Biomedical subjects

C Schaller

Publications and source records attributed to C Schaller.

At least 19 recordsLinked to original sources

PubMed2003

Hippocampal function and visual object processing in temporal lobe epilepsy.

Limbic event-related potentials related to verbal but not to visual recognition memory have been found to be attenuated within the epileptic hippocampus of patients with temporal lobe epilepsy (TLE). To identify hippocampal contributions to visual processing and memory we recorded intracranial ERPs directly from within the epileptic and the non-epileptic hippocampus in 12 patients with unilateral TLE during a visual object decision and naming task. While the non-epileptic hippocampus differentiated reliably between real and nonsense objects, this effect was completely eliminated within the epileptic mesial temporal lobe. This finding suggests that the hippocampus proper contributes to the semantic processing of visual objects and may help to explain visual memory deficits in TLE.

Adult↗

PubMed2003

[Dangers in skiing].

The current study deals with the results of the examination of 685 patients, who were treated in the department of traumatology in the KKH Garmisch-Partenkirchen during the winter season 99/00 and 00/01. The study included 259 injured carvers (120 female, 139 male) with an average age of 33.9 years and 426 injured conventional skiers (212 female, 214 male) with an average age of 33.2 years. The aim of the investigation was to compare both ski groups concerning injuries, the pathomechanism and the skiing experience. The results of the investigation showed that the knee injuries of carvers were more severe than in the conventional skiers. The difference was significant (p < 0.05).

Adult↗

PubMed2002

Results for microsurgical removal of tentorial meningiomas.

OBJECTIVE: Growth patterns of tentorial meningiomas are related to the deep cerebral venous system and to cranial nerves IV-XI. Localization and surgical aggressiveness are decisive for the outcome to be expected. PATIENTS AND METHODS: n = 25 patients (22 f, 3 m), aged from 26-77 (mean: 56.4) years underwent microsurgical removal of their tentorial meningioma. Tumor size was as follows: n = 11 < 3 cm, n = 6 3-5 cm, n = 8 > 5 cm. The median of the preoperative Karnofsky scores was 90. The operative approaches chosen were suboccipital in n = 14, subtemporal in n = 6, occasionally a combined supra- and infratentorial approach was chosen. Data regarding surgery, histology and postoperative course were available through the patient's charts and through outpatient clinic. RESULTS: n = 20 (80%) of the tumors were rated WHO grade I, n = 5 (20%) WHO grade II. Tumor removal according to Simpson was degrees I in n = 9 (36%), degrees II in n = 14 (56%), degrees III in n = 2 (8%). Mortality was 0%. In n = 6 patients (24%) neurological worsening, mainly due to transient cranial nerve deficits was noted. Surgical complications (CSF fistula, wound healing problems) occurred in n = 5 patients (20%). The median of the postoperative Karnofsky scores on last follow up was 90 after a median of 41.9 months. Two patients (8%), one of whom underwent reoperation developed tumor recurrency during follow up. CONCLUSIONS: Neurological deficits following microsurgical removal of tentorial meningiomas are transient in the majority of patients. The apparently high rate of incomplete tumor resection (app. 60% Simpson grades II and III) is due to the close topographical relationship of these tumors with important neurovascular structures. Thus, the operative strategy should not be excessively aggressive, but rather take into account the option to observe residual tumor or to apply additional stereotactic convergent beam radiation in selected cases.

Adult↗

PubMed2002

Vertebral artery injury after cervical spine trauma: a prospective study.

OBJECTIVES: Vertebral artery (VA) -injury is rarely symptomatic and can therefore easily be overlooked. However, thromboembolic complications may result in permanent morbidity or mortality due to brainstem ischemia and infarction. In this prospective study a standardized protocol for the diagnosis and management of VA-injury following blunt cervical spine trauma with subluxation or fractures affecting the transverse foramen was evaluated. METHODS: During a 48 months period 31 (12 female, 19 male; mean age 44.2 years) of 119 patients with blunt cervical spine trauma were suspicious for VA-injury and subjected to a predefined radiological work-up. Selective digital subtraction angiography (DSA) was performed at admission in 31 patients. For comparison magnetic resonance angiography (MRA) was added within 2 days in 7 patients. RESULTS: The incidence of VA injury detected by DSA (n = 5) was 4% in all types of blunt cervical spinal injury, 16% in cases suspicious for VA injury, i.e. cases with mono- or bifacet dislocation and/or cases with fractures extending into the transverse foramen. Unilateral VA-stenosis was found in 4 and VA-occlusion in one patients. In one case a VA-stenosis by an intimal flap after transverse foramen fracture was detected by DSA but not by MRA. In 2 patients with VA injury headache occurred without signs of vertebro-basilar insufficiency. All 5 patients with VA-injury were treated with anticoagulation without complications or side effects. 14 of 31 patients which had DSA/MRA had unstable spine conditions and were treated surgically within 4 days after admission. CONCLUSION: The subgroup of patients with dislocation or fracture related stenosis of the transverse foramen should undergo early angiography for establishment of anticoagulation to prevent thromboembolic complications. It appears that the radiological diagnosis of VA-insufficiency is more sensitive than clinical findings, which rarely indicate VA-insufficiency. In this series one VA injury was overlooked with MRA.

Adolescent↗

PubMed2001

SorCS1, a member of the novel sorting receptor family, is localized in somata and dendrites of neurons throughout the murine brain.

The expression of the sorCS1 protein in the central nervous system of adult mice was studied by immunohistochemistry. A detailed mapping revealed a distribution of sorCS1 immunoreactivity in a widespread population of neurons throughout the brain. Two different types of cellular localization were observed. Many neurons exhibited a punctate cytoplasmic staining which extended into the dendrites, in other neurons sorCS1 immunoreactivity was associated with the plasma membrane. This suggests variable functions for sorCS1 in the neurons of the brain.

Animals↗

PubMed2001

Human herpes virus-8 is not associated with primary central nervous system lymphoma in HIV-negative patients.

Primary central nervous system lymphomas (PCNSL) are derived from germinal center B cells. Recent molecular studies indicate that the tumor cells or their precursors have experienced antigenic stimulation. Attractive candidates for such antigens are pathogens with the capacity to reside in the brain. The aim of the present study was to evaluate whether human herpes virus (HHV)-8 is involved in the pathogenesis of PCNSL. A series of 46 PCNSL, 31 from HIV-negative and 15 from HIV-positive patients, were analyzed using various molecular biological and immunological approaches. Nested PCR with two different protocols unequivocally demonstrated that PCNSL from HIV-negative patients did not harbor HHV-8 DNA. Among AIDS-associated PCNSL, HHV-8 DNA was found in only 1 tumor. In situ hybridization studies revealed that the lymphoma cells were HHV-8 negative in all cases. Single small mononuclear cells, most likely corresponding to bystander lymphocytes, were identified as the cellular source of HHV-8 in the HIV-positive patient with an HHV-8 PCR signal. These studies largely rule out a role for HHV-8 in the pathogenesis of PCNSL in both HIV-negative as well as HIV-positive patients.

Adult↗

PubMed2001

Isolation and characterisation of five neurotoxic and cardiotoxic polypeptides from the sea anemone Anthopleura elegantissima.

Five toxins (APE 1 to APE 5) of the sea anemone species Anthopleura elegantissima (Brandt) have been isolated from a toxic by-product fraction of its concentrated crude watery-methanolic extract, prepared previously for the isolation of a neuropeptide (the head-activator) by Schaller and Bodenmüller (Proc. Natl. Acad. Sci. USA 78 (1981) 7000) from 200kg sea anemones. Toxin purification was performed by desalting of the starting material by dialysis (MWCO 3500) against distilled water, anion exchange chromatography on QAE-Sephadex A25 at pH 8, twice gel filtration on Sephadex G50 m, repeated chromatography on QAE-Sephadex at pH 10 and chromatography on the cation exchanger Fractogel EMD SO(3)(-)-650 M.Final purification of the toxins was achieved by HPLC on MN SP 250/10 Nucleosil 500-5 C(18) PPN and MN SP 250/21 Nucleosil 300-7 C(18). Each toxin was composed of at least two isotoxins of which APE 1-1, APE 1-2, APE 2-1, APE 2-2 and APE 5-3 were isolated in preparative scale. With exception of APE 5-3 the sequences of the isotoxins have been elucidated. They resemble the 47 residue type-I long polypeptide toxins native to Anemonia sulcata (Pennant). All isotoxins paralyse the shore crab (Carcinus maenas) by tetanic contractions after i.m. application. The toxins modify current passing through the fast Na(+) channel in neuroblastoma cells, leading to delayed and incomplete inactivation. APE 1-1, APE 2-1 and APE 5-3 produce a positive inotropic effect in mammalian heart muscle, although they differ in potency. The order of potency is APE 2-1>APE 1-1>APE 5-3 (i.e. threshold concentrations are 1, 10 and 300nM, respectively). In addition, they enhance the spontaneous beating frequency in isolated right atria (guinea pig). The most potent cardiotoxic isotoxin is APE 2-1, its sequence is identical with that of AP-C, a toxin isolated and characterised previously by Norton et al. (Drugs and Foods from the Sea, 1978, University of Oklahoma Press, p. 37-50).LD50 APE 2-1:1 micro g/kg b.w. C. maenas (i.m.). LD50 APE 1-1:10 microg/kg b.w. C. maenas (i. m.). LD50 APE 5-3:50 microg/kg b.w. C. maenas (i.m.).

Animals↗

PubMed2001

Human memory formation is accompanied by rhinal-hippocampal coupling and decoupling.

In humans, distinct processes within the hippocampus and rhinal cortex support declarative memory formation. But do these medial temporal lobe (MTL) substructures directly cooperate in encoding new memories? Phase synchronization of gamma-band electroencephalogram (EEG) oscillations (around 40 Hz) is a general mechanism of transiently connecting neural assemblies. We recorded depth-EEG from within the MTL of epilepsy patients performing a memorization task. Successful as opposed to unsuccessful memory formation was accompanied by an initial elevation of rhinal-hippocampal gamma synchronization followed by a later desynchronization, suggesting that effective declarative memory formation is accompanied by a direct and temporarily limited cooperation between both MTL substructures.

Action Potentials↗

PubMed2001

Fixed and dilated pupils after trauma, stroke, and previous intracranial surgery: management and outcome.

OBJECTIVES: To clarify whether different causative events (trauma, stroke, intracranial surgery), time of intervention, and treatment mode influence outcome, patients with fixed and dilated pupils (FDPs) in a prospective neurosurgical series were evaluated. METHODS: Ninety nine consecutive patients who presented with or developed one or two FDPs, were split into three groups according to the respective aetiology: 46 patients had a trauma, 41 patients a stroke (subarachnoid or intracerebral haemorrhage), and 12 patients had undergone previous elective intracranial surgery. Appropriate therapy was performed depending on the CT findings. Outcome was classified according to the Glasgow outcome scale (GOS). RESULTS: Overall mortality was 75%. In 15% outcome was unfavourable (GOS 2 and 3), and in 10% favourable (GOS 4, 5) at 24 month follow up. No differences in outcome were found between trauma, stroke, and postelective surgery groups. Unilaterally FDP was associated with a better chance of survival (46% v 13%; p<0.01). Age did not correlate with survival, but younger survivors had a significantly better outcome. Patients in whom an intracranial mass was removed surgically had a 42% survival rate, compared with 8% with conservative treatment (p<0.01). Patients with a shorter delay from FDPs to intervention had a better chance of recovery after trauma and previous intracranial surgery (p<0.05). No patient survived better than a vegetative state, if previous FDPs did not become reactive shortly after therapy. If both pupils became reactive on therapy, the chance of survival was 62%. Of these survivors 42% had a favourable outcome. CONCLUSION: Bilateral restoration of pupillary reactivity shortly after therapy is crucial for survival. Surgical evacuation of an intracranial mass, unilateral FDPs, early intervention, and younger age are related to better chances of survival or recovery. The prognosis of patients with FDPs after trauma, stroke, and previous elective intracranial surgery is similar.

Adolescent↗

PubMed2001

Is stagnating flow in former feeding arteries an indication of cerebral hypoperfusion after resection of arteriovenous malformations?

OBJECT: The authors' goal in this study was to challenge the proposed mechanism of the occlusive hyperemia theory, in which it is asserted that stagnating flow in the former feeding arteries of cerebral arteriovenous malformations (AVMs) leads to parenchymal hypoperfusion or ischemia, from which postoperative edema and hemorrhage originate. METHODS: Cortical oxygen saturation (SaO2) was measured in 52 patients by using microspectrophotometry in areas adjacent to AVMs before and after resection. The appearance of the former feeding arteries was categorized as normal (Group A); moderately stagnating (Group B); and excessively stagnating (Group C) on postoperative angiographic fast-film series. Patients and SaO2 values were pooled accordingly and compared using analysis of variance and Duncan tests (p < 0.05). Angiographic stagnation times in former feeding arteries were correlated in a linear regression/correlation analysis with SaO2 data (p < 0.05). All values are given as the mean +/- standard deviation. The average median postoperative SaO2 in Group C (15 patients) was significantly higher than in Groups B (17 patients) and A (20 patients) (Group C, 75.2 +/- 8.5; Group B, 67.5 +/- 10.8; Group A, 67.1 +/- 12 %SaO2), as was the average postoperative increase in SaO2 (Group C. 25.9 +/- 14.9; Group B, 14.6 +/- 14; Group A, 11.1 +/- 14 %SaO2). Angiographically confirmed stagnation times were also significantly longer in Group C than in Group B (Group C, 5.6 +/- 2.5; Group B, 1.3 +/- 0.6 seconds). A significant correlation/regression analysis showed a clear trend toward higher postoperative SaO2 levels with increasing stagnation time. CONCLUSIONS: Stagnating flow in former feeding arteries does not cause cortical ischemia, but its presence on angiographic studies is usually indicative of hyperperfusion in the surrounding brain tissue after AVM resection. In the context of the pathophysiology of AVMs extrapolations made from angiographically visible shunt flow to blood flow in the surrounding brain tissue must be regarded with caution.

Adolescent↗

PubMed2001

[Microcirculatory changes in the development of the cerebrovascular adaptation].

Recently, long-term cerebrovascular adaptations after unilateral carotid ligation that increase the tolerance of the brain to subsequent episode of ischemia was reported(J Cereb Blood Flow Metab, 1998). However, the pathophysiological mechanisms underlying the phenomenon was unknown. We examined regional cerebral blood flow(rCBF) before, during and after subsequent ischemia in the development of the adaptation. Male Wistar rats(n = 18) were used. Unilateral(right) carotid artery ligation was performed 3 hours(group A: n = 8), 3 days(group B: n = 10) before forebrain ischemia. With bilateral carotid arteries occlusion, mean arterial blood pressure(MABP) was reduced by hypobaric hypotension down to 50 mmHg and maintained constant for 30 min. After hypotension, the experiment continued for 90 min. Local CBF were registered at 25(5 x 5) identical locations by laser Doppler scanning in the cortex during the experiment in bilateral hemispheres(at control phase, after the left carotid artery ligation, during ischemia and after hypotension). The physiological variable such as blood pressure and gas analysis were within normal range in all groups. There were no differences of rCBF between the right and left hemispheres in group A during the experiment. In group A, rCBF of both hemispheres significantly decreased after the ligation of the left carotid artery, during the induced ischemia (P < 0.05), and recovered to the value of before ischemia. Whereas, in group B rCBF of the left side(non-occluded side) decreased after the ligation of the left carotid artery, during the induced ischemia(P < 0.05), and recovered to the value of before ischemia, but rCBF of the right side(occluded side) decreased only during the induced ischemia(P < 0.05) and rCBF of the right side was significantly higher than the left brain after ligation of the carotid artery, during ischemia and after hypotension(P < 0.05). On the basis of these data, we concluded that cerebrovascular adaptations can be acquired by 3 days after unilateral carotid artery occlusion and the tolerance phenomenon is certainly attributed to microcirculatory improvement.

Animals↗

PubMed2000

Limbic encephalitis not associated with neoplasm as a cause of temporal lobe epilepsy.

OBJECTIVE: To describe four patients with temporal lobe epilepsy with limbic encephalitis unrelated to neoplasm. METHODS: The authors performed a retrospective evaluation of patient data obtained during presurgical evaluation, with additional CSF analyses, serum analyses, and histopathologic investigations. RESULTS: The patients shared the following clinical features: onset of the disease in young adulthood with subacute onset or exacerbation of frequent intractable temporal lobe seizures, verbal and visual memory deficits, and affective abnormalities. MRI showed variably extended areas of increased T2 signal in limbic structures and adjacent areas. In the histopathologic investigation, chronic inflammation was observed without evidence of a viral origin. There was no evidence of an underlying malignancy. CONCLUSIONS: Nonparaneoplastic limbic encephalitis should be included in the differential diagnosis of adult patients with temporal lobe epilepsy.

Adult↗

PubMed2000

Is there a benefit of preoperative meningioma embolization?

OBJECTIVE: To evaluate the effect of preoperative embolization of meningiomas on surgery and outcomes. METHODS: In a prospective study, 60 consecutive patients with intracranial meningiomas who were treated in two neurosurgical centers were included. In Center A, embolization was performed for none of the patients (n = 30). In Center B, 30 consecutive patients with embolized meningiomas were treated. Preoperatively, tumor size and location, neurological status, and Barthel scale score were recorded. In Center B, the extent of tumor devascularization was evaluated using angiography and postembolization magnetic resonance imaging. Intraoperatively, blood loss, the numbers of blood units transfused, and the observations of the neurosurgeon concerning hemostasis, tumor consistency, and intratumoral necrosis were recorded. Postoperatively, the neurological status and duration of hospitalization were recorded. Six months after surgery, the outcomes were assessed using the Barthel scale and neurological examinations. RESULTS: The mean tumor sizes were 22.9 cc in Center A and 29.6 cc in Center B (P > 0.1). The mean blood losses did not differ significantly (646 ml in Center A versus 636 ml in Center B; P > 0.5). However, for a subgroup of patients with subtotal devascularization (>90% of the tumor) on postembolization magnetic resonance imaging scans in Center B, blood loss was less, compared with the entire group in Center A (P < 0.05). The observations of the neurosurgeon regarding hemostasis, tumor consistency, and intratumoral necrosis did not differ significantly. There were no surgery-related deaths in either center. The rates of surgical morbidity, with permanent neurological worsening, were 20% (n = 6) in Center A and 16% (n = 5) in Center B. There was one permanent neurological deficit (3%) caused by embolization. CONCLUSION: In this preliminary study, only complete embolization had an effect on blood loss. The value of preoperative embolization for all meningiomas must be reconsidered, especially in view of the high costs and risks of embolization.

Adult↗

PubMed1999

Expression of the 100-kDa neurotensin receptor sortilin during mouse embryonal development.

Recently, sortilin a non G-protein-coupled receptor has been identified as the 100-kDa neurotensin receptor. In this paper we describe the expression of its gene during mouse embryonal development. We show that the nervous system is the main location of sortilin gene expression and that with ongoing development the forebrain exhibits the highest accumulation of transcripts.

Adaptor Proteins, Vesicular Transport↗

PubMed1999

Specific, uncompetitive inhibition of beta-galactosidases by a 5,6-isopropylidenedioxyfuro[2,3-d]isoxazole-3-methanol derivative.

(-)-(3aS,5S,6S.6aR)-3a,5,6,6a-Tetrahydro-5,6-isopropylide nedioxyfuro [2,3-d]isoxazole-3-methanol ((-)-5) has been tested toward 25 glycohydrolases and found to inhibit beta-galactosidase from Aspergillus niger (Ki = 18 microM) and that from Aspergillus orizae (Ki = 72 microM). Hydrolysis of the acetonide or exchange of CH2OH group for a CHO, CH2OMe or a CH2OMOM group suppresses the inhibitory activity.

Aspergillus↗

PubMed1999

Primary central nervous system lymphomas are derived from germinal-center B cells and show a preferential usage of the V4-34 gene segment.

Primary central nervous system lymphomas (PCNSLs) have recently received considerable clinical attention due to their increasing incidence. To clarify the histogenetic origin of these intriguing neoplasms, PCNSLs from 10 HIV-negative patients were analyzed for immunoglobulin (Ig) gene rearrangements. All tumors exhibited clonal IgH gene rearrangements. Of the 10 cases, 5 used the V4-34 gene segment, and all of these lymphomas shared an amino acid exchange from glycine to aspartate due to a mutation in the first codon of the complementarity-determining region 1. No preferential usage of D(H), J(H), V(kappa), J(kappa), V(lambda), or J(lambda) gene segments was observed. All potentially functional rearrangements exhibited somatic mutations. The pattern of somatic mutations indicated selection of the tumor cells (or their precursors) for expression of a functional antibody. Mean mutation frequencies of 13. 2% and 8.3% were detected for the heavy and light chains, respectively, thereby exceeding other lymphoma entities. Cloning experiments of three tumors showed ongoing mutation in at least one case. These data suggest that PCNSLs are derived from highly mutated germinal-center B cells. The frequent usage of the V4-34 gene and the presence of a shared replacement mutation may indicate that the tumor precursors recognized a shared (super) antigen.

B-Lymphocytes↗

PubMed1999

Percutaneous ventriculostomy--evolution of a device.

The technique applied for external ventriculostomy should allow simple, fast, stable and clean performance of this procedure. The stepwise development of a metallic ventriculostomy kit should help overcome shortcomings of traditional methods of external ventriculostomy such as catheter obstruction and propensity for infection. A rigid ventriculostomy set for precoronary puncture was developed, consisting of a screw with selfbiting conical thread and a cannula with distal holes for CSF drainage. The rate of infection was < 2% in nonseptic patients with a mean duration of the ventriculostomy of 11 days (maximum: 2 months). Hemorrhage occurred in 1% of patients. Problems were secondary wound healing after prolonged periods with ventriculostomy in place and rapid CSF-infection in cases of loosened screws which were not instantly removed. Ventriculostomy can be performed bedside within 5 min and clotted cannulas can be exchanged via the indwelling screw. The system can be resterilized and the titanium device is MRI-compatible. The method tested compares favorably with conventional techniques of external ventriculostomy. Use of the system requires continuous education of the personnel involved in order to avoid complications such as hemorrhage and loosening of the screw.

Bone Screws↗

PubMed1999

Distributions of local oxygen saturation and its response to changes of mean arterial blood pressure in the cerebral cortex adjacent to arteriovenous malformations.

BACKGROUND AND PURPOSE: To test the hypothesis that neither "steal" as cortical ischemia caused by reduced perfusion pressure nor "breakthrough" on the grounds of loss of pressure autoregulation exist in brain tissue surrounding arteriovenous malformations (AVMs), we established patterns of cortical oxygen saturation (SO(2)) adjacent to AVMs and its behavior after alterations of mean arterial blood pressure. METHODS: With a microspectrophotometer, SO(2) was scanned in the cortex around AVMs of 44 patients before and after resection and in that of a non-AVM group (n=42) before transsylvian dissection. Autoregulation was evaluated by linear regression analysis after elevation of mean arterial blood pressure (5 microg/min IV noradrenaline). SO(2) values were calculated as medians, percentage of critical values (<25% SO(2)), and coefficients of variance (approximate heterogeneity of SO(2) distributions). All values are given as mean+/-SD. RESULTS: Forty patients with AVM had an uneventful postoperative course (group A). Four hyperemic complications ("breakthrough") occurred (group B). Autoregulation was tested intact in all groups at all times. Preoperative SO(2) distributions in groups A and C (non-AVMs) were identical. In group B, significantly (P<0.05) lower medians (group A, 52.9+/-16.3%; group B, 44.2+/-17.1%; group C, 51.9+/-11.5% SO(2)), more critical values (group A, 6.5+/-5.1%; group B, 14.7+/-11.1%; group C, 7.1+/-4.9%), and heterogeneous SO(2) distributions (group A, 20.2+/-12.7%; group B, 27.9+/-12.4%; group C, 26.8+/-10.9%) were seen. Increase of median values was significantly higher in group B (76.3+/-10.4% SO(2)) than in group A (65.9+/-13.4% SO(2)) after resection. CONCLUSIONS: Severely hypoxic areas are uncommon in the cortex adjacent to AVMs and occur predominantly in patients prone to hyperemic complications. Reduced perfusion pressure is compensated in most cases, and moderate hyperemia prevails after excision. Reperfusion into unprotected capillaries of severely hypoxic cortical areas results in "breakthrough," for which vasoparalysis appears not to be the underlying mechanism.

Adolescent↗