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C Rickert

Publications and source records attributed to C Rickert.

6 recordsLinked to original sources
PubMed2000

Evaluation of the extension of cerebral gliomas by scintigraphy.

BACKGROUND: Single photon emission computed tomography (SPECT) with 201Tl and 123I-alpha-methyl tyrosine (123I-IMT) are routine methods for the evaluation of brain tumors. 123I-IMT transport across the blood brain barrier is mediated by an amino acid carrier, 201Tl accumulation is analogous to cerebral potassium uptake. PATIENTS AND METHODS: To determine the differences in glioma extension as shown by the 2 methods, 17 patients with malignant gliomas were included in this comparative imaging study: astrocytoma III: n = 6, ependymoma III: n = 1, oligodendroglioma III: n = 1, glioblastoma IV: n = 9. The tomographic image sets were matched anatomically and the slices showing maximal tumor extension were identified in both image sets respectively. Tumor spread was compared visually and the tumor extension was quantified. RESULTS: In gliomas WHO III tumor extension was delineated significantly larger by 123I-IMT-SPECT than by 201Tl-SPECT (mean +/- SD: 816 +/- 281 pixels vs 600 +/- 220 pixels, n = 8, p < 0.05). The size of glioblastomas was shown in a comparable manner by the 2 methods (977 +/- 571 vs 1.051 +/- 588, n = 9, ns, p = 0.57), but there were considerable regional differences between the area of 201Tl uptake and amino acid retention. In the whole group a weak but significant negative correlation between intensity of 201Tl uptake on the one hand and a ratio of the area as depicted by 123I-IMT vs area as depicted by 201Tl on the other hand, was found (n = 17, r = 0.49, p < 0.05). Thus the differences in the delineation of areas became smaller with increasing 201Tl uptake. CONCLUSIONS: These preliminary data indicate that the extension of gliomas is depicted differently by the 2 methods. 123I-IMT-SPECT shows a larger tumor extension especially in gliomas WHO III. Since 201Tl uptake has previously been shown to correlate with disruption of the blood brain barrier, 123I-IMT-SPECT may delineate tumor parts without endothelial leakage. This additional information may be helpful in planning surgical or radiation therapy. The advantages of 123I-IMT in this respect decrease with increasing 201Tl uptake and with increasing malignancy.

Adult↗
PubMed2000

Sequential scintigraphic strategy for the differentiation of brain tumours.

Both thallium-201 and iodine-123 alpha-methyltyrosine (123I-IMT) have been shown to be useful in the diagnostic evaluation of brain tumours. The aim of this study was to investigate the respective contributions of 201Tl and 123I-IMT single-photon emission tomography (SPET) in the non-invasive evaluation of intracerebral tumours. We analysed 65 patients with the following brain tumours: 8 non-neoplastic lesions, 4 meningiomas, 12 low-grade gliomas, 28 high-grade gliomas, 11 metastases and 2 high-grade lymphomas. 201Tl SPET and 123I-IMT SPET were performed [start of 201Tl SPET: 15 min p.i. (early) and 180 min p.i. (delayed); start of 123I-IMT SPET: 15 min p.i.]. The intensity of uptake was quantified as the ratio between tracer accumulation in the tumour and in the contralateral hemisphere. None of the non-neoplastic lesions or low-grade gliomas expressed marked 201Tl uptake. All malignant tumours except one small metastasis and all meningiomas except one small, cystic and degenerated lesion showed significant 201Tl accumulation [Tl(15')>2.0]; 123I-IMT uptake was either absent or intermediate in non-malignant lesions except in two low-grade gliomas; the highest levels were observed in high-grade gliomas followed by metastases and lymphomas (mean IMT: 2.7 vs. 2.1 vs. 1.8), with metastases showing a high variability in 123I-IMT uptake (range: 0.8-3.6). Using 201Tl to distinguish non-neoplastic lesions from malignant tumours and meningiomas, 63 of 65 patients were characterised correctly. In the latter group, high-grade gliomas were correctly identified in 27 of 28 cases by their amino acid uptake. It is concluded that the combination of 201Tl and 123I-IMT surpasses the accuracy of each single test in the differentiation of space-occupying lesions of the brain. Based on these preliminary results, a sequential strategy is proposed involving an initial 201Tl SPET study and an additional 123I-IMT SPET study in the event of positive 201Tl uptake.

Adult↗
PubMed1997

The embryonic central nervous system lineages of Drosophila melanogaster. II. Neuroblast lineages derived from the dorsal part of the neuroectoderm.

In Drosophila, central nervous system (CNS) formation starts with the delamination from the neuroectoderm of about 30 neuroblasts (NBs) per hemisegment. They give rise to approximately 350 neurons and 30 glial cells during embryonic development. Understanding the mechanisms leading to cell fate specification and differentiation in the CNS requires the identification of the NB lineages. The embryonic lineages derived from 17 NBs of the ventral part of the neuroectoderm have previously been described (Bossing et al., 1996). Here we present 13 lineages derived from the dorsal part of the neuroectoderm and we assign 12 of them to identified NBs. Together, the 13 lineages comprise approximately 120 neurons and 22 to 27 glial cells which we include in a systematic terminology. Therefore, NBs from the dorsal neuroectoderm produce about 90% of the glial cells in the embryonic ventral ganglion. Two of the NBs give rise to glial progeny exclusively (NB 6-4A, GP) and five to glia as well as neurons (NBs 1-3, 2-5, 5-6, 6-4T, 7-4). These seven NBs are arranged as a group in the most lateral region of the NB layer. The other lineages (NBs 2-4, 3-3, 3-5, 4-3, 4-4, 5-4, clone y) are composed exclusively of neurons (interneurons, motoneurons, or both). Additionally, it has been possible to link the lateral cluster of even-skipped expressing cells (EL) to the lineage of NB 3-3. Along with the previously described clones, the vast majority (more than 90%) of cell lineages in the embryonic ventral nerve cord (thorax, abdomen) are now known. Moreover, previously identified neurons and most glial cells are now linked to certain lineages and, thus, to particular NBs. This complete set of data provides a foundation for the interpretation of mutant phenotypes and for future investigations on cell fate specification and differentiation.

Animals↗
PubMed1995

The homeobox gene repo is required for the differentiation and maintenance of glia function in the embryonic nervous system of Drosophila melanogaster.

We describe the cloning, expression and phenotypic characterisation of repo, a gene from Drosophila melanogaster that is essential for the differentiation and maintenance of glia function. It is not, however, required for the initial determination of glial cells. In the embryo, the gene, which encodes a homeodomain protein, is expressed exclusively in all developing glia and closely related cells in both the central and peripheral nervous systems. The only observed exceptions in the CNS are the midline glia derived from the mesectoderm and two of three segmental nerve root glial cells. Using a polyclonal antibody we traced the spatial and temporal pattern of the protein expression in detail. Embryos homozygous for null alleles of the protein exhibit late developmental defects in the nervous system, including a reduction in the number of glial cells, disrupted fasciculation of axons, and the inhibition of ventral nerve cord condensation. The expression of an early glial-specific marker is unaffected in such homozygotes. By contrast, the expression of late glial-specific markers is either substantially reduced or absent. The specificity of expression is also observed in the locust Schistocerca gregaria and is thus evolutionarily conserved.

Animals↗