processing of chloroplast RNA is discussed.