Biomedical subjects

G Leser

Publications and source records attributed to G Leser.

16 recordsLinked to original sources

PubMed2000

The curative and palliative potential of the monoclonal antibody MOv18 labelled with 211At in nude mice with intraperitoneally growing ovarian cancer xenografts--a long-term study.

The purpose of the present study was to investigate the therapeutic efficacy of 211At-labelled specific monoclonal antibody MOv18 in nude mice with intraperitoneal growth of the human ovarian cancer cell line OVCAR3. In the first part of the study the antibody was injected intraperitoneally when the cancer growth was microscopic. The injected activity was 485-555 kBq. The median survival for treated mice was 213 days compared to 138 days for untreated mice (p < 0.014, log-rank test). No obvious toxicity was seen. Thirty-three percent of the mice were apparently free of cancer after 7 months and were probably cured. In the second part of the study mice with macroscopic cancer and signs of ascites were injected intraperitoneally with the same 211At-labelled antibody (377-389 kBq). This treatment possibly delayed the production of ascites. Hopefully radioimmunotherapy with regionally administered 211At-labelled antibody will be of value in women with ovarian cancer as well.

Animals↗

PubMed1999

Biokinetics of the monoclonal antibodies MOv 18, OV 185 and OV 197 labelled with 125I according to the m-MeATE method or the Iodogen method in nude mice with ovarian cancer xenografts.

The biodistribution of the radiolabelled monoclonal antibodies MOv18, OV185 and OV197 in nude mice with subcutaneous tumours of the human ovarian cancer cell line OVCAR3 was investigated. The early uptake of MOv18 (1-24 h) and the uptake in relation to tumour size were also studied. The antibodies were labelled with 125I according to the Iodogen method or the m-MeATE method, the latter also being suitable for labelling with 211Astatine. The tumour/blood ratio and the localization index for Mov 18 72 h after antibody injection were 2.21 +/- 0.25 and 4.62 +/- 1.27, respectively. This is significantly higher than for the other two specific antibodies. The early tumour uptake of MOv18 was low with a tumour/blood ratio of 0.23 +/- 0.04 after 6 h, and the uptake was higher in small tumours. The two labelling methods were found to be equivalent. We conclude that MOv18 labelled according the m-MeATE method should be suitable for further therapeutic studies with 211Astatine in nude mice.

Animals↗

PubMed1997

Tumour growth and cell kinetics in variants of a human endometrial adenocarcinoma expressing either wild-type or mutant p53.

We have compared the baseline cell proliferation and tumour growth in two variants of a human endometrial adenocarcinoma grown in nude mice. One of these tumour variants expressed wild-type p53 whereas the other had mutations of the p53 gene at codon 175 in both alleles and at codon 248 in one allele. There was no difference in growth rate between the tumour variants. Cell proliferation parameters, such as labelling index and S-phase fraction, were significantly increased in the tumour with mutated p53 and consequently there was a significantly lower proportion of cells in the G1-phase, proposing an at least partial loss of suppressor function in this tumour. Semi-quantitative analysis of the p53 and bcl-2 proteins showed a significant overexpression of p53 and a decreased expression of the bcl-2 protein in the p53 mutated tumour variant compared with the variant with wild-type p53. We conclude that wild-type p53 protein acts as an active suppressor in the regulation of the baseline growth and cell kinetics of this tumour and could be linked through a p53--bcl-2 system in human endometrial adenocarcinomas.

Alleles↗

PubMed1991

Immunoelectron microscopic localization of small nuclear ribonucleoproteins during bovine early embryogenesis.

Small nuclear ribonucleoproteins (snRNPs) were localized using human autoimmune or monoclonal anti-snRNP antibodies and ultrastructural immunocytochemistry in early preimplantation bovine embryos before and at transcription onset. Bovine cleavage stages up to 16-cell embryos were obtained either by culture of in vitro-fertilized ovarian oocytes or by isolation at slaughter of embryos fertilized and developed in vivo. Before transcription onset, up to the four-cell stage, diffuse labeling of nucleoplasm was detected, whereas cytoplasm labeling remained low. At the transcription onset, labeling of all eight-cell embryo nuclei was markedly concentrated at the borderline of already formed, condensed chromatin aggregates, where it was associated mainly with perichromatin fibrils. The condensed chromatin blocks revealed by several different staining methods were more prominent than is the case in most somatic cells. The degree of chromatin condensation and the pattern of its distribution differed between in vivo- and in vitro-produced eight-cell embryos: the in vitro embryos showed a higher degree of chromatin condensation and a peripheral distribution of chromatin blocks. A relation of this observation to the developmental potential of cow embryos is suggested. In two- and four-cell embryos, intensive labeling was seen in interchromatin granules, which, in their turn, were often seen in close proximity to the nucleolus precursor bodies, or in the four-cell stage were interconnected to them. No labeling was ever seen, using antibodies specific for the snRNP Sm antigen, in nucleolar precursor bodies during embryonic nucleologenesis nor in the resulting nucleoli. There was some incidental labeling of the large central vacuole appearing at the beginning of the nucleolus precursor body transformation, testifying the nucleoplasmic origin of this entity.

Animals↗

PubMed1990

Immunoelectron microscopical visualization of ribonucleoproteins in the chromatoid body of mouse spermatids.

The chromatoid body (CB), a cytoplasmic organelle present only in germ cell line, was studied at the electron microscopic level in mouse spermatids using cytochemical techniques and specific antibodies directed against sn-RNPs, hnRNPs, and ribosomal proteins. We found that specific staining for DNA as well as the use of monoclonal anti-DNA antibodies show a complete absence of DNA in the CB. The CB remains stained, however, after the application of the ethidium bromide-PTA technique, suggesting the presence of RNA within this organelle. snRNP as well as hnRNP proteins are demonstrated within the CB by means of specific monoclonal or polyclonal antibodies, especially during earlier spermiogenic stages. Monoclonal antibodies directed against the large ribosomal subunit proteins P1/P2 detect these antigens on the CB essentially along the internal threads of dense fibrillar material. Our findings suggest that the CB may function as a source of mRNA and/or of its partially processed precursors during the late stages of spermiogenesis, when the spermatid nucleus becomes gradually inactive.

Animals↗

PubMed1986

Immunoelectron microscope visualization of nuclear ribonucleoprotein antigens within spread transcription complexes.

The ultrastructural distribution of nuclear ribonucleoproteins (RNP) within spread active chromatin has been investigated using specific anti-RNP antibodies. Monoclonal antibodies directed against the core proteins of heterogeneous nuclear (hn)RNP or against small nuclear (sn)RNP have been incubated directly with lysed mouse or Drosophila tissue culture cells and the bound antibodies visualized by means of a protein A-colloidal gold complex. The hnRNP core proteins have been localized on growing RNP fibrils within non-nucleolar transcription complexes. Anti-snRNP antibodies, directed either against the Sm-antigen (common for nucleoplasmic snRNP species containing U1, U2, U4, U5, and U6 RNAs) or against U1-snRNP, were bound by two morphological types of RNP structures. Within areas of chromatin that do not completely disperse, labeling was observed on RNP-fibril gradient type structures or on groups of fibrogranular material. In the well dispersed regions containing individual nonribosomal transcription complexes, snRNP antigens were associated with growing RNP fibrils. Our results provide direct evidence for association of some U-snRNP species (including U1-snRNP) with extranucleolar RNA as early as during transcription elongation. In addition, the presence of core hnRNP proteins on the same type of nascent RNA transcripts has been confirmed.

Animals↗

PubMed1984

Ultrastructural distribution of nuclear ribonucleoproteins as visualized by immunocytochemistry on thin sections.

The ultrastructural distribution of nuclear ribonucleoproteins (RNP) has been investigated by incubation of thin sections of mouse or rat liver, embedded in Lowicryl K4M or prepared by cryoultramicrotomy, with antibodies specific for RNP. The antibodies were localized by means of a protein A-colloidal gold complex. Anti-small nuclear (sn)RNP antibodies, specific for determinants of the nucleoplasmic snRNP species containing U1, U2, U4, U5, and U6 RNAs, were found associated preferentially with perichromatin fibrils, interchromatin granules, and coiled bodies. This indicates an early association of snRNP with structural constituents containing newly synthesized heterogeneous nuclear RNA. It also suggests a possible structural role of some snRNPs in nuclear architecture. Antibodies against the core proteins of heterogeneous nuclear RNP particles associate preferentially with the border regions of condensed chromatin, and in particular with perichromatin fibrils and some perichromatin granules. These results are discussed in view of recent knowledge about the possible role of nucleoplasmic RNP-containing components in the functions of the cell nucleus.

Animals↗

PubMed1984

[Not Available].

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Folklore↗

PubMedDate not supplied

Radioimmunotherapy of nude mice with intraperitoneally growing ovarian cancer xenograft utilizing 211At-labelled monoclonal antibody MOv18.

The aim of this study was to investigate the therapeutic efficacy of 211At-labelled monoclonal antibody given intraperitoneally to nude mice with intraperitoneal growth of a human ovarian cancer cell line. Female nude mice were inoculated intraperitoneally with 1 x 10(7) cells of the human ovarian cancer cell line NIH:OVCAR 3. After about two weeks they were injected with the 211At-labelled specific monoclonal antibody MOv18 intraperitoneally. For comparison, other groups of mice were given the same labelled antibody intravenously, 211At-labelled unspecific antibody C242 intraperitoneally or unalbelled MOv18 intraperitoneally. Six weeks later the animals were sacrificed and the occurrence of tumour and ascites was determined. When the mice were treated with 211At-labelled MOv18 intraperitoneally 9 out of 10 were apparently free of both ascites and tumour compared to none of the mice given unlabelled antibody. 211At-labelled MOv18 given intravenously or 211At-labelled unspecific antibody given intraperitoneally were less effective. Regional radioimmunotherapy with the alpa-emitter 211Astatine seems to be an effective treatment of nude mice with intraperitoneally growing human ovarian cancer. Hopefully this treatment can be given in an adjuvant setting to women with minimal residual ovarian cancer in the future.

Animals↗

PubMedDate not supplied

Comparison of the therapeutic efficacy of 211At- and 131I-labelled monoclonal antibody MOv18 in nude mice with intraperitoneal growth of human ovarian cancer.

The purpose of the present study was to compare the therapeutic efficacy of the alpha-emitter Astatine-211 with the beta-emitter Iodine-131 bound to the specific monoclonal antibody MOv18. The measurements were performed in an ovarian cancer cell line (NIH:OVCAR 3) growing intraperitoneally in nude mice. Two weeks after the intraperitoneal inoculation of 1 x 10(7) cells of the human ovarian cancer cell line NIH:OVCAR-3 twenty mice were treated intraperitoneally with the specific monoclonal antibody MOv-18 labelled with either 211At (310-400 kBq) or 131I (5100-6200 kBq). The pharmacokinetics and biodistribution of labelled antibody in tumour-free animals were studied and the resulting bone marrow dose was estimated. When the mice were treated with 211At-labelled antibody 9 out of 10 mice were free of macro- and microscopic tumour compared to 3 out of 10 when Iodine-131 was used. The equivalent dose to the bone marrow was 2.4-3.1 Sv from 211At- and 3.4-4.1 Sv from 131I-irradiation. The therapeutic efficacy of 211At-labelled specific antibody is very good and, at approximately equivalent bone marrow doses, better than that of 131I.

Alpha Particles↗

PubMedDate not supplied

Protein expression of p53 and Rb suppressor genes during the first passages of human endometrial adenocarcinomas heterotransplanted into nude mice.

Five human endometrial adenocarcinomas were heterotransplanted into nude mice to study changes in p53 and Rb protein expression and loss of heterozygosity of these genes during the first nude mice passages. Three of five heterotransplanted tumours were established and measured. In one tumour over-expression of p53 protein was found in passage 1 and subsequently, whereas the original tumour did not over-express the protein. We concluded that the heterotransplantation, i.e. the new host environment, may lead to mutations in the p53 gene. Two tumours from patients and also during nude mice passages expressed p53 protein in two bands, which were probably the result of allele polymorphism. Both p53 and Rb protein expression were increased after growth in estradiol-treated animals. Our results suggest that several changes in the function of these suppressor genes, including mutations, occur during the first passages in nude mice. Consequently, the growth regulation of established tumours may differ from that in their original counterparts in the patients.

Animals↗

PubMedDate not supplied

Tumor volume growth and cell proliferation in an estradiol resistant human endometrial adenocarcinoma growing in nude mice.

Ten human endometrial adenocarcinoma grafts were subsequently transplanted from an original tumour growing in nude mice for several years and nine were investigated for cell proliferation, tumour volume growth, allele imbalance and protein products of Rb and p53 suppressor genes to study a possible inherited connection between these factors. We did not find faster tumour volume growth in tumours with increased cell proliferation, in contrast to melanomas and breast cancers growing in nude mice. We concluded that a probably existing link between mechanisms regulating cell proliferation and cell loss in these two tumours does not operate in endometrial carcinoma as measured by us. The tumour progression may be one important factor which influences mechanisms regulating cell proliferation and cell loss.

Adenocarcinoma↗

PubMedDate not supplied

Estradiol influences p53 expression in a human endometrial adenocarcinoma heterotransplanted into nude mice.

The influence of different estradiol concentrations on the expression of the p53 suppressor gene and on cell kinetics was examined by semiquantitative analysis of protein and bromodeoxyuridine labelling in a human endometrial adenocarcinoma grown in nude mice. We found that increasing the circulating estradiol increases (p = 0.001), and decreasing the hormone value decreases (p = 0.001) the expression of p53 in this tumor. The number of cells in the G1/G0 phase of the cell cycle was significantly higher (p = 0.03), and the number of cells in the G2/M phase was significantly lower (p = 0.01) in tumors grown in estradiol-treated mice than in tumors obtained from the nontreated group. Changes in p53 expression may possibly be explained by either altered transcription activity of the gene or increased half-life of the protein. Our results suggest an important role of estradiol in the progression of estrogen receptor (ER) positive human endometrial adenocarcinomas.

Adenocarcinoma↗

PubMedDate not supplied

Estradiol regulates tumor growth by influencing p53 and bcl-2 expression in human endometrial adenocarcinomas grown in nude mice.

This study analyzes the effects of estradiol on p53 and bcl-2 expression, tumor growth and cell kinetic parameters in three human endometrial adenocarcinomas grown in nude mice. The tumors used were estradiol receptor (ER) positive but differed in receptor concentration and hormone sensitivity. All three tumors expressed wild-type p53 protein. Using a tumor with an estradiol independent but responsive (inhibited) growth phenotype, we found that an increase in the circulating estradiol concentration led to increases in p53 expression and a decrease in bcl-2 levels, resulting in increased cell loss (CL) measured as delayed tumor growth. In another tumor which demonstrated estradiol independent and resistant growth, we observed an estradiol dose-related increase in p53 expression but no changes in bcl-2 expression or cell kinetic parameters. The ER mechanism of these cells was at least partly intact, as evidenced by maintained PgR induction. The third tumor showed an estradiol independent and resistant growth phenotype and a non-functional ER mechanism, lacking PgR induction. After estradiol treatment of the tumor-bearing animals no changes were observed in p53 or bcl-2 expression or in cell kinetics. We conclude that estradiol may regulate tumor growth in some ER positive human endometrial adenocarcinomas through regulation of p53 expression, which in turn regulates the bcl-2 protein concentration. Furthermore, this regulation of p53 expression is estradiol dose dependent. These growth regulating functions appear to be strongly influenced by ER mechanisms and do not seem to operate synchronously in tumors with an estradiol resistant growth phenotype.

Animals↗

PubMedDate not supplied

Characterisation of a human endometrial adenocarcinoma established in vivo and in vitro.

A moderately differentiated human endometrial adenocarcinoma was heterotransplanted into nude mice and later established as a continuous in vitro cell line. Western blot analysis showed an accumulation of p53 protein in the cell line compared to the original tumour and heterotransplants. Sequential analysis of the p53 gene revealed point mutations in codons 175 and 248 in the cell line while no mutations were found prior to in vitro establishment. Immunohistochemistry confirmed the epithelial origin of the heterotransplants and of retransplants of the cell line. The intraperitoneal retransplants remained moderately differentiated, whereas subcutaneous retransplants became less differentiated. Heterotransplants were estrogen receptor (ER) positive and progesterone receptor (PgR) negative, indicating preservation of normal steroid receptor status. The ER could not be detected in the in vitro cell line using an enzyme immunoassay, but was detected with Western blot using a polyclonal antibody toward the carboxy terminus. After estradiol treatment, the in vitro cell line became weakly positive for the PgR, suggesting the ER mechanism was at least partly intact. Tumour growth in vivo was independent of endogenous estrogen but was inhibited when the tumour-bearing animals were treated with estradiol. Analysis of cell growth kinetics by flow cytometry (FCM) after bromodeoxyuridine (BrdU)-labelling revealed no difference in S-phase fraction (SPF) or labelling index (LI) between the treated and control groups. Cell loss (CL) was significantly increased from 42% to 89%, resulting in increased tumour volume doubling time (TVDT). Under in vitro conditions estradiol treatment resulted in an increase in cell doubling time and this growth retardation was accompanied by a significant decrease in SPF and LI. The estrogen responsive (inhibited) phenotype was thus preserved in the in vitro cell line but was probably mediated through another mechanism. This cell line thus appears to represent the development of a more malignant clone with divergent receptor function and growth behaviour, and provides us with an interesting new tool for the study of tumorigenesis in the human endometrium.

Adenocarcinoma↗

PubMedDate not supplied

Estradiol induces DNA fragmentation in a human endometrial adenocarcinoma with estradiol-inhibited growth phenotype.

A moderately differentiated human endometrial adenocarcinoma heterotransplanted into nude mice was investigated for morphological and molecular changes in the tumours after treating the animals with estradiol. The tumour growth was previously characterised as estradiol-independent but responsive (inhibited) without any changes in cell proliferation. In response to hormonal treatment rather the cell loss factor increased. In this experiment tumours influenced by estradiol were investigated at different time-points after treatment by an in situ labelling technique to detect cells undergoing DNA fragmentation as a sign of apoptosis. Expression of the apoptosis related protein bcl-2 was evaluated by Western blotting. Tumours from animals treated with estradiol showed an increase in tumour volume doubling time from 5.4 days to 16 days compared to control tumours. Histologically, tumours influenced by estradiol were better differentiated than control tumours and showed a significant increase in cells staining positively with the in situ apoptosis detection technique. A parallel time dependent decreased expression of bcl-2 protein was observed. These results confirm our previous findings where estradiol influenced the cell loss factor without changes in the growth fraction, indicating increased apoptotic activity in response to hormonal treatment.

Adenocarcinoma↗