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Biomedical subjects

M Aebi

Publications and source records attributed to M Aebi.

At least 145 records · Page 8Linked to original sources
PubMed1990

[Osteoid osteoma of the spine and pelvic area].

We describe 8 cases of osteoid osteoma of the spine and the pelvis. In the rare cases of this tumor the clinical symptoms are not specific. The typical nocturnal exacerbation of the pain was absent in 2 of our 8 patients. More often the main symptoms were abnormalities of the gait or deformation of the spine, partly secondary to the often absent pain. Pain relief after aspirin is described but not constant. The aspirin test was positive in 4 of our 8 cases (in 20-50% of the cases in the literature). It must be emphasized that conventional-x-ray is often not diagnostic, and therefore the diagnosis is often delayed. If there is suspicion of osteoid osteoma a technetium bone scan should be performed. CT-scan is required for preoperative evaluation. Treatment of choice is the excision of the tumor in healthy tissue, which was successful in all our 8 cases.

Adolescent↗
PubMed1990

[Stabilization surgery of the spine].

New diagnostic tools and alternatives such as CAT-scan, NMRI, discography, functional X-rays, infiltrations and immobilization tests have made spinal instability a more rational diagnosis than it was only a few years ago. Neurological deficit, radicular pain and pseudo-radicular pain may only be an expression of instability and are best treated by stabilizing operations. Laminectomy has few indications and is not a logical procedure, especially if used as decompression of the dural sac in tumor involvement of the spine, which usually comes from the front (vertebral body). Therefore, anterior surgery is indicated rather than so-called posterior decompression. In accordance with osteosynthesis techniques of limb disorders, high stability can be achieved through special implants, on the basis of a better understanding of the biomechanics of implants and the healthy and impaired spine. Short fusion and fixation have therefore become a principle which is the standard of reference for present and future spinal surgery. The spectrum of indications for spinal surgery has vastly increased in the last few years, though exact diagnosis is mandatory for optimal treatment.

Adolescent↗
PubMed1990

A yeast mutant, PRP20, altered in mRNA metabolism and maintenance of the nuclear structure, is defective in a gene homologous to the human gene RCC1 which is involved in the control of chromosome condensation.

We report on the characterization of the yeast prp20-1 mutant. In this temperature-sensitive mutant, multiple steps of mRNA metabolism are affected. The prp20-1 mutant strain showed alterations in mRNA steady-state levels, defective mRNA splicing and changes in transcription initiation or termination when shifted from the permissive to the non-permissive temperature. In addition, a change in the structure of the nucleus in these cells became apparent. Electron microscopy revealed an altered structure of the nucleoplasm of prp20-1 mutant cells when grown at the non-permissive temperature that was not observed in cells grown at the permissive temperature or in wild-type cells. The wild-type PRP20 gene was isolated and sequenced. The putative PRP20 protein has a molecular weight of 52 kDa. We found that the PRP20 gene is identical to the yeast SRM1 gene (Clark and Sprague 1989). In addition, the PRP20 protein sequence shows significant sequence similarity to the human RCC1 protein (Ohtsubo et al. 1987). This protein has been implicated in the control of chromosome condensation. Based on the phenotype of the prp20-1 mutant and the observed sequence similarity to the human RCC1 protein, we postulate that the yeast PRP20 protein is involved in the control of nuclear organization.

Amino Acid Sequence↗
PubMed1990

[Bone and joint transplantation. Alternatives to bridging segmental bone defects and a model for allogenic bone transplantation].

Fresh allogeneic diaphyseal bone segments were transplanted into 12 dogs. We attempted to improve the immunogenity and incorporation of the bone segments through "graft manipulation" with and without immunosuppression. Through clinical and radiological study during the 20-week experimental period, we observed transplant healing with differing structural phenomena. After autologous knee joint replantation in 4 dogs and allogeneic transplantation in 2 dogs (with and without revascularization and immunomodulation with Cyclosporin A) we present a canine model to investigate all open questions about the transplantation of allogeneic, fresh joints (i.e. transplant biology, immunology, and vitality).

Animals↗
PubMed1990

[Spinal metastases and metastasis-induced pathological fractures of the spine].

The vertebral column is a common site of metastatic disease to the bone. The incidence is very high and varies with tumor type. Radiation therapy is effective in the treatment of most cases of spinal metastases. Pathologic fractures of the vertebral body occur in 30-50% of the patients affected, indicating an operative intervention. The ultimate aim of the operation is to increase the patients' quality of life. The tumor mass is normally located in the vertebral body. Therefore, only with an anterior approach can excellent decompression of the spinal cord and reduction of the tumorous tissue be achieved. In patients with advanced metastatic disease, however, in whom an anterior approach is not practicable, tumor decompression may be accomplished through a costotransversectomy combined with posterior stabilization of the spine. Laminectomy is rarely indicated, and then for posteriorly located tumor tissue, and should be combined with dorsal stabilization of the spine. With reference to a few actual cases, we present the approaches and stabilization methods currently in use at our clinic.

Adult↗
PubMed1990

[Osteosynthesis in high-grade osteoporosis].

Operative treatment of fractures in osteoporotic bone using standard techniques such as are applied in normal bone leads to special problems. The major difficulty is the limited anchorage of any implant in osteoporotic bone. To improve the stability of an implant in osteoporotic bone the following techniques are applicable, either singly or in combination: impaction, long-distance splinting, large-area surface buttressing, osteotomy, and the use of bone cement as a spacer and to improve the purchase of screws. The different techniques are discussed and examples of their application are presented.

Adolescent↗
PubMed1989

Segmental bone grafting. Comparison of different types of graft in dogs.

We have compared the biological behaviour of eight types of segmental tibial grafts in dogs under different immunological conditions: autografts, allografts, allografts with short-term immunosuppression (4 weeks), and allografts with longterm suppression (20 weeks). Some grafts were revascularised by microsurgical anastomosis, others were not. The long-term immunosuppressed allografts are most similar to autografts in terms of perfusion pattern and graft-host interface healing. The difference between long-term immunosuppressed allografts and allografts which were not immunosuppressed was highly significant (P less than 0.01). The viability of long-term immunosuppressed allografts, as measured by fluorochrome-labelled osteons, did not reach the level of the autografts, but still differed significantly from the allografts which were not immunosuppressed. Immunosuppression, therefore, improves the survival and the quality of the graft, more so for long-term immunosuppressed grafts, and also in revascularised grafts.

Animals↗
PubMed1989

Reconstruction of the lumbar spine using AO DCP plate internal fixation.

Augmentation of lumbar spine fusion with internal fixation using pedicle screw systems has gained wide currency because it offers rigid stabilization to foster fusion healing. The AO DCP plate has been employed in Europe as a spinal implant with pedicle fixation using 6.5 mm, full-threaded cancellous bone screws with success. This report details the experience of using this device for lumbar spine fusion in a series of 46 North American patients with a mean follow-up of 1.25 years (range 1-2.5 years). Thirty-one patients had had prior lumbar spine surgery with poor outcomes, and 15 had had no prior surgery. All were treated surgically for lumbar degenerative disease with canal decompression, internal fixation with AO plates, and fusion with autologous bone grafting posterolaterally. Complications included two early and one delayed wound infection; five cases of screw loosening; three cases of screw breakage; and three cases of screw impingement upon a nerve. Results of surgery in 17 patients with failed interbody fusion included good to excellent pain relief in 59%, and solid fusion in 76%. In 14 patients with failed posterior surgery the good to excellent pain relief rate was 79%, and the fusion rate was 86%. In 15 patients undergoing primary surgery there was 89% good to excellent pain relief and a solid fusion rate of 87%. The benefits accruing from augmentation of the fusion with internal fixation using AO DCP plates are positive and justify its continued use. Complications encountered in the early experience have been significantly reduced in subsequent series, indicating the existence of a "learning curve" effect which would mandate specific training of spinal surgeons in the technique.

Bone Plates↗
PubMed1989

Fractures of the odontoid process. Treatment with anterior screw fixation.

Seventeen cases of Anderson and D'Alonzo Type II and "shallow" Type III fractures of the odontoid, treated by anterior screw fixation, were reviewed and compared with previously published series of fractures treated nonoperatively, treated with posterior C1-C2 arthrodeses, and with anterior screw fixation series. Although the nonunion rate (12%) and major complication rate (24%) in the present series were higher than those previously reported, the combined rates of all anterior screw fixation series were comparable to those of posterior C1-C2 arthrodesis studies. Three of the complications presented occurred in cases that in retrospect were inappropriate for the use of this technique. These included a verified nonunion and 2 individuals with markedly osteoporotic bone and unfavorable fracture type. Because of the difficulty involved in mastering anterior screw fixation of the dens, its use should be limited to experienced spine surgeons with the appropriate surgical facilities.

Axis, Cervical Vertebra↗
PubMed1989

cDNA structures and regulation of two interferon-induced human Mx proteins.

Human cells treated with interferon synthesize two proteins that exhibit high homology to murine Mx1 protein, which has previously been identified as the mediator of interferon-induced cellular resistance of mouse cells against influenza viruses. Using murine Mx1 cDNA as a hybridization probe, we have isolated cDNA clones originating from two distinct human Mx genes, designated MxA and MxB. In human fibroblasts, expression of MxA and MxB is strongly induced by alpha interferon (IFN-alpha), IFN-beta, Newcastle disease virus, and, to a much lesser extent, IFN-gamma, MxA and MxB proteins have molecular masses of 76 and 73 kilodaltons, respectively, and their sequences are 63% identical. A comparison of human and mouse Mx proteins revealed that human MxA and mouse Mx2 are the most closely related proteins, showing 77% sequence identity. Near their amino termini, human and mouse Mx proteins contain a block of 53 identical amino acids and additional regions of very high sequence similarity. These conserved sequences are also present in a double-stranded RNA-inducible fish gene, which suggests that they may constitute a functionally important domain of Mx proteins. In contrast to mouse Mx1 protein, which accumulates in the nuclei of IFN-treated mouse cells, the two human Mx proteins both accumulate in the cytoplasm of IFN-treated cells.

Amino Acid Sequence↗
PubMed1989

[Long-term results of primary hip total prosthesis with acetabulum reinforcement ring].

The Müller acetabular reinforcement ring has proven very useful, especially in total hip revision when the bone of the acetabulum is of poor quality or deficient. However, the acetabular reinforcement ring may also be indicated in primary total hip replacement, especially in the case of poor quality bone in the acetabular bone stock, e.g. in chronic polyarthritis or protrusio acetabuli, or of deficient morphology of the acetabulum, e.g. in hip dysplasia. We analysed the results recorded in 145 patients operated on between 1977 and April 1983. Each of these patients had received a total hip prosthesis for the first time, with the polyethylene cup supplemented by an acetabular reinforcement ring. This patient group cannot be compared with the usual patient populations reported on in connection with primary hip replacement, since most of our 145 patients had several risk factors and had undergone previous surgery on up to seven occasions on the hip ultimately replaced by a prosthesis. Radiological analysis did not show a significant correlation between malposition of the acetabular reinforcement ring and signs of loosening, except when the acetabular component had been implanted in a most atypical manner. The infection rate was 4.8%, but it must be borne in mind that from 1977 to 1983 there was no routine prophylaxis with antibiotics. The incidence of aseptic loosening of the acetabular reinforcement ring necessitating revision was 0.7% after a mean follow-up of 7.7 years (range 5.5-11 years).(ABSTRACT TRUNCATED AT 250 WORDS)

Acetabulum↗
PubMed1989

[After-care and rehabilitation following surgical treatment of vertebral fractures].

The surgical treatment of spinal injuries has significantly contributed to the general progress in spinal surgery. Better understanding of the biomechanics of the healthy and injured spine, better diagnostic tools and relevant innovation in implants to stabilize and correct spinal segments have fundamentally changed the treatment options in the spinal trauma. Long duration of immobilization either in bed or with uncomfortable external fixation devices may be avoided by immediate internal fixation of the injured spine. This type of surgery allows early active motion and mobilization. The aftercare of patients with spinal injuries without neurological deficit, therefore, has become quite simple and is limited to active stabilizing muscle exercises and reestablishing of the muscle equilibrium. The tetraplegic and paraplegic patient, however, belongs still and clearly to a specialized center--immediately after the primary care in a surgical center--and should profit from an interdisciplinary team approach. But in this type of fatal injuries, too, the place of immediate surgical stabilization and correction of the injured spine is established today in order to help the rehabilitation and to shorten demoralizing immobilization and bed rest time.

Combined Modality Therapy↗
PubMed1989

[Bone screw osteosynthesis of dens fractures. Technical surgical aspects and results].

Twenty cases of Anderson and d'Alonzo type II and "shallow" type III fractures of the dens were treated by anterior screw fixation: the results were reviewed and compared with previously published results obtained in series of such fractures treated non-surgically, by posterior C1-C2 arthrodesis or anterior screw fixation. The complication rate of 25% in our series is comparable to those reported in a previously published review of studies on posterior wiring for C1-C2 arthrodesis. Three of our cases in which complications occurred (15%) were recognized in retrospect as inappropriate for the use of this technique: in one of these patients there was confirmed non-union, and the other two had markedly osteoporotic bone. A meticulous operative technique and the use of special instruments may improve the success rate. The anterior screw fixation method, however, allows for maximal post-treatment cervical motion, since it makes arthrodesis unnecessary and minimizes the degree and duration of postoperative external immobilization. It also reduces the iatrogenic trauma since an anterior rather than a posterior cervical approach is taken and supplementary bone grafting is not required. Anterior screw fixation of type II dens fractures appears to be the ideal method of treatment for these injuries, but since it is difficult to perform its use should be limited only to experienced spine surgeons with access to the appropriate surgical facilities.

Adolescent↗
PubMed1988

In vitro splicing of mRNA precursors: 5' cleavage site can be predicted from the interaction between the 5' splice region and the 5' terminus of U1 snRNA.

Combinations of different mutations within the 5' splice region of the rabbit beta-globin large intron were analyzed for their effect on in vitro splicing. Based upon the complementarity of the 5' splice region to the 5' terminal region of the U1 snRNA, the exact location of the 5' cleavage site of different mutants could be predicted and was experimentally confirmed. These findings add further strong support to the hypothesis (1) that the exact location of the 5' cleavage site in pre-mRNA splicing of higher eukaryotes is determined by the overall 5' splice region via the complementarity to the 5' end of the U1 snRNA, and not by the strongly conserved GU dinucleotide.

DNA Mutational Analysis↗
PubMed1988

Morphometric analysis of the thoracolumbar and lumbar pedicles, anatomo-radiologic study.

The geometric properties of 380 vertebral pedicles, ranging from T6 to L5, were analysed. Measurement were made directly from the specimens as well as from roentgenograms. The parameters considered were the horizontal and vertical pedicle diameters, pedicle angles in the transverse and sagittal planes, and the transverse and anteroposterior widths of the spinal canal and vertebral body. In addition, the length of the pedicle and the length of the pedicle including the vertebral body to the anterior cortex were measured along the pedicle axis and in a line parallel to the midline of the vertebral body. The smallest horizontal and vertical pedicle diameters were found at vertebral levels from T6 to T10. The correlation between pedicle widths and screw dimensions is obvious. In the transverse plane, the pedicle angle diverged from the vertebral body at all levels, except at T12. In the sagittal plane, the pedicles were angled cephalad from T6 to L3 and slightly caudally at L5. Knowledge of the length of the pedicle to the anterior vertebral body cortex is very important for safe screw purchase. At all levels, with the exception of T12, this length was found to be significantly greater along the pedicle axis than along a line parallel to the midline of the vertebral body.

Adult↗
PubMed1988

Organization of the murine Mx gene and characterization of its interferon- and virus-inducible promoter.

Specific resistance of Mx+ mice to influenza virus is due to the interferon (IFN)-induced protein Mx. The Mx gene consists of 14 exons that are spread over at least 55 kilobase pairs of DNA. Surprisingly, the Mx gene promoter is induced as efficiently by Newcastle disease virus as it is by IFN. The 5' boundary of the region required for maximal induction by both IFN and Newcastle disease virus is located about 140 base pairs upstream of the cap site. This region contains five elements of the type GAAANN, which occurs in all IFN- and virus-inducible promoters. The consensus sequence purine-GAAAN(N/-)GAAA(C/G)-pyrimidine is found in all IFN-inducible promoters.

Amino Acid Sequence↗