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C B Ostertag

Publications and source records attributed to C B Ostertag.

At least 73 records · Page 4Linked to original sources
PubMed1990

Glucocorticoid therapy obscures the diagnosis of cerebral lymphoma.

Neuropathological and radiographical findings of two patients with primary CNS B cell lymphoma are presented. Prior to computerized tomographic (CT)-guided stereotactic biopsy both patients had received glucocorticoid therapy which led to marked tumor regression on CT scans and transient improvement of neurological deficits. Despite careful targeting and serial sampling, multiple biopsy specimens examined cytologically, histologically and immunomorphologically showed nonspecific reactive astrogliosis and conspicuous perivascular infiltrates of T lymphocytes. A second biopsy performed after an interval of 2 and 8 weeks, respectively, and short-term discontinuation of dexamethasone therapy in one case, unequivocally established the diagnosis of Non-Hodgkin lymphoma. It is concluded that steroid therapy may obscure the bioptic diagnosis of cerebral lymphoma. In addition to the well-known antiedematous effect of glucocorticoids neuropathologists and neurosurgeons should be aware of a rapid and pronounced lymphodepletive action of steroids on malignant CNS lymphomas.

Astrocytes↗
PubMed1990

L-buthionine-sulfoximine-mediated radiosensitization in experimental interstitial radiotherapy of intracerebral D-54 MG glioma xenografts in athymic mice.

An intracranial (i.c.) interstitial radiotherapy model in athymic nude mice bearing i.c. D-54 MG human glioma xenografts was developed, allowing evaluation of the therapeutic benefits seen after L-buthionine-S,R-sulfoximine (L-BSO)-mediated depletion of tumor glutathione levels. Administration of L-BSO [2.5 mmol/kg intraperitoneal injections x 4 doses plus concomitant availability in acidified (pH 3.0) drinking water at a concentration of 20 mM] resulted in depletion of tumor glutathione levels to 0.15 mumol/g wet weight (7.9% of control). The therapeutic activity of i.c. interstitial radiotherapy with an 125I seed was enhanced after L-BSO-mediated glutathione depletion, with increases in median survival of 13.4 to 30.5% over that seen with 125I seeds alone. These studies demonstrate a potential role for BSO in enhancing the therapeutic activity of interstitial radiotherapy.

Animals↗
PubMed1989

Experimental radiofrequency (RF) coagulation with computer-based on line monitoring of temperature and power.

The safety and reliability of radiofrequency coagulative techniques are questioned after each coagulation, especially in functional neurosurgery. In spite of the high level of technical development of modern surgical RF generators there is still uncertainty about the character of the coagulative lesion. For the present study, a 500 kHz RF generator was connected through a module for analog/digital conversion and for regulation to a personal computer provided with a software programme for the graphic display in real time of the RF power and of the temperature/time curves. The effects of thermocoagulation were studied in fresh egg white, and monopolar lesions were made in the subcortical white matter of rabbits with a probe with a 0.5 mm diameter and a bare tip of 3 mm in length. The regularity of thermocoagulation depends on the accurate temperature reading at the tip of the electrode. The ideal course of the temperature is a smoothly ascending curve from the level of 37 degrees C to the level present for coagulation, followed by a straight horizontal line. With too slow a response of the probe to temperature changes there is an inherent danger of overheating in the initial phase of the procedure. Additionally the power level has to be adjusted for each probe. On line monitoring with graphic display of the physical parameters provides a direct control of the course of the coagulation. Regular curves of the physical parameters without temperature overshoot correspond to reproducible lesions in vitro and in vivo.

Animals↗
PubMed1989

[KI-67 PAP stain for histologic grading of brain tumors by squash preparations].

Using Ki-67 monoclonal antibody to the nuclear antigen of proliferating cells, the squash preparations of 141 brain tumors and the 36 frozen sections from corresponding tumor tissues were stained with peroxidase-antiperoxidase method. The staining indices in squash preparations correlated well to those in the corresponding frozen sections. There were good correlations between the percentage of stained cells and the histologic grade in agreement with known biologic behavior. In order of decreasing malignancy, the averages of Ki-67 staining indices were 26.7% for metastatic carcinomas, 12.6% for glioblastomas, and less than 2.8% for benign mesodermal tumor groups. Ki-67 staining with squash preparations could be applied to small tissues obtained by transsphenoidal surgery and stereotactic surgery as valuable adjuncts to intraoperative histologic diagnosis and the estimation of histologic malignancy.

Adenoma↗
PubMed1988

Occlusion of experimental artery aneurysms by intrasaccular injection of fibrin sealant.

Aneurysms were produced by grafting a vein pouch onto the cervical carotid artery of rabbits following the removal of an elliptical piece of the arterial wall. The diameter of the opening was 3-4 mm and the maximum height 8 mm. Through direct puncture of the aneurysm a clot of the fibrin sealant Tissucol was injected into the aneurysm. The sequential morphological changes were studied by light microscopy. One case was examined after 3 weeks by scanning electron microscopy. Complete resorption of the fibrin sealant was observed. The aneurysm cavity was filled with a dense connective tissue covered by a layer of newly formed endothelial cells.

Animals↗
PubMed1988

New head fixation for the Riechert stereotaxic system. Technical note.

The combined use of stereotaxic and microsurgical techniques makes it possible to minimize damage to critical nervous tissue during operations in subcortical regions. The Riechert stereotaxic system has been further modified. The patient's head is fixed in the new head ring with standard Mayfield pins. The headring is connected to a standard Mayfield clamp at symmetrical bearings at 0, 90, 180, and 270 degrees, which holds the head stable in any desired position and allows unhindered access to the cranial vault and skull base.

Humans↗
PubMed1988

Cerebral angiography under stereotactic conditions. Technical note.

A simple system for cerebral angiography under stereotactic conditions using standard components is described. X-ray tubes and power generator belong to the usual equipment of the stereotactic operating room. A film changer and an injection pump were integrated into the stereotactic arrangement. Angiographic documents with reduced X-ray magnification were obtained. For topographical orientation 5 films per seriogram were sufficient. The system also allows stereoscopic viewing by performing an additional oblique sequence after the head ring is rotated exactly 6 degrees. The combination of the necessary diagnostic procedures, as CT scan, angiography, ventriculography, serial biopsy within a single three coordinate reference system offers considerable advantages for brain tumour patients.

Adolescent↗
PubMed1987

[Interstitial stereotactic radiotherapy of brain tumors].

The narrow margin between tumour sensitivity and healthy brain sensitivity to radiation considerably limits conventional radiation therapy (teletherapy). Interstitial radiotherapy (brachytherapy) with iodine-125 permanent implants is effective for local tumour control. So far, interstitial radiotherapy using low activity permanent implants has been carried out in 72 patients with differentiated gliomas (55 cases) and other tumours in functionally critical cortical or deep-seated location. The overall response rate was 64%. In 15 patients, local radiotherapy did not halt clinical deterioration. Brachytherapy with I-125 permanent implants is recommended for slowly proliferating, differentiated, non-resectable tumours in functionally critical areas. It enables the surgeon to achieve radiosurgical tumour removal while carefully avoiding radiation and operative damage to the healthy brain. On the basis of biological, experimental and clinical data, individualized treatment for each patient is desirable.

Brachytherapy↗
PubMed1987

The monoclonal antibody Ki-67 as a marker for proliferating cells in stereotactic biopsies of brain tumours.

The monoclonal antibody Ki-67 has been tested as a marker of proliferating cells in 52 stereotactic brain tumour biopsies. The antibody reacts with a nuclear protein expressed in G1,S, G2n and M-phases of the cell cycle. Using the immunoperoxidase technique on squash preparations the percentage of Ki-67 positive cells was determined as a fraction of the total number of tumour cells present. This Ki-67 index was in close correlation with the histological grade. Highest values were found in a pineal germinoma (46.3%) and in 3 primary cerebral non-Hodgkin lymphomas (mean 39.5%). Among the gliomas, the highest fraction of proliferating cells was seen in 2 anaplastic paediatric brain stem gliomas (mean 17.4%) and in an anaplastic ependymoma (12.5%). Anaplastic astrocytomas and glioblastomas varied considerably with mean values of 9.5% and 8%, respectively. To some extent this variability may reflect tumour heterogeneity which is more likely to manifest in small stereotactic samples than in large tissue specimens obtained during open surgery. Pilocytic astrocytomas, mixed gliomas and fibrillary astrocytomas had moderate to low percentages. Ki-67 staining of squash preparations can easily be performed on a routine basis and is, in our experience, superior to frozen sections. This method allows the determination of the growth fraction of an individual tumour and could become an important additional criterion for the decision among alternative and potentially harmful therapeutic regimens.

Antibodies, Monoclonal↗
PubMed1987

Experimental aneurysms in the rabbit: occlusion by intrasaccular injection of fibrin sealant.

Experimental aneurysms of the carotid artery were produced using the microsurgical technique of grafting a venous sack onto the artery in the neck of rabbits after the removal of an elliptical piece of arterial wall. Twenty-five aneurysms were occluded with the fibrin sealant Tissucol. Microscopic examination showed complete resorption of the fibrin clot and the formation of dense granulation tissue within the aneurysm, which was covered with a layer of endothelial cells after 2 weeks. The results are only tentative and require further experimental studies.

Animals↗
PubMed1987

[Spatial definition of cerebral tumors].

The spatial definition of brain tumors can be obtained by CT and angiography carried out under stereotactic conditions. A standard CT software is used to obtain stereotactic coordinates of any intracranial point. Serial stereotactic biopsies provide a precise and detailed histologic diagnosis, including grading and volume estimation. The stereotactic approach is directed at a better understanding of the relationship between the brain and the lesion. It provides a rational basis for the choice among treatment modalities. Our experience so far with a series of 401 cases is reported on.

Adolescent↗
PubMed1987

The effect of 125I interstitial radiotherapy on blood-brain barrier function in normal canine brain.

Blood-brain barrier (BBB) function was studied in 14 normal dogs at time periods from 7 to 717 days after permanent insertion of 5- to 7-mCi seeds of iodine-125 (125I) for interstitial radiation. The BBB function was measured with carbon-14-labeled alpha aminoisobutyric acid (AIB) and quantitative autoradiography, and expressed as a unidirectional blood-to-brain transfer constant, K. The 125I radiation lesions consisted of three concentric histologically and functionally distinct zones: 1) a central zone of calcified necrosis; 2) a spongy fluid-filled zone; and 3) a narrow rim (2.6 +/- 0.6 mm wide) of viable brain tissue with increased permeability. Within this rim, the mean value of the K of AIB was 5.8 times that of normal cortex. Over the 7- to 392-day time period the value of K remained rather constant, and by 716 days K values had returned to normal. There was moderate regional variation in the value of K; it was highest in the white matter and lowest in the gray matter surrounding the radiation lesion. The radiation lesion progressively increased in size from 7 to 80 days, after which there was little change. This study illustrates that the geographically circumscribed radiation from 125I seeds is accompanied by similarly well-defined changes in BBB function, which may persist for over 1 year following insertion of the 125I seed. This altered BBB function is probably responsible for the cerebral edema associated with 125I interstitial radiotherapy.

Aminoisobutyric Acids↗
PubMed1986

Early and late effects on the normal dog brain of permanent interstitial iridium-192 irradiation.

To investigate the effects of a permanent interstitial source of gamma-irradiation on normal brain tissue, single iridium-192 (Ir-192) wires (1.05 mCi) were stereotactically implanted into the left centrum semiovale of adult dogs (survival times, 25, 46, 74, 230 and 362 days). Within 25 days, a coagulation necrosis developed in the immediate vicinity of the radioactive source. In later stages, the necrosis increased in size and became progressively mineralized. Staining for extravascular immunoreactive serum proteins revealed the presence of a chronic perifocal vasogenic edema, which extended into the white matter of the entire ipsilateral hemisphere. This edema persisted through all stages and showed a significant decrease only in the animal with a 1-year survival. A reactive gliosis with formation of a dense network of glial fibrillary acidic protein-positive astrocytes developed around the central necrosis in the adjacent white matter and, at later stages, in the contralateral hemisphere. Demyelination was restricted to the ipsilateral centrum semiovale without affecting the internal capsule or the contralateral hemisphere. It was present as early as 25 days and showed no tendency to increase at later stages. Analysis of the sequential morphological changes following Ir-192 implantation suggests that the central coagulation necrosis represents a direct radiation effect, the sharp focal delineation of which can be explained by the physical characteristics of the radiation source, i.e., rapid fall-off of the dose at short distances. Due to the continuous emission of radiation energy, there is a perifocal zone with overlapping of progressive radiation damage and tissue organization. This focus becomes the source of a chronic vasogenic edema, which in turn is most likely to be responsible for the partial demyelination of the adjacent centrum semiovale. The widespread reactive gliosis observed at all stages may also, in part, be a consequence of chronic vasogenic edema, but its distribution suggests that direct radiation effects may also be involved.

Animals↗
PubMed1986

Cavum vergae cyst as a cause of hydrocephalus, "almost forgotten"? Successful stereotactic treatment.

Cavum vergae cysts (CVC) are cerebral midline malformations, which usually have no clinical manifestations. In rare cases, however, non-communicating cysts can cause hydrocephalus by obstruction of the aqueduct. Initially, from 1930 to 1960 operative treatment consisted in open cysto-ventriculostomy, i.e. establishing a communication between CVC and the ventricles, via a transventricular approach. In the era of CT, symptomatic treatment of the hydrocephalus by ventriculo-atrial or ventriculo-peritoneal shunts is preferred. All the wellknown complications of shunting are encountered. Based on the experience of our cases of CVC with clinical manifestations, we here propose a definitive causal treatment which can be achieved by draining the cyst contents into the ventricles via a stereotactically introduced catheter.

Adult↗