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Biomedical subjects

L Wiesner

Publications and source records attributed to L Wiesner.

At least 19 recordsLinked to original sources
PubMed2006

Pulmonary embolism caused by polymethylmethacrylate during percutaneous vertebroplasty in orthopaedic surgery.

Vertebroplasty consists of percutaneous injection of acrylic cement--polymethylmethacrylate (PMMA)--into a partially collapsed vertebral body in order to obtain pain relief and augment mechanical stability of the vertebral body. Although vertebroplasty is an efficient treatment it is not free of complications. Our present case report describes a woman with pulmonary polymethylmethacrylate embolism during percutaneous vertebroplasty who presented with hypotension, arrhythmia and hypocapnia.

Anticoagulants↗
PubMed2005

Neural driven angiogenesis by overexpression of nerve growth factor.

Mechanisms regulating angiogenesis are crucial in adjusting tissue perfusion on metabolic demands. We demonstrate that overexpression of nerve growth factor (NGF) in brown adipose tissue (BAT) of NGF-transgenic mice elevates both mRNA and protein levels of vascular endothelial growth factor (VEGF) and VEGF-receptors. Increased vascular permeability, leukocyte-endothelial interactions (LEI), and tissue perfusion were measured using intravital microscopy. NGF-stimulation of adipocytes and endothelial cells elevates mRNA expression of VEGF and its receptors, an effect blocked by NGF neutralizing antibodies. These data suggest an activation of angiogenesis as a result of both: stimulation of adipozytes and direct mitogenic effects on endothelial cells. The increased nerve density associated with vessels strengthened our hypothesis that tissue perfusion is regulated by neural control of vessels and that the interaction between the NGF and VEGF systems is the critical driver for the activated angiogenic process. The interaction of VEGF- and NGF-systems gives new insights into neural control of organ vascularization and perfusion.

Adipocytes, Brown↗
PubMed2004

[Therapy of cervical rheumatoid arthritis].

The rheumatoid involvement of the cervical spine can be divided into three phases. In the early stage of the disease there is an isolated atlantoaxial subluxation (AAS), followed by vertical instability and subaxial instability. If patients show clear symptoms of cervical myelopathy, which can occur during any stage of the disease, the progression cannot be stopped by conservative treatment, which is of great importance at the beginning of the cervical manifestation. Patient education, physiotherapy and immobilization with a stiff collar can significantly reduce pain. Early and effective DMARD therapy can have a positive effect on the natural history of the disease. In case of progressive instability, cervical myelopathy or severe pain operative treatment is indicated. If there is an isolated AAS, fusion can be restricted to the C1/C2 segment. The Magerl transarticular screw fixation is the preferred technique for stabilization. If there is evidence for vertical instability or severe destruction of the C0/C1 joints, occipital cervical fusion has to be performed. Durin the preoperative planning it is necessary to look for signs of subaxial instability. If this is the case, fusion should include the entire cervical spine. Transoral decompression may be necessary when there is persistent anterior compression of the myelon, typically seen in fixed AAS. Non-ambulatory myelopathic patients are more likely to develop severe surgical complications. Therefore, it is important to avoid the development of severe cervical instability by early surgical intervention. The right timing for surgery is still a matter of controversy. Future prospective randomized trials should address this topic to improve the treatment concept for the rheumatoid patient.

Arthritis, Rheumatoid↗
PubMed2004

[Columnotomy in ankylosing spondylitis].

Depending on its severity the fixed flexion deformity of the spine in patients with ankylosing spondylitis leads to significant disturbance in the activity of daily living. The surgical correction of such a deformity requires a special knowledge in the context of spinal surgery. Meticulous surgical procedures were especially developed for this kind of spinal deformity. Considering the rate of complications it is necessary to select carefully the patients undergoing these procedures. The surgeon must be familiar in handling these patients and these special surgical procedures.

Humans↗
PubMed2004

A new model of primary human adipocytes reveals reduced early insulin signalling in type 2 diabetes.

The aim of this study was to establish a diabetic model of primary human adipocytes for investigating potential defects in early insulin signalling. Specimens of human subcutaneous adipose tissue were obtained during orthopaedic surgical procedures. Preadipocytes were isolated and differentiated to adipocytes. Western blot analysis and immunoprecipitation were performed to determine protein content of IRS-1, IRS-2, p85, phosphorylation of IRS-1, IRS-2, Akt and MAPK as well as association between p85 and IRS-1/IRS-2. In addition to short-term insulin stimulation, the effect of hyperinsulinaemia was investigated by treating cells with insulin over a period of 36 hours. We found a significantly reduced basal expression of IRS-1 (54 +/- 15%) in adipocytes from type 2 diabetic subjects compared to controls with a further significant reduction in expression after long-term treatment (30 +/- 12%) compared to short-term treatment. IRS-2 expression also showed a significant reduction under hyperinsulinaemic conditions (20 +/- 2%) in diabetics vs. controls. Furthermore, long-term treatment with insulin in diabetic adipocytes led to a significant reduction in the phosphorylation of IRS-1(68 +/- 11%), IRS-2 (82 +/- 11%), Akt (42 +/- 2%), and MAPK (92 +/- 12%) and in the subsequent association between p85 to IRS-1 and IRS-2 (100 +/- 16% and 96 +/- 12%) in comparison to controls. Investigating glucose uptake diabetic adipocytes revealed a significant reduction of 90 +/- 2%. In this study, we were able to establish a new diabetic model of primary human adipocytes. A defect in early insulin signalling in type 2 diabetic patients under hyperinsulinaemic conditions was determined. These results might help to give further insights in early insulin action; additionally, this human model represents a useful target for the study of new therapeutic approaches.

Adipocytes↗
PubMed2002

[Rheumatoid arthritis of the cervical spine. Current concepts for diagnosis and therapy].

The involvement of the cervical spine in patients with rheumatoid arthritis (RA) is common,and has recently received growing attention. In the early stage of the disease, there is an isolated atlantoaxial subluxation (AAS). With further progression, osseous destruction of the joints can lead to vertical instability. While the involvement of the middle and lower cervical spine can cause a subaxial instability, neurological deficits can occur at any time. The onset of cervical myelopathy in patients with RA is often missed because of additional problems related to the hands and feet. If patients show clear symptoms of cervical myelopathy, the progression of the disease cannot be stopped by conservative treatment. Other indications for operative treatment are severe pain and radiological evidence of progressive instability. In the case of an isolated AAS, fusion can be restricted to the C1/C2 segment. If there is evidence for vertical or subaxial instability, an occipitocervical fusion has to be performed. To avoid instability adjacent to the fusion, the surgeon must check for signs of potential subaxial instability. If this is the case, fusion should include the entire cervical spine. Additional transoral decompression may be necessary when there is persistent retrodental pannus or osseous compression by an irreducible transverse dislocation or cranial migration of the dens. Non-ambulatory myelopathic patients are more likely to present severe surgical complications with limited prospects of functional recovery. Therefore, it is important to avoid the development of severe cervical myelopathy by early surgical intervention.

Atlanto-Axial Joint↗
PubMed2002

[Morphological diagnosis of spinal diseases. Current technical possibilities and challenges for the histological preparation of transpedicular biopsies].

The spine is the central component for the mobility of the human body. Both locally limited and diffuse pathologies of the spine are a challenge for the treating physician due to the difficult anatomy. The biopsy of a pathologically altered vertebral body is a fast and reliable basis for further therapy but until now this has not regularly been made use of as a diagnostic standard for spinal diseases, since the tissue gained was often microfractured because of the difficult anatomical position. Our own experience with transpedicular vertebral biopsies of 70 patients with different diseases is reported because of the considerable improvement in the biopsy technique and the methodical possibilities for processing the bony tissue. Methods which have proven particularly valuable are contact radiographs, embedding in plastic, careful decalcifying with EDTA and immunohistological procedures. In this way a definite diagnosis can be made in 97% of the cases. A close cooperation with the clinician carrying out the biopsy and a greater use of methods other than just fast decalcification is recommended.

Biopsy↗
PubMed2001

Computer navigation of parapedicular screw fixation in the thoracic spine: a cadaver study.

STUDY DESIGN: An in vitro study to investigate the advantages of computer assistance for the purpose of parapedicular screw fixation in the upper and middle thoracic spine. OBJECTIVES: To evaluate the feasibility and application accuracy of parapedicuar screw insertion with the assistance of an optoelectronic navigation system. SUMMARY OF BACKGROUND DATA: Because of anatomic limitations, thoracic pedicle screw insertion in the upper and middle thoracic spine remains a matter of controversy. The technique of parapedicular screw insertion has been described as an alternative, although the exact screw position is difficult to control. With the assistance of computer navigation for the screw placement, it might become possible to overcome these challenges. METHODS: Four human specimens were harvested for this study; 6-mm screws were inserted from T2 to T8 with the assistance of a CT-based optoelectronic navigation system. During surgery virtual images of the screw position were documented and compared with postoperative contact radiographs to determine the application accuracy. The following measurements were obtained: axial and sagittal screw angles as well as the screw distances to the anterior vertebral cortex and the medial pedicle wall. RESULTS: All 54 screws were inserted in a parapedicular technique without violation of the medial pedicle wall or the anterior or lateral vertebral cortex. The mean +/- standard deviation difference between the virtual images and the radiographs was 1.0 +/- 0.94 mm for the distance to the medial pedicle wall and 1.9 +/- 1.44 mm for the distance to the anterior cortex. The angular measurements showed a difference of 1.6 +/- 1.1 degrees for the transverse screw angle and 2.1 +/- 1.6 degrees for the sagittal screw orientation. CONCLUSION: With the assistance of computer navigation it is possible to achieve a safe and reliable parapedicular screw insertion in the upper and middle thoracic spine in vitro. The application accuracy varies for the linear and angular measurements and is higher in the axial than in the sagittal plane. It is important for the surgeon to understand these limitations when using computer navigation in spinal surgery.

Aged↗
PubMed2001

Fluoroscopy-guided transpedicular trocar biopsy of the spine--results, review, and technical notes.

The purpose of this study was to evaluate the technique and value of fluoroscopy-guided percutaneous transpedicular trocar biopsy in obtaining diagnostic tissue from vertebral body lesions and to review the current literature. The bone cores from 32 patients who underwent 34 transpedicular Jamshidi trocar biopsies for lesions in the thoracic, lumbar and sacral spine were examined. All samples were examined macroscopically for length and breakage and microscopically for trabeculae, marrow, and artifacts. Each sample was graded for its value for histologic examination. The diagnostic accuracy was assessed by the patient's clinical course and follow-up examinations. In 30 (93.8%) of the 32 patients a confirmed diagnosis or exclusion of pathology could be made. In 31 (91.2%) of 34 biopsies the quality of the specimen was assessed as "excellent". Two (5.9%) specimens were "good" and one (2.9%) was "poor". There were two minor complications (5.9%). Transpedicular biopsy of the spine using a Jamshidi trocar with an internal diameter of 3.1 mm under fluoroscopic guidance can be performed safely and efficiently and provides suitable bone cores for histologic examination. A combined clinical, radiological and pathological approach to the lesions leads to an excellent diagnostic yield.

Adolescent↗
PubMed2000

Clinical evaluation and computed tomography scan analysis of screw tracts after percutaneous insertion of pedicle screws in the lumbar spine.

STUDY DESIGN: An examination of the accuracy of percutaneous pedicle screw placement in the lumbar spine. Using computed tomography scan analysis after implant removal, the screw tracts could be analyzed regarding the degree and direction of screw dislocation. OBJECTIVES: To investigate the misplacement rate and related clinical complications of percutaneous pedicle screw insertion in the lumbar spine. SUMMARY OF BACKGROUND DATA: The feasibility of the external fixation test has been investigated in several studies. Although pedicle screw misplacement has been reported as one of the main complications, there are no reliable data on the misplacement rate for this difficult surgical procedure. METHODS: In this study, 51 consecutive patients with suspected segmental instability were investigated after external transpedicular screw insertion for the external fixation test. Computed tomography scans of all instrumented pedicles from L2 to S1 were performed after screw removal. The screw tracts were analyzed, and the direction and degree of the pedicle violations were noted. In addition, the screw and pedicle angles were measured. RESULTS: Of 408 percutaneously inserted pedicle screws, only 27 screws (6.6%) were misplaced. There were 19 medial pedicle violations, 6 lateral cortical defects, and only 1 cranial and 1 caudal displacement. With respect to the spinal level, S1 showed the highest misplacement rate, with 11 screw dislocations (12%). After surgery, found two nerve root injuries were found. Only one of the injuries (L4) was related to the malposition of a screw. CONCLUSIONS: This study has shown that percutaneous insertion of pedicle screws in the lumbar spine is a safe and reliable technique. Despite the low misplacement rate of only 6.6%, it should be kept in mind that the surgical procedure is technically demanding and should be performed only by experienced spine surgeons.

Adult↗
PubMed1999

Anatomic evaluation of two different techniques for the percutaneous insertion of pedicle screws in the lumbar spine.

STUDY DESIGN: An in vitro study in which a human cadaver model was used to examine the accuracy of two different techniques of percutaneous pedicle screw insertion in the lumbar spine. OBJECTIVES: To investigate the in vitro misplacement rate of pedicle screw insertion for two different percutaneous techniques: 1) the well established Magerl technique, and 2) a new modified technique. SUMMARY OF BACKGROUND DATA: Numerous anatomic and biomechanical studies have been conducted to analyze the in vitro and in vivo characteristics of pedicle screw insertion in the lumbar spine via an open approach, whereas there is a lack of experimental data concerning the more sophisticated percutaneous procedure. METHODS: Thirty human specimens from L1 to S1 were separated into two groups (A and B). In group A, the screws were placed in accordance with the technique described by Magerl; in group B, a new modified technique developed by the authors' research group was used. After screw placement, the specimens were dissected, and pedicle violations were noted with respect to the degree and direction of the screw misplacement. RESULTS: The dissection of the specimens showed that of 360 pedicle screws, 37 were misplaced. This finding translates into an overall misplacement rate of 10%. With the Magerl technique, 23 pedicle violations (misplacement rate, 13%) were found; with the modified technique, only 14 dislocated pedicle screws (misplacement rate, 8%) were detected. This difference was not statistically significant (P = 0.118). In both groups, there were significantly more medical pedicle violations than lateral (32 medial and 5 lateral screw dislocations). The degree of the screw misplacements varied between 1.0 and 5.0 mm. The majority of pedicle violations (30 of 37) were minor, i.e., less than 3.0 mm. CONCLUSIONS: This in vitro study showed that the percutaneous technique of pedicle screw insertion in the lumbar spine is a safe and reliable procedure. Compared with the well-established Magerl technique, the new modified technique did not decrease the misplacement rate significantly, although less pedicle violations were found in the upper lumbar spine.

Bone Screws↗
PubMed1999

Anaesthetic management of patients with mucopolysaccharidosis IV presenting for major orthopaedic surgery.

Mucopolysaccharidosis IV, also known as Morquio-Brailsford syndrome, is an inherited autosomal recessive disorder of mucopolysaccharide metabolism leading to accumulation of keratan sulphate in the connective tissue of multiple organ systems. Based on a case report, the anaesthetic implications for the treatment of patients with MPS IV presenting for major orthopaedic surgery are discussed.

Anesthesia↗
PubMed1998

Trace element supplementation modulates pulmonary infection rates after major burns: a double-blind, placebo-controlled trial.

Infections remain the leading cause of death after major burns. Trace elements are involved in immunity and burn patients suffer acute trace element depletion after injury. In a previous nonrandomized study, trace element supplementation was associated with increased leukocyte counts and shortened hospital stays. This randomized, placebo-controlled trial studied clinical and immune effects of trace element supplements. Twenty patients, aged 40 +/- 16 y (mean +/- SD), burned on 48 +/- 17% of their body surfaces, were studied for 30 d after injury. They consumed either standard trace element intakes plus supplements (40.4 micromol Cu, 2.9 micromol Se, and 406 micromol Zn; group TE) or standard trace element intakes plus placebo (20 micromol Cu, 0.4 micromol Se, and 100 micromol Zn; group C) for 8 d. Demographic data were similar for both groups. Mean plasma copper and zinc concentrations were below normal until days 20 and 15, respectively (NS). Plasma selenium remained normal for group TE but decreased for group C (P < 0.05 on days 1 and 5). Total leukocyte counts tended to be higher in group TE because of higher neutrophil counts. Proliferation to mitogens was depressed compared with healthy control subjects (NS). The number of infections per patient was significantly (P < 0.05) lower in group TE (1.9 +/- 0.9) than in group C (3.1 +/- 1.1) because of fewer pulmonary infections. Early trace element supplementation appears beneficial after major burns; it was associated with a significant decrease in the number of bronchopneumonia infections and with a shorter hospital stay when data were normalized for burn size.

Adult↗
PubMed1996

Experimentally induced ulno-carpal instability. A study on 13 cadaver wrists.

This experimental work studies the role of ligamentous structures in suspending the carpal bones from the radius and ulna. Thirteen human cadaver wrists underwent a distal radio-ulnar arthrodesis in a neutral position and an arthrodesis between the three bones of the first carpal row. Progressive postero-anterior forces in a palmar direction were applied to the fused carpal bones. Displacement was measured by two dial gauges before and after sequential section of the different fibrous structures. The largest absolute average displacement (both, dorso-palmar and induced rotational displacement) was observed after section of the ulnar styloid process. No significant differences were observed after section of the extensor retinaculum, extensor carpi ulnaris sheath, posterior ulno-carpal and posterior radio-carpal ligaments. This work suggests that the carpus is suspended not only from the radius, but also from the distal ulna and particularly at the ulnar styloid and the structures which insert onto it.

Arthrodesis↗
PubMed1994

Mid-term results with cultured epidermal autografts, allogenic skin transplants and cyclosporin A medication.

Transplantation of allogenic split thickness skin grafts (STSG) and immunosuppression with cyclosporin A enable early and definitive skin replacement of extensive, deep partial and full thickness burns. Covering burn defects with definitely engrafted, allogenic dermis and cultivated epithelial autografts (CEA) permits the subsequent withdrawal of cyclosporin A medication. Light-microscopy examination of biopsies, taken 12 and 24 months postgrafting, and electron microscopy of biopsies taken 12 months postgrafting, demonstrates a re-established, but somewhat reduced anchoring of the CEA as compared with a normal epidermal-dermal junction. Clinical inspection, 20 months postgrafting, confirms the histological observations that epifascial transplantation is qualitatively inferior to placing the allogenic STSG on the subcutaneous tissue. In the first situation, the dermis is inelastic and collagen deposition is excessive, whereas in the second case collagen deposition is comparatively reduced and the dermis shows clinically some elasticity.

Adult↗
PubMed1992

Current concepts in pediatric burn care: management of burn wounds with cultured epidermal autografts.

Our experience with CEA is based on 21 patients operated on from 1986 to 1991. The areas covered with CEA measured 500 cm2 to 3160 cm2. At one setting no more than 40 sheets of 40 cm2 CEA have been transplanted. The take of CEA is over 75% when applied to dermis. The same holds true when covering "deepithelialised" skin homografts on immunosuppressed patients. Scar formation has not been a problem, and the overall results have been good.

Adolescent↗