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Biomedical subjects

M Schulte

Publications and source records attributed to M Schulte.

At least 37 records · Page 2Linked to original sources
PubMed2000

[Therapy of aneurysmal bone cyst].

The aneurysmal bone cyst represents a tumor-like lesion, which does not occur frequently. Every site of the skeleton may be involved. Although it can be observed at any age, it distinctly predominates from 10 to 20 years of age. Distinction of aneurysmatic bone cysts from certain benign or malignant bone tumours requires subtle imaging techniques and an experienced bone tumour pathologist. Since the lesion shows a heterogeneous biological behaviour and typically occurs in the growing skeleton, a wide range of surgical procedures must be provided concerning tumour resection and defect reconstruction. In the current retrospective study results of 41 surgically treated aneurysmal bone cysts, thereof 5 latent, 31 active, and 5 aggressive lesions, were investigated. While morbidity due to the therapeutic measures was comparatively low even in extended lesions and demanding reconstructions, a recurrence rate of 19.5% had to be observed in our series. Taking into consideration the biological activity of the lesion, analysis of the recurrences revealed inappropriate surgical margins had been chosen at the primary operation in all of these patients. Since the risk of a local relapse is linked both to aggressiveness of the primary lesion and to surgical radicality, therapy of aneurysmal bone cyst requires preoperative staging and stage-dependent surgical procedures.

Adolescent↗
PubMed2000

Vertebral body replacement with a bioglass-polyurethane composite in spine metastases--clinical, radiological and biomechanical results.

Metastatic spine lesions frequently require corpectomy in order to achieve decompression of the spinal cord and restoration of spinal stability. A variety of systems have been developed for vertebral body replacement. In patients with prolonged life expectancy due to an improvement of both systemic and local therapy, treatment results can be impaired by a loosening at the implant-bone interface or mechanical failure. Furthermore, early detection of a metastatic recurrence using sensitive imaging modalities like computed tomography (CT) and magnetic resonance imaging (MRI) is possible in these patients without artefact interference. The aim of our pilot study was to evaluate the clinical applicability and results of a new radiolucent system for vertebral body replacement in the lumbar spine. The system consists of bone-integrating biocompatible materials - a polyetherurethane/bioglass composite (PU-C) replacement body and an integrated plate of carbon-fibre reinforced polyetheretherketone (CF-PEEK) - and provides high primary stability with anterior instrumentation alone. In a current prospective study, five patients with metastatic lesions of the lumbar spine were treated by corpectomy and reconstruction using this new system. Good primary stability was achieved in all cases. Follow-up (median 15 months) using CT and MRI revealed progressive osseous integration of the PU-C spacer in four patients surviving more than 6 months. Results obtained from imaging methods were confirmed following autopsy by biomechanical investigation of an explanted device. From these data, it can be concluded that implantation of the new radiolucent system provides sufficient long-term stability for the requirements of selected tumour patients with improved prognosis.

Adult↗
PubMed2000

The perception of coherent and non-coherent auditory objects: a signature in gamma frequency band.

The pertinence of gamma band activity in magnetoencephalographic and electroencephalographic recordings for the performance of a gestalt recognition process is a question at issue. We investigated the functional relevance of gamma band activity for the perception of auditory objects. An auditory experiment was performed as an analog to the Kanizsa experiment in the visual modality, comprising four different coherent and non-coherent stimuli. For the first time functional differences of evoked gamma band activity due to the perception of these stimuli were demonstrated by various methods (localization of sources, wavelet analysis and independent component analysis, ICA). Responses to coherent stimuli were found to have more features in common compared to non-coherent stimuli (e.g. closer located sources and smaller number of ICA components). The results point to the existence of a pitch processor in the auditory pathway.

Acoustic Stimulation↗
PubMed2000

Bisoprolol and nifedipine retard in elderly hypertensive patients: effect on quality of life.

Subjects over the age 60 with sustained sitting diastolic pressures of 95-115 mm Hg were randomised to a regime based on bisoprolol (n = 368) or nifedipine retard (n = 379) for 24 weeks. The goal diastolic pressure was < or =90 mm Hg and to achieve this, double-blind medication could be doubled (5/10 mg bisoprolol, 40/80 mg nifedipine retard) or hydrochlorothiazide 25 mg (unblinded) could be added to the higher dose. In an intention-to-treat analysis, 309 subjects in both the bisoprolol and nifedipine retard treated group provided at least a baseline and a second quality of life assessment (82%). An excess of symptoms was observed in the nifedipine group for oedema of the legs, nocturia, constipation, racing heart and heart thumping. Fewer patients reported wheeze in the nifedipine group. For quality of life, there were no statistically significant differences between the two groups after 8 weeks. However, when analysing the results of the last available assessment (usually at 24 weeks) there were significant (P < 0.05) improvements in tension/anxiety, anger/ hostility, vigour/activity, and confusion/bewilderment, assessed by the Profile of Mood States (POMS) in patients receiving bisoprolol in comparison to those receiving nifedipine retard. The Sickness Impact Profile and objective tests of cognitive function did not differ statistically between the two groups. Quality of life was maintained at a good level on both treatments with advantages for bisoprolol in certain areas. Journal of Human Hypertension (2000) 14, 205-212.

Adrenergic beta-Agonists↗
PubMed2000

Influence of etiology in heterotopic bone formation of the hip.

OBJECTIVE: Heterotopic ossification (HO) in periarticular tissue can appear after brain or local joint trauma. The aim of this study was to investigate differences of manifestation and outcome after surgical therapy of patients suffering from HO of the hip after isolated brain injury (n = 18), local hip trauma (n = 21), or the combination of both (n = 25). HO can cause progressive lost of joint movement; once mature, the only therapy to improve joint mobility is the excision. METHODS: All patients underwent surgical removal of HO and postoperative irradiation therapy. On the basis of plain radiographic findings, we evaluated the recurrent ossification after 1-year and 5-year follow-up periods. Within this prospective study, clinical performance status was scored according to the classification of d'Aubigne and a planimeter was used to evaluate the area of heterotopic bone formation in standard x-rays films. RESULTS: The severity of brain trauma observed by Glasgow Coma Scale correlated with the ossification size (square centimeters). Correlation was noticed as well between severity of brain injury and functional outcome. The evaluation of an average 1-year and 5-year follow-up period showed relief of pain and clear improvement of range of motion in all patients. There was mild recurrence of heterotopic bone growth within the first postoperative year without deterioration of the functional results. CONCLUSION: The severity of brain trauma has an influence on the extent of HO near the hip joint and also on the rehabilitation process. The histologic findings and recurrence of HO after excision were not affected by the localization of initial trauma. There was only mild recurrence of heterotopic bone growth between the first and fifth postoperative year. For objective evaluation of heterotopic bone formation in standard x- ray films, planimetric measurement is a useful method.

Brain Injuries↗
PubMed2000

Grading of tumors and tumorlike lesions of bone: evaluation by FDG PET.

UNLABELLED: Clinical diagnosis of skeletal tumors can be difficult, because such lesions compose a large, heterogeneous group of entities with different biologic behaviors. The aim of this prospective study was to assess the value of PET in grading tumors and tumorlike lesions of bone. METHODS: Two hundred two patients with suspected primary bone tumors were investigated using FDG PET. Uptake of FDG was evaluated semiquantitatively by determining the tumor-to-background ratio (T/B). All patients underwent biopsy, resulting in the histologic detection of 70 high-grade sarcomas, 21 low-grade sarcomas, 40 benign tumors, 47 tumorlike lesions, 6 osseous lymphomas, 6 plasmacytomas, and 12 metastases of an unknown primary tumor. RESULTS: All lesions, with the exception of 3 benign tumors, were detected by increased FDG uptake. Although sarcomas showed significantly higher T/Bs than did latent or active benign lesions (P < 0.001), aggressive benign lesions could not be distinguished from sarcomas. Using a T/B cutoff level for malignancy of 3.0, the sensitivity of FDG PET was 93.0%, the specificity was 66.7%, and the accuracy was 81.7%. CONCLUSION: FDG PET provides a promising tool for estimating the biologic activity of skeletal lesions, implicating consequences for the choice of surgical strategy.

Adult↗
PubMed1999

[Intraoperative extracorporeal irradiation and replantation (EIR) in the treatment of primary malignant bone tumors].

In 6 patients with primary malignant bone tumors (4 Ewing, 1 recurrent Adamantinoma, 1 maligne Haemangioperizytoma) the local therapy was performed as intraoperative extracorporeal irradiation and replantation. During the follow-up 10 (6-24) months no local recurrence in the replanted segment occurred. One recurrence occurred in the host bed; in two cases the replanted segment had to be removed because of severe infection. The other cases showed good functional and radiological results. These clinical findings and the reports in the literature seem to allow the application of the intraoperative extracorporeal irradiation and replantation procedure for defect reconstruction in cases of chemo- and radiotherapy-sensitive bone tumors.

Adolescent↗
PubMed1999

Fluorodeoxyglucose positron emission tomography of soft tissue tumours: is a non-invasive determination of biological activity possible?

Since musculoskeletal tumours comprise a large heterogeneous group of entities with different biological behaviour, clinical diagnosis of such lesions can be very difficult. The aim of this prospective study was to assess the usefulness of 2-[F-18]-fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET) in the non-invasive evaluation of soft tissue tumours. One hundred and two patients with suspected soft tissue neoplasms were investigated by FDG-PET. The uptake of FDG was evaluated semiquantitatively by determining the tumour to background ratio (TBR). All patients underwent biopsy, resulting in the histological detection of 39 high-grade sarcomas, 16 intermediate-grade sarcomas, 11 low-grade sarcomas, 25 benign tumours, 10 tumour-like lesions such as spontaneous myositis ossificans (n = 6) and one non-Hodgkin lymphoma. All lesions except for two lipomas disclosed an increased FDG uptake. Sarcomas showed significantly higher TBR values than latent or active benign lesions (P<0.001) and aggressive benign lesions (P<0.05). Using a TBR cut-off level of 3.0 for malignancy, sensitivity of FDG-PET was 97.0%, specificity 65.7% and accuracy 86. 3%. From our data there are three main conclusions: (1) Except for patients with pseudotumoral myositis ossificans, lesions with a TBR >3 were sarcomas (91.7%) or aggressive benign tumours (8.3%). (2) Tumours with a TBR <1.5 were latent or active benign lesions, exclusively. (3) The group with intermediate TBR values (<3 and >1. 5) comprised primarily latent or active benign lesions, but also four aggressive benign tumours and two low-grade sarcomas. Our data suggest that FDG-PET represents a useful tool for the evaluation of the biological activity of soft tissue neoplasms.

Female↗
PubMed1999

Megaprosthetic replacement of the pelvis: function in 17 cases.

Between 1980 and 1997, we treated 39 patients (mean age 39 (16-66) years, 24 men) with megaprosthetic replacement of a large bone defect (> 10 cm) of the pelvis. The bone resection was necessary in 38 cases due to malignant bone and soft tissue tumors and in 1 case due to hydatid disease. Polyacetal hemipelvic replacement was performed in 29 cases, CAD hemipelvic replacement in 8 cases, and a saddle prosthesis was inserted in 2 cases. All patients were followed clinically and radiographically. The mean follow-up was 58 (15-110) months. 20 patients have died of their tumor. 10 local infections occurred, in 2 cases necessitating hemipelvectomy. Hip dislocation occurred in 6 cases. 13 of the remaining 17 survivors had good or excellent clinical results according to the Enneking evaluation (MSTS). In 6 of the 17 survivors, radiographs revealed implant loosening.

Adolescent↗
PubMed1999

Evaluation of neoadjuvant therapy response of osteogenic sarcoma using FDG PET.

UNLABELLED: According to the current treatment protocol of the Cooperative Osteosarcoma Study (COSS), monitoring preoperative chemotherapy response and estimating grade of tumor regression in patients with osteosarcoma is mandatory before surgical removal of the tumor, particularly if a limb salvage procedure is intended. In addition, response to neoadjuvant chemotherapy is considered as an important prognostic indicator. The aim of this prospective study was to assess the usefulness of 2-(18F) fluoro-2-deoxy-D-glucose (FDG) PET in the noninvasive evaluation of neoadjuvant chemotherapy response in osteosarcoma. METHODS: In 27 patients with osteosarcoma, we determined tumor-to-background ratios (TBRs) of FDG uptake with PET, before and after neoadjuvant chemotherapy according to COSS 86c or COSS 96 protocols, respectively. We compared changes in glucose metabolism of osteosarcomas with the histologic grade of regression in the resected specimen, according to Salzer-Kuntschik, discriminating responders (grades I-III; n = 17) and nonresponders (grades IV-VI; n = 10). RESULTS: The decrease of FDG uptake in osteosarcomas expressed as a ratio of posttherapeutic and pretherapeutic TBRs showed a close correlation to the amount of tumor necrosis induced by polychemotherapy (P < 0.001; Spearman). With a TBR ratio cutoff level of 0.6, all responders and 8 of 10 nonresponders could be identified by PET. In addition, lung metastases of osteosarcoma were detected with FDG PET in 4 patients. CONCLUSION: FDG PET provides a promising tool for noninvasive evaluation of neoadjuvant chemotherapy response in osteosarcoma. This could imply consequences for the choice of surgical strategy, because a limb salvage procedure cannot be recommended in patients nonresponsive to preoperative chemotherapy unless wide surgical margins can safely be achieved.

Adolescent↗
PubMed1998

[Color Doppler controlled needle biopsy in diagnosis of soft tissue and bone tumors].

In a prospective study we investigated 168 patients with musculoskeletal tumors, including 71 sarcomas, by core needle biopsy using the high-speed device Autovac. Monitoring with colour-coded duplex sonography allowed a well-aimed puncture of smaller or deeply localized lesions and also permitted the discrimination of necrotic and viable parts of the tumor. Adequate material for histologic diagnosis including grading and determination of tumor subtype was obtained from soft tissue sarcomas, soft tissue metastases, malignant lymphomas, plasmacytomas, and osteolytic skeletal secondaries. In contrast, in benign soft tissue and bone tumors the diagnosis could be established in only 66% of cases. Although skeletal sarcomas were identified as malignant mesenchymal lesions, a complete histologic classification of tumor subtype frequently was not possible due to an insufficient tissue specimen. With an accuracy of 97% for the diagnosis of malignancy and of 94% for the diagnosis of soft tissue sarcoma the results of core needle biopsies were comparable to those of incisional biopsies, the reference standard in the diagnosis of musculoskeletal tumors. Regarding the known disadvantages and the oncological risks of incisional biopsies, needle biopsy should replace the open procedure as the primary means of diagnosis in soft tissue and osteolytic bone tumors.

Adult↗
PubMed1998

The effect of dimethylsulfoxide on the water transport response of rat hepatocytes during freezing.

Successful improvement of cryopreservation protocols for cells in suspension requires knowledge of how such cells respond to the biophysical stresses of freezing (intracellular ice formation, water transport) while in the presence of a cryoprotective agent (CPA). This work investigates the biophysical water transport response in a clinically important cell type--isolated hepatocytes--during freezing in the presence of dimethylsulfoxide (DMSO). Sprague-Dawley rat liver hepatocytes were frozen in Williams E media supplemented with 0, 1, and 2 M DMSO, at rates of 5, 10, and 50 degrees C/min. The water transport was measured by cell volumetric changes as assessed by cryomicroscopy and image analysis. Assuming that water is the only species transported under these conditions, a water transport model of the form dV/dT = f(Lpg([CPA]), ELp([CPA]), T(t)) was curve-fit to the experimental data to obtain the biophysical parameters of water transport--the reference hydraulic permeability (Lpg) and activation energy of water transport (ELp)--for each DMSO concentration. These parameters were estimated two ways: (1) by curve-fitting the model to the average volume of the pooled cell data, and (2) by curve-fitting individual cell volume data and averaging the resulting parameters. The experimental data showed that less dehydration occurs during freezing at a given rate in the presence of DMSO at temperatures between 0 and -10 degrees C. However, dehydration was able to continue at lower temperatures (< -10 degrees C) in the presence of DMSO. The values of Lpg and ELp obtained using the individual cell volume data both decreased from their non-CPA values--4.33 x 10(-13) m3/N-s (2.69 microns/min-atm) and 317 kJ/mol (75.9 kcal/mol), respectively--to 0.873 x 10(-13) m3/N-s (0.542 micron/min-atm) and 137 kJ/mol (32.8 kcal/mol), respectively, in 1 M DMSO and 0.715 x 10(-13) m3/N-s (0.444 micron/min-atm) and 107 kJ/mol (25.7 kcal/mol), respectively, in 2 M DMSO. The trends in the pooled volume values for Lpg and ELp were very similar, but the overall fit was considered worse than for the individual volume parameters. A unique way of presenting the curve-fitting results supports a clear trend of reduction of both biophysical parameters in the presence of DMSO, and no clear trend in cooling rate dependence of the biophysical parameters. In addition, these results suggest that close proximity of the experimental cell volume data to the equilibrium volume curve may significantly reduce the efficiency of the curve-fitting process.

Animals↗
PubMed1998

[Primary malignant tumors of the sacrum].

The oncological and functional results of 16 patients with primary malignant sacral tumors (12 chordomas, 3 chondrosarcomas, 1 fibrosarcoma) during the past decade are reported. Dorsal approach was used in 10 cases, ventral or combined ventrodorsal procedure in 5 cases; in 1 case only biopsy was taken. Amputation of rectum with colostomy was necessary in 9 cases, ileosacral stabilization in 2 cases. Eight patients died, 5 of the disease and 3 of complications, with a mean survival time of 25.8 months. Local recurrence occurred in 4, distant metastases in 3 cases. Six of the 8 survivors--mean survival is 59 (21-112) months--showed good or excellent functional results according to the Enneking score system. Local complications, mostly wound healing problems, were observed in 9 (56%), neurological disorders in respect of the resected sacral nerve roots in 11 (68%) cases. The oncological and functional results after resection of primary malignant sacral tumors, especially of chordomas, justify radical surgical procedures sacrificing the sacral nerve roots.

Chondrosarcoma↗
PubMed1997

Secretion of brain natriuretic peptide in patients with aneurysmal subarachnoid haemorrhage.

BACKGROUND: Subarachnoid haemorrhage is commonly associated with natriuresis and hyponatraemia. One possible explanation for these features is a defect in the central regulation of renal sodium reabsorption with increased secretion of a natriuretic factor. We investigated whether excess sodium secretion in patients with subarachnoid haemorrhage is related to increased secretion of natriuretic peptides or to the presence of digoxin-like immunoreactive substances. METHODS: We measured the plasma concentrations of digoxin-like immunoreactive substances (by a fluorescence polarisation immunoassay) and natriuretic peptides, aldosterone, renin, and antidiuretic hormone (by radioimmunoassay) in ten patients with aneurysmal subarachnoid haemorrhage, ten patients undergoing elective craniotomy for cerebral tumours, and 40 healthy controls of similar age and sex distribution. Samples were collected before surgery, 1 h, 4 h, and 12 h after surgery, then daily until 7 days postoperatively in the two groups of patients. FINDINGS: All patients with subarachnoid haemorrhage, but none of the tumour patients, showed increased urine output and urinary excretion of sodium (p = 0.018 for comparison of means of curves to 7 days). The patients with subarachnoid haemorrhage had much higher plasma concentrations of brain natriuretic peptide (BNP) than controls, on admission (mean 15.1 [SE 3.8] vs 1.6 [1.0] pmol/L, p < 0.001) and throughout the study period, accompanied by lower than normal aldosterone concentrations and normal plasma concentrations of atrial and C-type natriuretic peptides (ANP, CNP). The patients with tumours had similar plasma concentrations of ANP, BNP, and CNP to the controls. We did not detect digoxin-like immunoreactive substances in either group of patients. INTERPRETATION: Salt-wasting of central origin may induce hyponatraemia in patients with aneurysmal subarachnoid haemorrhage, possibly as a result of increased secretion of BNP with subsequent suppression of aldosterone synthesis.

Brain Neoplasms↗
PubMed1997

Bone and soft tissue manifestations of alveolar echinococcosis.

OBJECTIVE: The present study demonstrates the osseous and soft tissue manifestations of alveolar echinococcosis (AE). PATIENTS: We report on eight patients with AE with bone or soft tissue involvement confirmed at biopsy or needle cytology. RESULTS: All eight patients showed hepatic involvement. Four exhibited infiltration of the spine as a result of direct spread of the hepatic primary lesion; distant metastases were observed in only three of these patients. Calcifications, which are typical for hepatic manifestations of the disease, were observed in soft tissue in only two of eight cases (25%); we observed no instances of endovesicular daughter cysts. CONCLUSIONS: AE manifests itself in the vertebral column as a form of spondylitis and in soft tissue presents similar to an abscess. Since in most of these cases spread of the disease per continuitatem from the liver is present, the diagnosis is easily made from the characteristic hepatic findings.

Adult↗