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PubMed1989

tRNA derived insertion element in histone gene repeating unit of Drosophila melanogaster.

Analysis of 41 histone homologous clones from an isogenic gene library of Drosophila melanogaster showed that non-histone fragments interrupt the histone repetitive clusters at several sites. Long (L) and short (S) forms of the repeating units are distinguished by the insertion of 240 bp into the spacer between H1 and H3 of the L units; Each form appears to be clustered with its own kind. The complete DNA sequence of the histone 5.0 kb repeating unit was determined. Five histone genes (H1, H2A, H2B, H3, H4) were identified in a repeating unit and several sequence blocks common to the five histone genes were found in the 5'- and 3'-regions. The insertion sequence of 240 bp was found to be similar to the Alu family, an element derived from tRNA.

Amino Acid Sequence↗
PubMed2006

Methylation and repeats in silent and nonsense mutations of p53.

All exonic CG sequences in p53 are methylated; this epigenetic modification is correlated with frequent G:C-->A:T transitions in p53. Recent reports reveal the presence in p53 of non-CG methylation in CC and CCC sequences, complementary to sites of selective guanosine adduct formation (GG and GGG), and the association of genetic instability with methylation at repetitive sequences. We presently investigated the distribution of methylation sites and repetitive elements in silent and nonsense p53 mutations (2051) among the IARC's TP53 somatic mutation database for exons 5-8. Silent mutations are nonrandom, but mostly involve G:C-->A:T transitions (62%); in particular C-->T mutations (39% of all silent mutations) are mostly correlated with CC and CCC sequences, while G-->A mutations with GG sequences. Sequence analysis of all non-G:C-->A:T silent mutations reveals the frequent formation of new methylation sites (CG), new CCC and GGG sequences in the resulting sequence, refinement of symmetry elements at interrupted microsatellite-like sequences and formation of small repeats (55.3%). The G:C-->A:T silent mutations characterize cancers associated with cigarette smoking (e.g. bladder or lung and bronchus cancer versus colorectal cancer); on the contrary, non-G:C-->A:T silent mutations have similar frequencies in most cancers. Nonsense mutations in exons 5-8, all resulting in mutants lacking amino acids 307-393, which are crucial for p53 activity, were also analyzed. The frequency of nonsense mutations is higher at methylated sites or repeats 1-2 nucleotides removed from methylation sites. Frameshift mutations are also more frequent at repeated sequences. The frequent G:C-->A:T silent mutations could indicate that CC and CCC sequences of exons 5-8 are occasionally targets of non-CpG methylation of cytosine. This process of de novo methylation in the presence of microsatellite-like sequences and small repeats might influence the genetic stability of a variety of genes.

Base Sequence↗
PubMed2003

Role of histidine interruption in mitigating the pathological effects of long polyglutamine stretches in SCA1: A molecular approach.

Polyglutamine expansions, leading to aggregation, have been implicated in various neurodegenerative disorders. The range of repeats observed in normal individuals in most of these diseases is 19-36, whereas mutant proteins carry 40-81 repeats. In one such disorder, spinocerebellar ataxia (SCA1), it has been reported that certain individuals with expanded polyglutamine repeats in the disease range (Q(12)HQHQ(12)HQHQ(14/15)) but with histidine interruptions were found to be phenotypically normal. To establish the role of histidine, a comparative study of conformational properties of model peptide sequences with (Q(12)HQHQ(12)HQHQ(12)) and without (Q(42)) interruptions is presented here. Q(12)HQHQ(12)HQHQ(12) displays greater solubility and lesser aggregation propensity compared to uninterrupted Q(42) as well as much shorter Q(22). The solvent and temperature-driven conformational transitions (beta structure <--> random coil --> alpha helix) displayed by these model polyQ stretches is also discussed in the present report. The study strengthens our earlier hypothesis of the importance of histidine interruptions in mitigating the pathogenicity of expanded polyglutamine tract at the SCA1 locus. The relatively lower propensity for aggregation observed in case of histidine interrupted stretches even in the disease range suggests that at a very low concentration, the protein aggregation in normal cells, is possibly not initiated at all or the disease onset is significantly delayed. Our present study also reveals that besides histidine interruption, proline interruption in polyglutamine stretches can lower their aggregation propensity.

Amino Acid Sequence↗
PubMed1997

Variation in sperm precedence during mating in male flies, Dryomyza anilis

To understand how individual differences in fertilization success arises in the fly Dryomyza anilisvariation in sperm precedence between and within males was studied. In D. anilisa mating consists of a copulation followed by tapping sequences during which the male taps the external genitalia of the female. These tapping sequences increase last male sperm precedence. Each male in the experiment was repeatedly mated with a set of females. In the first treatment, mating was interrupted after the male had an intromission. In the second treatment, the male was allowed to perform five tapping sequences after an intromission. In the third treatment, the male was allowed to perform an unlimited number of tapping sequences after an intromission until interrupted by female resistance. There were large differences between males in all three treatments as shown by the 95% confidence limits of the mean fertilization success. Repeatabilities of mating time and the number of tapping movements per tapping sequence were high indicating clear differences between males in these components of mating behaviour. Within individual males, the more tappings per sequence, the higher the fertilization success. In matings with an unlimited number of tapping sequences, fertilization success depended on female resistance. Within-male variation in fertilization success was higher in matings with an unlimited number of tapping sequences than in matings interrupted after a copulation. Several components of male mating behaviour thus contribute to the variation in sperm precedence in D. anilisFemale behaviour, in particular, resistance of tapping movements, can also increase variation in sperm precedence.

Journal Article↗
PubMed2004

DNA elements important for CAG*CTG repeat thresholds in Saccharomyces cerevisiae.

Trinucleotide repeat (TNR) instability is of interest because of its central role in human diseases such as Huntington's and its unique genetic features. One distinctive characteristic of TNR instability is a threshold, defined as a minimal repeat length that confers frequent mutations. While thresholds are well established, important risk determinants for disease-causing mutations, their mechanistic analysis has been delayed by the lack of suitably tractable experimental systems. In this study, we directly compared for the first time three DNA elements-TNR sequence, purity and flanking sequence-all of which are suggested in the literature to contribute to thresholds. In a yeast model system, we find that CAG repeats require a substantially longer threshold to contract than CTG tracts, indicating that the lagging template repeat sequence helps determine the threshold. In contrast, ATG interruptions within a CTG run do not inhibit contractions via a threshold mechanism, but by altering the likelihood of forming a hairpin intermediate. The presence of a GC-rich flanking sequence, similar to a haplotype found in some Huntington's patients, does not detectably alter expansions of Okazaki fragment CTG tracts, suggesting no role for this flanking sequence on thresholds. Together these results help better define TNR thresholds by delineating sequence elements that modulate instability.

DNA↗
PubMed1998

Re-examination of factors associated with expansion of CGG repeats using a single nucleotide polymorphism in FMR1.

In at least 98% of fragile X syndrome cases, the disease results from expansion of the CGG repeat in the 5' end of FMR1. The use of microsatellite markers in the FMR1 region has revealed a disparity of risk between haplotypes for CGG repeat expansion. Although instability appears to depend on both the haplotype and the AGG interspersion pattern of the repeat, these factors alone do not completely describe the molecular basis for the linkage disequilibrium between normal and fragile X chromosomes, in part due to instability of the marker loci themselves. In an effort to better understand the mechanism of dynamic mutagenesis, we have searched for and discovered a single nucleotide polymorphism in intron 1 of FMR1 and characterized this marker, called ATL1, in 564 normal and 152 fragile X chromosomes. The G allele of this marker is found in 40% of normal chromosomes, in contrast to 83% of fragile X chromosomes. Not only is the G allele exclusively linked to haplotypes over-represented in fragile X syndrome, but G allele chromosomes also appear to transition to instability at a higher rate on haplotypes negatively associated with risk of expansion. The two alleles of ATL1 also reveal a highly significant linkage disequilibrium between unstable chromosomes and the 5' end of the CGG repeat itself, specifically the position of the first AGG interruption. The data expand the number of haplotypes associated with FMR1 and specifically allow discrimination, by ATL1 alleles, of single haplotypes with differing predispositions to expansion. Such haplotypes should prove useful in further defining the mechanism of dynamic mutagenesis.

Adenine Nucleotides↗
PubMed1987

Structural organization of the 5' region of the thyroglobulin gene. Evidence for intron loss and "exonization" during evolution.

More than one third of thyroglobulin (1190 residues out of 2750) is made of one peptide motif repeated ten times in tandem. Segments unrelated to the motif interrupt this structure at various places. The corresponding gene region, which extends over 40 x 10(3) bases, was studied in detail. All exon borders and exon/intron junctions were localized precisely and sequenced, and their positions were correlated with the repetitive organization of the protein. When intron positions were compiled on a consensus sequence of all repeats, three categories of introns were observed. Except between repeats numbers 5 and 6, an intron was invariably found within the Cys codon making the limit of each motif. This category of intron most probably reflects the serial duplication events responsible for the evolution of this region of the gene. All other introns, except no. 2, are found at positions were the repetitive structure is disrupted by "inserted" peptides. We present the hypothesis that this second category of introns was already present in the original unit before the first duplication. Thereafter, they would have experienced either complete loss (some units do not contain any intron) or partial or total exonization, resulting in the slipping of intronic material into coding sequence. Intron no. 2, finally, separates motif no. 1 at a position on the boundary between two segments presenting sequence homology. This last type of intron probably reflects an initial duplication event at the origin of a primordial thyroglobulin gene motif. With all these characteristics, the thyroglobulin gene is presented as a paradigm for the analysis of the fate of introns in gene evolution.

Amino Acid Sequence↗
PubMed1991

Deletion mutagenesis independent of recombination in bacteriophage T7.

Deletion between directly repeated DNA sequences in bacteriophage T7-infected Escherichia coli was examined. The phage ligase gene was interrupted by insertion of synthetic DNA designed so that the inserts were bracketed by 10-bp direct repeats. Deletion between the direct repeats eliminated the insert and restored the ability of the phage to make its own ligase. The deletion frequency of inserts of 85 bp or less was of the order of 10(-6) deletions per replication. The deletion frequency dropped sharply in the range between 85 and 94 bp and then decreased at a much lower rate over the range from 94 to 900 bp. To see whether a deletion was predominantly caused by intermolecular recombination between the leftmost direct repeat on one chromosome and the rightmost direct repeat on a distinct chromosome, genetic markers were introduced to the left and right of the insert in the ligase gene. Short deletions of 29 bp and longer deletions of approximately 350 bp were examined in this way. Phage which underwent deletion between the direct repeats had the same frequency of recombination between the left and right flanking markers as was found in controls in which no deletion events took place. These data argue against intermolecular recombination between direct repeats as a major factor in deletion in T7-infected E. coli.

Base Sequence↗
PubMed1987

Balloon dilation angioplasty of postoperative aortic obstructions.

Balloon dilation angioplasty (BDA) was attempted 29 times in 27 patients, aged 3 months to 22 years, with postoperative aortic obstructions. Previous operations included end-to-end anastomosis (n = 10), subclavian flap angioplasty (n = 7) and patch angioplasty (n = 3) for aortic coarctation, end-to-end anastomosis for interrupted aortic arch type B (n = 4) and aortic arch reconstruction for hypoplastic left heart syndrome (n = 3). Two of the patients with interrupted arch had multiple areas of obstruction. Balloon sizes were between 2 and 6 times the diameter of the lesion and up to twice the diameter of the proximal transverse arch (mean 1.1). BDA was at least partially successful (more than 50% decrease in gradient and more than 30% increase in diameter) in 26 of the 29 procedures (90%). BDA failed in the 2 lesions with an initial diameter of more than 8 mm. No differences were apparent in the success rate among any of the clinical groups. Peak systolic gradient decreased from 42 +/- 14 to 14 +/- 15 mm Hg (p less than 0.01) and mean diameter increased from 4.1 +/- 2.6 to 6.8 +/- 3.2 mm (p less than 0.01). There was no mortality or significant acute morbidity associated with the procedure. After 1 to 24 months of follow-up, restenosis has occurred in only 1 patient. Aneurysm formation was found in 2 of 5 patients who had undergone repeat catheterization; both aneurysms occurred in patients with repaired interruption of the aortic arch.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon↗
PubMed1991

The use of prosody in highlighting alterations in repairs from unrestricted speech.

A speaker has several ways in which he or she may highlight the fact that an error or imprecision of speech has been made and subsequently altered. The three principal ones are by signalling through the structure of the speech that surrounds the error (the repair-syntax), by the use of prosody, and through the semantic content. The role of prosody in the correction process is investigated in the current studies. Analysis of the prosody of a number of errors and their alterations drawn from unrestricted speech are reported. The analysis shows that pauses occur at the moment of interruption and that an increase in stress occurs at the start of the alteration. Pauses could indicate the moment of interruption, and stress could highlight what has been altered. Two sets of perceptual experiments were carried out to assess whether these cues are salient for listeners who hear constructions containing an error and its alteration. Two paradigms were employed in each set of experiments: (1) direct judgement about the comprehensibility of sentences containing errors and alterations, and (2) repeating a message that had an error and alteration without the error. The effects of stress and pauses on (Experiments 1A and 1B) or pauses around (Experiment 2A and 2B) the alterations were assessed. In the first set of experiments it was shown that pauses and stress help listeners process repairs. When a word is spoken in error, the speaker may repeat a section of speech immediately preceding the alteration and/or a section immediately following that word. Inclusion of these repeated sections allows assessment of whether pauses signal where the interruption occurred. The second experiment shows that the placing of the pause before the retrace, rather than at other locations, indicates to listeners where the repair starts.

Adult↗
PubMed1992

The integrated state of the rolling-circle plasmid pTB913 in the composite Bacillus plasmid pTB19.

pTB19, a 27 kb plasmid originating from a thermophilic Bacillus species, contains integrated copies of two rolling-circle type plasmids on a 10.6 kb DNA fragment. In the present study we analysed the part of pTB19 that contains the rolling-circle plasmid pTB913 and the region in between the two rolling-circle plasmids. We show that, in the integrated state, pTB913 was flanked by a 55 bp direct repeat that duplicated part of the replication initiation gene repB. Since repB was interrupted, the integrated pTB913 could not initiate rolling-circle replication. Autonomously replicating pTB913 was produced from pTB19, probably through recombination between the 55 bp direct repeats; this was a rare event. Since the second integrated rolling-circle type plasmid also contained a non-functional replication initiation gene, replication of pTB19 must be controlled by the RepA determinant. Theta-type replication, controlled by RepA is likely to account for the high stability of pTB19. In between the two integrated rolling-circle plasmids was present an open reading frame (447 codons) which could encode a protein of unknown function.

Amino Acid Sequence↗
PubMed2000

Hematologic toxic reaction to radiation therapy adjuvant to autologous peripheral blood stem cell transplantation for recurrent or refractory Hodgkin disease.

PURPOSE: To evaluate the hematologic toxic reaction to external-beam radiation therapy after high-dose chemotherapy with peripheral blood stem cell (PBSC) support in patients with Hodgkin disease. MATERIALS AND METHODS: A retrospective study of 30 cases of Hodgkin disease in patients who underwent high-dose carmustine, etoposide, and cyclophosphamide chemotherapy with PBSC support was performed. Thirteen patients underwent radiation therapy (28.8-39.0 Gy) a median of 45 days after PBSC repeat infusion. RESULTS: Radiation therapy was delivered as planned, without interruption, in all patients. Five patients developed thrombocytopenia (one with grade 1 thrombocytopenia; two, grade 2; and two, grade 3) and included three with progressive disease prior to radiation therapy and two with a history of prior irradiation. None developed a bleeding complication or required transfusion support. Five patients who underwent irradiation had thrombocytopenia (three with grade 1 and two with grade 2) 100 days after PBSC repeat infusion, compared with three patients (two with grade 1 and one with grade 3) who did not undergo posttransplantation irradiation. At the most recent follow-up, no patient without evidence of disease had a platelet count of less than 100 x 10(9)/L. CONCLUSION: External-beam radiation therapy was well tolerated in the posttransplantation setting in patients with Hodgkin disease. Thrombocytopenia was common but was not related to clinical complications.

Adolescent↗
PubMed2004

SMARCA2 and THAP11: potential candidates for polyglutamine disorders as evidenced from polymorphism and protein-folding simulation studies.

CAG repeat expansion is the cause of an ever-increasing list of neurodegenerative disorders, especially hereditary ataxias. However, genes responsible for 10-50% of the clinically diagnosed ataxias are still unidentified in different populations. Traditional linkage and repeat expansion-detection based methods complemented with human genome sequence and expression information can now accelerate the pace of identification of putative disease candidates. We have analyzed two CAG repeat containing loci, human SMARCA2 and THAP11, which are expressed in the brain as putative candidates for SCAs, using computational as well as polymorphism scanning approaches. Both loci exhibited features characteristic of genes associated with repeat disorders. These loci are polymorphic with respect to size and interruption pattern in the Indian population. Furthermore, computational analysis of glutamine-stretch embedded domains in the respective proteins predicted these regions to be "natively unfolded" beyond a threshold of 40 glutamines. Comparative genome analysis suggested a stabilizing influence of CAA interspersions in repeat tract in THAP11 but not in SMARCA2. Although repeat expansion could not be detected within these genes in unidentified ataxia patients reported in India, we suggest that these loci be screened in other populations, as there is a wide heterogeneity in the prevalence of these disorders in different populations.

Animals↗
PubMed2003

Cochlear toughening, protection, and potentiation of noise-induced trauma by non-Gaussian noise.

An interrupted noise exposure of sufficient intensity, presented on a daily repeating cycle, produces a threshold shift (TS) following the first day of exposure. TSs measured on subsequent days of the exposure sequence have been shown to decrease relative to the initial TS. This reduction of TS, despite the continuing daily exposure regime, has been called a cochlear toughening effect and the exposures referred to as toughening exposures. Four groups of chinchillas were exposed to one of four different noises presented on an interrupted (6 h/day for 20 days) or noninterrupted (24 h/day for 5 days) schedule. The exposures had equivalent total energy, an overall level of 100 dB(A) SPL, and approximately the same flat, broadband long-term spectrum. The noises differed primarily in their temporal structures; two were Gaussian and two were non-Gausssian, nonstationary. Brainstem auditory evoked potentials were used to estimate hearing thresholds and surface preparation histology was used to determine sensory cell loss. The experimental results presented here show that: (1) Exposures to interrupted high-level, non-Gaussian signals produce a toughening effect comparable to that produced by an equivalent interrupted Gaussian noise. (2) Toughening, whether produced by Gaussian or non-Gaussian noise, results in reduced trauma compared to the equivalent uninterrupted noise, and (3) that both continuous and interrupted non-Gaussian exposures produce more trauma than do energy and spectrally equivalent Gaussian noises. Over the course of the 20-day exposure, the pattern of TS following each day's exposure could exhibit a variety of configurations. These results do not support the equal energy hypothesis as a unifying principal for estimating the potential of a noise exposure to produce hearing loss.

Animals↗
PubMed2006

FMR1 CGG repeat patterns and flanking haplotypes in three Asian populations and their relationship with repeat instability.

Hyper-expansion of a CGG repeat in the 5' untranslated region of the FMR1 gene followed by methylation and silencing is the predominant cause of Fragile X syndrome, the most common inherited mental retardation disorder. Most detailed studies of the FMR1 gene have focused on Caucasian populations and patients. We performed a detailed haplotype and linkage disequilibrium analysis of the FMR1 gene in a total of 454 unselected normal X chromosomes from three Asian populations, Chinese, Malay and Indian. Compared to Caucasians and African Americans, the diversity of normal FMR1 CGG repeat lengths, patterns and flanking haplotypes were lower in Asians. Strong linkage disequilibrium was observed between the CGG repeat and flanking FMR1 markers in all three Asian populations, with strong association between specific CGG repeat alleles and flanking marker alleles observed only in the Chinese and Malays. A test for randomness of distribution between FRAXA CGG repeat patterns and flanking FMR1 marker haplotypes also revealed a highly significant non-random distribution between CGG repeat patterns and flanking haplotypes in all three ethnic groups (P < 0.001). Extending previous findings in Caucasians and African Americans we present a novel statistical approach, using data from unselected population samples alone, to show an association between absence of at least one AGG interruption in any position (5', 3', or middle) and increased CGG repeat instability.

5' Flanking Region↗
PubMed1997

Site-directed mutagenesis of alpha II spectrin at codon 1175 modulates its mu-calpain susceptibility.

Intracellular proteolysis by the calpains, a family of Ca2+ activated cysteine proteases, is a ubiquitous yet poorly understood process. Their action is implicated in an array of cellular and pathologic processes, including long-term potentiation, synaptic remodeling, protein kinase C and steroid receptor activation, ischemic cellular injury, and apoptosis. Unlike most proteases, the calpains display unusually strict substrate specificity, often cleaving only one or two bonds in proteins with hundreds of potential sites. Studies of synthetic peptides have defined sequences that modulate their specificity, but little data exist in the context of a bona fide protein. A prominent substrate for mu-calpain is alpha II spectrin (fodrin, brain spectrin), which is cleaved between Tyr1176 and Gly1177 within spectrin's 11th structural repeat unit. We have cloned and characterized human fetal brain alpha II spectrin (GenBank no. U26396) and identified a new Thr1300 to Ile polymorphism. From this clone, recombinant GST-fusion proteins representing repeat units 8-14 have been prepared and used to systematically explore the in vitro determinants of mu-calpain sensitivity. Twenty different amino acids were substituted by site-directed mutagenesis for wild-type Val1175, the penultimate (P2) residue flanking the major calpain cleavage site in alpha II spectrin. Gly, Pro, and Asp, and to a lesser extent Phe and Glu, substantively inhibited the susceptibility of this site to mu-calpain; other substitutions yielded lesser effects. Dynamic molecular modeling of the 11th structural repeat of human alpha II spectrin incorporating the various mutations suggests that the calpain cleavage site with its flanking calmodulin binding domain interrupts helix C of alpha II spectrin's 11th repetitive unit without significantly disrupting the repeat's triple-helical motif. This model predicts that the critical Tyr1176-Gly1177 bond occurs in a highly exposed loop juxtaposed between helix C and the calmodulin binding domain and that mutations at the P2 position subtly alter the conformation about this site. We conclude that secondary and tertiary conformational features surrounding the cleavage site, rather than the linear sequence itself, dominate the determinants that define alpha II spectrin's mu-calpain susceptibility.

Amino Acid Sequence↗
PubMed1985

Tsp transposons: a heterogeneous family of mobile sequences in the genome of the sea urchin Strongylocentrotus purpuratus.

In the preceding paper (J.B. Cohen, B. Hoffman-Liebermann, and L. Kedes, Mol. Cell. Biol., 5:2804-2813, 1985), we described the nucleotide sequence of ISTU4, which is a member of a new family of repetitive sequences, the Tsp family, present in a higher eucaryote, the sea urchin Strongylocentrotus purpuratus. We provided evidence that individual members of this family can act as transposable elements. Here we describe our structural analysis of the Tsp element family, which numbers about 1,000 members per haploid genome. Hybridization and nucleotide sequence analysis of several genomic Tsp clones demonstrate that structurally most Tsp elements resemble ISTU4. Tsp elements range in size up to about 1.3 kilobase pairs, have terminal domains that are conserved between the various examples studied, and contain a central portion of varying size, which may be extensively diverged. Structurally, however, the central portions are very similar and consist of several approximately 150-base-pairs-long, tandemly arranged, imperfect repeats, which are followed by a truncated repeat. The structural analysis is consistent with the possibility that the individual Tsp elements differ by multiples of these 150-base-pair repeats. One variant genomic clone has a solitary repeat and lacks the truncated repeat. The nucleotide sequences of different repeats of a single Tsp element can diverge extensively. The truncated repeat is divergent from most of the repeats, but in one case it is almost identical to a repeat of the same element. Comparison of the sequences from different elements enabled us to determine the boundaries of each structural domain and allows us to propose that each of these domains may be independent units of genetic information. Analysis of the population of Tsp-related sequences in the S. purpuratus genome by genomic blot hybridization suggests that most Tsp family members share the same overall structure. In addition, there is a structural element, about 70 base pairs long, that appears to interrupt the tandem arrangement of the 150-base-pair repeats at regular intervals.

Animals↗
PubMed2005

3D ultrasound navigation in syrinx surgery - a feasibility study.

BACKGROUND: The prototype of a 3D ultrasound navigation system, with a trackable 4- to 8-MHz phased-array ultrasound probe was used in syrinx-surgery. The aim of this study was to evaluate the advantages offered by 3D ultrasound and navigation in syringomyelial surgery. METHODS AND MATERIALS: After laminectomy, with a free-handed tilt of the ultrasound probe, the 3D volume of the target area is acquired within 15 seconds. The data are visualized after reconstruction in an axial, coronal, and sagittal view, offering the possibility of ultrasound-based guided surgery. RESULTS: Based on the intraoperative volume information, it was possible to navigate with the 3D ultrasound images in all cases. The orientation and image quality with respect to resolution, spatial information, and the identification of anatomical structures facilitated the surgery in all seven cases. The navigation tool, with a length of 12 cm and a tip diameter of 1 mm, was simple to place into the surgical site. The availability of an up-to-date 3D-image resulted in less interruption of the surgical procedure, with no need to repeatedly fill the cavity with sterile saline for new ultrasound acquisitions. New ultrasound images were only required if shift occurred. The coronal and "trajectory-plane" views, offer additional information about the syrinx cavity. The target borders are easier to determine and orientation in separated cavities was possible. Particularly in syringomyelial surgery it was helpful to determine the surface point of the syrinx to place the myelotomy or insert a catheter. CONCLUSION: 3D ultrasound offers the advantages of visualizing the third dimension of the target. For orientation and border determination navigation within the 3D ultrasound volume is very helpful and can take place with the ultrasound probe out of the way. Any disruption in the surgical procedure is minimized by not having to repeatedly fill the cavity with a sterile saline solution, there are fewer difficulties with image orientation because of new image adjustments.

Cervical Vertebrae↗