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Biomedical subjects

E Behrens

Publications and source records attributed to E Behrens.

At least 19 recordsLinked to original sources
PubMed1999

C6 produced by macrophages contributes to cardiac allograft rejection.

The terminal components of complement C5b-C9 can cause significant injury to cardiac allografts. Using C6-deficient rats, we have found that the rejection of major histocompatibility (MHC) class I-incompatible PVG.R8 (RT1.A(a)B(u)) cardiac allografts by PVG.1U (RT1.A(u)B(u)) recipients is particularly dependent on C6. This model was selected to determine whether tissue injury results from C6 produced by macrophages, which are a conspicuous component of infiltrates in rejecting transplants. We demonstrated that high levels of C6 mRNA are expressed in isolated populations of macrophages. The relevance of macrophage-produced C6 to cardiac allograft injury was investigated by transplanting hearts from PVG. R8 (C6-) donors to PVG.1U (C6-) rats which had been reconstituted with bone marrow from PVG.1U (C6+) rats as the sole source of C6. Hearts grafted to hosts after C6 reconstitution by bone marrow transplantation underwent rejection characterized by deposition of IgG and complement on the vascular endothelium together with extensive intravascular aggregates of P-selectin-positive platelets. At the time of acute rejection, the cardiac allografts contained extensive perivascular and interstitial macrophage infiltrates. RT-PCR and in situ hybridization demonstrated high levels of C6 mRNA in the macrophage-laden transplants. C6 protein levels were also increased in the circulation during rejection. To determine the relative contribution to cardiac allograft rejection of the low levels of circulating C6 produced systemically by macrophages, C6 containing serum was passively transferred to PVG.1U (C6-) recipients of PVG.R8 (C6-) hearts. This reconstituted the C6 levels to about 3 to 6% of normal values, but failed to induce allograft rejection. In control PVG.1U (C6-) recipients that were reconstituted with bone marrow from PVG.1U (C6-) donors, C6 levels remained undetectable and PVG.R8 cardiac allografts were not rejected. These results indicate that C6 produced by macrophages can cause significant tissue damage.

Animals↗
PubMed1998

[Solid craniopharyngioma in the 3rd ventricle--differential diagnostic aspects].

We report on a 54-year-old man with a solid craniopharyngioma in the third ventricle. Differentiation from a meningeoma was possible by visualization of a small cystic component in the suprasellar cistern and a central hypodensity/ hypointensity on CT and MRI, respectively. The latter seems to be a rather typical finding. Considering the differential diagnosis of tumors within the third ventricle, it must be emphasized that tumors arising within the ventricle are rare and invasion from primary extraventricular tumors is more common. A craniopharyngioma of the papillary type often has the typical imaging appearance described above.

Cerebral Ventricle Neoplasms↗
PubMed1997

Surgical and neurological complications in a series of 708 epilepsy surgery procedures.

OBJECTIVE: There are few modern data on the complications of surgery for epilepsy from the neurosurgeon's point of view. A survey of complications observed in a large current epilepsy surgery series is presented to facilitate the assessment of a risk:benefit ratio, which must be known when planning for epilepsy surgery and counseling patients. METHODS: A series of 429 consecutive patients operated on during 6.5 years in the newly established University of Bonn epilepsy surgery program was, in part, retrospectively, and, in larger part, prospectively analyzed for complications originating from 279 invasive diagnostic procedures and 429 therapeutic procedures. Neuropsychological and psychiatric complications as well as the rate of failure to control seizures are not addressed in this article. RESULTS: Two hundred and seventy-nine temporal operations, 59 frontal operations, 22 other extratemporal operations, 33 callosotomies, 3 multilobectomies, and 33 hemispherectomies were performed. Complications were grouped into general surgical and neurological complications. No mortality resulted from 708 invasive procedures. Two hundred and seventy-nine invasive diagnostic procedures (various combinations of strip, grid, and depth electrode insertions) resulted in 3.6% transient morbidity (2.9% surgical complications, 0.7% neurological complications) and 0.7% permanent morbidity (dysphasia). During 429 therapeutic procedures, 33 surgical complications were encountered. None of these resulted in permanent morbidity, except for the necessity for permanent shunt insertion in three patients. Wound infection was the most frequent surgical complication, but we were able to demonstrate a steady decrease during the 6.5-year observation period. The total rate of neurological complications in 429 therapeutic procedures was 5.4%, with 3.03% causing transient morbidity and 2.33% causing permanent morbidity. CONCLUSION: Our data indicate that epilepsy surgery can be performed with an acceptable rate of resultant morbidity. The indications for epilepsy surgery, the learning curve determined, and the results from other series are discussed in the light of these figures.

Adolescent↗
PubMed1997

Surgical treatment of neoplasms associated with medically intractable epilepsy.

OBJECTIVE: Surgical treatment in patients with brain tumors and medically intractable epilepsy is aimed at the removal of the neoplasm and complete seizure control. However, an adequate surgical approach is still controversial. This study was designed to analyze the factors for the optimum surgical treatment of these patients. METHODS: The clinical, electrophysiological, operative, and histopathological data of 146 consecutive patients who underwent surgery between November 1987 and May 1995 for intrinsic brain tumors and pharmacoresistant epilepsy were evaluated. RESULTS: The majority of the tumors were located in the temporal lobe (n = 116) and involved the cortical gray matter. The most frequent tumors were gangliogliomas (n = 65), pilocytic astrocytomas (n = 21), and dysembryoplastic neuroepithelial tumors (n = 19). All but three tumors (98%) were of low histopathological grade (World Health Organization Grades I or II). The biological behavior of the tumors was strikingly indolent, as indicated by a long preoperative history of chronic seizures (mean, 14 yr). In all cases, complete resection of the tumor, including the epileptogenic area (as determined by noninvasive and/or invasive recordings of the zone of seizure onset and persistent interictal activity), was intended. Complications were encountered in 11 cases (8%). However, no patient died and there was no permanent morbidity. Of the 124 patients who had postoperative follow-up examinations more than 6 months after resection, 71% were seizure-free, 11% had no more than two seizures per year, 13% showed a reduction of seizure frequency of at least 75%, and 5% had no appreciable reduction in seizure frequency. CONCLUSION: The data indicate that neoplasms associated with medically intractable epilepsy constitute a distinct clinicopathological group of tumors that arise in young hosts, involve the cortex, and exhibit indolent biological behavior for many years. Complete surgical removal of these tumors, including the epileptogenic area, can achieve excellent seizure control.

Adolescent↗
PubMed1996

Surgical treatment of extratemporal epilepsy: clinical, radiologic, and histopathologic findings in 60 patients.

PURPOSE AND METHODS: The aim of this study was to analyze clinical, radiologic, and histopathologic findings in 60 consecutive patients with medically intractable extratemporal epilepsy who were operated on between November 1987 and May 1993. RESULTS: Histologically, there were distinct structural abnormalities in 50 (83%) of the surgical specimens. Signal abnormalities on magnetic resonance imaging (MRI) were present in all patients with neoplastic lesions (n = 17) and in 94% of patients with nonneoplastic focal lesions (n = 32). Overall, structural abnormalities were detected by MRI in 47 (96%) of 49 patients with focal lesions. During a mean follow-up of 4 years, 30 (54%) patients remained completely seizure free, 11 (20%) had < or = 2 seizures per year, seven (12%) showed a seizure reduction of > or = 75%, and eight (14%) had < 75% reduction in seizure frequency. The fraction of seizure-free patients was 12 (80%) of 15 in patients with neoplastic lesions, 16 (52%) of 31 in patients with nonneoplastic focal lesions, and two (20%) of 10 for those without histopathologic abnormalities. The differences in seizure outcome between patients with and without focal lesions were statistically significant (p < 0.05), if seizure-free outcome was compared with persistent seizures. CONCLUSIONS: Focal lesions and particularly neoplasms are associated with improved postoperative seizure control compared with patients without histopathologic abnormalities. We advise caution in considering surgery to treat extratemporal epilepsy in patients who have normal MRI scans, because the outcome with the approach described in this study is poor in such cases.

Adolescent↗
PubMed1995

Percutaneous needle trephination for external CSF drainage: experience with 226 punctures.

We report on our experience with 226 percutaneous needle trephinations in a total of 192 consecutive patients. Trephination was performed with a hand-driven drill. A special puncture needle was inserted into the anterior horn of the lateral ventricle. The main indication for this procedure was the treatment of occlusive hydrocephalus in an emergency. Duration of drainage ranged from 1 to 34 days and was 7 days on the average. We encountered 14 cases of infection (6.2%) and one case of symptomatic bleeding (0.4%). All these complications eventually resolved without permanent sequelae. In our opinion, ventricle puncture with this device is a simple and effective method and can especially be recommended for external CSF drainage in cases of emergency.

Adolescent↗
PubMed1995

Surgical treatment of temporal lobe epilepsy: clinical, radiological, and histopathological findings in 178 patients.

The surgical treatment of pharmacoresistant temporal lobe epilepsy is increasing rapidly. The correlation of preoperative MRI, histopathological findings, and postoperative seizure control is reported for 178 patients with chronic medically intractable temporal lobe epilepsy who were operated on between November 1987 and January 1993. Histopathologically there were distinct structural abnormalities in 97.2% of the surgical specimens. Signal abnormalities on MRI were present in 98.7% of patients with neoplastic lesions (n = 79), 76.6% of patients with non-neoplastic focal lesions (n = 55), and 69.2% of patients with Ammon's horn sclerosis (n = 39). Overall, structural abnormalities were detected by MRI in 82.7% of all patients. The mean postoperative follow up period was three years. Some 92% of the patients benefited from surgery: 103 patients (61.7%) were seizure free, 26 (15.5%) had no more than two seizures a year, and 24 (14.4%) showed a reduction of seizure frequency of at least 75%. Fourteen patients (8.4%) had a < 75% reduction of seizure frequency. The percentage of patients who were completely free of seizures after operation was 68.5% for patients with neoplastic lesions, 66.7% for Ammon's horn sclerosis, and 54.0% for patients with non-neoplastic focal lesions. By contrast, none of the patients in whom histopathological findings were normal became seizure free postoperatively. The data show that the presence of focal lesions or Ammon's horn sclerosis as determined by histopathological examination is associated with improved postoperative seizure control compared with patients without specific pathological findings. Brain MRI was very sensitive in detecting neoplasms; however, its sensitivity and specificity were limited with respect to non-neoplastic focal lesions and Ammon's horn sclerosis. Improvement of imaging techniques may provide a more precise definition of structural lesions in these cases and facilitate limited surgical resections of the epileptogenic area rather than standardised anatomical resections.

Adolescent↗
PubMed1995

Hemispherical deafferentation: an alternative to functional hemispherectomy.

An alternative technique for so-called functional hemispherectomy has been developed to be used for the classical indications of hemispherectomy or the various modifications of functional hemispherectomy. The technique entails a smaller trepanation, less operation time, and less blood loss, and it leaves more brain tissue in place as compared with other functional hemispherectomy techniques. It starts with either hippocampectomy alone or with hippocampectomy and anterior temporal lobectomy. After this, deafferentation of the white matter of the temporal, occipital, parietal, and frontal lobe, using either a transcortical transventricular approach along the outline of the lateral ventricle or a sylvian key hole approach, is performed. The technique includes a transventricular callosotomy, and it leaves in place only a small portion of the suprainsular cortex and the insular cortex. However, as one modification, removal of the insular cortex can easily be performed, if necessary, and, as a second modification, the entire transventricular deafferentation can be performed through a sylvian key hole. In this report, the technique is described and the surgical experience for the first 13 patients is outlined. The immediate seizure relief with an average follow-up of 12 months was similar to that for patients with functional hemispherectomy, but the follow-up period for these 13 patients is not long enough to allow definite conclusions concerning long-term control of seizures and long-term complications.

Adolescent↗
PubMed1994

Subdural and depth electrodes in the presurgical evaluation of epilepsy.

From 1987 to 1992, invasive EEG studies using subdural strips, grids or depth electrodes were performed in a total of 160 patients with medically intractable epilepsy, in whom scalp EEG was insufficient to localize the epileptogenic focus. Dependent on the individual requirements, these different electrode types were used alone or in combination. Multiple strip electrodes with 4 to 16 contacts were implanted in 157 cases through burrholes, grids with up to 64 contacts in 15 cases via boneflaps, and intrahippocampal depth electrodes in 36 cases using stereotactic procedures. In every case, localization of the electrodes with respect to brain structures was controlled by CT scan and MRI. Visual and computerized analysis of extra-operative recordings allowed the localization of a resectable epileptogenic focus in 143 patients (89%), who subsequently were referred for surgery, whereas surgery had to be denied to 17 patients (11%). We did not encounter any permanent morbidity or mortality in our series. In our experience, EEG-monitoring with chronically implanted electrodes is a feasible technique which contributes essentially to the exact localization of the epileptogenic focus, since it allows nearly artefact-free recording of the ictal and interictal activity. Moreover, grid electrodes can be used for extra-operative functional topographic mapping of eloquent brain areas.

Adolescent↗
PubMed1993

[Primary intracerebral non-Hodgkin's lymphoma--a clinicopathologic study].

Primary cerebral lymphomas (PCL) were diagnosed with increasing frequency also in our retrospective study of 44 patients. Clinically these tumors presented with signs of a rapidly growing brain neoplasm. The analysis of CCT data showed that the tumors were of varying density before and showed mostly (60%) homogeneous enhancement after contrast medium application. MR imaging was more sensitive, but could not aid in distinguishing PCL from other brain tumors. The lesions lay mainly (82%) in the supratentorial space and involved the frontal lobe in 42% of cases. Only 16% were located in the periventricular region including corpus callosum and basal ganglia. 20% of cases showed multiple lesions. Suspected diagnoses were therefore mainly meningeoma, glioma and metastases. Morphological diagnosis was easily possible with the aid of immunohistological methods: there were 41 B-cell lymphomas (93%), two T-cell lymphomas and one large cell anaplastic lymphoma of the non-B non-T phenotype. An unequivocal correlation between morphology and radiological picture existed in the way that tumors with a dense cellular infiltrate appeared mainly as hyperdense lesions with homogeneous contrast enhancement. The clinical course was characterized by CNS-relapses frequently with multiple cerebral lesions and a spinal recurrence in one case. 7% of cases showed evidence of extracerebral disease in a bone marrow biopsy specimen or at autopsy. The average survival of the patients was 15 months, one year survival was 36%, two year survival 12% and 5% of patients lived for more than 5 years.

Adult↗
PubMed1993

Equine cricoid cartilage densitometry.

The density of the cricoid cartilage from 29 equine larynges collected from an abattoir was determined by dual photon absorptiometry (DPA). Densities of the right and left cricoid cartilages were highly correlated. No correlation was found between age of the horse and the density of the cricoid cartilage.

Absorptiometry, Photon↗
PubMed1987

[Interrater reliability of a German version of the "International Classification of Impairments, Disabilities, and Handicaps (ICIDH)" of the World Health Organization].

A German version of the "International Classification of Impairments, Disabilities, and Handicaps (ICIDH)" edited by the World Health Organization (1980) has tested in respect to the interrater reliability. The investigation was carried out with 36 staff members from three rehabilitation institutions for the blind or partially sighted, who rated in pairs a visually impaired child or adult with the classification system. The calculation of the interrater reliability was based both on the method of the relative agreement between the raters and on the measure "kappa". Altogether, the KAPPA-calculation yielded unsatisfactory interrater agreements. The reasons for the low reliability figures can be seen on one hand in the classification system itself, on the other hand in motivational barriers within the group of raters. The investigation however also indicates, that by modifying the classification system and by intensively training the raters, improvement concerning the reliability figures can be expected.

Blindness↗
PubMed1985

Urokinase therapy for Silastic catheter-induced intravascular thrombi in infants and children.

Among the serious complications encountered with long-term, indwelling Silastic central venous catheters are catheter-induced intravascular thrombi. These thrombi are usually treated by removal of the catheter to prevent thrombus propagation, embolization, or infection. We treated ten patients with urokinase infusion who had experienced 12 incidents of induced intravascular thrombi. Catheter phlebography and two-dimensional echocardiography were used for diagnosis and follow-up. Eleven of the 12 episodes were treated successfully, with complete dissolution of the thrombus. One patient with a calcific thrombus had only partial clot lysis and required catheter removal. By utilizing urokinase infusion to treat Silastic catheter-induced intravascular thrombi, nine of ten central venous catheters were preserved and the possible need for thrombectomy was averted. No serious complications were encountered. In our experience, urokinase therapy has been an effective and safe method for treating Silastic catheter-induced intravascular thrombi.

Catheters, Indwelling↗