Structural basis for regulated assembly of the mitochondrial fission GTPase Drp1

Mitochondrial fission is a critical cellular event to maintain organelle function. This multistep process is initiated by the enhanced recruitment and oligomerization of dynamin-related protein 1 (Drp1) at the surface of mitochondria. As such, Drp1 is essential for inducing mitochondrial division in mammalian cells, and homologous proteins are found in all eukaryotes. As a member of the dynamin superfamily of proteins (DSPs), controlled Drp1 self-assembly into large helical polymers stimulates its GTPase activity to promote membrane constriction. Still, little is known about the mechanisms that regulate correct spatial and temporal assembly of the fission machinery. Here we present a cryo-EM structure of a full-length Drp1 dimer in an auto-inhibited state. This dimer reveals two key conformational rearrangements that must be unlocked through intramolecular rearrangements to achieve the assembly-competent state observed in previous structures. This structural insight provides understanding into the mechanism for regulated self-assembly of the mitochondrial fission machinery.

Disease-associated mutations in Drp1 have fundamentally different effects on the mitochondrial fission machinery

Patient mutations have been identified throughout dynamin-related protein 1 (Drp1), the key protein mediator of mitochondrial fission. These changes generally impact young children and often result in severe neurological defects and, in some instances, death. Until now, the underlying functional defect leading to patient phenotypes has been largely speculative. We therefore analyzed six disease-associated mutations throughout the GTPase and middle domains (MD) of Drp1. The MD plays a role in Drp1 oligomerization, and three mutations in this region were predictably impaired in self-assembly. However, another mutant in this region (F370C) retained oligomerization capability on pre-curved membranes despite being assembly-limited in solution. Instead, this mutation impaired membrane remodeling of liposomes, which highlights the importance of Drp1 in generating local membrane curvature before fission. Two GTPase domain mutations were also observed in different patients. The G32A mutation was impaired in GTP hydrolysis both in solution and in the presence of lipid but remains capable of self-assembly on these lipid templates. The G223V mutation also exhibited decreased GTPase activity and was able to assemble on pre-curved lipid templates; however, this change impaired membrane remodeling of unilamellar liposomes similar to F370C. This demonstrates that the Drp1 GTPase domain also contributes to self-assembly interactions that drive membrane curvature. Overall, the functional defects caused by mutations in Drp1 are highly variable even for mutations that reside within the same functional domain. This study provides a framework for characterizing additional Drp1 mutations to provide a comprehensive understanding of functional sites within this essential protein.

Blocked O-GlcNAc cycling alters mitochondrial morphology, function, and mass

O-GlcNAcylation is a prevalent form of glycosylation that regulates proteins within the cytosol, nucleus, and mitochondria. The O-GlcNAc modification can affect protein cellular localization, function, and signaling interactions. The specific impact of O-GlcNAcylation on mitochondrial morphology and function has been elusive. In this manuscript, the role of O-GlcNAcylation on mitochondrial fission, oxidative phosphorylation (Oxphos), and the activity of electron transport chain (ETC) complexes were evaluated. In a cellular environment with hyper O-GlcNAcylation due to the deletion of O-GlcNAcase (OGA), mitochondria showed a dramatic reduction in size and a corresponding increase in number and total mitochondrial mass. Because of the increased mitochondrial content, OGA knockout cells exhibited comparable coupled mitochondrial Oxphos and ATP levels when compared to WT cells. However, we observed reduced protein levels for complex I and II when comparing normalized mitochondrial content and reduced linked activity for complexes I and III when examining individual ETC complex activities. In assessing mitochondrial fission, we observed increased amounts of O-GlcNAcylated dynamin-related protein 1 (Drp1) in cells genetically null for OGA and in glioblastoma cells. Individual regions of Drp1 were evaluated for O-GlcNAc modifications, and we found that this post-translational modification (PTM) was not limited to the previously characterized residues in the variable domain (VD). Additional modification sites are predicted in the GTPase domain, which may influence enzyme activity. Collectively, these results highlight the impact of O-GlcNAcylation on mitochondrial dynamics and ETC function and mimic the changes that may occur during glucose toxicity from hyperglycemia.

GFP fluorescence tagging alters dynamin-related protein 1 oligomerization dynamics and creates disassembly-refractory puncta to mediate mitochondrial fission

Green fluorescent protein (GFP)-tagging is the prevalent strategy to monitor protein dynamics in living cells. However, the consequences of appending the bulky GFP moiety to the protein of interest are rarely investigated. Here, using a powerful combination of quantitative fluorescence spectroscopic and imaging techniques, we have examined the oligomerization dynamics of the GFP-tagged mitochondrial fission GTPase dynamin-related protein 1 (Drp1) both in vitro and in vivo. We find that GFP-tagged Drp1 exhibits impaired oligomerization equilibria in solution that corresponds to a greatly diminished cooperative GTPase activity in comparison to native Drp1. Consequently, GFP-tagged Drp1 constitutes aberrantly stable, GTP-resistant supramolecular assemblies both in vitro and in vivo, neither of which reflects a more dynamic native Drp1 oligomerization state. Indeed, GFP-tagged Drp1 is detected more frequently per unit length over mitochondria in Drp1-null mouse embryonic fibroblasts (MEFs) compared to wild-type (wt) MEFs, indicating that the drastically reduced GTP turnover restricts oligomer disassembly from the mitochondrial surface relative to mixed oligomers comprising native and GFP-tagged Drp1. Yet, GFP-tagged Drp1 retains the capacity to mediate membrane constriction in vitro and mitochondrial division in vivo. These findings suggest that instead of robust assembly-disassembly dynamics, persistent Drp1 higher-order oligomerization over membranes is sufficient for mitochondrial fission.

Immunohistochemically visualized localisation of gangliosides Glac2 (GD3) and Gtri2 (GD2) in cells of human intracranial tumors

Antibodies against two major gangliosides detected in human brain and brain tumors--Glac2 (GD3) and Gtri2 (GD2)--were tested by immunohistochemistry in an unselected sample of intracranial tumors during the years 1986 through 1991. Two groups emerged as evaluable samples, namely gliomas of different grades and meningiomas. In a pilot series, it was shown that these gangliosides could be visualized in frozen sections of cells of gliomas and meningiomas (as well as neurinomas) and in some structures of the normal brain. It was however not possible in frozen sections to further analyze the cellular or subcellular expression pattern of the mentioned components and paraffin sections with conventional processing were only weakly and diffusely stained. A modified protocol therefore was created that replaced alcohol processing by acetone. With this protocol, interpretable results in paraffin sections were obtained. With this method, 133 single intracranial tumors were investigated as to their immunohistologically detectable ganglioside expression. The most consistent result was that the whole cytoplasm of highly fibrillary (gemistocytic) astrocytes in all grades of gliomas was stained by Gtri2 (GD2) and Glac2 (GD3) with high preponderance of Gtri2 (GD2) expression. In all meningiomas, Glac2 (GD3) had a higher expression than Gtri2. No constant pattern in the other entities emerged. By comparison with GFAP expression in gliomas and vimentin in meningiomas, the colocalisation of gangliosides and intermediary filament proteins is supposed.

Glycosphingolipid component profiles or human gliomas--correlation to survival time and histopathological malignancy grading

BACKGROUND

Glycosphingolipids (GSL) are expressed on the surface of neuroectodermal cells. The correlation of a variety of distinct GSL with different primary brain tumors has been demonstrated. Three distinct GSL-component profiles (GSL-types I, II and III) of human gliomas have been defined by our group. The purpose of this study was to evaluate the correlation of the established GSL-types I-III with survival time and histopathological malignancy grading in 40 human gliomas.

METHODS

Neutral and acidic GSL-component patterns, histopathological malignancy grade and survival time, and a number of other relevant variables were examined. Kaplan-Meier survival curves were analyzed with the log rank test.

RESULTS

GSL-type I was expressed in 18 tumors (17 Glioblastoma multiforme (GBM) and 1 anaplastic astrocytoma (AA)). GSL-type II was expressed in 11 tumors (7 GBM, 3 AA, 1 low grade astrocytoma (LGA)). 10 patients presented with GSL-type III (3 GBM, 4 AA, 3 LGA). Kaplan Meier survival curves of GSL-types I-III differed significantly (p = 0.0231, log-rank-test). However, survival time correlated better to the WHO grades. Within a given malignancy grade, GSL-types gave additional informations about the proliferative properties.

CONCLUSIONS

This is the first report of a correlation between survival time and human glioma neutral and acidic GSL-components. The results are in agreement with observations of other investigators. The analysis of GSL-type expression might give useful additional information about proliferative properties of human gliomas in a given malignancy grade. In particular, the early prediction of outcomes in anaplastic or low grade gliomas might be possible.

Basidiolipids from Agaricus are novel immune adjuvants

The primary aim of the present study was to compare the immune adjuvanticity of two different groups of glycolipids, i.e., the newly discovered basidiolipids from Basidiomycete mushrooms (Bl-1, Bl-2, Bl-3, and Bl-4), and saponin fractions from Quillaja saponaria. The basidiolipids, though with differential effectiveness of the Bl-components, stimulated the expression of serum immune globulins in mice that recognized co-injected antigens, bovine serum albumin (BSA) or a keyhole-limpet hemocyanin-ganglioside Gfpt1 conjugate (KLH-Gfpt1), respectively. The immune adjuvanticity of the basidiolipids was comparable to that of acidic (QAS2, QAS5, QAS10), and novel neutral (QNS1, QNS2, QNS3) saponin compounds isolated and purified from Quillaja saponaria bark bulk material. Basidiolipids, as well as, the Q. saponin fractions were only marginally antigenic. MPL-A, by contrast, a comparable immune adjuvant, stimulated the expression of specific antibodies that recognized this glycophospholipid. Different from the Q. saponins with restricted toxicity, the basidiolipids displayed no toxic or hemolytic properties.

Novel glycoinositolphosphosphingolipids, basidiolipids, from Agaricus

From the edible mushroom, the basidiomycetes Agaricus bisporus and Agaricus campestris, a novel carbohydrate-homologous series of four glyco-inositol-phospho-sphingolipids, designated basidiolipids, was isolated and the constituents purified. The chemical structures of the basidiolipids were elucidated to be: Manpbeta1-2inositol1-phospho-ceramide, Galpalpha-6[Fucpalpha-2]Galpbeta-6Manpbeta-2i nositol1-phospho-ceramide, Galpalpha-6Galpalpha-6[Fucpalpha-2]Galpbeta- 6Manpbeta-2inositol1-phospho-ceramide and Galpalpha-6Galpalpha-6Galpalpha-6[Fucpalpha-2] Galpbeta-6Manpbeta-2ino sitol1-phospho-ceramide. All four glycolipids contained a ceramide which was composed of phytosphingosine and predominantly alpha-hydroxy-behenic and alpha-hydroxy-lignoceric acid.

Endoscopic stereotaxy--an eight year's experience

During the 10th meeting of the WSSFN in Maebashi in 1989, we discussed 'endoscopic stereotaxy', and presented our preliminary results. This technique was first designed to optimize stereotactic biopsy, but it proved to be effective for other neurosurgical indications as well, including endoscopic stereotactic evacuation of intraparenchymal and intraventricular space-occupying cysts, endoscopic stereotactic cystoventriculostomy, third ventriculostomy, evacuation of brain abscess and intracerebral hematoma, and retrieval of adherent or free-floating ventricular catheters. Our results with endoscopic stereotaxy in different indications are encouraging, compared to conventional microsurgical techniques and pure stereotactic techniques. From 1989 to 1997 we have performed more than 400 stereotactic endoscopic procedures. The mortality rate is below 1%, the operative morbidity is below 3%.

Continuous intrathecal baclofen infusion in severe spasticity after traumatic or hypoxic brain injury

Severe spinal spasticity has been shown to be a good indication for continuous intrathecal baclofen infusion (CIBI), but there is only limited experience with this treatment in patients with supraspinal spasticity. Eighteen patients with severe spasticity from traumatic or hypoxic brain injury were treated with CIBI. In all patients spasticity could be reduced significantly. The mean Ashworth score was reduced from 4.5 to 2.33 and the mean Spasm frequency score from 2.16 to 0.94. This reduction of spasticity led to a marked pain reduction. Nursing, perineal care and mobilization became much easier. The complication rate was low. In this series we saw one infection in the pump pocket, one epileptic seizure after a bolus application of baclofen and one spinal catheter displacement. The results are similar to those reported from series of patients with spinal spasticity and correspond to the limited experience we have so far with supraspinal spasticity patients. To prevent limb contractures CIBI should be performed as soon as the patient is in a stable clinical condition after brain injury. Further prospective clinical trials will be necessary to obtain more experience with patients suffering from supraspinal spasticity.

The degradation of glycosphingolipids by air

Exposure of glycosphingolipids to air irreversibly destroys the integrity of these lipids within a few hours. It was established that among the natural constituents of air, ozone, at commonly observed daytime levels, is responsible for the observed degradation. As one product of the reaction of glycosphingolipids with air, an aldehydic fragment containing the carbohydrate moiety was identified. This aldehydic fragment was identical to the one obtained by classical glycosphingolipid ozonolysis. Identical with the latter, the air-induced product is further fragmented by mild alkali treatment with concomitant liberation of the free reducing oligosaccharide. As a consequence of the alteration of glycosphingolipids by air, it was shown that the accuracy of methods of analysis of these glycoconjugates that depend on their physico-chemical integrity, e.g., by tlc-immune overlay, is severely influenced by their prior exposure to the atmosphere.

Endoscopic treatment of septated chronic subdural hematoma

BACKGROUND

Chronic subdural hematomas are well delineated collections of fluid (blood) between the dura mater and the arachnoid space. Two types of encapsulated chronic subdural hematoma can be distinguished: the nonseptated and the septated form. The nonseptated form can be treated easily using the burrhole-drainage method, whereas treatment of septated chronic subdural hematoma remains a therapeutical problem. The main problem is the division of the hematoma by neomembranes into compartments, which hinder the efflux of the hematoma fluid through one or two burrholes.

METHODS

Since 1991 we have operated on 14 patients with septated subdural hematoma using flexible steerable endoscopes through a burrhole approach. The flexible endoscopes are fixed and guided with the help of the Marburg Neuroendoscopy Fixation and Guiding System. For resection of neomembranes small microscissors or microforceps were used. This technique avoids blunt rupture of the membranes which may cause bleeding. A closed drainage system is applied temporarily to guarantee the efflux of the remaining hematoma.

RESULTS

From January 1991 to May 1994, 14 patients with the septated variant of chronic subdural hematoma were operated on using the endoscopic technique. After the neuroendoscopic intervention 12 patients had a sufficient or complete hematoma evacuation. One patient had to be operated on a second time, and there was one postoperative subdural infection. Long term follow up of all patients shows no recurrence of the subdural hematoma.

CONCLUSION

Treatment of membraneous septated CSH using an endoscopic operative technique combined with the application of a closed drainage system is a minimally invasive method and a therapeutic alternative to the craniostomy-membranectomy technique.

Effects of monophosphoryllipid-A on the immunization of mice with keyhole limpet hemocyanin- and muramyldipeptide-ganglioside Gfpt1 conjugates

Since it was considered that an active immunization against ganglioside Gfpt1 (IV2Fuc-, II3NeuAc-Gg4Cer) expressed by human small cell lung cancer cells may be beneficial in the treatment of this neoplasm in humans, an optimal mode of vaccination in model mice was investigated. A novel Gfpt1-muramyldipeptide conjugate (Gfpt1-MDP) was synthesized. Its ganglioside carbohydrate-directed immunogenicity in mice as measured by serum antibody titers was comparable to that of the previously described Gfpt1-keyhole limpet hemocyanin conjugate (Gfpt1-KLH). Similar immunogenicity was displayed by free Gfpt1 in muramyldipeptide-phosphoethanolamine-containing phosphatidyl-choline, -serine (PC,PS) liposomes. Immunization with Gfpt1-vaccines in the presence of monophosphoryllipid A (MPL), in general, raised titers of anti-Gfpt1 antibodies effectively. Immunization with PC, PS-liposomes containing unconjugated Gfpt1 and MPL stimulated the highest titers observed, thereby effectively preventing tumor growth in Balbc nu/nu-mice challenged with human small cell lung cancer cells. However, there was a strong crossreaction of these and most other sera with the structurally related and widely distributed ganglioside Gtet1 (II3NeuAc-Gg4Cer). Only immunization with Gfpt1-KLH conjugate in the presence of MPL stimulated selectively high anti-Gfpt1 antibody titers showing comparably low crossreactivity to ganglioside Gtet1.

[Post-traumatic seizure prevention--results of a survey of 127 neurosurgery clinics]

Starting in November, 1993, until January, 1994, we performed a survey among 127 Neurosurgical Departments in Austria, Germany, and Switzerland concerning the practice of antiepileptic prophylaxis in head injured patients. Seventy seven percent of the 12-item multiple choice questionnaires were completed and returned. They indicate a variety of attitudes towards prophylaxis for seizures: in 12% of the responding institutions, antiepileptic prophylaxis is given to every brain trauma patient, in 36%, no prophylaxis is carried out. and in 52% some patients receive prophylaxis while others do not. Penetrating injuries, intracranial haemorrhages and electroencephalographic abnormalities were the most frequent reasons why prophylaxis was initiated. Phenytoin is by far the most popular drug, given usually for at least three months, and in most cases monitored by routine serum level observations. Nevertheless, about three out of four neurosurgeons conceded that a general renunciation of antiepileptic prophylaxis after brain trauma might be justified. There is no uniform way in which patients are informed about a possible risk of seizures, as it may be relevant, for instance, in respect of driving abilities.

Stereotactic endoscopic interventions in cystic brain lesions

Stereotactic endoscopic techniques are extremely helpful in diagnosis and therapy of cystic intracerebral space occupying lesions. Acute space occupying lesions can be managed effectively and without major tissue traumatization. Up to now we have operated on more than 70 cystic intracerebral space occupying lesions with a stereotactic endoscopic technique. The main diagnoses were colloid cysts, cystic craniopharyngeoma, arachnoidal and pineal cysts. In must be stressed that in cystic anaplastic astrocytomas and glioblastomas as well as metastases only an acute inner cerebral decompression can be achieved by neuroendoscopic techniques in combination with the application of reservoir systems. In benign parenchymal or intraventricular cysts neuroendoscopic intervention is performed for definitive treatment. The results are overall encouraging. There was no operative mortality and operative morbidity was below 3%. Postoperative follow-up in patients with benign cysts showed no evidence of recurrence.

Malignant transformation of benign gliomas during interstitial irradiation

Interstitial curietherapy with 125-Iodine is an effective therapeutic option in the treatment of low grade gliomas. Four cases with astrocytoma grade II are presented, where tumour growth characteristics have changed to anaplasia during interstitial irradiation after a primary period of tumour regression. Anaplastic transformation could be due to a radiation effect or an insufficient therapeutic influence of interstitial irradiation on natural tumour progression of glioma growth due to genetic events.

Serum immunoglobulins in Heymann's experimental nephritis modulate binding of properdin and factor-H to sulpho-glycosphingolipids II3SO3(-)-Gg3Cer and III3SO3(-)-,II3SO3(-)-Gg3Cer

The nephropathic effects of Heymann's experimental nephrites involve autoallergic serum antibodies directed against rat kidney membrane constituents. In assessing the action of glycolipids as possible autoallergens in these conditions, it was found that heterologous and autologous Heymann's nephritis sera antibodies recognize that rat kidney sulphatides, II3SO3(-)-Gg3Cer (Stri1), and III3SO3(-)-,II3SO3(-)-Gg3Cer (Stri2). Two antibody populations in Heymann's sera, each reacting with only one of the two sulphatides, could be observed. It was further shown that human factor-H and properdin, pivotal regulators of the alternative pathway of complement activation, both bound to Stri2 in vitro. This binding of factor-H and properdin was differentially affected by affinity-purified anti-Stri2 antibodies of Heymann's nephritis sera. Whereas the interaction between factor-H and Stri2 was inhibited by the antibody, that of properdin was enhanced.

Specific immunization using keyhole limpet hemocyanin-ganglioside conjugates

In a search for adjuvants of non-bacterial origin for immunization with ganglioside, we investigated whether chemical coupling to immune stimulatory protein could increase the immunogenicity of sialoglycosphingolipid. A novel method for the linkage of glycosphingolipids, including gangliosides, to protein was established. The procedure includes lysis of the sphingoid double bond by ozone, reduction of the ozonolysis product to the aldehyde, and coupling to amino groups, either directly by reductamination, or by conjugation via a long aliphatic chain dicarboxylic acid linker. Using this method, gangliosides Gfpt1 (IV2-Fuc-, II3NeuAc-Gg4Cer), Glac2 [II3(NeuAc)2-LacCer], and Gtet1 (II3NeuAc-Gg4Cer) were coupled to keyhole limpet hemocyanin (KLH), and the immunogenicity of the conjugates was tested. Immunization of mice with the KLH-ganglioside conjugates led in each case to the formation of IgG- and IgM antibodies that recognized the underivatized gangliosides, respectively. In contrast to this, mixtures of KLH and ganglioside proved ineffective for immunization. KLH-tumor-associated ganglioside conjugates may, therefore, be considered as possible vaccines in immune therapy of cancer.

Glycosphingolipid component profiles of human gliomas correlate with histological tumour types: analysis of inter-individual and tumour-regional distribution

Three types of glycosphingolipid (GSL) component profiles have been established for human intracranial gliomas. GSL-type I shows only Glac- and lacto-series-sialoglycolipids. Type II consist of Glac- and Gtri-gangliosides, whereas only GSL-type III contains sulphatide and, as a major neutral glycolipid, galactocerebroside, besides gangliosides of the Glac-, Gtri-, and Gtet-families. Whole gliomas of malignancy grading I/II, III and IV, display GSL-Types III, II, and I, respectively. Thus, the GSL component distribution of the samples taken after surgery from three individual gliomas and two biopsies correlate closely with the general diagnosis of these tumours. Arthrobacter ureafaciens sialidase was used for the characterization of gangliosides. GSL-type analysis of multiple regional samples, taken from necropsy and biopsy, were determined by microanalysis of microscopic cryostat section, and shown to be in good agreement with their histology. The results validate the relevance of tumour ganglioside analysis for the characterization and diagnosis of gliomas.

Peri-operative changes of cellular and humoral components of immunity with brain tumour surgery

Nosocomial infections, which are not uncommon in neurosurgical intensive care medicine, may possibly be favoured by an impairment of immunological competence of the patient. In a prospective observational trial, we investigated several parameters of cellular and humoral immunity in 32 patients before and after resection of an intracranial tumour. We quantified the effects of operative procedure, dexamethasone pretreatment, and tumour type. Dexamethasone alone causes an increase of neutrophilic granulocyte count and monocytes, whereas IgG and eosinophilic granulocytes decrease as well as lymphocytes. CD4+ T lymphocytes (T helper cells) and CD8+ T lymphocytes (T cytotoxic/suppressor cells) were more severely affected than B lymphocytes. Dexamethasone and operation in combination act synergistically on T lymphocytes and IgG, while no synergism is obvious in other clinical test parameters. The skin sensitivity reaction was depressed accordingly. With intracerebral tumours (gliomas WHO grades II to IV), levels of T helper cells and eosinophilic granulocytes were lower, and levels of IgM and neutrophilic granulocytes were higher than with benign extracerebral neoplasms. Postoperative nosocomial infections of the lower respiratory tract occurred almost exclusively in patients subject to severe depression of T helper cells.

[Results and reliability of stereotactic and endoscopic biopsies in brain tumors]

Stereotactic neurosurgery was the first "minimal invasive method" in the field of neurosurgery, later followed and partly replaced by endoscopic techniques. One reason for such an approach is sampling of small tissue probes for diagnosis, e.g. in brain tumours not accessible to open surgery. The appropriate method in the hands of the experienced is the "Quetsch" or smear technique. Its reliability is limited by the fact, that the "architectural" or "tissular" components of tumours lack in those purely cytological preparations. Tissue architecture however is crucial for the assessment of different grades in glial tumour progression. The grade of a glial tumour is the most critical information for the patient and the therapist; grading of the supratentorialf gliomas of the adult by means of cellular and tissue pleomorphism therefore forms the basis of Zülchs system of classification and grading of all intracranial tumours by comparison of postoperative survival. The resulting four grade system--slightly modified--is part of the old and new issue of the WHO classification of brain tumours. In order to specify the possibility of correct diagnosis and grading in probes gained by the minimal invasive techniques, we present results of three diagnostic approaches: First: We report results of a study performed during the last twelve years in which a diagnosis of smear preparations had been made on neurosurgical specimens prior to conventional handling. The "blind" cytological diagnosis was then compared with the final diagnosis of the tumour using light and electron microscopy and immunohistochemistry. Second: We report results and estimates of tissue probes gained by the so called sandwich technique in which the removal of material for cytological analysis is done stepwise. By doing so, material representative for different compartments of the neoplasm is obtained. This implies collaboration between neurosurgeon and neuropathologist not only during the time of stereotactic action but also in the planing period; the correct interpretation of the different compartments delivered by imaging methods in this context is essential. Third: We present selected cases of probe sampling under direct visual control by endoscopy. This method is especially useful for tumours bordering the ventricular system. Surface structures and cyst linings can be visualized directly if the endoscopist is familiar with normal and pathological tissue appearance. The specimen for analysis may therefore be taken from the most relevant tumour region and the sandwich technic which means tissue damaging in multiple localisations can be partly or fully avoided.(ABSTRACT TRUNCATED AT 400 WORDS)

Endoscopic stereotactic treatment of brain abscesses

Treatment of brain abscess is still a subject of controversy. Craniotomy with primary extirpation and resection of the abscess membrane, burrhole craniotomy with puncture or insertion of a drain, marsupialization, or stereotactic aspiration are different therapeutic approaches. As a consequence of our experiences and results with neuro-endoscopic interventions we have introduced endoscopic stereotactic techniques in brain abscess treatment. Seven patients with brain abscesses were operated on stereotactically using an endoscope. In all cases the abscess contents were aspirated, while the abscess membrane was left in situ. The patients received postoperative antibiotic therapy according to microbial diagnosis. The longest follow-up period was 48 months. Six patients showed a marked improvement of neurological deficit after treatment. One patient died from sepsis caused by a bacterial endocarditis. The results emphasize that endoscopic stereotactic technique as a minimally invasive neurosurgical method can also be used for treatment of brain abscess.

Minimally invasive endoscopic neurosurgery--a survey

In 1989 we introduced "endoscopic stereotaxy" as a new operative procedure into neurosurgery. This technique was first scheduled to optimize stereotactic biopsy. In its further development it proved to be effective for other indications. We choose the term "Minimal Invasive (Endoscopic) Neurosurgery (MIEN)" for these interventions. Minimal invasive endoscopic techniques are applied preferably for diagnostic and therapeutic interventions on preformed or pathological cavities of the central nervous system. The indications are, endoscopic-stereotactic biopsy of space-occupying lesions, ventriculoscopy and endoscopic ventriculostomy in diagnosis and treatment of hydrocephalus, endoscopic evacuation of cystic space occupying lesions, endoscopic evacuation of intracerebral haematoma, endoscopic evacuation of septated chronic subdural haematoma, endoscopic evacuation of subacute or chronic brain abscesses, endocavitary syringostomy. Our results with minimal invasive endoscopic interventions for different indications are encouraging when compared to conventional microsurgical techniques. We have performed more than 300 minimal invasive endoscopic interventions. The mortality rate was below 1%, the operative morbidity was below 2%.

Endoscopic anatomy of the third ventricle

42 cadaver brains in situ were examined endoscopically to work out topographical anatomical landmarks for orientation. The endoscopic route from the chosen precoronal trepanation point to the defined ventricular landmarks has been measured in 22 cases. The identification and measurements of the anatomical landmarks are helpful for safe and atraumatic endoscopical navigation within the ventricular system. Furthermore this article describes and discusses cerebral lesions during ventriculoscopy.

Cerebellar primitive neuroectodermal tumor with multipotent differentiation in a family with von Hippel-Lindau disease. Case report

A family with von Hippel-Lindau disease (vHLD) is presented. Three family members suffered from typical cerebellar hemangioblastomas. Another family member presented with a cerebellar neoplasm of different histology. Detailed histological analysis revealed a primitive neuroectodermal tumor (PNET) with neuronal, glial, myoid and ependymal differentiation. This is apparently the first description of the association of vHLD and a cerebellar PNET with multipotent differentiation.

Expression of GD2-epitopes in human intracranial tumors and normal brain

Two monoclonal antibodies (mabs) were raised against ganglioside GD2 (Gtri2) and tested on human intracranial tumors and normal brain by immunohistochemical methods both in frozen and paraffin embedded sections. In normal brain structures, astrocytes were visualized with both mabs (BW 625 and BW 704) almost exclusively in the subventricular and subpial layer. A minor amount of myelin sheaths in well defined localisation was only recognized in frozen sections. Consequently in astrocytic tumors of different grades of malignancy (WHO I-IV), astrocytes were depicted in their characteristic shape and arrangement around vessels. In addition, staining was observed in meningiomas and schwannomas, but not in pituitary adenomas or metastatic carcinomas. In meningioma und schwannoma the staining was restricted to the cellular periphery and was again present in frozen section material and absent in paraffin embedded tissue. In astrocytes, reactive and neoplastic, obviously fibrous processes and cytoplasm were distinctly stained both in frozen and paraffin embedded sections. It is concluded that some neuroectodermal derived cells as well as myelin of defined localisation express GD2 on the membrane surfaces and in the cytoplasm. The latter may primarily be the case in fibrous astrocytes, which were stained in reactive and pathologic conditions. The reaction can be used as diagnostic tool in astrocytic tumors; its positive therapeutic significance is hampered by the fact that (1) not all cells in heterogeneous tumor populations express the epitope and (2) there are normal structures which do so.

Gangliosides in meningiomas: correlation of Glac2 to intermediary filament

Human meninges and 29 meningiomas were analyzed as to their glycosphingolipid composition. In the neutral fraction GSL, a mostly even distribution of mono-, di-, tri-and tetrahexoside was demonstrated. In the group of the gangliosides, Glac1 in one broad band in chromatograms occurred in almost all meningiomas; Glac2 was present in 84% of tumours. Members of the Gtn-family were only found in a small minority of tumours while various Gtet-gangliosides were detectable in nearly half of them. No constant pattern or patterns emerged and no correlation to either morphological subtype or malignancy grade could be established. Immunohistochemistry revealed focal presence of Glac2 in a pattern similar to that of vimentin expression. Semiquantitative evaluation showed good correlation between both parameters.

[Idiopathic hydrocephalus in adolescence]

BACKGROUND

Decompensation of chronic idiopathic hydrocephalus can occur at every age, but seems to be rather frequent in the middle of the second decade. From this observation, the question arises, whether or not in these cases a special manifestation of hydrocephalus occurs and, should the situation arise, whether this finding might influence the discussion about pathogenesis.

METHODS

We give some casuistic material about six hydrocephalic patients who became symptomatic between their 12th and 16th year of life.

RESULTS

All of these patients showed a tri-ventricular appearance of hydrocephalus as well as radiological signs of chronicly elevated intracranial pressure, while clinical signs and symptoms differed considerably. These findings are linked to the discussion of the pathogenesis of so-called aqueductal stenosis.

CONCLUSIONS

Whenever, after normal development in childhood, symptoms like increasing headache, poor concentration, dizziness or disturbances of gait appear during puberty, X-ray diagnosis of the skull is recommended. If it shows the signs of chronic elevated intracranial pressure, further investigations are necessary.

Minimally invasive neurosurgery by means of ultrathin endoscopes

The term "minimally invasive neurosurgery" (MIN) is defined and the present indications for MIN are described. They include endoscopic stereotactic interventions, endoscopic evacuations of chronic subdural haematomas and intracerebral mass-haemorrhages, endoscopic spinal and ventriculoscopic procedures. The advantages compared to conventional diagnostic and therapeutic neurosurgical approaches consist of less operative risk and reduced tissue-traumatization. Endoscopy makes interventions under (real-time) conditions possible. The operative stress for the patient is minimized.

Gangliosides: the relevance of current research to neurosurgery

Gangliosides are complex glycolipids found on the outer surface of most cell membranes: they are particularly concentrated in tissues of the nervous system. Gangliosides form part of the immunological identity of mammalian cells and are involved in a variety of cell-surface phenomena such as cell-substrate binding and receptor functions. In tumorous tissue, the ganglioside composition is altered, sometimes in direct proportion to the degree of malignancy. The literature on the glycosphingolipid composition and immunology of intracranial tumors is reviewed. Some gangliosides induce neuritogenesis and exhibit a trophic effect on nerve cells grown in vitro. In vivo, a particular ganglioside, GM1, reduces cerebral edema and accelerates recovery from injury (traumatic and ischemic) to the peripheral and central nervous systems of laboratory animals. Preliminary clinical studies have shown that treatment with gangliosides may have corresponding effects on lesions of the human peripheral nervous system. Gangliosides have not been tested in human subjects with brain injury.

Tissue architecture and glycosphingolipid content in human gliomas II-IV

Contradictory results have been reported claiming either none, partial or almost complete correlation between the complexity of GSL compound profiles and the assumed glial tumor differentiation. Therefore an attempt was made to compare GSL patterns with both the general (final) tumor diagnosis and malignancy grade (WHO) as well as the regional evaluation of the histology and the grading in the tumor tissue pieces directly subjected to biochemical analysis. Regional and general (final) diagnosis did not always correspond, especially when more than one tissue sample of a given tumor was analyzed. Four GSL component patterns were identified by TLC: GSL-type I with gangliosides primarily of the simple Glac-family lacking sulfatide and the more complex Gtri- and Gtet-gangliosides, GSL-type II with ganglioside of the Glac- and Gtri-families, also without sulfatide, and GSL-type III, with more complex gangliosides of the Gtri- and Gtet-families in addition to Glac-gangliosides and sulfatide, similar to the normal brain pattern, and the pattern of normal brain. There was only insufficient correlation between these GSL-type patterns and final diagnoses. However, between regional diagnosis of astrocytoma II and GSL-type III on the one hand and glioblastoma multiforme IV and GSL-type I on the other hand, a coincidence of more than 85% was found. In only 50% the intermediate GSL-type II and glioma III were associated. There was no relation between GFAP or vimentin expression and histology or GSL-type both with regard to final and regional diagnoses. Regional astrocytoma architectures exhibiting GSL-type III were mostly fibrillary, whilst glioblastomas with GSL component pattern I had often a giant cell make up.(ABSTRACT TRUNCATED AT 250 WORDS)

Stereotactic-endoscopic procedures on processes of the cranial midline

The term "midline tumour" is defined partly from the topographic and from the pathogenetic point of view. Problems of modern imagegenerating procedures in establishing the diagnosis of cerebral midline lesions are described. The role of stereotactic diagnostic and therapeutic interventions is emphasized. Stereotactic brain tumour biopsy, installation of shunts and reservoirs under visual control are performed. Interstitial radiotherapy is carried out for low-grade gliomas. As an important innovation, stereotactic procedures are combined with endoscopic techniques. Particular diagnostic and therapeutic difficulties of typical midline tumours such as craniopharyngeoma, germinoma, glioma and primary cerebral lymphoma as a local extension are discussed. A reasonable concept in diagnosis and therapy of cerebral midline lesions is proposed.

Endoscopic procedures in stereotactic neurosurgery

A new prototype of an endoscope for stereotactic interventions is described. This endoscope is adapted to the Mundinger-Birg stereotactic system. Stereotactic endoscopic procedures are carried out for brain-tumour-biopsy as well as for evacuation of haematomas, brain-cysts and abscesses. Ventriculoscopy is performed on hydrocephalus and biopsy of ventricle-relating tumours. One-year experience with stereotactic endoscopy is reviewed.

Dorsal column stimulation (DCS): cost to benefit analysis

In order to analyse the ratio of costs to clinical benefit of the implantation of a neurostimulator (type Medtronic SE-4) we examined a group of 14 patients who required treatment for chronic lumboischialgia after repeated surgery for herniated discs. Over a period of two years we evaluated the pre- and postimplantation costs. The implantation of a DC-Stimulator resulted in a striking decrease in drug requirements, in the total time of clinical treatment, and in the degree of disability. The DCS provides a satisfying method of treatment for chronic lumboischialgia after repeated surgery for herniated discs. Despite relatively high primary costs, treatment with a DCS results in a significant decrease in the accumulated expenses in comparison to other methods of medical treatment in similar cases.

Glycosphingolipids of human gliomas

Histologically characterized human gliomas of various grades of malignancy obtained during surgery were extracted, and their glycolipids were isolated and partially identified. Among the gliomas analyzed, three types of glycolipid component distribution could be identified. The glycosphingolipid (GSL) type I pattern correlated closely with that of the most malignant gliomas (Grade IV). Its neutral GSLs consisted of glucosyl- and, as a major component, dihexosylceramide, in addition to globo- and neolactotetraosylceramide. Galactosylceramide and sulfatide were absent. The gangliosides of GSL type I were almost exclusively of the GLac family, aside from small amounts of neolacto-series-derived species. The neutral components of GSL type II were similar to those of GSL type I. The acidic compounds of GSL type II were gangliosides of the Gtri family and trace amounts of neolacto-series sialoglycolipids, in addition to GLac1 and GLac2. GSL type II contained no Gtet gangliosides and no sulfatide. The GSL type III pattern was that of the most benign gliomas, with all glycolipids present that are found in normal brain and, in addition, those of the GSL type II.

Cystic meningioma with unusual histopathological features

A parasagittal meningioma of an eighty year old female patient showed by light and electron microscopy cystic architecture (forme humide) as well as nuclear vacuoles (indentations) and cytoplasmic inclusions. The latter are the known pseudopsammoma bodies or hyaline inclusions as demonstrated by light and electron microscopy. Light microcopy on paraffin sections and cytological smear preparations revealed, in addition to the cells of endotheliomatous meningioma and those containing the inclusions a third type with small granular cytoplasmic content. Electron microscopy showed characteristic features of meningioma such as folded double membranes, desmosomes and filaments and thus gave evidence of the meningiomatous nature of the tumor. By immunohistochemistry tumor cells in slightly focal distribution contained vimentin, whereas small clusters of cells with hyaline inclusions were strongly positive for cytokeratin. The dispersed cells of granular cytoplasmic content were positive for fibronectin. These findings, especially of the inclusion containing cytokeratin positive cell clusters may shed new light upon the concept of histogenesis and classification.

Dumb-bell ganglioneuroma of the spine misinterpreted as progressive idiopathic scoliosis. Case report

A giant ganglioneuroma generating a progressive scoliosis in a 16-year-old girl is presented. The interval between the start of the orthopaedic treatment and the diagnosis of the true nature of the disease was more than 4 years, thus allowing the development of a giant partly intracanalicularly partly retroperitonealy expanding tumor mass. The report emphasizes and describes the combined neurosurgical, general surgical and orthopaedic surgical treatment and presents the results of light- and electron microsopical, immunohistochemical and quantitative neurochemical investigations of the resected tumor.

Monoclonal antibodies against epitopes on ganglioside GD2 and its lactones. Markers for gliomas and neuroblastomas

Monoclonal antibodies (mAbs) BW 625 and BW 704, of the IgG3 isotype, bound to immunochemically indistinguishable epitopes on ganglioside II3(Neu-Ac)2-GgOse3-Cer. Despite this fact the mAbs showed a differential binding pattern on human glioma cell lines i.e. immunohistochemical data indicate that the detected epitopes are not identical. Furthermore, either mAb is able to mediate the antibody-dependent cellular cytotoxicity reaction (ADCC) and the human-complement-dependent cytotoxicity reaction (CDC) with epitope-expressing tumor cells. All cryopreserved tissue specimens from gliomas and neuroblastomas were immunohistochemically stained, whereas the other small round cell tumors of childhood, as well as melanomas and small-cell lung carcinomas, were essentially negative. Positive staining of normal cryopreserved tissues was restricted to amyelinic axons, Hassal's bodies and some connective tissue fibers in thymus and the tegumentary epithelium of skin. The high selectivity of mAb BW 704 for gliomas and neuroblastomas, the lack of cross-reactivity with major tissues and the strong ADCC and CDC potential argue for the use of mAb BW 704 in immunotherapy of neuroblastomas and gliomas.

Intraoperative angiography in cerebral aneurysm and AV-malformation

The device is constructed for intra-operative angiographic studies. The main features of the unit are: semi-automatic positioning of the tube into preset coordinates, TV camera serving as receptor, reproduction of the videosignal with twice the number of lines compared with that used normally, retrieval technique permitting one to study the flow of the contrast medium in slow motion at the required speed. Further advantages: Intra-operative control of the correct operative technique. No need for postoperative anaesthesia and cerebral angiography.

Suitability of non-glucose-carbohydrates for parenteral nutrition

Postoperative parenteral nutrition can only be optimally effective if the characteristics of post-traumatic metabolism are taken into account. Two main possibilities are discussed for the carbohydrate component of parenteral nutrition during this phase: glucose with high doses of insulin or non-glucose carbohydrates (sugar substitutes) possibly in a suitable combination with glucose. The risks as well as the technical and organisational problems involved in the use of them are discussed and the authors prefer the second of the two alternatives. Possible side effects of non-glucose carbohydrates are pointed out and it is shown how these can be avoided by observing dose guidelines. So far a combination of frucose : glucose : xylitol in a ratio of 2 : 1 :1 with a total dose of 0.50 g/kg/hour has been studied most thoroughly. This combination normalises the fat metabolism and improves glucose tolerance without requiring exogenous insulin. Experiences with this combination as well as individual non-glucose carbohydrates on operated patients have been given continuously for up to 7 days and in some cases even for several weeks. No side effects, no deviations from a steady state and no abnormal changes of the laboratory values occurred. The authors are of the opinion that non glucose carbohydrates are necessary if the facilities for frequent blood sugar controls are not available.