Fishing for the signals that pattern the face

Zebrafish are a powerful system for studying the early embryonic events that form the skull and face, as a model for human craniofacial birth defects such as cleft palate. Signaling pathways that pattern the pharyngeal arches (which contain skeletal precursors of the palate, as well as jaws and gills) are discussed in light of a recent paper in BMC Developmental Biology on requirements for Hedgehog signaling in craniofacial development

Zebrafish (Danio rerio) Hoxb6: An Exploration into the Divergence of Genomic DNA Sequence and Gene Expression Across Teleost Fishes Post-Genome Duplication

Hoxb6 is an evolutionarily conserved developmental regulatory gene that functions, in part, to pattern several organs and organ systems within the embryonic trunk during vertebrate embryogenesis. The cis-regulatory circuitry mediating trunk expression in mouse (Mus musculus) may be conserved across gnathostome vertebrates, as several other species show similar trunk expression patterns, including chicken (Gallus gallus), dogfish shark (Scyliorhinus canicula), and several teleost fishes. A whole genome duplication event that occurred in the lineage leading to teleost fishes has generated at least two Hoxb6 genes, hoxb6a and b6b. Two teleost fishes of the superorder Acanthopterygii, Japanese medaka (Oryzias latipes) and Nile tilapia (Oreochromis niloticus), exhibit divergent Hoxb6 expression patterns from those of non-teleost vertebrates. This includes an anterior expansion of expression for both hoxb6a and b6b into pharyngeal arch 7, the posterior-most pharyngeal arch that, along with the other posterior pharyngeal arches, gives rise to the pharyngeal jaw apparatus in teleost fishes. While these patterns of expression are observed for both duplicate Hoxb6 genes in Acanthopterygians, it is uncertain whether this pharyngeal arch expression is shared with other teleost taxa. Here we present the expression patterns of hoxb6a and b6b in zebrafish (Danio rerio), a member of the Ostariophysi superorder. We show that, unlike the strict orthologs from medaka and tilapia, zebrafish hoxb6a is expressed in pharyngeal arches 5-7, whereas hoxb6b is not expressed in any of the pharyngeal arches. Further, we show through comparative genomic DNA sequence analyses that, although all teleost-specific sequences exhibit moderate conservation with the region functionally tested in mouse, zebrafish hoxb6a and b6b exhibit little to no conservation in sequence with their strict orthologs of medaka or tilapia outside of this region. Our data suggest that divergence in the cis-regulatory circuitry post-genome duplication has generated divergent hoxb6a and b6b expression patterns among teleost fishes

HDAC-mediated control of ERK- and PI3K-dependent TGF-β-induced extracellular matrix-regulating genes

Histone deacetylases (HDACs) regulate the acetylation of histones in the control of gene expression. Many non-histone proteins are also targeted for acetylation, including TGF-ß signalling pathway components such as Smad2, Smad3 and Smad7. Our studies in mouse C3H10T1/2 fibroblasts suggested that a number of TGF-ß-induced genes that regulate matrix turnover are selectively regulated by HDACs. Blockade of HDAC activity with trichostatin A (TSA) abrogated the induction of a disintegrin and metalloproteinase 12 (Adam12) and tissue inhibitor of metalloproteinases-1 (Timp-1) genes by TGF-ß, whereas plasminogen activator inhibitor-1 (Pai-1) expression was unaffected. Analysis of the activation of cell signalling pathways demonstrated that TGF-ß induced robust ERK and PI3K activation with delayed kinetics compared to the phosphorylation of Smads. The TGF-ß induction of Adam12 and Timp-1 was dependent on such non-Smad signalling pathways and, importantly, HDAC inhibitors completely blocked their activation without affecting Smad signalling. Analysis of TGF-ß-induced Adam12 and Timp-1 expression and ERK/PI3K signalling in the presence of semi-selective HDAC inhibitors valproic acid, MS-275 and apicidin implicated a role for class I HDACs. Furthermore, depletion of HDAC3 by RNA interference significantly down-regulated TGF-ß-induced Adam12 and Timp-1 expression without modulating Pai-1 expression. Correlating with the effect of HDAC inhibitors, depletion of HDAC3 also blocked the activation of ERK and PI3K by TGF-ß. Collectively, these data confirm that HDACs, and in particular HDAC3, are required for activation of the ERK and PI3K signalling pathways by TGF-ß and for the subsequent gene induction dependent on these signalling pathways

Zebrafish endochondral growth zones as they relate to human bone size, shape and disease

Research on the genetic mechanisms underlying human skeletal development and disease have largely relied on studies in mice. However, recently the zebrafish has emerged as a popular model for skeletal research. Despite anatomical differences such as a lack of long bones in their limbs and no hematopoietic bone marrow, both the cell types in cartilage and bone as well as the genetic pathways that regulate their development are remarkably conserved between teleost fish and humans. Here we review recent studies that highlight this conservation, focusing specifically on the cartilaginous growth zones (GZs) of endochondral bones. GZs can be unidirectional such as the growth plates (GPs) of long bones in tetrapod limbs or bidirectional, such as in the synchondroses of the mammalian skull base. In addition to endochondral growth, GZs play key roles in cartilage maturation and replacement by bone. Recent studies in zebrafish suggest key roles for cartilage polarity in GZ function, surprisingly early establishment of signaling systems that regulate cartilage during embryonic development, and important roles for cartilage proliferation rather than hypertrophy in bone size. Despite anatomical differences, there are now many zebrafish models for human skeletal disorders including mutations in genes that cause defects in cartilage associated with endochondral GZs. These point to conserved developmental mechanisms, some of which operate both in cranial GZs and limb GPs, as well as others that act earlier or in parallel to known GP regulators. Experimental advantages of zebrafish for genetic screens, high resolution live imaging and drug screens, set the stage for many novel insights into causes and potential therapies for human endochondral bone diseases

Patient Characteristics and Preferences Regarding Anticoagulant Treatment in Venous Thromboembolic Disease

Background: Anticoagulants are the recommended treatment for venous thromboembolic disease (VTE). The mode of anticoagulant administration may influence compliance, and therefore the effectiveness of the treatment. Unlike in atrial fibrillation or cancer-associated thrombosis, there is only limited data on patient preferences regarding the choice of anticoagulation in VTE. This study aims to evaluate patient preferences regarding anticoagulants in terms of administration: types (oral or injectable treatment) and number of doses or injections per day.Patients and Methods: This is a national survey through a questionnaire sent by e-mail to 1936 French vascular physicians between February and April 2019. They recorded the responses for each patient admitted for VTE.Results: Three hundred and eleven (response rate of 16%) of the 1936 contacted physicians responded for 364 patients. Among these, there were 167 fully completed questionnaires. Most patients (63%) express concerns about VTE and prefer oral treatment (81.5%), justified by the ease of administration (74%) and a fear of the injections (22%). When patients were taking more than three oral treatments they statistically chose injectable treatment more often (54%) than oral treatment (25%, p = 0.002). Patients who chose injectable treatment were also older (70 ± 16 vs. 58 ± 17 years old, p = 0.001). There was no statistically difference in anticoagulation preference according to gender or to the expected duration of treatment (6 weeks, 3 months, 6 months or unlimited). When oral treatment was preferred (81%), most chose oral treatment without dose adjustment and biomonitoring (74.3%). Among them, very few (5.8%) preferred a twice-daily intake.Conclusion: Patient preference in terms of anticoagulant treatment in VTE disease is in favor of oral treatment without adjustment or biomonitoring and with once-daily intake. When an injectable treatment is chosen, a prolonged duration of treatment does not seem to be a constraint for the patient.Clinical Trial Registration:ClinicalTrials.gov, identifier [NCT03889457]

Entwicklung von Biosensoren für die biotechnologische Praxis

Zur Verbesserung biotechnologischer Prozesse ist es notwendig, die wichtigsten Schlüsselkomponenten in den Kultivierungsmedien zu überwachen und zu regeln. Voraussetzung dafür ist die In-situ- und On-line-Messung dieser Größen. Dazu müssen die Analyseninstrumente an den Produktionsreaktor direkt angekoppelt werden. Wegen des hohen Preises dieser Instrumente würde die Ausstattung eines jeden Reaktors mit einem Analysensystem sehr aufwendig und teuer. Hier können die einfachen und preisgünstigen Biosensoren Abhilfe schaffen. Biosensoren bestehen aus einem chemisch-spezifischen Empfänger (Enzym, Antikörper, Zelle), der mit einem sog. Transducer verbunden ist. Der Transducer ist ein physikalischer Sensor, der die chemischen Änderungen in der Empfängerschicht in Licht- oder elektrische Signale umwandelt. Abhängig davon, welchen physikalischen Sensor man verwendet, unterscheidet man zwischen - potentiometrischen, amperometrischen, kalorimetrischen, optischen und mechanischen Sensoren. Im Institut für Technische Chemie (TCI) der Universität Hannover werden potentiometrische, kalorimetrische und optische Sensoren entwickelt und zur Überwachung und Regelung biotechnologischer Prozesse eingesetzt. Daher werden hier nur diese Sensoren behandelt

Effects of sildenafil on maximum walking time in patients with arterial claudication: The ARTERIOFIL study

BACKGROUND: Patients with lower extremity peripheral artery disease (PAD) frequently experience claudication, a clinical symptom indicative of reduced walking capacity. Recommended care consists of exercise rehabilitation combined with optimal medical treatment and surgery. The effects of a single oral dose of sildenafil, a phosphodiesterase type-5 inhibitor, on patients with claudication are discussed. The aim of this study was to test the efficacy of a single 100 mg dose of sildenafil compared to placebo in terms of maximal walking time (MWT) in patients with claudication. METHODS: The ARTERIOFIL study is a crossover, double-blind, prospective, randomized, single-center study conducted at Angers University Hospital in France. MWT (primary endpoint) was assessed using a treadmill test (10% incline; 3.2 km/h). Secondary endpoints (pain-free walking time (PFWT), transcutaneous oximetry during exercise and redox cycle parameters and safety) were also studied. RESULTS: Fourteen patients were included of whom two were ultimately excluded. In the 12 remaining patients, the MWT was significantly improved during the sildenafil period compared with the placebo period (300 s [95% CI 172 s-428 s] vs 402 s [95% CI 274 s-529 s] p < 0.01). Sildenafil had no significant effect on pain-free walking time or skin tissue oxygenation during exercise. According to redox cycle parameters, sildenafil significantly reduced blood glucose and pyruvate levels and the 3-hydroxybutyrate/acetoacetate ratio, while there was no significant effect on lactate, 3-hydroxybutyrate, acetoacetate and free fatty acid levels. Symptomatic transient hypotension was observed in two women. CONCLUSIONS: The ARTERIOFIL study has shown that a single 100 mg oral dose of sildenafil had a significant effect on increase in MWT but had no significant effects on PFWT and oxygenation parameters in patients with claudication. A double-blind, prospective, randomized, multicenter study (VIRTUOSE©) is ongoing to evaluate the chronic effect of six month-long sildenafil treatment on MWT in PAD patients with claudication. CLINICAL TRIAL REGISTRATION: This clinical trial was registered at clinicaltrials.gov, registration. number: NCT02832570, (https://clinicaltrials.gov/ct2/show/NCT02832570)

Internal Carotid Artery Hypoplasia: A New Clinical Feature in Pseudoxanthoma Elasticum

International audienc