Biomedical subjects
Publications and source records attributed to E Helseth.
Primary intracranial tumours develop in 30-35 Norwegian children each year. Of these tumours, astrocytomas are the most frequent, followed by medulloblastomas, oligoastrocytomas and ependymomas. In this article we give an overview of tumour classification, epidemiology, diagnosis, treatment and prognosis of intracranial tumours in children.
Primary intracranial tumours develop in 420 adult Norwegians each year. Of these tumours, gliomas are the most frequent, followed by meningiomas, pituitary adenomas and acoustic neurinomas. Glioblastomas represent more than 50% of the gliomas. Less than 10% of the patients with glioblastoma survive for two years, despite aggressive therapy (surgery, radiotherapy and chemotherapy). The prognosis for low grade gliomas is much better. In the case of meningiomas, 95% of the tumours are benign. The primary treatment for meningiomas is surgery. If surgery is impossible, radiosurgery should be considered. Pituitary adenomas are often hormone-secreting (e.g. prolactin, growth hormone, adrenocorticotrophic hormone). Many prolactinomas are treated with bromocriptine alone. The rest of the pituitary adenomas are treated by microsurgery and radiotherapy. The prognosis for patients with pituitary adenomas is good. Acoustic neurinomas, which in most cases are benign, are treated by microsurgery or radiosurgery. Postoperative morbidity due to cochlear nerve and facial nerve dysfunction is a problem. Brain metastases are far more frequent than primary intracranial tumours. Solitary metastases in patients with stable systemic disease should be treated by surgery or radiosurgery.
The authors review head injuries during sport. Among 3,206 such injuries treated at the Regional Hospital, Trondheim, in the course of one year, 12% were injuries to head and face. Minor injuries are classified as. Mild (no amnesia or loss of consciousness), no symptoms, the activity can continue, but one week of rest is recommended. Moderate (amnesia or loss of consciousness < 1 min), medical examination, and two weeks of rest are recommended. Major (loss of consciousness < 5 min), CT scan and one month of rest are recommended. With repeated moderate or triple mild traumas, CT and the possible termination of the sporting season should be considered. Serious head injuries with intracranial pathology will generally disqualify the person from further elite competition. The possible consequences of repeated head injuries during football and other contact sports are stressed, and more regular use of neurophysiologic methods (EEG) and magnetic resonance (MR) in selected cases is recommended. The authors also point out the advantages of using helmets and protective gear, and the doctors' role in advocating such equipment.
Normal and neoplastic human intracranial tissues were examined by immunohistochemistry for c-erbB-2/HER-2 protein expression. Positive staining was observed in 1/41 gliomas, 1/2 medulloblastomas, 1/1 germinoma, 11/16 meningiomas, 1/3 anaplastic meningiomas and 11/19 metastatic brain carcinomas. No positive staining was observed in normal intracranial tissues. Thus, the expression of the c-erbB-2/HER-2 protein is limited to intracranial tumour tissues, principally meningiomas and metastatic carcinomas to the brain.
This paper describes a method for purification of human myeloma cells. Mononuclear cells from six bone marrow samples and one pleural fluid sample from multiple myeloma patients were incubated with B-B4, a monoclonal antibody that is specific for plasma cells, and the B-B4+ cells were isolated using monosized magnetic beads coated with sheep anti-mouse Ig. With this positive selection method it was possible to achieve primary cultures with more than 99% myeloma cells. The average viability of these cultures was 81%. The B-B4 antibody did not alter proliferation or cytokine production of the myeloma cell lines U-266 and JJN-3. The B-B4+ myeloma cultures did not produce IL-1 and made only small amounts of IL-6 (< 93 pg/ml), whereas the cells remaining after extraction of the B-B4+ cells produced IL-1 (89-350 pg/ml) and large amounts of IL-6 (520-17,000 pg/ml). This indicates that the B-B4+ myeloma cells are not directly responsible for the overproduction of these cytokines in multiple myeloma. This separation technique gave higher purity of myeloma cells than has been previously reported for any negative selection method and is recommended when high culture purity is of critical interest.
Changes were introduced into conserved amino acids within the ectodomain of the human immunodeficiency virus type 1 (HIV-1) gp41 transmembrane envelope glycoprotein. The effect of these changes on the structure and function of the HIV-1 envelope glycoproteins was examined. The gp41 glycoprotein contains an amino-terminal fusion peptide (residues 512 to 527) and a disulfide loop near the middle of the extracellular domain (residues 598 to 604). Mutations affecting the hydrophobic sequences between these two regions resulted in two phenotypes. Some changes in amino acids 528 to 562 resulted in a loss of the noncovalent association between gp41 and the gp120 exterior glycoprotein. Amino acid changes in other parts of the gp41 glycoprotein (residues 608 and 628) also resulted in subunit dissociation. Some changes affecting amino acids 568 to 596 resulted in envelope glycoproteins partially or completely defective in mediating membrane fusion. Syncytium formation was more sensitive than virus entry to these changes. Changes in several amino acids from 647 to 675 resulted in higher-than-wild-type syncytium-forming ability. One of these amino acid changes affecting tryptophan 666 resulted in escape from neutralization by an anti-gp41 human monoclonal antibody, 2F5. These results contribute to an understanding of the functional regions of the HIV-1 gp41 ectodomain.
The aim of this study was to determine possible relationships between Ki-67 labelling index (Ki-67 LI), amplification of the epidermal growth factor receptor (EGFR) gene, and prognosis in human glioblastomas. Ki-67 LI was determined on cryosections of biopsy specimens of 20 human glioblastomas with a mouse anti-human Ki-67 monoclonal antibody. Amplification of the EGFR gene was determined by slot blot and Southern blot analyses of DNA extracted from the tumour biopsies. The Ki-67 LI was higher in the glioblastoma group with EGFR gene amplification (8 tumours, median value of Ki-67 LI 4.2, range 0.4-24.6) than in those without EGFR gene amplification (12 tumours, median value of Ki-67 LI 0.8, range 0.2-11.8) (0.05 p less than 0.1). The glioblastoma patients with Ki-67 LI greater than 1.5 (10 tumours) had a statistically significant shorter survival than those with Ki-67 LI less than 1.5 (10 tumours) (p less than 0.05). The glioblastoma patients with EGFR gene amplification lived shorter time than those without EGFR gene amplification (p greater than 0.05).
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.
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.
The noncovalent association of the gp120 and gp41 envelope glycoproteins of human immunodeficiency virus type 1 (HIV-1) is disrupted by soluble CD4 binding, resulting in shedding of the gp120 exterior envelope glycoprotein. This observation has led to the speculation that interaction of gp120 with the CD4 receptor triggers shedding of the exterior envelope glycoprotein, allowing exposure of gp41 domains necessary for membrane fusion steps involved in virus entry or syncytium formation. To test this hypothesis, a set of HIV-1 envelope glycoprotein mutants were used to examine the relationship of soluble CD4-induced shedding of the gp120 glycoprotein to envelope glycoprotein function in syncytium formation and virus entry. All mutants with a threefold or greater reduction in CD4-binding ability exhibited marked decreases in gp120 shedding in response to soluble CD4, even though several of these mutants exhibited significant levels of envelope glycoprotein function. Conversely, most fusion-defective mutants with wild-type gp120-CD4 binding affinity, including those with changes in the V3 loop, efficiently shed gp120 following soluble CD4 binding. Thus, soluble CD4-induced shedding of gp120 is not a generally useful marker for conformational changes in the HIV-1 envelope glycoproteins necessary for the virus entry or syncytium formation processes. Some gp120 mutants, despite being expressed on the cell surface and capable of efficiently binding soluble CD4, exhibited decreased gp120 shedding. These mutants were still sensitive to neutralization by soluble CD4, indicating that, for envelope glycoproteins exhibiting high affinity for soluble CD4, competitive inhibition may be more important than gp120 shedding for the antiviral effect.
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.
Insertion of four amino acids into various locations within the amino-terminal halves of the human immunodeficiency virus type 1 gp120 or gp41 envelope glycoprotein disrupts the noncovalent association of these two envelope subunits (M. Kowalski, J. Potz, L. Basiripour, T. Dorfman, W. C. Goh, E. Terwilliger, A. Dayton, C. Rosen, W. A. Haseltine, and J. Sodroski, Science 237:1351-1355, 1987). To localize the determinants on the gp120 envelope glycoprotein important for subunit association, amino acids conserved among primate immunodeficiency viruses were changed. Substitution mutations affecting either of two highly conserved regions located at the amino (residues 36 to 45) and carboxyl (residues 491 to 501) ends of the mature gp120 molecule resulted in nearly complete dissociation of the envelope glycoprotein subunits. Partial dissociation phenotypes were observed for some changes affecting residues in the third and fourth conserved gp120 regions. These results suggest that hydrophobic regions at both ends of the gp120 glycoprotein contribute to noncovalent association with the gp41 transmembrane glycoprotein.
Overexpression of the EGF-receptor gene is associated with the malignant nature of some tumors. We have recently reported the establishment of a human carcinoma cell line (T-CAR1), derived from a brain metastasis, that had 7 million EGF receptors per cell and was growth inhibited by EGF. The present study was carried out in order to further characterize the EGF-receptor protein in T-CAR1 cells, and to see if the overexpression of the EGF-receptor gene in these cells was associated with abnormalities at the genomic level. We have compared the T-CAR1 cells with the human glioblastoma cell line T-MG1, which has 135,000 EGF-receptors and is growth stimulated by EGF. The MW of the EGF receptors in T-CAR1 cells and T-MG1 cells was estimated to be 170 kDa, equal to the normal EGF-receptor. However, in T-CAR1 cells an additional protein reacted with the monoclonal antibody directed against the internal domain of the EGF receptor. The levels of EGF receptor-related RNAs in T-CAR1 cells and T-MG1 cells reflected the number of EGF receptors in these cell lines. The EGF-receptor gene was amplified ten-fold in T-CAR1 cells, while it was not amplified in T-MG1 cells. No restriction fragment length polymorphism of DNA digested with various restriction enzymes was seen in either of the cell lines. Chromosomal analysis of T-CAR1 cells showed polysomy of chromosome 7 and marker chromosomes derived partly from chromosome 7. Thus, in the T-CAR1 cell line it was an association between polysomy of chromosome 7 and EGF-receptor gene amplification.
The binding of the CD4 receptor by the human immunodeficiency virus type 1 gp120 exterior envelope glycoprotein is important for virus entry and cytopathic effect. To investigate the CD4-binding region of the gp120 glycoprotein, we altered gp120 amino acids, excluding cysteines, that are conserved among the primate immunodeficiency viruses utilizing the CD4 receptor. Changes in two hydrophobic regions (Thr-257 in conserved region 2 and Trp-427 in conserved region 4) and two hydrophilic regions (Asp-368 and Glu-370 in conserved region 3 and Asp-457 in conserved region 4) resulted in significant reductions in CD4 binding. For most of the mutations affecting these residues, the observed effects on CD4 binding did not apparently result from global conformational disruption of the gp120 molecule, as assessed by measurements of precursor processing, subunit association, and monoclonal antibody recognition. The two hydrophilic regions exhibit a strong propensity for beta-turn formation, are predicted to act as efficient B-cell epitopes, and are located adjacent to hypervariable, glycosylated regions. This study defines a small number of gp120 residues important for CD4 binding, some of which might constitute attractive targets for immunologic intervention.
The charged amino acids near or within the membrane-spanning region of the human immunodeficiency virus type 1 gp41 envelope glycoprotein were altered. Two mutants were defective for syncytium formation and virus replication even though levels of envelope glycoproteins on the cell or virion surface and CD4 binding were comparable to those of the wild-type proteins. Thus, in addition to anchoring the envelope glycoproteins, sequences proximal to the membrane-spanning gp41 region are important for the membrane fusion process.
Rapid assays which measure the ability of mutant human immunodeficiency virus type 1 envelope glycoproteins to mediate cell-free and/or cell-to-cell transmission of virus are described. By using these assays, envelope glycoprotein mutants with varying degrees of syncytium-forming ability were tested for ability to complement viral replication in trans. As expected, mutants that dramatically affect association of the gp120-gp41 envelope subunits, CD4 binding, or membrane fusion were unable to form syncytia or to support cell-free or cell-to-cell transmission. Surprisingly, some membrane fusion-defective mutants significantly attenuated in syncytium-forming ability were able to complement viral replication. Conversely, mutations in the carboxyl terminus of gp41 transmembrane glycoprotein, although not affecting syncytium-forming ability, significantly attenuated both forms of virus transmission. These results indicate that syncytium formation is not sufficient for cell-to-cell transmission of human immunodeficiency virus type 1. Furthermore, virus transmission appears to be less sensitive to inhibition of membrane fusion than is syncytium formation.
Abnormally high expression of epidermal growth factor receptors (EGF-receptors) may contribute to the unregulated growth of some tumors. We here report the EGF-receptor numbers and the effects of epidermal growth factor (EGF) on two human cell lines. The glioblastoma cell line T-MG1 had 135,000 EGF-receptors per cell, was slightly growth stimulated by EGF and showed no obvious change in morphology after exposure to EGF. The carcinoma cell line T-CAR1, derived from a brain metastasis of a carcinoma of the adrenal cortex, had approximately 7 million EGF-receptors per cell. EGF had a significant antiproliferative effect on these cells and caused rounding and detachment of cells in adherent cultures. The cell lines may become useful in future studies concerning the role of the EGF-receptors in malignant growth.
Tumor necrosis factor-alpha (TNF-alpha) was found to induce type-1 plasminogen activator inhibitor (PAI-1) antigen in the human fibrosarcoma cell line HT-1080, and PAI-1 and urokinase-type plasminogen activator (u-PA) antigens in the human carcinoma cell line T-CAR1; tissue-type plasminogen activator (t-PA) antigen was not affected or slightly decreased. The effects in HT-1080 and T-CAR1 cells were preceded by increases in the cellular levels of the corresponding mRNAs. Cycloheximide caused an increase of PAI-1 mRNA in T-CAR1 cells, but not in HT-1080 cells; during this increase the relative abundance of the two PAI-1 mRNA species, of 2.3 kb and 3.4 kb, respectively, changed strongly in favor of the longer transcript. We conclude that TNF-alpha may affect proteolytic activity in the microenvironment of cells in malignant tumors by affecting gene expression of u-PA and PAI-1.