Generation of a floxed allele of Smad5 for cre-mediated conditional knockout in the mouse

Smad5 is a member of the Smad family of intracellular mediators of BMP signals and in endothelial cells of TGF-beta signals. We and others previously showed that loss of Smad5 in the mouse results in embryonic lethality (between E9.5-E11.5) due to multiple embryonic and extraembryonic defects. To circumvent the early embryonic lethality and to allow tissue- and time-specific Smad5 inactivation, we created a conditional Smad5 allele in the mouse. Floxed Smad5 (Smad5(flE2,Neo/flE2,Neo)) mice were generated in which both exon2 and the Neo-cassette were flanked by loxP sites. Here we demonstrate that embryos with ubiquitous Cre-mediated deletion of Smad5 (Smad5(flDeltaE2/flDeltaE2)) phenocopy the conventional Smad5 knockout mice. Smad5(flE2/flE2) mice are now available and will be a valuable tool to analyze the role of Smad5 beyond its crucial early embryonic function throughout development and postnatal life.     

Clinical and angiographic results with the NIR stent: First International NIR Endovascular Stent Study (FINESS-II)

BACKGROUND: Although safety and efficacy of the NIR trade mark stent have been reported, the long-term angiographic and clinical outcomes have yet to be investigated. The FINESS-II study (First International NIR Endovascular Stent Study) was designed to assess the procedural safety of single 9 and 16 mm NIR stent implantation, the six-month restenosis rate and finally the six- and 12-month clinical outcome of patients treated with this novel coronary stent. METHODS: Patients with angina and a single de novo lesion in a native coronary artery of >3 and <5 mm diameter were included in this multicentre, prospective, observational trial. Clinical follow-up was obtained at one, six and 12 months. Angiography was performed before and after the stent implantation and at six months. The primary endpoint included major adverse cardiac events (death, myocardial infarction and target lesion revascularization) within 30 days after the procedure. Major bleeding complications and subacute stent thrombosis within the first 30 days were also reported as specific endpoints. Secondary endpoints were major cardiac-event-free survival at six- and 12-month follow-up and angiographic restenosis at six months. RESULTS: A total of 156 patients (81% male, mean age 60 +/- 10 years), with stable (54%), unstable (40%) angina pectoris or silent ischemia (6%) were enrolled. The target vessel diameter was 2.94 +/- 0.54 mm. The minimal lumen diameter pre, post and at follow-up was 1.04 +/- 0.32 mm, 2.64 +/- 0.42 mm and 1.88 +/- 0.63 mm, respectively. Restenosis rate according to the >50% diameter stenosis criterion at six month follow-up was 19% (26/136). At 12 months, the event-free survival rate was 83% (two deaths, one Q-wave and three non-Q-wave myocardial infarctions, four bypass surgery and 17 target lesion revascularizations), while 87% of the patients were free of angina pectoris. CONCLUSION: the outcome of the FINESS-II trial is comparable to those observed in previous stent trials (Benestent II), indicating that the coronary NIR stent is safe and effective as a primary device for the treatment of native coronary artery lesions in patients with (un)stable angina pectoris.     

The association of the MYH9 gene and kidney outcomes in American Indians: the Strong Heart Family Study

Chronic kidney disease (CKD) is an important public health problem in American Indian populations. Recent research has identified associations of polymorphisms in the myosin heavy chain type II isoform A (MYH9) gene with hypertensive CKD in African-Americans. Whether these associations are also present among American Indian individuals is unknown. To evaluate the role of genetic polymorphisms in the MYH9 gene on kidney disease in American Indians, we genotyped 25 SNPs in the MYH9 gene region in 1,119 comparatively unrelated individuals. Four SNPs failed, and one SNP was monomorphic. We inferred haplotypes using seven SNPs within the region of the previously described E haplotype using Phase v2.1. We studied the association between 20 MYH9 SNPs with kidney function (estimated glomerular filtration rate, eGFR) and CKD (eGFR < 60 ml/min/1.73 m² or renal replacement therapy or kidney transplant) using age-, sex- and center-adjusted models and measured genotyped within the variance component models. MYH9 SNPs were not significantly associated with kidney traits in additive or recessive genetic adjusted models. MYH9 haplotypes were also not significantly associated with kidney outcomes. In conclusion, common variants in MYH9 polymorphisms may not confer an increased risk of CKD in American Indian populations. Identification of the actual functional genetic variation responsible for the associations seen in African-Americans will likely help to clarify the lack of replication of this gene in our population of American Indians.     

Functional redundancy of TGF-beta family type I receptors and receptor-Smads in mediating anti-Mullerian hormone-induced Mullerian duct regression in the mouse

Amniotes, regardless of genetic sex, develop two sets of genital ducts: the Wolffian and Müllerian ducts. For normal sexual development to occur, one duct must differentiate into its corresponding organs, and the other must regress. In mammals, the Wolffian duct differentiates into the male reproductive tract, mainly the vasa deferentia, epididymides, and seminal vesicles, whereas the Müllerian duct develops into the four components of the female reproductive tract, the oviducts, uterus, cervix, and upper third of the vagina. In males, the fetal Leydig cells produce testosterone, which stimulates the differentiation of the Wolffian duct, whereas the Sertoli cells of the fetal testes express anti-Müllerian hormone, which activates the regression of the Müllerian duct. Anti-Müllerian hormone is a member of the transforming growth factor-beta (TGF-beta) family of secreted signaling molecules and has been shown to signal through the BMP pathway. It binds to its type II receptor, anti-Müllerian hormone receptor 2 (AMHR2), in the Müllerian duct mesenchyme and through an unknown mechanism(s); the mesenchyme induces the regression of the Müllerian duct mesoepithelium. Using tissue-specific gene inactivation with an Amhr2-Cre allele, we have determined that two TGF-beta type I receptors (Acvr1 and Bmpr1a) and all three BMP receptor-Smads (Smad1, Smad5, and Smad8) function redundantly in transducing the anti-Müllerian hormone signal required for Müllerian duct regression. Loss of these genes in the Müllerian duct mesenchyme results in male infertility due to retention of Müllerian duct derivatives in an otherwise virilized male.     

Einthoven dissertation prizes 2014

For the 26th time in a row the Interuniversity Cardiology Institute of the Netherlands (ICIN-Netherlands Heart Institute) and the Netherlands Society of Cardiology (NVVC) have supported the competition for the best three cardiovascular PhD theses, published in the year 2014 [1–3]. The dissertation prize carries the name of one of the greatest Dutchmen in the history of cardiovascular medicine, Willem Einthoven, who in 1902 for the first time recorded the human ECG, for which he received the Nobel Prize in 1924 [4].This time the jury received a total of 28 PhD dissertations published in 2014. The jury members were very much impressed by the high scientific quality of the PhD fellows. The ultimate selection was based on a combination of several parameters: the curriculum vitae of the candidate, the scientific originality of the PhD thesis and its relevance for the cardiovascular field. In addition, several objective bibliometric parameters were used: (1) the number of articles in first-rate journals both in PubMed and the Web of Science (WOS), (2) the number of citations in WOS, (3) the Hirsch index and (4) the contribution as a first author (or shared first author).Based on a combination of these results, the jury finally selected three nominees: K.Y. van Spaendonck-Zwarts (University Medical Centre Groningen), N.M. van Mieghem (Erasmus Medical Centre, Rotterdam) and W.J. Dewilde (Sint Antonius Hospital, Nieuwegein).The members of the jury were: J.W. Deckers (Director CVOI), S. Heymans (ICIN professor), A. Mosterd (Chairman WCN), M.J. Schalij (Chairman Concilium NVVC) and V.A. Umans (President NVVC).The three candidates presented their Ph.D. theses at the annual spring meeting of the NVVC, held at the Congress Centre “De Leeuwenhorst” in Noordwijkerhout, 9–10 April 2015. Based on the quality of the presentation, the audience determined the ranking of the laureates. Mrs. dr. K.Y. van Speandonck-Zwarts received the third prize, dr. N.M. van Mieghem the second prize, and dr. W.J. Dewilde the first prize. We like to congratulate the three winners with their excellent PhD Theses. Summaries of the three nominated PhD theses are given below.     

Individual optimization: Mechanisms shaping the optimal reaction norm

In general, optimal reaction norms in heterogeneous populations can be obtained only by iterative numerical procedures (McNamara, 1991; Kawecki and Stearns, 1993). We consider two particular, but biologically plausible and analytically tractable cases of individual optimization to gain insight into the mechanisms which shape the optimal reaction norm of fecundity in relation to an environmental variable or an individual trait. In the first case, we assume that the quality of the environment (e.g. food abundance) or the quality of the individual (e.g. body size) is fixed during its entire life; it may also be a heritable individual trait. In the second case, individual quality is assumed to change randomly such that the probability distribution of quality in the next year is the same for the parent and for her offspring. For these two cases, we obtain analytical expressions for the shape of the optimal reaction norm, which are heuristically interpretable in terms of underlying selective mechanisms. It is shown that better quality may reduce the optimal fecundity. This outcome is particularly likely if better quality increases a fecundity-independent factor of parental survival in a long-lived species with fixed quality. This revised version was published online in July 2006 with corrections to the Cover Date.     

NVVC/NHJ Durrer prizes 2014

At the annual 2015 Spring Congress of the NVVC, the Durrer prizes were awarded to the authors of two of the best original/review articles published in the year 2014, one paper being more basically oriented and one paper being more clinically oriented. This has been an annual tradition since the year 2006.