Motoneurones (MNs) are particularly affected by the inhibition of mitochondrial metabolism, which has been linked to their selective vulnerability during pathophysiological states like hypoxia and amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disorder. To elucidate underlying events, we used sodium cyanide (CN) as a pharmacological inhibitor of complex IV of the mitochondrial respiratory chain (‘chemical hypoxia’) and investigated the cellular response in vulnerable and resistant neurone types. Bath application of 2 mm CN activated TTX‐insensitive Na+ conductances in vulnerable hypoglossal MNs, which depolarized these MNs by 10.2 ± 1.1 mV and increased their action potential activity. This response was mimicked by sodium azide (2 mm) and largely prevented by preincubation with the antioxidants ascorbic acid (1 mm) and Trolox (750 μm), indicating an involvement of reactive oxygen species (ROS) in the activation mechanism. CN also elevated cytosolic [Ca2+] levels through (i) Ca2+ release from mitochondria‐controlled stores, (ii) significant retardation of cytosolic Ca2+ clearance rates, even when cytosolic ATP levels were held constant during whole‐cell recording, and (iii) secondary Ca2+ influx during elevated firing rates. Blocking mitochondrial ATP production additionally raised cytosolic Ca2+ levels and prolonged recovery of Ca2+ transients with a delay of 5–6 min. Comparative studies on hypoglossal MNs, facial MNs and dorsal vagal neurones suggested that CN responses were dominated by the activation of K+ conductances in resistant neurones, thus reducing excitability during mitochondrial inhibition. In summary, our observations therefore support a model where selective MN vulnerability results from a synergistic accumulation of risk factors, including low cytosolic Ca2+ buffering, strong mitochondrial impact on [Ca2+]i, and a mitochondria‐controlled increase in electrical excitability during metabolic disturbances.

We report cytogenetic findings in 19 c-Kit-positive gastrointestinal stromal tumors (GISTs) that represent a heterogenous group of mesenchymal neoplasms with respect to site, histology, and biologic behavior. All of the GISTs (5 low-risk, 11 high-risk, 3 recurrences) displayed clonal chromosomal aberrations; 15 were hypo- to near-diploid, and 4 were near-triploid and hypotetraploid. The most common abnormalities were loss of chromosomes 14 and/or 22, demonstrated in 14 GISTs irrespective of site or predominant phenotype. Ten cases (2 low-risk, 5 high-risk, 3 recurrences) were characterized by loss of both chromosomes 14 and 22, 2 cases (1 low-risk, 1 high- risk), by loss of chromosome 14; and 2 high-risk cases, by loss of chromosome 22. Additional chromosomal aberrations occurred preferentially in high-risk and recurrent GISTs, including loss of 9p and 1p in 8 cases each, loss of 15 in 6 cases, loss of 3p in 5 cases, loss of 13q and 10q in 4 cases each, loss of 19 in 3 cases, and complete or partial gains of chromosomes 5 and 4 in 2 cases each. More significantly, 5 of 6 patients with clinically aggressive GISTs, including 2 recurrences and 3 metastasing GISTs, were additionally characterized by loss of 9p; four of these had additional loss of chromosomes 1p and 15. The presented results herein indicate that loss of chromosome 14 and/or 22 is an early change in GIST tumorigenesis irrespective of site or differentiation, whereas malignant transformation and progression of GISTs appear to be associated with an increasing incidence of additional secondary aberrations.

Neuronal injury in bacterial meningitis is caused by the interplay of host inflammatory responses and direct bacterial toxicity. We investigated the mechanisms by which pneumolysin, a cytosolic pneumococcal protein, induces damage to neurons. The toxicity after exposure of human SH-SY5Y neuroblastoma cells and hippocampal organotypic cultures to pneumolysin was time- and dose-dependent. Pneumolysin led to a strong calcium influx apparently mediated by pores on the cell membrane formed by the toxin itself and not by voltage-gated calcium channels. Buffering of intracellular calcium with BAPTA-AM [1, 2-bis (o-aminophenoxy) ethane N, N, N′, N′-tetraacetic acid tetra(acetomethoxyl) ester] improved survival of neuronal cells following challenge with pneumolysin. Western blotting revealed increased phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK) as early as 30 min after challenge with pneumolysin. SB 203580, a potent and selective inhibitor of p38 MAPK, rescued human neuronal cells from pneumolysin-induced death. Inhibition of the mitochondrial permeability transition pore using bongkrekate and caspase inhibition also improved survival following challenge with the toxin. Modulation of cell death pathways activated by pneumolysin may influence the outcome of pneumococcal meningitis.

To analyze the CT appearance of papillary renal cell tumor (pRCT) under consideration of gross pathology.Preoperative CT-scans of 10 patients suffering from pRCT were re-evaluated by two experienced radiologists. CT appearance was correlated to gross morphology.On CT, 9/10 tumors were depicted as rounded, well circumscribed and sharply delineated masses. These tumors presented a hypodense central area correlating to necrosis in gross pathology. The central area of necrosis was surrounded by vital tumor tissue, presenting as a serpiginous, contrast-enhancing margin on CT. One tumor was polycyclic due to multiple tumor nodules, but sharply demarcated towards the surrounding renal tissue.pRCT presents a quite unique CT appearance similar to its gross pathology.

OBJECTIVE:To analyze the CT appearance of papillary renal cell tumor (pRCT) under consideration of gross pathology.MATERIAL AND METHODS:Preoperative CT-scans of 10 patients suffering from pRCT were re-evaluated by two experienced radiologists. CT appearance was correlated to gross morphology.RESULTS:On CT, 9/10 tumors were depicted as rounded, well circumscribed and sharply delineated masses. These tumors presented a hypodense central area correlating to necrosis in gross pathology. The central area of necrosis was surrounded by vital tumor tissue, presenting as a serpiginous, contrast-enhancing margin on CT. One tumor was polycyclic due to multiple tumor nodules, but sharply demarcated towards the surrounding renal tissue.CONCLUSIONS:pRCT presents a quite unique CT appearance similar to its gross pathology.

We report cytogenetic findings in short-term cell cultures from five enchondromas and four chondrosarcomas. Clonal chromosome aberrations were found in one case of enchondroma, and in all cases of chondrosarcoma. The only enchondroma with nonrandom abnormalities had a reciprocal t(8;17)(q23;p13), and monosomies 9, 19, and/or 22. In contrast to the few karyotypic findings in one of five enchondromas, the four chondrosarcomas were commonly characterized by cytogenetic heterogeneity, with a tendency for increasing karyotypic complexity in higher grade tumors. Two cases, one grade III and one metastasizing grade II chondrosarcoma, revealed hypodiploid stem- and sidelines with loss of chromosomes 6, 10, 13, 14, and 22, as common chromosomal abnormalities, suggesting a distinct karyotypic pattern in a subset of biologically aggressive chondrosarcomas.

Clonal chromosome aberrations identified after short-term culture are presented for three cases of chromophobe renal cell carcinomas (RCC). All tumors revealed abnormal karyotypes with a varying proportion of polyploid tumor cells. Common numerical abnormalities were combined losses of chromosomes 1, 2, 6, 10, 13, and 17. Clonal karyotypic evolution was demonstrated in one case in which several related clones could be identified. An additional balanced translocation t(3;14)(p24;q22) observed in this case proved to be of constitutional nature by cytogenetic analysis of normal kidney cells and peripheral blood lymphocytes. These cytogenetic findings provide further evidence that chromophobe renal cell carcinomas are characterized by a highly specific combination of chromosomal losses most commonly including chromosomes 1, 2, 6, 10, 13, and 17.

Aims: Cytogenetic studies on renal cell carcinomas (RCCs) have disclosed a correlation between chromosome aberrations and histomorphological features. Nevertheless, it is still controversial whether the cytomorphology of the tumour cells (clear cell, chromophilic, chromophobe) or their growth pattern (non-papillary, papillary) is more discriminative for the combined histomorphological-cytogenetic classification of RCCs.Methods and results: Three RCCs with papillary growth pattern and clear cell cytomorphology were analysed by classical cytogenetics using standard G-banding techniques. Each tumour displayed clonal aberrations leading to loss of terminal 3p chromosomal segments. Monosomy :14 was also consistently found. Trisomy 17 was not observed in any of the tumours.Conclusions: This series of three RCCs consisting of clear cells with papillary architecture revealed chromosomal aberrations characteristic for the conventional (clear cell) RCC. Irrespective of the predominant papillary growth pattern, none of the cases were characterized by trisomy of chromosomes 3q, 7, 8, 12, 16, 17 and 20 and loss of Y chromosome which are widely regarded as the most consistent genetic alterations for papillary RCC. Therefore, our cytogenetic findings provide evidence that papillary clear cell RCCs should be classified according to their cytomorphology rather than their growth pattern even when papillary architecture is prominent.

With recent developments in the cytogenetics of benign and malignant soft tissue tumors, recurring and consistent chromosomal aberrations have been identified, which may serve as diagnostic and prognostic indicators. For malignant fibrous histiocytoma (MFH), cytogenetic data are still comparatively few, and specific primary anomalies have not been established yet. However, from cytogenetic studies which have already been published to date, a common chromosomal pattern for the majority of MFHs can be deduced. We present clonal chromosomal abnormalities identified after short term cell culture in 4 cases of MFH, with structural aberrations affecting 3p as the most obvious finding, together with recurrent rearrangements of chromosomes 1, 5p, 11p, 14p, 15p, 19 and/or ring chromosomes. The establishment of characteristic chromosomal patterns might eventually be helpful to differentiate MFH from other tumors with which they may be confused.

We carried out cytogenetic analysis on 11 renal oncocytomas by using G-banding and DAPI-banding techniques. Four of our tumors exhibited structural rearrangements affecting chromosome 11 at band q13. Together with another case previously described by us, our tumors constitute the largest series of renal oncocytomas displaying translocations involving 11q13. A review of the literature disclosed only 6 similar oncocytomas, 1 tumor with a t(9;11)(p23;q12), 2 tumors with a nearly identical t(9;11)(p23;q13), and 3 tumors with a t(5;11)(q35;q13). Therefore, our findings provide further cytogenetic evidence that genes located on 11q12–13 may be involved in the tumorigenesis of renal oncocytomas.

Gastrointestinal stromal tumors (GIST) may present with myogen or neurogen differentiation, mixed differentiation or with morphological features which cannot be further specified. 14 GIST of the stomach (9), the duodenum (2) and small bowel (3) were examined by immunohistochemistry and electron microscopy. Diagnosis was consistent for such tumors located distally from the stomach, however, evaluation of GIST of the stomach was different (apart from one case). Light microscopy and immunohistochemistry did not allow to discriminate between the different subtypes of GIST, however, electron microscopy revealed cellular differentiation. Hence, ultrastructural analysis is an useful tool for diagnosis of GIST, particularly those of the stomach.

We describe a newly established human sarcoma cell line derived from an endometrial stromal sarcoma (ESS). The cell line has been maintained in long-term cell culture for more than 2 years. It has been repeatedly analyzed in terms of morphology, immunocytochemical features, ultrastructure and karyotypic characteristics. In contrast to uniform endometrial stromal differentiation in vivo, the tumor cells were shown to display distinct phenotypical heterogeneity in vitro. In addition to the predominant cell type, which retained sarcomatous differentiation, foci of epithelial-like cells were observed in the cell culture. Immunocytochemical and ultrastructural analysis demonstrated a mainly mesenchymal phenotype with signs of epithelial characteristics, such as expression of cytokeratins, and the presence of desmosomes and kinetocilia, respectively. Cytogenetic analyses in early and late passages revealed unbalanced translocations between chromosomes 3 and 6 and an additional i(19)(q10), as common karyotypic changes in all tumor cells, indicating a monoclonal origin. Our new cell line can be used as an in vitro model to study the mechanisms of heterogenous differentiation patterns in ESS. (C) 1998 Wiley-Liss, Inc.

Malignant mesenchymal mixed tumors of the uterus consist of mesenchymal and epithelial components. They can show all variations from endometrial stromal sarcomas to endometrial adenocarcinomas. Light microscopic differential diagnosis of these components may be difficult. In order to characterize these tumors ultrastructurally, Me examined two carcinosarcomas, a metastasis of a mixed mullerian tumor and a stromal tumor by electron microscopy. Based on cytological criteria, epithelial and mesenchymal components were distinguished. Thus, a characterization of the different sarcomas of the uterus became possible. Interestingly, epithelial components were found in the malignant mixed tumor as well as in the endometrial stromal tumor. In the stromal tumor only single epithelial cells were present whereas in the malignant mesenchymal mixed tumor the epithelial cells were organized in nests and were surrounded by a basal lamina.The presence of epithelial cells in mesenchymal mixed rumors and in endometrial stromal sarcomas refer to a common origin from the mullerian duct.

We present cytogenetic findings in five gastrointestinal stromal tumors (GISTs). Three of these five cases had abnormal karyotypes with clonal chromosomal aberrations. The most common karyotypic pattern was a combined loss of chromosomes 14 and 22 in a total of three cases. Among these cases, additional recurrent chromosomal abnormalities were loss of 1p and/or 9, detected in two cases each. Another karyotypic feature consisted of polyploidisation, leading to hypotetraploid chromosome numbers in one case. These cytogenetic results provide evidence for a characteristic karyotypic pattern consisting of -14 and -22 in a subset of GISTs.

We report a case of a solitary enchondroma located in the head of the left fibula in a 50-year-old patient and present the findings of histopathologic investigation and cytogenetic analysis. The tumor revealed simple karyotypic abnormalities with t(8;17)(q23;p13) and loss of chromosomes 9, 19, and 22 as clonal chromosomal changes. Only a few enchondromas with chromosome aberrations have been published previously; nevertheless, it appears that benign and malignant cartilaginous tumors may have similar chromosomal abnormalities.