Nanopulse Generators: Their Design and Application to Cancer Therapy Studies

Effective nanopulse generators have become critical in recent decades concerning the study of subcellular affects in response to nanosecond pulsed electric fields. It has been observed that nanosecond duration electric pulses can target intracellular organelles, ultimately leading to cell apoptosis, suggesting the possibility of a new, minimally invasive, low risk cancer therapy methodology. The standard topology for developing a medical nanopulser is the Blumlein “transmission line” approach. This approach relies on the nearly infinitesimal, yet finite amount of time required for an electromagnetic field to propagate down a short transmission line. Prior to design, requirements and constraints must be defined that are determined by the specific applications and experiments that the nanopulser will be used for. Special effort must be put into nanopulser design to prevent undesirable reflections and oscillations at the load. Critical design objectives common to most nanopulse generators include choosing effective switching elements that facilitate a minimal rise time, configuring the load electrodes to be compatible with experimental setups, and enabling a wide degree of versatility and adjustability concerning pulse parameters

Koordinierte Regionalentwicklung: Zielorientierung von Entwicklungsprozessen

Die Forderung nach Koordination ist eine beliebte, weil griffige und plakative Metapher, um sowohl auf Planungsprobleme als auch gleichzeitig auf deren (putative) Lösung hinzuweisen. Doch geht man der Frage nach, was Koordination eigentlich ist und wie denn Koordination gelingen kann, erhält man eher selten überzeugende Antworten. Der vorliegende Band "Koordinierte Regionalentwicklung: Zielorientierung von Entwicklungsprozessen" aus der Reihe "Arbeitsberichte der ARL" versucht, diese Antworten anhand der Betrachtung des Zusammenwirkens zwischen räumlicher Gesamtplanung und teilräumlichen Entwicklungsansätzen vor dem Hintergrund theoretischer Überlegungen zur Herstellung von Handlungskontexten sowie am Beispiel von ILE und LEADER auf Basis von Fallstudienbetrachtungen zu geben.Calls for coordination are a well-loved way of drawing attention to both planning problems and their (putative) solution. However, further exploration of this bold and simple metaphor seldom provides convincing answers as to the actual nature of coordination or how coordination can be successful. "Coordinated regional development: goal orientation of development processes" presents work by the ARL in an attempt to provide such answers. Observation is made of the interaction between spatial master planning and sub-regional development approaches and a background provided by theoretical reflections on the production of contexts of action and by case-studies from the IRD and LEADER programmes

Utility of cannulated prolactin to exclude stress hyperprolactinemia in patients with persistent mild hyperprolactinemia

Background: Stress-induced hyperprolactinemia can be difficult to differentiate from true hyperprolactinema and may result in patients having unnecessary investigations and imaging. We report the results of cannulated prolactin tests with serial prolactin measurements from an indwelling catheter to differentiate true from stress-induced hyperprolactinemia in patients with persistently mildly elevated prolactin levels in both referral and repeat samples. Methods: Data were collected for 42 patients who had a cannulated prolactin test between January 2017 and May 2018. After cannula insertion, prolactin was measured at 0, 60, and 120 minutes. Normalization is defined as a decline in prolactin to gender-defined normal ranges. Results: The mean age was 33.8 years (SD ± 9.9), and 37 (88%) were female. Menstrual irregularities were the main presenting symptom in 28.57% of the patients. Prolactin normalized in 12 (28.6%) patients of whom cannulated prolactin test was done. Repeat random prolactin levels were significantly higher in patients whose prolactin did not normalize during the cannulated prolactin test. MRI of the pituitary gland showed an abnormality in 23 out of 28 (82%) patients who did not normalize prolactin, a microadenoma in the majority of patients (18 patients). Conclusion: The cannulated prolactin test was useful in excluding true hyperprolactinemia in 28.6% of patients with previously confirmed mildly elevated random prolactin on two occasions, thus avoiding over-diagnosis and unnecessary imaging

Alexander Meissner: Learning the reprogramming code

Meissner studies the epigenomics of pluripotent cells

Gene regulation via nucleosome stability modulation and RNA:DNA triplex formation

Gene regulation is a tightly controlled process in Eukaryotes. Coding and non-coding regions work together to ensure proper spatiotemporal gene expression through 3D chromatin organization, nucleosome positioning, histone tail post-translational modifications, epigenetic DNA modifications, and non-canonical nucleic acid structures such as RNA:DNA triplexes. In this thesis, I investigate two of these mechanisms, nucleosomes and RNA:DNA triplexes. In the first chapter, I focus on characterizing nucleosomal properties, such as stability and accessibility, and explore how these properties change to regulate gene expression. I show that Eukaryotic organisms can modulate nucleosome stability and change the RNA polymerase pausing rate, which in turn regulates gene expression. Intriguingly, I find a distinct group of un-stable nucleosomes enriched at the TSS of promoters marked with motif one, an M1BP TF-specific motif, in D. melanogaster. Modulation of stability may ensure a fast response to environmental cues and proper spatiotemporal expression of developmental genes. Furthermore, I developed a bioinformatic pipeline called nucMACC, with which scientists can study nucleosomal properties and positioning in their projects. I show the nucMACC pipeline is consistent and robust and provide recommendations for minimum sequencing depth, MNase titrations, and spike-in use. In summary, the nucMACC pipeline provides high-resolution nucleosome positions and an automated way of calling non-canonical nucleosomes, un-stable nucleosomes, hyper-accessible nucleosomes, hypo-accessible nucleosomes, and stable canonical nucleosomes. In the second chapter, I study the triplex binding code and explore how the code changes based on the triplex motif (Purine, pyrimidine, and mixed), sequence Guanine content, length, and the nucleic acid (RNA or DNA). Triplexes are non-canonical DNA/RNA structures consisting of three nucleotide strands, most commonly a double-stranded DNA molecule and a single-stranded RNA molecule in its major groove. I show that major differences exist between the triplex motifs and between RNA:DNA and DNA:DNA triplexes. Interestingly, I discovered that the mixed RNA:DNA triplex motif permits triplex formation only at very narrow Guanine contents, while DNA:DNA mixed motif triplexes are able to form at almost any Guanine content. Moreover, I confirm the newly defined triplex code by testing published triplex pairs, of which half are unable to form a triplex under physiological conditions. Furthermore, I developed a high throughput method to investigate the triplex binding code in the context of molecular crowding and competition. I find that certain mismatches in the motif stabilize triplex formation and are preferentially selected for triplex formation over the complementary Hoogsten base-pairing motif. Moreover, I investigate how the location of a mismatch modifies triplex stability and show that the middle section of the triplex is more sensitive to mismatches than flanking regions. In summary, I add to the existing triplex code by delineating the differences in the binding code between triplex motifs and RNA:DNA and DNA:DNA triplexes. I show how the binding code changes in the context of molecular crowding and competition and moreover, show the differential effect of different mismatch locations

Reprogramming of postnatal neurons into induced pluripotent stem cells by defined factors

Pluripotent cells can be derived from different types of somatic cells by nuclear reprogramming through the ectopic expression of four transcription factors, Oct3/4, Sox2, Klf4, and c-Myc. However, it is unclear whether postmitotic neurons are susceptible to direct reprogramming. Here, we show that postnatal cortical neurons, the vast majority of which are postmitotic, are amenable to epigenetic reprogramming. However, ectopic expression of the four canonical reprogramming factors is not sufficient to reprogram postnatal neurons. Efficient reprogramming was only achieved after forced cell proliferation by p53 suppression. Additionally, overexpression of repressor element-1 silencing transcription, a suppressor of neuronal gene activity, increased reprogramming efficiencies in combination with the reprogramming factors. Our findings indicate that terminally differentiated postnatal neurons are able to acquire the pluripotent state by direct epigenetic reprogramming, and this process is made more efficient through the suppression of lineage specific gene expression. STEM CELLS 2011;29:992–1000National Institutes of Health (U.S.) (Grant NIH HD045022)National Institutes of Health (U.S.) (Grant 5R37CA084198)Howard Hughes Medical Institut

On the Streets of San Francisco: Highlights from the ISSCR Annual Meeting 2010

The 2010 Annual Meeting of the International Society for Stem Cell Research (ISSCR) was held in San Francisco in June with an exciting program covering a wealth of stem cell research from basic science to clinical research