| 31. |
- Cunningham, J L, et al.
(författare)
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Transmembrane protein tyrosine phosphatase IA-2 (ICA512) is expressed in human midgut carcinoids but is not detectable in normal enterochromaffin cells.
- 2000
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Ingår i: Journal of Endocrinology. - 0022-0795 .- 1479-6805. ; 164:3
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Tidskriftsartikel (refereegranskat)abstract
- A potential upregulation of receptor type protein tyrosine phosphatase IA-2 (ICA512) expression was detected by differential display and investigated in midgut carcinoid tumours. Normal intestine tissue and tumour tissue from 13 midgut carcinoid patients were studied by in situ hybridisation using an IA-2 ribonucleotide probe and confocal microscopy using specific IA-2 antibodies. Previously, it had been shown that IA-2 is located in the secretory granules of virtually all neuroendocrine cells. However, we found that IA-2 was not detectable in resting normal enterochromaffin (EC) cells of the small intestine, while high expression of IA-2 mRNA and protein was confirmed in both primary and metastatic carcinoid tissue. This difference in expression was not observed with chromogranin A or serotonin, two secretory granule hormones known to be expressed in EC cells, indicating that IA-2 was seemingly not necessary for the basal production and packaging of these hormones. When comparing patients receiving biotherapy before operation with untreated patients, we found expression of IA-2 to be lower in tumours from patients that had been treated with a combination of alpha-interferon and the somatostatin analogue, octreotide. There was no correlation between IA-2 expression and proliferation rates as measured by immunohistochemistry with antibodies against the Ki 67 antigen. Furthermore, we show that IA-2 is co-localised with serotonin in carcinoid tumours as well as in the pancreatic tumour cell line, BON1, which is interesting as serotonin secretion rate is presumably higher in tumour cells than in resting EC cells. Taken together, these findings may indicate a role for IA-2 in the later stages of the regulated secretory process.
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| 32. |
- Dannaeus, Karin
(författare)
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Studies on myeloid differentiation: cytokine influence and identification of a novel marker gene
- 2000
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Hematopoiesis is a highly complex process by which a range of specialized blood cells are generated from a small pool of multipotent stem cells in the bone marrow. The survival, proliferation, and differentiation of hematopoietic stem cells are tightly regulated by both soluble and membrane-bound cytokines produced within the bone marrow microenvironment. Kit Ligand (KL) and Flt3 Ligand (FL) are two important hematopoietic cytokines, and signal via related tyrosine kinase receptors; c-kit and flt3. The first part of this thesis is focused on the influence of KL and FL on differentiation of a stem and progenitor cell-enriched cell population (c-kit+Lin- cells), isolated from mouse bone marrow. We found that KL and FL have different effects, and favor development of granulocytic and monocytic cells, respectively. A clear discrepancy was also seen on the expansion of multilineage progenitors (pre-CFCmulti) and granulocyte/macrophage colony-forming progenitors (CFC-G/M) which was strongly favored by KL. Furthermore, FL induced development of a biphenotypic cell population coexpressing monocytic and B-cell characteristics, restricted to the macrophage lineage. The second part of this thesis, describes the identification and characterization of a novel myeloid-associated differentiation marker gene (MYADM) which is preferentially expressed in myeloid cells, but absent in B and T lymphocytes. The predicted 32-kDa protein contains eight transmembrane domains and localizes to intracellular membranes. Although, the function of MYADM is unknown, antisense oligonucleotides inhibit colony formation of c-kit+Lin- cells, suggesting an important role for MYADM in myeloid differentiation. To gain further insight into the transcriptional control of the MYADM gene, we have analyzed a 1.5-kb sequence upstream the transcription start site for promoter activity in myeloid and lymphoid cells. We conclude that the sequence analyzed in this study does not confer the promoter tissue-specificity, thus additional regulatory elements may be located outside the region upon which this study has concentrated.
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| 33. |
- Daşu, Alexandru, et al.
(författare)
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Inducible repair and intrinsic radiosensitivity: a complex but predictable relationship?
- 2000
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Ingår i: Radiation Research. - 0033-7587 .- 1938-5404. ; 153:3, s. 279-288
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Tidskriftsartikel (refereegranskat)abstract
- Two groups have proposed a simple linear relationship between inducible radioresistance in a variety of mammalian cells and their intrinsic radiosensitivity at 2 Gy (Lambin et al., Int.J. Radiat. Biol. 69, 279-290, 1996; Alsbeih and Raaphorst, unpublished results, 1997). The inducible repair response (IRR) is quantified as a ratio, alpha(S)/alpha(R), i.e. the slope in the hypersensitive low-dose region, alpha(S), relative to the alpha(R) term of the classical linear-quadratic formula. These proposals imply that the intrinsic radiosensitivity at clinically relevant doses is directly linked to the cell's ability to mount an adaptive response as a result of exposure to very low doses of radiation. We have re-examined this correlation and found that the more extensive data set now available in the literature does not support the contention of a simple linear relationship. The two parameters are correlated, but by a much more complex relationship. A more logical fit is obtained with a log-linear equation. A series of log-linear curves are needed to describe the correlation between IRR and SF2, because of the spectrum of alpha/beta ratios among the cell lines and hence the confounding effect of the beta term at a dose of 2 Gy. The degree of repair competence before irradiation starts could also be a major factor in the apparent magnitude of the amount of repair induced. There appears to be a systematic difference in the data sets from different series of cell lines that have been obtained using flow cytometry techniques in the laboratory in Vancouver and using dynamic microscope imaging at the Gray Laboratory. We suggest that the use of a brief exposure to a laser beam in flow cytometry before the cells are irradiated might itself partially induce a stress response and change the DNA repair capacity of the cells. The clinical consequences of the relationship for predicting the benefits of altered fractionation schedules are discussed. [ru5]
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| 34. |
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| 35. |
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| 36. |
- Edgren, M, et al.
(författare)
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Estramustine a radio sensitising agent.
- 2000
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Ingår i: Anticancer research. - 0250-7005. ; 20:4, s. 2677-80
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Tidskriftsartikel (refereegranskat)abstract
- The present study revealed that estramustine acts as a radio sensitising agent on the human renal cell cancer cell lines, A498 and CAKI-2. In vitro experiments used the Bürker chamber technique. Both cell lines were markedly resistant to external beam irradiation. While pretreatment of the cell cultures with estramustine prior to external beam irradiation revealed an arrest of cell growth in both cell lines. The results of this study suggest that estramustine could be utilised as a radiosensitizing agent. This in turn could open a new method for the management of patients with advanced renal cell carcinoma (RCC).
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| 37. |
- Ejeskär, Katarina, 1969
(författare)
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Genetic alterations in Scandinavian neuroblastoma tumors
- 2000
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The results presented here derive from our efforts to find genes and chromosomal regions of interest in the formation and progression of the childhood tumor neuroblastoma.Neuroblastoma is the most common extracranial solid tumor of childhood. It is a tumor of the postganglionic sympathetic nervous system, and clinically, the hallmark of neuroblastoma is its heterogeneity.In order to characterize chromosomal regions of interest the methods loss of heterozygozity (LOH) studies using PCR-based polymorphic markers, representational difference analysis (RDA), somatic cell hybrid mapping, fluorescent in situ hybridization (FISH), radiation hybrid mapping and physical mapping by construction of a BAC-contig have been used. For mutation analysis of genes the methods single strand conformation polymorphism (SSCP), heteroduplex (HD) and DNA-sequencing have been used, and the expression studies of candidate genes have been performed using RT-PCR.In the Scandinavian neuroblastoma tumor material we have been able to show that deletions of chromosome arm 3p is the second most common deleted chromosomal region (16%) next to 1p (22%). We could also see a difference in clinical outcome between patients with tumors displaying deletion of the entire chromosome 3 versus the ones with tumors displaying deletions of region 3p only. The ones with 3p-deletion have all died of disease whereas the ones with entire chromosome 3 loss are alive and well. We have also characterized a region on chromosome 1, 1p36, shown, by others and us, to be commonly deleted in neuroblastoma tumors. A critical region of app. 25 cM between genetic markers D1S80 and D1S244 could be defined. We have also by using combined LOH-data from both neuroblastoma and germ cell tumors defined a region of common deletion for both tumor types, this region could be defined by markers D1S508 and D1S244 and is app. 5 cM.Also some 1p36 putative tumor suppressor genes, i.e. CDC2L1, TP73 and CORT, have been fine mapped and tested for expression and mutations in neuroblastomas. No evidence for any of them to be the 1p36 neuroblastoma tumor suppressor gene has however been discovered.
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| 38. |
- Ekblad, Lars, et al.
(författare)
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Purification of rabbit lacrimal gland plasma membranes by aqueous two-phase affinity partitioning
- 2000
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Ingår i: Journal of Chromatography. B. - 1387-2273. ; 743:1-2, s. 397-401
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Tidskriftsartikel (refereegranskat)abstract
- We describe the purification of lacrimal gland plasma membranes by affinity partitioning using a two-phase system containing polyethylene glycol and dextran in which wheat germ agglutinin conjugated to dextran is used as affinity ligand. When partitioning a microsomal fraction, the plasma membrane marker 5'-nucleotidase was obtained in the affinity ligand-containing bottom phase, whereas the endoplasmic reticulum marker NADH-ferricyanide reductase remained in the top phase. The affinity partitioning behaviour of components involved in exocytosis and cellular signalling was also examined.
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| 39. |
- Elmroth, Kerstin, 1970, et al.
(författare)
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Effect of hypothermic irradiation of the growth characteristics of two human cell lines
- 2000
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Ingår i: Anticancer Res. - 0250-7005. ; 20:5B, s. 3429-33
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Tidskriftsartikel (refereegranskat)abstract
- The effect of hypothermic irradiation on the growth characteristics of two human cell lines was investigated. Low temperature (2 degrees C) X-irradiation of MCF-7 cells (2, 3 and 4 Gy) resulted in higher surviving fractions compared to irradiation at 37 degrees C as assessed by the colony forming assay. The ratios for the surviving fraction between the two temperatures were 1.2, 1.5 and 1.7 at 2, 3 and 4 Gy, respectively. Correspondingly, the dose modifying factor was 1.23. The distribution of colony sizes (of those with more than 50 cells) was different with proportionally more small-sized colonies from cells irradiated at 2 degrees C. Colonies from diploid fibroblasts (HS27) were ill-defined and could not be counted. In conclusion, hypothermia during irradiation seems to influence the radioresponse in MCF-7 cells. The growth in multiwell plates of MCF-7 cells and human diploid fibroblasts (HS27) after irradiation with 3 and 4 Gy, respectively, at 2 degrees C or 37 degrees C was assessed by using the crystal violet growth assay. No difference between 2 degrees C or 37 degrees C irradiation was found for either of the two cell lines.
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| 40. |
- Elmroth, Kerstin, 1970, et al.
(författare)
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Radiation-induced double-strand breaks in mammalian DNA: influence of temperature and DMSO
- 2000
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Ingår i: Int J Radiat Biol. - : Informa UK Limited. - 0955-3002 .- 1362-3095. ; 76:11, s. 1501-8
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To investigate the effects of subphysiological irradiation temperature (2 28 degrees C) and the influence of the radical scavenger DMSO on the induction of double-strand breaks (DSB) in chromosomal DNA from a human breast cancer cell line (MCF-7) as well as in intact cells. The rejoining of DSB in cells irradiated at 2 degrees C or 37 degrees C was also investigated. MATERIALS AND METHODS: Agarose plugs with [14C]thymidine labelled MCF-7 cells were lysed in EDTA-NLS-proteinase-K buffer. The plugs containing chromosomal DNA were irradiated with X-rays under different temperatures and scavenging conditions. Intact MCF-7 cells were irradiated in Petri dishes and plugs were made. The cells were then lysed in EDTA-NLS-proteinase-K buffer. The induction of DSB was studied by constant field gel electrophoresis and expressed as DSB/100/Mbp, calculated from the fraction of activity released into the gel. RESULTS: The induction of DSB in chromosomal DNA was reduced by a decrease in temperature. This protective effect of low temperature was inhibited when the DNA was irradiated in the presence of DMSO. No difference was found when intact cells were irradiated at different temperatures. However, the rapid phase of rejoining was slower in cells irradiated at 37 degrees C than at 2 degrees C. CONCLUSIONS: The induction of DSB in naked DNA was reduced by hypothermic irradiation. The temperature had no influence on the induction of DSB in the presence of a high concentration of DMSO, indicating that the temperature effect is mediated via the indirect effects of ionizing radiation. Results are difficult to interpret in intact cells. Rejoining during irradiation at the higher temperature may counteract an increased induction. The difference in rejoining may be interpreted in terms of qualitative differences between breaks induced at the two temperatures.
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