Biomedical subjects

S H Torp

Publications and source records attributed to S H Torp.

27 records · Page 2Linked to original sources

PubMed1992

Expression of the epidermal growth factor receptor gene in human brain metastases.

Biopsy specimens of human brain metastases were examined for amplification and expression of the proto-oncogene c-erbB1 (located on chromosome 7) encoding the epidermal growth factor receptor (EGFR). Moreover, the tumour DNA was also examined for amplification of other cancer-related genes on this chromosome: the proto-oncogene c-met, the gene for platelet-derived growth factor A-chain, and the gene for plasminogen activator inhibitory type 1. All 18 brain metastases demonstrated positive binding of biotinylated EGF on cryosections. Three out of 18 metastases had amplification of the EGFR gene; the other chromosome-7 genes tested were not amplified. Thus, an increased EGFR gene expression seems to be a general finding in a wide range of carcinomas metastatic to the brain, whereas we found only occasional selective EGFR gene amplifications in single cases.

Adult↗

PubMed1992

Expression of epidermal growth factor receptor in human meningiomas and meningeal tissue.

The aim of this study was to examine meningeal tissue under normal, reactive, and neoplastic conditions for expression of epidermal growth factor receptor (EGFR) using an improved histochemical method, namely biotinylated epidermal growth factor. EGFR was found in all the examined meningiomas (12 benign and three anaplastic) and in neonatal rat meninges, whereas normal and injured adult human and rat meninges did not exhibit detectable EGFR. These observations indicate that EGFR is involved in the development of meningeal tissue. Further, EGFR is abnormally expressed in meningeal tumours, indicating a role of EGFR in the neoplastic process of these tumours. The regular expression of EGFR in human meningiomas suggests EGFR as a tumour marker for this tumour type.

Adult↗

PubMed1991

Epidermal growth factor receptor expression in human gliomas.

The expression of epidermal growth factor receptor (EGFR) was determined in cryosections of 42 human gliomas using biotinylated epidermal growth factor (B-EGF) and two monoclonal antibodies (mAb) against EGFR. All gliomas were found to express EGFR when examined with B-EGF, whereas 33 expressed EGFR when examined with the two mAbs. The highly malignant gliomas (glioblastomas and anaplastic astrocytomas) had a more heterogeneous staining strongly with B-EGF than did the low-grade gliomas (astrocytomas, oligodendrogliomas, mixed gliomas, and ependymomas). This indicates that high-grade gliomas contain more tumour cells rich in EGFR than do the low-grade gliomas. Reactive astrocytes, ependymal cells, and many types of nerve cells (cerebral cortical pyramidal cells, pyramidal and granular hippocampal cells, Purkinje cells, cerebellar granular cells and neurons in the molecular layer of the cerebellum) expressed EGFR, whereas small neurons and normal glial cells were not found to express EGFR.

Adult↗

PubMed1990

The reliability of frozen section diagnosis.

We undertook a retrospective study of 594 consecutive diagnosis by frozen section. Clinically important discrepancies were found between the frozen section and final diagnoses in 18 (3%), and unimportant discrepancies in 35 (6%). The reasons for the discrepancies were misinterpretation in 22 (41%), the presence of focal lesions in 29 (55%), and technical errors in 2 (4%). There were 4 false positive and 18 false negative diagnoses, giving a sensitivity of 93% and a specificity of 99%. Diagnoses from frozen sections were deferred in 40 cases (7%). These results are in accordance with those of similar studies, and confirm that frozen section is a highly accurate, but not infallible, method of rapid histological diagnosis.

Abdominal Neoplasms↗

PubMedDate not supplied

Comparative investigation of proliferation markers and their prognostic relevance in human meningiomas.

OBJECTIVE: In human meningiomas, histology alone does not always predict the clinical outcome. Proliferative activity has therefore, become a potential tool in the histopathological grading of these tumors. The aim of this study was to investigate different Ki67 antibodies on meningiomas, to compare their proliferation indices (PI) and with other proliferation markers, such as S-phase fraction and mitotic activity, and to see whether these factors correlate with histological tumor grade. MATERIAL AND METHODS: The study included 43 meningiomas graded according to the criteria of WHO and Jääskeläinen et al. [1985, 1986]. Paraffin sections were used for immunohistochemical detection of Ki67 antigen and flow-cytometric determination of S-phase fraction. RESULTS: The PIs displayed an overall increase with increasing histological grade, however, the range of values for benign, atypical and anaplastic meningiomas were wide, resulting in considerable overlap between the groups. There were for the most significant correlations between the different proliferation markers. CONCLUSIONS: Ki67-equivalent antibodies and S phase fraction have no advantage over counting mitoses to assess the proliferative activity in meningiomas. Thus, mitotic activity justifies its role in meningioma grading.

Adolescent↗

PubMedDate not supplied

Diagnostic and prognostic role of Ki67 immunostaining in human astrocytomas using four different antibodies.

OBJECTIVE: Astrocytomas have an inherent tendency to progress, and histopathological examination and grading do not always identify these subsets of tumors. The aim of this study was therefore to investigate whether different Ki67 antibodies could assist in the diagnostic and prognostic evaluation of these tumors. MATERIAL AND METHODS: Forty-one cerebral astrocytomas, graded according to the latest criteria of the World Health Organization, were included in the study: 22 diffuse fibrillary astrocytomas, 10 anaplastic astrocytomas and 9 glioblastomas. Standard immunohistochemical analyses were performed using 4 different commercially available Ki67 antibodies. The immunohistochemical data were correlated with the clinical course. RESULTS: There were positive correlations between the proliferation indices (PI) obtained with the different Ki67 antibodies. The Ki67 PIs increased significantly with increasing malignancy grade, and the antibodies discriminated well between low- (grade II) and high-grade tumors (grade III and IV). For the entire tumor material, the use of median values as cutoff divided the astrocytomas into 2 groups: those tumors with the higher Ki67 PIs had significantly poorer prognosis than those with lower indices. CONCLUSIONS: Ki67 immunostaining serves as an important supplementary tool in the diagnostic and prognostic evaluation of human astrocytomas.

Adult↗

PubMedDate not supplied

Prognostic significance of Ki-67/MIB-1 proliferation index in meningiomas.

Even though tumor grade, subtype, and extent of resection are strong prognostic factors in human meningiomas, the growth of this tumor is still unpredictable, and additional prognostic markers are needed. Thus, immunohistochemical determination of proliferative activity using the Ki-67 equivalent antibody MIB-1 has gained increased attention. However, the reported prognostic significance of this marker in meningiomas is not fully clarified. The aim of this study was to investigate the prognostic role of MIB-1 proliferation index (PI) in a series of meningiomas comprising 23 benign, 17 atypical, and 9 anaplastic tumors. MIB- 1 PI increased with increasing tumor grade and discriminated significantly benign from atypical and anaplastic meningiomas whereas no difference was found between the latter two grades. However, due to the considerable overlap of PI values between the various grades, one should be circumspect before using this criterion for tumor grading. Furthermore, MIB-1 PIs were significantly higher in recurrent tumors compared with non-recurrent and a reliable MIB-1 PI cut-off value of 10% was established. This value, however, cannot automatically be adapted by other laboratories and must be regarded just as a guideline. In conclusion, MIB-1 PI appears as an important prognostic factor and should be used in combination with traditional histological criteria for malignancy in order to identify meningiomas with increased risk of recurrence.

Adult↗

PubMedDate not supplied

Amplification of the epidermal growth factor receptor gene in human gliomas.

Biopsy specimens of 19 human gliomas (10 glioblastomas, 2 anaplastic astrocytomas, 4 astrocytomas, one mixed glioma, one oligodendroglioma and one ependymoma) were examined for amplification of tumour-related genes located on chromosome 7: the proto-oncogene c-erb-B1 (encoding the epidermal growth factor receptor (EGFR], the proto-oncogene c-met, the platelet-derived growth factor A-chain gene, and the plasminogen activator inhibitor type-1 gene. Gene amplification was observed in 6 glioblastomas, and the EGFR gene was the only chromosome-7-gene examined that was amplified. The selective EGFR gene amplification in human glioblastomas suggests its potential role in the progression of some of these tumours.

Adult↗

PubMedDate not supplied

EGF-effects in vitro and in vivo on a carcinoma cell line rich in EGFR.

T-CAR1 is a human carcinoma cell line established from a brain metastasis. The tumour cells overexpress EGFR and contain an amplified EGFR gene. In vitro in the presence of 5% human serum the tumour cells grow as adherent cells in monolayer. Shortly after exposure to EGF a large number of tumour cells round up and detach, whereas some remain adherent. At the same time a redistribution of actin occurs. Cytochalazin B prevented this reaction, which indicates that actin is involved in the detachment of the tumour cells. The EGF-detached tumour cells however, did not differ from the tumour cells which remained adherent after EGF-exposure with regard to parameters such as growth in soft agar, growth response to EGF, tumour necrosis factor-alpha, interferon-gamma, and carmustin (BCNU), level of EGFR gene expression and EGFR gene amplification, S-phase fraction, and amount of DNA. It was speculated whether the EGF-induced cellular detachment in vitro could be correlated to metastatic potential in vivo or not. In order to address this issue, in vivo studies with subcutaneous T-CAR1 tumours in nude mice were performed. Administration of EGF resulted in growth stimulation in contrast to growth inhibition in vitro, whereas no effect of EGF on the metastatic potential was observed. Thus, the EGF-mediated tumour cell detachment seems to be restricted to in vitro conditions only.

Actins↗