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J Gielen

Publications and source records attributed to J Gielen.

At least 55 records · Page 3Linked to original sources
PubMed1998

Repeated cycles of retrovirus-mediated HSVtk gene transfer plus ganciclovir increase survival of rats with peritoneal carcinomatosis.

Peritoneal carcinomatosis is a common clinical situation that requires novel therapeutic approaches. We investigated the efficiency of an HSVtk gene therapy for the treatment of peritoneal carcinomatosis induced in syngeneic rats by DHD/K12 colon carcinoma cells. In this setting, the efficiency of two different retrovirus producing cell lines (GP+AmEnv12 and FLYA13) was compared. Rats treated with a single injection of retrovirus producing cells followed by a 5-day course of ganciclovir treatment showed an increased survival as compared with control animals. Animals treated with three injections of producing cells, each followed by a 4-5-day course of ganciclovir treatment, showed an increased survival as compared with control rats and with those treated with a single cycle of retrovirus producing cells plus ganciclovir. However, only a few animals remained tumor-free after day 180. There was no difference between the two producing cell lines in any of the experiments. RT-PCR demonstrated a faint expression of the tk transgene in the liver, spleen, epiploon, bowels and the lung of the animals injected with the HSVtk producing cells, reflecting most likely the transduction of only a limited number of cells.

Animals↗
PubMed1998

Mutation analysis of exon 3 of the LDL receptor gene in patients with severe hypercholesterolemia.

Single-strand conformation polymorphism analysis was used to screen for mutations in exon 3 of the low density lipoprotein receptor gene in a group of 218 unrelated patients with severe hypercholesterolemia (low density lipoprotein cholesterol > 6.7 mmol/l) living in the Cologne area of Germany. Including the complementary primers the fragment studied had a length of 176 bp. An abnormal single-strand conformation polymorphism pattern was observed in eight patients, four of whom had an identical abnormal fragment pattern indicating that five different mutations were present. By direct DNA sequencing, the underlying mutations could be confirmed (Cys54-->Tyr, Trp66-->Gly, Glu80-->Lys, 2 bp insertion (AT between codon 44 and 45, 9 bp deletion (codons 65 to 67)). The analysis of the pathogenicity indicates that all mutations were causative for the low density lipoprotein cholesterol elevation. The Trp66-->Gly and Glu80-->Lys mutations were previously described in a French-Canadian population and in an English population, respectively. The 2 bp insertion was detected in four unrelated patients and is one of the most frequent mutations detected up to now in the German population.

Base Sequence↗
PubMed1997

Sequence analysis of a 24-kb contiguous genomic region at the Arabidopsis thaliana PFL locus on chromosome 1.

As part of the European Union program of European Scientist Sequencing Arabidopsis (ESSA), the DNA sequence of a 24.053-bp insert of cosmid clone CC17J13 was determined. The cosmid is located on chromosome 1 at the PFL locus (position 30 cM). Analysis of the sequence and comparison to public databases predicts seven genes in this area, thus approximately one gene every 3.3 kb. Three cDNAs corresponding to genes in this region were also sequenced. The homologies and/or possible functions of the (putative) genes are discussed. Proteins encoded by genes in this region include a polyadenylate-binding protein (PAB-3) and a GTP-binding protein (Rab7) as well as a novel protein, possibly involved in double-stranded RNA unwinding and apoptosis. Intriguingly, the gene encoding the PAB-3 protein, which is very specifically expressed, is flanked by putative matrix attachment regions.

Arabidopsis↗
PubMed1997

An abscisic-acid- and salt-stress-responsive rice cDNA from a novel plant gene family.

A novel cDNA clone osr40cl, encoding a abscisic acid (ABA)-responsive 40-kDa protein previously associated with salt tolerance (Moons et al. '1995' Plant Physiol 107: 177-186), was isolated from roots of rice seedlings (Oryza sativa L.). Exogenously applied ABA and salt shock induced a marked increase of the osr40cl transcript level in roots of seedlings whereas constant osr40cl mRNA levels were found in the shoot. The root-specific salinity-induced osr40cl mRNA accumulation was rapid and gradually declined upon prolonged salt shock. Plant growth regulators, signalling the wounding and the pathogen response, did not enhance osr40cl expression, indicating a salt- and osmotic-stress-specific response. The encoded OSR40cl protein was found to be hydrophilic, rich in histidine residues (6%) constituting putative metal-binding domains, and to consist of a duplicated domain of 151 amino acids (75% identical), that can form amphiphilic alpha-helical structures. The gene osr40cl belongs to a multigene family. Two osr40 genes were isolated, osr40g2 and osr40g3, tandemly arranged in an 8-kb region of the rice genome. Antisera raised against a conserved OSR40 peptide recognized different OSR40 proteins that accumulated in roots upon exposure to salt stress. The OSR40 protein family included 29-KDa proteins and two 40-kDa proteins, the latter most probably corresponding to OSR40cl and OSR40g2 with duplicated domain structures. The osr40g3 transcript encoded a single copy of the OSR40 domain and exhibited a shoot-specific expression. Results indicate that OSR40cl plays a role in the adaptive response of roots to an hyper-osmotic environment and belongs to a novel plant protein family that most probably has structural functions.

Abscisic Acid↗
PubMed1997

HSV-1 thymidine kinase gene therapy for colorectal adenocarcinoma-derived peritoneal carcinomatosis.

Peritoneal carcinomatosis is a common clinical situation which, in most cases, cannot be eradicated by surgery or chemotherapy. The feasibility of an HSV-TK-based suicide gene therapy for peritoneal carcinomatosis induced by DHD/K12 colon carcinoma cells was investigated. DHD/K12 cells stably expressing the tk gene were killed in vitro in the presence of low concentrations of ganciclovir, they exhibited a 'bystander effect' when mixed with TK-negative cells. BD-IX rats injected intraperitoneally, either directly or after surgical peritoneal irritations, with DHD/K12 cells developed peritoneal carcinomatosis within 2 weeks. Ganciclovir treatment of animals injected with DHD/K12-TK cells allowed a significant reduction of the tumor volume as well as a prolonged survival. Of these animals 35-40% showed a long-term disease-free survival after ganciclovir therapy. Residual or relapsing tumors could be explained by a low expression of the transgene as demonstrated by RT-PCR.

Adenocarcinoma↗
PubMed1997

Semen parameters in a fertile versus subfertile population: a need for change in the interpretation of semen testing.

This prospectively designed study was conducted to compare a fertile and a subfertile population so as to define normal values for different semen parameters. Semen analyses were performed according to the World Health Organization (WHO) guidelines, except for sperm morphology (strict criteria). In the fertile population (n = 144), all patients had recently achieved pregnancy, within 12 months of unprotected coitus. As subfertile controls we examined semen samples from 143 consecutive men attending our infertility clinic during the same study period. Couples with tubal factor infertility and/or ovulatory disorders were excluded from our study. Using receiver operating characteristic (ROC) curve analysis we determined the diagnostic potential and cut-off values for single and combined sperm parameters. Sperm morphology scored best, with a value of 78% (area under the ROC curve). Summary statistics showed a shift towards abnormality for most semen parameters in the subfertile population. Using the 10th percentile of the fertile population as the cut-off value, the following results were obtained: 14.3 x 10(6)/ml for sperm concentration, 28% for progressive motility and 5% for sperm morphology. Using ROC analysis, cut-off values were 34 x 10(6)/ml, 45% and 10% respectively. Cut-off values for normality were different from those described in the WHO guidelines. Routine bacterial and non-bacterial cultures turned out to be of little prognostic value.

Adult↗
PubMed1996

Cloning and expression of a new HOXC6 transcript encoding a repressing protein.

Homeodomain-containing proteins are transcription factors that regulate the co-ordinated expression of multiple genes involved in development, differentiation and malignant transformation. In an attempt to characterize expressed homeobox (HOX) genes in breast cancer cells, we cloned two distinct HOXC6 transcripts from an MCF7 cDNA library, Interestingly, one of them represents a new HOXC6 mRNA encoding a homeodomain-containing protein harbouring a unique N-terminal sequence. Moreover we demonstrate that this HOXC6 transcript is less abundant in human breast cancer cells than in non-tumorigenic cell lines, is detected in breast carcinomas and adjacent tissues and is expressed in a variety of human tumours. In addition, transient co-transfection experiments illustrated that both HOXC6 transcripts encode gene products that repress transcription from a HOX binding sequence in MDA-MB231 cells and co-operate with other HOX gene products such as HOXB7 on their target genes. Taken together, our results suggest that HOXC6 proteins might contribute to the breast cell phenotype through co-operative interactions with other HOX-derived proteins and repression of their target genes.

Amino Acid Sequence↗
PubMed1996

Correlation between P450 CYP1A1 inducibility, MspI genotype and lung cancer incidence.

The aim of this study was to verify a possible correlation between CYP1A1 induction, MspI genotype and lung cancer incidence. A case-control study was performed on 48 lung cancer patients and 81 healthy subjects to test the existence of a correlation, within a European population. The hyperinducible group exhibited a significantly higher risk of lung cancer (odds ratio = 3.41; P = 0.036), especially for adenocarcinoma (odds ratio = 5.29; P = 0.033). In contrast with the situation observed in Asian populations, the frequency of the M2 allele did not differ significantly in the total lung cancer population (7.82%) and the group of healthy subjects (10.71%). The median inducibility value was slightly higher among cancer patients with one or two M2 alleles than among patients homozygous for the wild-type allele (P = 0.09). However, the percentage of individuals possessing at least one mutated allele was not significantly higher among hyperinducible patients (37.5%) than among non-hyperinducible patients (16.0%). No significant correlation could be found between M2 allele and lung cancer or between M2 allele and CYP1A1 inducibility; the only positive correlation found was between CYP1A1 hyperinducibility and lung cancer incidence. Our observations do not support the view that the presence of the M2 allele at the MspI site of the CYP1A1 gene constitutes a significant lung cancer risk in Caucasians.

Age Factors↗
PubMed1995

Characterization of three members of the ACC synthase gene family in Solanum tuberosum L.

Two genomic clones corresponding to three members of the 1-aminocyclopropane-1-carboxylic acid (ACC) synthase gene family in potato (Solanum tuberosum L.) have been isolated and sequenced. Two highly homologous genes, ST-ACS1A and ST-ACS1B, transcribed in opposite directions were found in an 8.9 kb region. Their coding sequences are interrupted by two introns at identical positions. Their closest relative in tomato is the LE-ACS3 gene. The third gene in potato, ST-ACS2, was found in a 4 kb region and shows a gene structure similar to that of the tomato LE-ACS4 gene and to the mung bean VR-ACS4 and VR-ACS5 genes. Based on its lack of significant homology to the tomato gene family and its closeness to the VR-ACS4 and VR-ACS5 genes, we propose that LE-ACS7 represents an additional isoform in the tomato genome. Moreover, in a phylogenetic comparison of known ACC synthases, the ST-ACS2 isoform was grouped in a separate lineage together with the mung bean VR-ACS4 and VR-ACS5, and the moth orchid DS-ACS1A and DS-ACS1B gene products. Expression of the three potato genes was studied by reverse transcription-polymerase chain reaction on total RNA. The twin genes are positively regulated by indole-3-acetic acid in hypocotyls and expression is modulated by wounding in the leaves. The third gene is responsive to ethylene and wounding mainly in tubers. The roles of these three genes and of other members of the ACC synthase gene family in vegetative processes of potato such as tuberization, dormancy, and sprouting have yet to be determined.

Amino Acid Sequence↗
PubMed1995

Tamoxifen and its active metabolite inhibit growth of estrogen receptor-negative MDA-MB-435 cells.

Tamoxifen (TAM), the non-steroidal anti-estrogen most widely administered to breast cancer patients, acts, at least in part, by competing with estrogen receptors (ER). However, the existence of an alternative mechanism of action for this drug is supported by the clinical observations that: (a) 30% of patients with ER-negative cancer cells respond to TAM, and (b) 30% of patients with ER-positive cancer cells are not sensitive to this anti-estrogen. In this study, we observed that growth of the human ER-negative breast cancer cell line MDA-MB-435 was inhibited by TAM and 4-hydroxytamoxifen (4OH-TAM) in a concentration-dependent fashion. Both monoclonal enzymoimmunoassay and Dextran Charcoal Coated Scatchard radioimmunoassay analysis demonstrated that this MDA-MB-435 cell line does not express ER. The absence of ER in MDA-MB-435 cells was also demonstrated at the mRNA level by both northern blot hybridization and reverse transcription-polymerase chain reaction techniques. MDA-MB-435 cell proliferation was not affected by 17 beta-estradiol or by the pure anti-estrogen ICI 164384, further demonstrating that the observed effects of TAM and its active metabolite on the proliferation of MDA-MB-435 cells were due to an ER-independent mechanism, yet to be identified. MDA-MB-435 thus appears to be a promising original model for the study of the alternative ER-independent mechanisms of action of TAM.

Breast Neoplasms↗
PubMed1995

P-fimbriae of Escherichia coli as carriers for gonadotropin releasing hormone: development of a recombinant contraceptive vaccine.

The demand for an effective and low cost means of fertility control of domestic animals has raised interest in the development of contraceptive vaccines. A promising candidate for a vaccine component is the brain peptide gonadotropin releasing hormone (GnRH), which plays a central role in the regulation of reproductive functions in vertebrates. Neutralization of GnRH by vaccine-induced antibodies is expected to prevent the reproductive activity in a wide range of species. A GnRH-protein conjugate was prepared by means of recombinant DNA technology. The oligonucleotides encoding GnRH were inserted in hypervariable regions of the subunit gene of P-fimbriae of Escherichia coli. Hybrid fimbriae encoded by the manipulated fimbrial gene clusters were expressed efficiently on the cell surface of Escherichia coli. Vaccination of female rats and bull calves with purified hybrid GnRH-fimbriae strongly affected the reproductive characteristics. We conclude that P-fimbriae represent a very attractive carrier system for application of GnRH in a new type of vaccine.

Amino Acid Sequence↗
PubMed1994

Homeobox genes: potential candidates for the transcriptional control of the transformed and invasive phenotype.

The transformation of a cell and the acquisition of the invasive and metastatic phenotype result from the activation of a group of complex cellular processes rather than from the effect of a single gene product. It is likely that the coordination of the multiple genes involved in malignancy is under the control of a few genes that act as master genes or orchestrator genes. The latter probably code for transcription factors that control the genetic program for tumor invasion and metastasis. Homeobox genes are a family of transcription factors that contain a 183 bp highly conserved nucleotide sequence coding for a 61 amino acid domain that binds specifically to DNA. First discovered in Drosophila as genes controlling segmentation and segment identity, homeobox genes have since been identified in many other species including nematodes, frog, mouse and human. There is strong support for the suggestion that homeobox genes play a key role in development and differentiation. In humans, there are 38 homeobox genes organized in four clusters that are localized on chromosomes 2, 7, 12 and 17. The specific functions of each of these genes are generally unknown. Alterations in expression of several homeobox genes have been reported in a variety of malignant lesions, suggesting that they could play a role in the development of cancer. Using reverse transcriptase reaction coupled with polymerase chain reaction and degenerate oligonucleotides corresponding to the 5' and 3' ends of the highly conserved homeodomain, we amplified 130 bp cDNA fragments from the human breast cancer cell line MCF7 that were subsequently cloned into pBluescript vector. Sequencing of the clones, resulted in the identification of the homeodomains of four different human homeobox genes: HOXB6, HOXA1, HOXA10 and HOXC6. Further studies should determine the specific role of these four homeobox genes in the development and progression of human breast cancer and potentially determine if they might be good targets for gene therapy.

Amino Acid Sequence↗
PubMed1994

Heat-inducible rice hsp82 and hsp70 are not always co-regulated.

We have characterized several heat-shock-induced genes in rice (Oryza sativa L.) and compared their expression under a variety of conditions. Three of these genes, which are analogs of the hsp82/90 family, lie within a cloned 18-kilobase (kb) region of the genome. The middle member of this cluster, designated hsp82B, has been fully sequenced. The gene uses a promoter containing six putative heat-shock elements as well as several unusual sequence motifs including a stretch of 11 thymidines alternating with 11 adenosines. The mRNA for this gene reaches its highest relative level of expression within 120 min after plants are shifted to 42 degrees C; no other conditions induce this gene. By contrast, we found that during heat stress the expression of hsp70 correlates well with increases in internal ion concentrations, and can also be induced by excess salt or ethanol at normal growth temperatures. These results appear to indicate that whereas hsp70 is induced by all stresses that lead to protein denaturation-including heat stress-HSP82 mRNA accumulates only upon heat stress.

Amino Acid Sequence↗