A new approach to equipment testing

Considerable controversy has arisen during the recent discussions over a new version of the RTCA DO160C/ED 14C Section 22 document at the European Committee for Aviation Electronics. Section 22 is concerned with lightning waveform tests to equipment. Investigations of some of these controversies with circuit analysis and measurements indicate the impedance characteristics required of the transient generators and the possibility of testing to a voltage limit even for current waveforms

Pregnancy Intendedness by Maternal Disability Status and Type in the United States

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154611/1/psrh12130.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154611/2/psrh12130_am.pd

Mesenchymal Stem Cell Responses to Bone-Mimetic Electrospun Matrices Composed of Polycaprolactone, Collagen I and Nanoparticulate Hydroxyapatite

The performance of biomaterials designed for bone repair depends, in part, on the ability of the material to support the adhesion and survival of mesenchymal stem cells (MSCs). In this study, a nanofibrous bone-mimicking scaffold was electrospun from a mixture of polycaprolactone (PCL), collagen I, and hydroxyapatite (HA) nanoparticles with a dry weight ratio of 50/30/20 respectively (PCL/col/HA). The cytocompatibility of this tri-component scaffold was compared with three other scaffold formulations: 100% PCL (PCL), 100% collagen I (col), and a bi-component scaffold containing 80% PCL/20% HA (PCL/HA). Scanning electron microscopy, fluorescent live cell imaging, and MTS assays showed that MSCs adhered to the PCL, PCL/HA and PCL/col/HA scaffolds, however more rapid cell spreading and significantly greater cell proliferation was observed for MSCs on the tri-component bone-mimetic scaffolds. In contrast, the col scaffolds did not support cell spreading or survival, possibly due to the low tensile modulus of this material. PCL/col/HA scaffolds adsorbed a substantially greater quantity of the adhesive proteins, fibronectin and vitronectin, than PCL or PCL/HA following in vitro exposure to serum, or placement into rat tibiae, which may have contributed to the favorable cell responses to the tri-component substrates. In addition, cells seeded onto PCL/col/HA scaffolds showed markedly increased levels of phosphorylated FAK, a marker of integrin activation and a signaling molecule known to be important for directing cell survival and osteoblastic differentiation. Collectively these results suggest that electrospun bone-mimetic matrices serve as promising degradable substrates for bone regenerative applications

Environmental and Molecular Mutagenesis Meeting Report Assessing Human Germ-Cell Mutagenesis in the Post-Genome Era: A Celebration of the Legacy of William Lawson (Bill) Russell

ABSTRACT Although numerous germ-cell mutagens have been identified in animal model systems, to date, no human germ-cell mutagens have been confirmed. Because the genomic integrity of our germ cells is essential for the continuation of the human species, a resolution of this enduring conundrum is needed. To facilitate such a resolution, we organized a workshop at The Jackson Laboratory in Bar Harbor, Maine on September [28][29][30] 2004. This interactive workshop brought together scientists from a wide range of disciplines to assess the applicability of emerging molecular methods for genomic analysis to the field of human germ-cell mutagenesis. Participants recommended that focused, coordinated human germ-cell mutation studies be conducted in relation to important societal exposures. Because cancer survivors represent a unique cohort with well-defined exposures, there was a consensus that studies should be designed to assess the mutational impact on children born to parents who had received certain types of mutagenic cancer chemotherapy prior to conceiving their children. Within this high-risk cohort, parents and children could be evaluated for inherited changes in (a) gene sequences and chromosomal structure, (b) repeat sequences and minisatellite regions, and (c) global gene expression and chromatin. Participants also recommended studies to examine trans-generational effects in humans involving mechanisms such as changes in imprinting and methylation patterns, expansion of nucleotide repeats, or induction of mitochondrial DNA mutations. Workshop participants advocated establishment of a bio-bank of human tissue samples that could be used to conduct a multiple-endpoint, comprehensive, and collaborative effort to detect exposure-induced heritable alterations in the human genome. Appropriate animal models of human germ-cell mutagenesis should be used in parallel with human studies to provide insights into the mechanisms of mammalian germ-cell mutagenesis. Finally, participants recommended that 4 scientific specialty groups be convened to address specific questions regarding the potential germ-cell mutagenicity of environmental, occupational, and lifestyle exposures. Strong support from relevant funding agencies and engagement of scientists outside the fields of genomics and germ-cell mutagenesis will be required to launch a full-scale assault on some of the most pressing and enduring questions in environmental mutagenesis: Do human germ-cell mutagens exist, what risk do they pose to future generations, and are some parents at higher risk than others for acquiring and transmitting germ-cell mutations?

Standards in semen examination: publishing reproducible and reliable data based on high-quality methodology

Biomedical science is rapidly developing in terms of more transparency, openness and reproducibility of scientific publications. This is even more important for all studies that are based on results from basic semen examination. Recently two concordant documents have been published: the 6th edition of the WHO Laboratory Manual for the Examination and Processing of Human Semen, and the International Standard ISO 23162:2021. With these tools, we propose that authors should be instructed to follow these laboratory methods in order to publish studies in peer-reviewed journals, preferable by using a checklist as suggested in an Appendix to this article