Biomedical subjects

Martin Paul

Publications and source records attributed to Martin Paul.

47 records · Page 3Linked to original sources

PubMed2002

Early onset of chondroitin sulfate and osteopontin expression in angiotensin II-dependent left ventricular hypertrophy.

BACKGROUND: Chondroitin sulfate proteoglycan (CSPG) is expressed during embryonic heart development and osteopontin (OPN) is an important mediator of the profibrotic effects of angiotensin II (Ang II). The objective of this study was to analyze extracellular matrix protein (ECMP) expression in Ang II-dependent left ventricular (LV) hypertrophy (LVH), LV dysfunction, and to investigate right ventricular changes. METHODS: We used the hypertensive transgenic rat line TGR(mRen2)27 (Ren2), which provides a well-established model of Ang II-driven cardiac remodeling and progressive LV dysfunction and compared young Ren2 rats at the age of 10 weeks with normotensive Sprague-Dawley (SD) rats (n = 15, each group). RESULTS: Systolic blood pressure and LV weight were elevated in Ren2 compared to SD rats (P < .001). Left ventricular end-diastolic pressure was not altered in Ren2, but +dP/dt(max) and -dP/dt(max) were decreased in Ren2 compared to SD rats (P < .01). Cardiomyocyte widths, interstitial and perivascular fibrosis were increased in left and right ventricles of Ren2 in comparison to SD rats (P < .05). The LV mRNA expression of atrial natriuretic factor, OPN, and collagen I were increased in Ren2 as compared to SD rats (P < .05, respectively). The LV CSPG, collagen I, collagen III, fibronectin, laminin, and OPN contents were elevated in Ren2 compared to SD rats as measured by image analysis and Western blotting (P < .01). CONCLUSIONS: Reactivated expression of CSPG in the adult heart may be an important component of LV ECMP remodeling in LVH. Elevated cardiac OPN expression could mediate the alterations in LV ECMP pattern in Ang II-dependent LVH, thus contributing to the development of contractile dysfunction in young Ren2 rats.

Angiotensin II↗

PubMed2002

Angiotensin II type 2 receptor gene polymorphism and cardiovascular phenotypes: the GLAECO and GLAOLD studies.

BACKGROUND: The angiotensin II type 2 (AT2) receptor is thought to play a role in cardiovascular disorders such as neointima formation after vascular injury, cardiac hypertrophy and myocardial infarction (MI). Recently, the biallelic polymorphism G + 1675A in intron 1 of the AT2 receptor gene has been associated with left ventricular posterior, septal and relative wall thickness, as well as left ventricular mass index in young hypertensive males. METHODS: To investigate its potential role in left ventricular hypertrophy (LVH) and other cardiovascular traits, 1968 individuals from two population samples (the Glasgow Heart Scan, GLAECO and Glasgow Heart Scan Old, GLAOLD studies) with echocardiographically and electrocardiographically assessed phenotypes, were genotyped for G + 1675A using allele-specific oligonucleotide hybridization. Both studies had a similar design, only the age-ranges differed, being 25-74 years in the GLAECO study and 55-74 years in the GLAOLD study, so that internal consistency of results could also be assessed. Since the AT2 gene is located on the X chromosome, males and females were analysed separately. RESULTS: The + 1675A allele frequency was 0.49 and 0.51, in the GLAECO and GLAOLD studies, respectively. In both studies, the genotype frequencies were similar in hypertensive and non-hypertensive individuals. In the GLAOLD study, in females with episodes of coronary ischemia and MI, the AT2 + 1675A allele was more common than in females with no episode (86.5% vs. 73.5%, respectively; P < 0.007). This effect was not observed in males. In the same study, AT2 + 1675A allele carriers were more common in males with LVH, than in those without LVH (60.3% vs. 46.0%, respectively; P = 0.047). This result was unchanged after exclusion of subjects taking antihypertensive drugs (including ACE inhibitors) (64.4% vs. 47.4%, P = 0.038). However, in the GLAECO study, these results could not be replicated, even when subjects > 55 years of age were considered separately. CONCLUSIONS: Our study gives rise to a potential implication of the AT2 G + 1675A polymorphism in LVH and coronary ischemia subgroups. Since these results were not consistent in both studies, but are partially in agreement with two independent investigations, further efforts should be made to elucidate the specific nature of these genotype/phenotype interactions.

Age Distribution↗

PubMed2002

Nitric oxide synthase isoform expression in acute versus chronic anti-Thy 1 nephritis.

BACKGROUND: Two inbred Lewis rat substrains (LEW/Moe, LEW/Maa) were identified responding differently to induction of anti-Thy 1 glomerulonephritis (aThy 1-GN). LEW/Moe rats show an acute mesangioproliferative glomerulonephritis with rapid healing of glomerular lesions within four weeks, while LEW/Maa rats develop severe glomerular injury followed by chronic glomerular sclerosis and persistent albuminuria. We investigated whether the glomerular expression pattern of nitric oxide synthase (NOS) isoforms could explain these substrain-related differences. METHODS: Rats (N = 5 to 7 per group) were investigated in a time course experiment. Severity of aThy 1-GN was determined by albuminuria measurements, glomerular matrix score and microaneurysm formation. Glomerular gene expression of NOS isoforms was determined by semiquantitative RT-PCR. Inducible NOS (iNOS) activity was determined in cultured glomeruli and peritoneal macrophages. Neuronal NOS (nNOS) protein expression was detected by Western blotting and enzyme histochemistry. Plasma renin activity (PRA) was measured by RIA. RESULTS: Induction of iNOS expression and activity was found significantly increased and sustained in LEW/Maa vs. LEW/Moe rats associated with an increased number of infiltrating macrophages and with an increased capacity of iNOS-expression and iNOS-activation by isolated macrophages in LEW/Maa rats. Glomerular nNOS mRNA and nNOS protein expression were constitutively increased in LEW/Maa rats. Renal nNOS localization was restricted to the macula densa region in both substrains and associated with increased PRA in LEW/Maa rats. No difference in glomerular endothelial NOS-mRNA expression between the substrains was observed. CONCLUSIONS: Increased glomerular iNOS and nNOS expression were associated with chronic anti-Thy 1 glomerulonephritis in LEW/Maa rats and may contribute to glomerular damage by separate mechanisms.

Acute Disease↗

PubMed2002

Simulated microgravity alters differentiation and increases apoptosis in human follicular thyroid carcinoma cells.

This study focuses on the effects of simulated microgravity (0g) on the human follicular thyroid carcinoma cell line ML-1. Cultured on a three-dimensional clinostat, ML-1 cells formed three-dimensional MCTSs (MCTS diameter: 0.3 +/- 0.01 mm). After 24 and 48 h of clinorotation, the cells significantly decreased fT3 and fT4 secretion but up-regulated the thyroid-stimulating hormone-receptor expression as well as the production of vimentin, vinculin, and extracellular matrix proteins (collagen I and III, laminin, fibronectin, chondroitin sulfate) compared with controls. Furthermore, ML-1 cells grown on the clinostat showed elevated amounts of the apoptosis-associated Fas protein, of p53, and of bax but showed reduced quantities of bcl-2. In addition, signs of apoptosis became detectable, as assessed by terminal deoxynucleotidyl transferase-mediated dUTP digoxigenin nick end labeling, 4', 6-diamidino-2-phenylindole staining, DNA laddering, and 85-kDa apoptosis-related cleavage fragments. These fragments resulted from enhanced 116-kDa poly(ADP-ribose)polymerase (PARP) activity and apoptosis. These observations suggest that clinorotation elevates intermediate filaments, cell adhesion molecules, and extracellular matrix proteins and simultaneously induces apoptosis in follicular thyroid cancer cells. In conclusion, our experiments could provide a regulatory basis for the finding that astronauts show low thyroid hormone levels after space flight, which may be explained by the increase of apoptosis in thyrocytes as a result of simulated 0g.

Adenocarcinoma, Follicular↗

PubMed2002

Polymorphisms of the beta2 -adrenoceptor (ADRB2) gene and essential hypertension: the ECTIM and PEGASE studies.

OBJECTIVES: The beta2-adrenoceptor (ADRB2) plays a pivotal role in signalling in relation to hypertension and obesity. Polymorphisms of the ADRB2 gene have been shown to be potentially related to essential hypertension and other non-cardiovascular disease phenotypes. We investigated whether genetic variation of the ADRB2 gene might be related to essential hypertension or myocardial infarction (MI). METHODS: Four ADRB2 gene polymorphisms C19R (T-47C), T-20C, G16R (G+46A), Q27E (C+79G) were investigated in two studies: PEGASE, a study of moderate to severe hypertension (707 cases) conducted in France, and ECTIM, a case-control study of MI (1178 cases, 1187 controls) conducted in France, Northern Ireland and Scotland. Genotyping was performed using allele-specific oligonucleotides. RESULTS: The ADRB2 polymorphisms T-20C and Q27E were found to be completely concordant, generating the haplotypes [T-20-Q27] and [C-20-E27]. Three main haplotypes accounted for 94% of all haplotypes: [R19-G16-E27] (39%), [C19-R16-Q27] (35%) and [C19-G16-Q27] (20%). Haplotype frequencies were not significantly different between countries. Allele and genotype frequencies did not differ significantly between cases with essential hypertension or MI and control subjects. There was no association of the polymorphisms with early onset hypertension, blood pressure level, coronary artery stenosis or any other phenotype measured in these study populations. In the ECTIM Study, our calculation revealed that we could have detected an odds ratio (OR) for MI of 1.3 with 80% power at a 5% type I error probability, the corresponding value for the PEGASE Study being an OR of 1.6 for hypertension. CONCLUSIONS: From our present analysis we conclude that the ADRB2 gene polymorphisms studied do not contribute in any important way to the risk of essential hypertension or MI in subjects of European ancestry.

Adult↗

PubMed2002

Inhibition of left ventricular fibrosis by tranilast in rats with renovascular hypertension.

BACKGROUND: Growth factors such as transforming growth factor-beta (TGF beta) are believed to have an essential role in cardiac fibrosis. Tranilast (N(3,4-dimethoxycinnamoyl) anthranilic acid) attenuates the increased expression of TGF beta mRNA in vitro. OBJECTIVE: To investigate whether tranilast reduces cardiac fibrosis in rats with two-kidney, one-clip (2K1C) renovascular hypertension. In addition, we tested the in-vitro effects of tranilast on cardiac myocytes and non-myocyte cells. METHODS: We analysed hearts from four groups of rats: sham-operated controls; rats with 2K1C renovascular hypertension; rats with 2K1C renovascular hypertension treated for 12 weeks with the angiotensin converting enzyme (ACE) inhibitor, quinapril (6 mg/kg per day); rats with 2K1C renovascular hypertension treated for 12 weeks with tranilast (400 mg/kg per day). RESULTS: Systolic blood pressure was reduced after quinapril treatment. Tranilast did not alter blood pressure (2K1C: 223 +/- 19 mmHg; 2K1C + quinapril: 149 +/- 15 mmHg (P < 0.01 compared with 2K1C); 2K1C + tranilast: 204 +/- 32 mmHg). Left ventricular weight was likewise reduced significantly by quinapril, but not significantly by tranilast (2K1C: 1.52 +/- 0.2 g; 2K1C + quinapril: 1.26 +/- 0.18 g (P < 0.05 compared with 2K1C); 2K1C + tranilast: 1.37 +/- 0.27 g). Using a computer-aided image analysis system, we demonstrated that tranilast prevented cardiac fibrosis in a blood-pressure-independent manner (P < 0.01 compared with 2K1C). Determination of the cardiac hydroxyproline content similarly revealed a significant reduction in cardiac fibrosis by tranilast (2K1C: 4.92 +/- 0.48 mg/mg; 2K1C + tranilast: 3.97 +/- 0.46 mg/mg; P < 0.05). The effect of tranilast on cardiac fibrosis was comparable to the effects of a blood-pressure-decreasing dose of the ACE inhibitor, quinapril. Cell culture experiments revealed that tranilast significantly decreased the proliferation of cardiac non-myocyte cells. Proliferation of cardiac myocytes was not altered. CONCLUSION: This study revealed that long-term treatment with tranilast markedly attenuated left ventricular fibrosis in rats with renovascular hypertension. This was most probably the result of an antiproliferative effect of tranilast on cardiac non-myocyte cells. Tranilast thus offers a unique new therapeutic approach to the reduction of TGF beta-mediated cardiac fibrosis in vivo.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed2002

Parent bisphenol A accumulation in the human maternal-fetal-placental unit.

Bisphenol A (BPA), an endocrine disruptor, is employed in the manufacture of a wide range of consumer products. The suggestion that BPA, at amounts to which we are exposed, alters the reproductive organs of developing rodents has caused concern. At present, no information exists concerning the exposure of human pregnant women and their fetuses to BPA. We therefore investigated blood samples from mothers (n = 37) between weeks 32 and 41 of gestation. Afer the births, we also analyzed placental tissue and umbilical cord blood from the same subjects. We developed a novel chemical derivatization-gas chromatography/mass spectrometry method to analyze parent BPA at concentrations < 1 micro g/mL in plasma and tissues. Concentrations of BPA ranged from 0.3 to 18.9 ng/mL (median = 3.1 ng/mL) in maternal plasma, from 0.2 to 9.2 ng/mL (median = 2.3 ng/mL) in fetal plasma, and from 1.0 to 104.9 ng/g (median = 12.7 ng/g) in placental tissue. BPA blood concentrations were higher in male than in female fetuses. Here we demonstrate parent BPA in pregnant women and their fetuses. Exposure levels of parent BPA were found within a range typical of those used in recent animal studies and were shown to be toxic to reproductive organs of male and female offspring. We suggest that the range of BPA concentrations we measured may be related to sex differences in metabolization of parent BPA or variable maternal use of consumer products leaching BPA.

Adult↗

PubMed2002

Effects of simulated microgravity on thyroid carcinoma cells.

We aimed to investigate whether simulated microgravity on thyroid carcinoma cells could help to perform in vitro cancer studies such as antitumor drug tests more reliable and to spare animal experiments. We cultured cancer cells at 0 g to enable formation of three-dimensional multicellular tumor spheroids (MCTS), which will resemble the originating tumors. Under microgravity human follicular cells (ML-1 cell line) keep floating with-out stirring so that initial cell-cell interactions required for spheroid formation will be induced by forces due to biochemical components actually expressed on surfaces of cells, whereas gravity related push- or shear events will not influence MCTS formation. Within 12 hours of clinorotation the monolayer turned spontaneously into MCTS with remarkable features: An increase of extracellular matrix proteins and TGF-beta 1. Thyroglobulin, ft3 and ft4 secretion were markedly reduced. These data are in agreement with the observation that astronauts show low thyroid hormone levels after spaceflight.

Journal Article↗

PubMed2002

Simulated microgravity induces programmed cell death in human thyroid carcinoma cells.

The present study focused on the effects of simulated microgravity on the human follicular thyroid carcinoma cell line ML-1. Cultured on a three-dimensional clinostat ML- 1 cells formed three-dimensional multicellular tumor spheroids (MCTS: 0.3 +/= 0.01mm in diameter). Furthermore, ML-1 cells grown on the clinostat showed elevated amounts of the apoptosis-associated Fas protein, of p53 and of bax, but reduced quantities of bcl-2. In addition, signs of apoptosis as assessed by TdT-mediated DUTP digoxigenin nick end labeling, DAPI staining, DNA laddering and 85-kDa apoptosis-related DNA fragments became detectable. The latter ones resulted from enhanced 116-kDa poly(ADP-ribose)polymerase activity. Electron microscopy revealed all morphological signs of apoptosis. Caspase 3 was clearly upregulated. In conclusion, our experiments show that conditions of simulated microgravity induce early programmed cell death and use different pathways of apoptosis.

Journal Article↗

PubMedDate not supplied

Harmonization of rat fetal external and visceral terminology and classification. Report of the Fourth Workshop on the Terminology in Developmental Toxicology, Berlin, 18-20 April 2002.

This article is a report on the Fourth Berlin Workshop on Terminology in Developmental Toxicology, which was held in April 2002. The workshop is part of an international project in the field of harmonization of terminology in developmental toxicology supported by IPCS. The goal of the Harmonization Project is to ensure better chemical risk assessment. The aim of this Fourth Workshop was to discuss the results of a previously conducted survey on classification of external and visceral anomalies, which are listed in the international glossary, developed under the auspices of IFTS (1997 glossary). The discussions among experts from research institutions, regulatory agencies, and industries were mainly focussed on terms for which there was disagreement and/or uncertainties and the possible reasons. For the illustration of "gray-zone" anomalies, pictures were provided by the participants, which constituted the basis for detailed discussions. There was high agreement that most of the external anomalies (>66%) should be classified as malformations. The few external anomalies for which there was low agreement to classify as a malformation were discussed in detail. None of the external findings, which had in the survey a high agreement, were categorized as a variation.A high agreement regarding the classification of approximately one-third of visceral anomalies was achieved with 34 and 2% being described as malformation and variation, respectively. Most of the visceral findings had low agreement indices and there appeared to be several reasons for this. Thus, the response, 'Not known/not used in the laboratory' (N) was often given. A couple of reasons for difficulties in the classification of an anomaly were that it is only rarely seen upon fetal examination or tends to be species specific. Furthermore, the classification of some anomalies as malformation or variation will remain vague as the decision must be made on a case-by-case basis. Factors affecting the decision include: the availability of appropriate historical control data, description of the grading and severity, whether the anomaly occurs in isolation or whether there is a relationship with an abnormal process, and finally, if the change represents an irreversible one, affecting human and/or animal health. It was concluded that a severity grading, supported by pictures of the anomaly, would be especially helpful to classify certain changes as malformation or as variation. Several of the soft tissue changes were considered likely to be the consequence of functional disorders and thus not strictly developmental anomalies. The possibility to describe a finding as 'Not Malformation' (Unclassified) was agreed upon. As a general conclusion it was emphasized that the observation of a permanent structural change should be considered to be a warning of possible consequences to humans, even when there is no apparent adverse effect on health and survival in adult animals of the species under investigation. Therefore, research is needed to further investigate postnatal consequences. Future collaboration in the field of reproductive and developmental toxicology should aim to further develop and implement a harmonized approach to the interpretation of study data. Therefore, this terminology work will continue in close cooperation with the IPCS Harmonization Project. A Steering Group should be established to facilitate the implementation of harmonized terminology into daily scientific work and its regulatory application.

Abnormalities, Drug-Induced↗

PubMedDate not supplied

Developmental effects of prenatal exposure to bisphenol a on the uterus of rat offspring.

Exposure to estrogenic compounds during critical periods of fetal development could result in adverse effects on the development of reproductive organs that are not apparent until later in life. Bisphenol A (BPA), which is employed in the manufacture of a wide range of consumer products, is a prime candidate for endocrine disruption. We examined BPA to address the question of whether in utero exposure affects the uterus of the offspring and studied the expression and distribution of the estrogen receptors alpha (ERalpha) and beta (ERbeta), because estrogens influence the development, growth, and function of the uterus through both receptors. Gravid Sprague-Dawley dams were administered by gavage either 0.1 or 50 mg/kg per day BPA or 0.2 mg/kg per day 17alpha-ethinyl estradiol (EE2) as reference dose on gestation days 6 through 21. Female offspring were killed in estrus. Uterine morphologic changes as well as ERalpha and ERbeta distribution and expression were measured by immunohistochemistry and Western blot analysis. Striking morphologic changes were observed in the uterine epithelium of postpubertal offspring during estrus of the in utero BPA-treated animals (the thickness of the total epithelium was significantly reduced). ERalpha expression was increased in the 50-mg BPA and EE2-treated group. In contrast, we observed significantly decreased ERbeta expression in all BPA- and EE2-treated animals when compared with the control. In summary, these results clearly indicate that in utero exposure of rats to BPA promotes uterine disruption in offspring. We hypothesize that the uterine disruption could possibly be provoked by a dysregulation of ERalpha and ERbeta.

Animals↗