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Biomedical subjects

M Engelhardt

Publications and source records attributed to M Engelhardt.

At least 19 recordsLinked to original sources
PubMed2005

[Spinal intramedullary tumors. When is surgical treatment indicated?].

OBJECTIVE: Timing of surgery in patients with intramedullary tumors is the subject of controversy. The aim of this retrospective study is to evaluate whether patients with intramedullary ependymomas and astrocytomas have a better postoperative prognosis without or with slight preoperative deficits than those with severe preoperative neurological disturbances. PATIENTS AND METHODS: During a period of 8.5 years (January 1992-August 2000), 34 patients with intramedullary tumors underwent surgery in our Neurosurgical Department. Among them there were five astrocytomas WHO grade II and ten ependymomas WHO grade II. Recurrences were observed in two patients with astrocytomas and one patient with ependymoma. Pre- and postoperative functional performance was classified according to the McCormick scale in grade I-IV (grade I: neurologically normal or mild focal deficit and grade IV: severe neurological deficits and without functional independence). The follow-up period varied from 4 to 76 months (mean: 27.9 months). RESULTS: All seven grade I patients remained unchanged after surgery. Two of four grade II patients improved to grade I; two deteriorated to grade III. Two of three grade III and IV patients remained unchanged and another one deteriorated from grade III to IV. CONCLUSION: At the best, intramedullary astrocytomas and ependymomas should be operated when symptoms are mild. Early surgery can achieve good functional outcome.

Adolescent↗
PubMed2005

[Injuries and response to overload stress in running as a sport].

Running is rarely associated with acute injuries (muscle injuries, ankle sprain, ruptures of the Achilles tendon). More than 80% of the complaints are due to overuse injuries, mainly concerning knee, foot and Achilles tendon. Risk factors are high-performance sports, high training quantity, rapid increase of training intensity, previous injuries, and skeletal axis malalignment. Running is not suitable for severely overweight people and those with significant skeletal malalignment, dysplastic hips, spondylolisthesis, or cartilage damage.

Ankle Injuries↗
PubMed2005

Duplex scanning criteria for selection of patients for internal carotid artery endarterectomy.

BACKGROUND: The value of carotid endarterectomy for stroke prevention depends on reliable identification of patients at higher risk for stroke from their internal carotid artery (ICA) occlusive disease than from surgery. This selection of patients is based on the degree of ICA stenosis. Therefore, preoperative diagnostic measures should strive for a prevalence independent probability for disease of 100%. Aim of this prospective study was to obtain clinically applicable duplex scanning criteria for ICA stenosis > or = 70% with a probability for disease of 100%. PATIENTS AND METHODS: In 124 ICA in 62 patients (79% male) angiography and duplex scanning were performed. Degree of stenosis was classified in 4 categories: I < 50%; II 50%-69%; III 70%-99%; IV 100%. Cohen's kappa statistic was used to estimate agreement between both methods within categories. To improve accuracy post-test likelihood for disease was calculated for each point on the receiver operating characteristics (ROC)-curve for peak systolic (PSV) and end-diastolic velocity (EDV), and cut-off points for velocity criteria were set at a positive likelihood of 100%. RESULTS: Diagnostic agreement was good with kappa = 0.77 (95% CI, 0.64-0.90; p < 0.001). For EDV a criterion of > or = 150 cm/sec was associated with a post-test likelihood for disease of 100%. For PSV no appropriate criterion could be detected. CONCLUSIONS: A probability of 100% for ICA stenosis > or = 70% can be achieved by mere preoperative duplex scanning. Vascular laboratory specific validation of duplex scanning criteria should consider prevalence independent post-test likelihood for disease to ensure the value of CEA for stroke prevention.

Aged↗
PubMed2005

Accidental dural tears occurring during supratentorial craniotomy -- a prospective analysis of predisposing factors in 100 patients.

OBJECT: Accidental dural tears during craniotomy constitute a possible source of CSF leakage and wound infection. This can turn an elective procedure into a complicated and cost-intensive problem. Only a few studies have addressed the incidence of dural tears, but there have been many studies dealing with various techniques that can be employed to repair dural tears. The present study was carried out to analyze predisposing factors for dural tears during trepanation in order to optimize the design of a robot-assisted trepanation system. PATIENTS: 100 patients were analyzed prospectively. An evaluation sheet was designed to document size and location of the lesion and the craniotomy, the geometry and number of burr holes, and the auxiliary tools used during bone flap removal. Furthermore, the suspected histology was noted and anatomical facts, including cranial vault thickness and the presence of hyperostosis frontalis interna, were documented. RESULTS: In 100 craniotomies performed, in the majority of cases (64 %), in order to gain access to intracerebral lesions, 30 dural tears were seen, involving both dural layers in 26 cases. There were 26 tears located under the margins of the craniotomy; the length was 0-3 cm in 18 patients (69 %). Significant predisposing factors were the thickness of the cranial vault and the presence of a hyperostosis frontalis. Furthermore, the location (frontal) and the diagnosis of an extracerebral pathology, including meningiomas, were significant factors for dural tears. Elderly patients and the use of the drill to complete the trepanation were also significant predisposing factors. Dural repair was done using suturing, in most of the cases combined with a free periostal flap. Central dural tears were integrated into the planned dural opening. A vascularized flap or muscle was used in the minority of cases. Postoperative cerebral fluid leakage was seen in two patients, wound infections in three. CONCLUSIONS: Dural tears occurring during craniotomy cannot be prevented, when predisposing factors are taken into account. The absence of brain damage may due to two factors: 1) in elderly patients with hyperostosis, an additional atrophy of the brain is present; 2) extracerebral tumors, with their space-occupying growth, shift the underlying brain away from the calvaria. Considering the design of a robot-assisted trepanation system, the following conclusions seem possible: dural tears cannot be avoided because predisposing factors are overriding. For improved safety, additional, specialized instrumentation is required.

Adolescent↗
PubMed2004

Early carotid endarterectomy in patients with a nondisabling ischemic stroke: results of a retrospective analysis.

BACKGROUND: There are several recent recommendations not to delay carotid endarterectomy (CEA) for at least 4 weeks in patients experiencing a nondisabling ischemic stroke. Therefore, we re-examined if these patients could be safely operated on earlier: The aim of our study was to review the perioperative stroke and death rates of CEA performed within 30 days of stroke onset. PATIENTS AND METHODS: During a 4 year period until December 2001, in 66 neurologically stable patients suffering a nondisabling stroke ipsilateral to a carotid artery stenosis > 50% CEA was performed after a median interval of 10 (1-28) days. The modified Rankin scale (mRS) was applied to characterize the severity of impairment of daily living activities pre- and postoperatively: Any postoperative deterioration > 24 hours on the mRS was considered as a new stroke. RESULTS: Operative mortality was 0%, and postoperative neurologic worsening > 24 hours occurred in 8/66 patients (12.1%). In 5/8 patients neurologic deterioration resolved within 5 days after surgery, only one stroke was permanent (1.5%). There was no correlation between timing of surgery or the presence of acute ipsilateral cranial CT defects with the occurrence of postoperative stroke. Stroke severity grading on admission according to the mRS, however, emerged to be a significant determinant of postoperative outcome: While 6/23 patients (26%) with an initial deficit > or = 3 on the mRS developed neurologic worsening, this was the case in only 2/43 patients (4.6%) with a deficit < or = 2 (Odds Ratio 7.2; 95% CI 1.32-39.49; two-sided p = 0.01). CONCLUSION: Our results suggest that selected patients with a minor stroke (mRS < or = 2 on admission) can safely undergo early CEA.

Aged↗
PubMed2004

Transperitoneal versus retroperitoneal approach for treatment of infrarenal aortic aneurysms: is one superior?

BACKGROUND: As endovascular treatment of asymptomatic infrarenal abdominal aortic aneurysm (AAA) increasingly competes with surgical repair, it is necessary to optimize the surgical technique. The aim of this study was therefore to evaluate the superiority of either retroperitoneal (RP) or transperitoneal (TP) approach. PATIENTS AND METHODS: Intra- and peri-operative data from 80 patients with infrarenal AAA and tube graft repair were analysed retrospectively. The RP-approach was used in 37 patients and in 43 the transperitoneal. RESULTS: There was no relevant difference in demographic data and anaesthetic regime; exceptions were differences between the two groups in terms of age (median RP 72.31 vs. TP 68.58 years, p = 0.0174), hypertension (RP 26/37 vs. TP 40/43, p = 0.0019), smoking (RP 25/37 vs. TP 38/43, p = 0.0462), pulmonary diseases (RP 15/37 vs. TP 7/43, p = 0.0232), and previous abdominal surgery (RP 3/37 vs. TP 12/43, p = 0.042). No patient died during the first 30 post-operative days. The RP-group had a longer cross-clamping time (median RP 50 vs. TP 45 min, p = 0.0115) but no difference was found in operating time. Intra-operative blood loss was higher in the RP-group (median RP 800 vs. TP 500 ml, p = 0.033) with an increased need for blood substitutes (median RP 1 vs. TP 0 packed red cells, p = 0.0068). Time spent in ICU was shorter (median RP 24 vs. TP 46 hours, p = 0.0104), but duration of hospitalisation was longer for the RP-group (median RP 13 vs. TP 10.5 days, p = 0.0156). No differences were found in the need for analgesics, the frequency of procedure related complications, and post-operative recovery. CONCLUSIONS: Surgical repair of AAA in selected patients by tube graft placement is a safe procedure independent of the approach. In particular, our findings do not support previously reported superiority of the RP-approach.

Aged↗
PubMed2004

Extramedullary vs medullary relapse after autologous or allogeneic hematopoietic stem cell transplantation (HSCT) in multiple myeloma (MM) and its correlation to clinical outcome.

Risk-adapted treatment of multiple myeloma (MM) includes autologous (auto-) and allogeneic (allo-) hematopoietic stem cell transplantation (HSCT). Case reports on extramedullary (EM) compared to bone marrow (BM) relapse after HSCT suggest a dismal prognosis. We compared the outcome of 78 MM patients relapsing after auto- (group A: n = 53) or allo- (group B: n = 25) HSCT, stratified into BM (64 patients) vs EM (14 patients) relapse. The relapse-specific groups were also compared with respect to risk factors, including age, beta2-microglobulin, pretreatment, cytogenetics and stage. EM relapse sites were lungs (5), soft tissue (4), pericardium (2), bone (1), skin (1) and CNS (1). As of May 2004, the overall (OS) and progression-free (PFS) survival after HSCT in patients relapsing from EM sites was not significantly different from BM relapse patients, both after auto- and allo-HSCT. Although MM patients relapsing from EM sites after allo-HSCT used to be regarded as having few therapeutic options, we observed encouraging responses to donor lymphocyte infusions (DLI). Treatment responses to DLIs were observed in 5/9 (56%) BM relapse patients, and in 3/4 (75%) EM relapse patients. These observations suggest that EM relapse after HSCT is common and needs an individualized diagnostic and therapeutic approach in MM during clinical follow-up after HSCT.

Adult↗
PubMed2004

[Impaired cerebral autoregulation in asymptomatic patients with carotid artery stenosis: comparison of acetazolamide-SPECT and transcranial CO(2)-dopplersonography].

PURPOSE: The indication for operation in patients with asymptomatic high-grade carotid artery stenosis is still under debate. Since impaired cerebrovascular autoregulation is associated with an increased risk for ischaemic events, assessment of cerebral vascular reactivity might be a valuable selection criterion for surgery. The aim of our study was therefore to evaluate the incidence of impaired autoregulation in asymptomatic patients with acetazolamide-single photon emission computed tomography (ACZ-SPECT) and transcranial CO (2)-dopplersonography (CO (2)-TCD). Furthermore, both methods were compared in regard to results and clinical practicability. METHODS: In 42 patients with high-grade (> 70 %) asymptomatic carotid artery stenosis, cerebral perfusion and vascular reactivity were assessed with resting and ACZ-enhanced SPECT scans. In 31 of these patients the CO (2) reactivity of cerebral perfusion was determined by TCD and expressed as normalized autoregulation reserve (NAR). RESULTS: Cerebral perfusion was decreased in 14.3 %. In ACZ-SPECT 26 % and in CO (2)-TCD 28 % revealed an impaired vascular reactivity. Conformity of both methods was high (kappa = 0.93). TCD was superior in practicability, but only applicable in 81 % due to a missing temporal bone window for insonation. CONCLUSION: In accordance ACZ-SPECT and CO (2)-TCD could detect impaired vascular reactivity in a quarter of asymptomatic patients. Both TCD and SPECT could be of value for preoperative selection in this group of patients, whereby sonography is recommended for daily diagnostic work-up.

Acetazolamide↗
PubMed2003

Cerebral vascular reactivity response to anaesthetic induction with propofol in patients with intracranial space-occupying lesions and vascular malformations.

BACKGROUND AND OBJECTIVE: In clinical trials, autoregulation and carbon dioxide reactivity are preserved during propofol anaesthesia. Paradoxical increases of blood flow velocity during induction of anaesthesia could be demonstrated in patients with brain tumours. This study evaluates the effects of propofol on cerebral blood flow velocity in patients undergoing surgery for brain tumours and vascular malformations. METHODS: Changes in cerebral blood flow velocity after the administration of propofol were assessed using bilateral 2 MHz transcranial Doppler probes in 47 patients undergoing surgery for brain tumours and in 22 patients undergoing surgery for aneurysms and angiomas. RESULTS: Flow reduction after propofol was slightly less pronounced on the side of the tumour; in patients with cerebrovascular lesions, no difference between the two sides was detectable. After the administration of propofol a flow increase was present on the side of the tumour in 2 patients. In 3 patients with angiomas, the flow decrease after the administration of propofol was less pronounced on the side of the angioma. Neither observation gave statistical proof of abnormality. CONCLUSIONS: The flow changes after propofol may give a hint of cerebrovascular reactivity. Further investigations should focus on combined measurements of cerebral autoregulation and carbon dioxide reactivity and should focus on patients with impaired consciousness to test for reliability.

Adolescent↗
PubMed2003

Telomere dynamics in childhood leukemia and solid tumors: a follow-up study.

Telomeres of hematopoietic cells shorten with age, possibly contributing to the aging-associated hematopoietic pathology (immunosenescence, malignant transformation). Accelerated telomere shortening is seen with replicative stress, such as during administration of serial chemotherapy cycles for the treatment of childhood cancer. To define the long-term consequences of pediatric cancer treatment on hematopoietic cell telomere length, we undertook a prospective 4-year follow-up study of a 61-patient cohort of pediatric malignancies in a community-based setting. We found that mononuclear cells (MNC) and granulocytes of children with standard-risk acute lymphoblastic leukemia (ALL) suffered minimal telomere shortening throughout therapy (less than 1 kbp; average follow-up, 20 months), while those of children with solid tumors showed greater and more heterogenous telomere attrition (0.5-2.8 kbp, average follow-up, 9 months). In addition, we evaluated the role of telomerase, the enzyme commonly up-regulated in pediatric leukemic and solid tumor cells for telomere length maintenance, as a disease marker. Serial determinations of telomerase in MNC were useful to confirm disease remission in leukemia, but play no role in the follow-up of children with solid tumors.

Adolescent↗
PubMed2003

Differences in hamstring muscle stretching of elite field hockey players and normal subjects.

OBJECTIVES: To investigate differences in stretching behaviour of hamstring muscles in elite field hockey players and normal subjects. METHODS: 16 normal healthy subjects (group A) and 16 elite field hockey players (group B). Stretching of the hamstrings was performed with a knee extension device. Two successive single stretches (1 and 2) until the maximum stretch tolerance was achieved were applied to each subject twice. Simultaneously range of movement (ROM), passive resistance to stretch (PRS) at 36 degrees ROM, and electromyographic (EMG) activity of the biceps femoris and semitendinosus muscles were recorded. RESULTS: ROM (p=0.02 for stretch 1; p=0.04 for stretch 2) and PRS (p=0.04 and p=0.03) were significantly higher in group B, as compared to group A. The EMG activity of the biceps femoris (p=0.02 for stretch 1; p=0.3 for stretch 2) and semitendinosus (p=0.03 and p=0.11) were significantly higher in group B only for stretch 1. From stretch 1 to 2, a significant increase in ROM was observed in both group A (p=0.002) and group B (p=0.0003), as well as a significant decrease of PRS (p=0.0002; p=0.002). EMG activity only showed a significant decrease in group B (biceps p=0.03;semitendinosus p=0.01), but not in group A (p=0.6; p=0.06). The EMG activity sets in when the subjects begin to perceptive pain in the stretched muscles. CONCLUSIONS: Significant differences exist. in the stretching behaviour of elite field hockey players and non-athletes. ROM, PRS and EMG activity are higher in athletes. Implications for treatment should be considered, but recommendations cannot be made on the basis of this study yet.

Adult↗
PubMed2003

Muscle cell-mediated gene delivery to the rotator cuff.

Rotator cuff lesions are one of the most common causes of upper extremity disability. Surgical therapy addresses mostly the extrinsic etiology, but not intrinsic factors such as aging, structural changes, low vascularity, and inflammatory processes. In this study, genetically engineered, highly purified muscle-derived cells (MDCs) were characterized and injected into the supraspinatus tendons of nude rats. The injected cells were monitored for 3 weeks. In vitro, the engineered, highly purified MDCs do not express vimentin; 98% of them are positive for the beta-galactosidase marker gene, and 99% hybridize with the specific pancentromeric mouse probe. beta-Galactosidase marker gene expression of the injected cells was detected up to 21 days. From day 7 after injection, the cell nuclei became spindle shaped, cells were integrated into the tendon collagen bundles, and the cells showed differentiation into vimentin-expressing fibroblastic cells. The results indicate that the rotator cuff tendon matrix and its original cellular components modulated the injected MDCs toward a fibroblastic phenotype. The compatibility and ability of MDCs to differentiate into other cell lineages, such as fibroblasts, might have high potential utility in tissue-engineering applications for tendon healing. This approach facilitates the application of muscle-derived progenitor cells and ex vivo gene therapy for the treatment of rotator cuff lesions.

Animals↗
PubMed2003

Identification of milling parameters for manual cutting of bicortical bone structures.

Within the framework of the development of a new neurosurgical robot system, parameters of conventional manual neurosurgical bone milling had to be determined. These results were used as a reference for the design and validation of the robotic versus manual milling task. Bovine scapulae were used for the tests because their bicortical structure is similar to the bone structure of the skull. The exercise was to cut defined geometries that had been registered on the bone prior to the start of the milling operation. The geometries had to be milled with a depth of 3 mm, which corresponded to the radius of the ball of the cutter. Different parameters like tool position, rotary speed, temperature, forces and time were registered. Eleven experienced neurosurgeons with practical experience of 80-1200 skull operations participated in this study. First results show a large variation in depth along the line. The lateral deviation was up to 5 mm, the depth error up to 2.5 mm, the tool temperature was 22 degrees C to 65 degrees C, and rotary speed varied from 15,000 to 80,000 rpm. Registered forces had maxima of 16 N in the feed direction and 21 N normal to the surface; average forces were approximately 1-2 N.

Animals↗
PubMed2002

[Rehabilitation after anterior cruciate ligament reconstruction].

The "Frankfurt rehabilitation regimen" following anterior cruciate ligament reconstruction is presented. ACL rehabilitation is discussed in the light of knowledge on knee biomechanics and proprioception as well as clinical results of reconstruction. Special emphasis is given to exercise therapy.

Anterior Cruciate Ligament↗
PubMed2002

CD34(+) or CD34(-): which is the more primitive?

Remarkable progress has been achieved in the characterization and isolation of primitive hematopoietic stem cells (HSC). HSC represent a very small subset of hematopoietic cells and provide self-renewal, possess differentiation capacity and allow a constant supply of the entire hematopoietic cell spectrum. Until recently, CD34 has been used as a convenient marker for HSC, since CD34(+) cells have been shown to possess colony-forming potential in short-term assays, maintain long-term colony-forming potential in in vitro cultures and allow the expression and differentiation of blood cells from different hematopoietic lineages in in vivo models. Clinical and experimental protocols have targeted CD34(+) cells enriched by a variety of selection models and have readily used these for transplantation, purging and gene therapies and targets for future organ replacement. Recent studies in murine and human models, however, have indicated that CD34(-) HSC exist as well, which possess engraftment potential and distinct HSC characteristics. These studies challenge the dogma that HSC are uniformly found in the CD34(+) subset, and question whether primitive HSC are CD34(+) or CD34(-). In this review, results on murine and human CD34(+) and CD34(-) HSC, differences between them and their possible interactions are examined.

Animals↗
PubMed2002

Manifestation of Y-chromosomal deletions in the human testis: a morphometrical and immunohistochemical evaluation.

BACKGROUND: Deletions of the AZF (azoospermia factor) subregions on the Y chromosome are accompanied by a diverse spectrum of spermatogenic disturbances ranging from hypospermatogenesis to total depletion of germ cells causing infertility. The AZF region encodes gene products which are candidates for the genetic control of spermatogenesis. Although it is known which genes are involved, a general principle of cause and effect cannot yet be deciphered and the deletion type has non-uniform histological phenotypes. METHODS AND RESULTS: We analysed morphological parameters of testicular biopsies from 17 patients diagnosed for Y chromosome microdeletions. As control groups we analysed testes from patients with idiopathic Sertoli cell-only (SCO) syndrome (n = 11), mixed atrophy (n = 10) and complete spermatogenesis (n = 11). A detailed genetic analysis on the extension of the observed microdeletions revealed similar breakpoints in the distal and proximal region of the AZFc region, indicating a common mechanism of homologous recombination for such deletions, as has been suggested before. Morphometric parameters such as the diameter of the tubules, lumen, thickness of the lamina propria and height of the tubule epithelia were investigated. The diameter of the tubules from patients with microdeletions was found to be significantly smaller compared with patients with mixed atrophy. Considering also the size of the tubules, lumen and epithelia, a Y-chromosomal microdeletion represents an intermediate state between an idiopathic SCO and normal spermatogenesis. The immunohistochemical analysis of six different Sertoli cell markers, cytokeratin 18, vimentin, inhibin alpha subunit, 14-3-3 theta, FSH receptor and androgen receptor, revealed no impact of AZF deletion on the specific expression pattern of these genes. CONCLUSIONS: Our results suggest that, notwithstanding the deletion of a common region in the AZFc region, microdeletions of the Y chromosome lead to an intermediate status between idiopathic SCO and complete spermatogenesis, resulting in a heterogeneous histological profile regardless of the seminiferous activity. The Sertoli cell function seems not to be altered.

Adult↗
PubMed2002

[Osseous processes of the skull--analysis of requirements for robot-assisted surgery].

To design a roboter-assisted trepanation setting of the cranium, an evaluation was done to classify patients with osseous lesions according to pathologies, dimensions and localisations. Emphasis was laid on dimensions and localisation of the pathology to gain information on future configurations of work spaces for robotics in the neurosurgical operation room. All patients with surgery of osseous lesions of the cranium in the years 1993-2001 were evaluated retrospectively. Localisations, dimensions of trepanation and histologic results were evaluated.

Adult↗