Design, Layout and Realization of an All NOR Enhancement Type PMOS Serial Adder

A four bit serial adder was designed with PMOS NOR gates from a truth table that models binary serial addition. Three storaqe reqisters were also included in the desiqn, two-four bit shift registers for the incoming digits and one-five bit register for the sum. A simple five gate latch was used for the bits of these registers. The cir­cuit was layed out using ICE , a software program designed to facilitate circuit layout for mask making at R.I.T

Impressions on Reliability and Students’ Perceptions of Learning in a Peer-Based OSCE

Background: Peer assessment of performance in the objective structured clinical examination (OSCE) is emerging as a learning instrument. While peers can provide reliable scores, there may be a trade-off with students’ learning. The purpose of this study is to evaluate a peer-based OSCE as a viable assessment instrument and its potential to promote learning and explore the interplay between these two roles. Methods: A total of 334 medical students completed an 11-station OSCE from 2015 to 2016. Each station had 1–2 peer examiners (PE) and one faculty examiner (FE). Examinees were rated on a 7-point scale across 5 dimensions: Look, Feel, Move, Special Tests and Global Impression. Students participated in voluntary focus groups in 2016 to provide qualitative feedback on the OSCE. Authors analysed assessment data and transcripts of focus group discussions. Results: Overall, PE awarded higher ratings compared with FE, sources of variance were similar across 2 years with unique variance consistently being the largest source, and reliability (rφ) was generally low. Focus group analysis revealed four themes: Conferring with Faculty Examiners, Difficulty Rating Peers, Insider Knowledge, and Observing and Scoring. Conclusions: While peer assessment was not reliable for evaluating OSCE performance, PE’s perceived that it was beneficial for their learning. Insight gained into exam technique and self-appraisal of skills allows students to understand expectations in clinical situations and plan approaches to self-assessment of competence

Localization of MMR proteins on meiotic chromosomes in mice indicates distinct functions during prophase I

Mammalian MutL homologues function in DNA mismatch repair (MMR) after replication errors and in meiotic recombination. Both functions are initiated by a heterodimer of MutS homologues specific to either MMR (MSH2–MSH3 or MSH2–MSH6) or crossing over (MSH4–MSH5). Mutations of three of the four MutL homologues (Mlh1, Mlh3, and Pms2) result in meiotic defects. We show herein that two distinct complexes involving MLH3 are formed during murine meiosis. The first is a stable association between MLH3 and MLH1 and is involved in promoting crossing over in conjunction with MSH4–MSH5. The second complex involves MLH3 together with MSH2–MSH3 and localizes to repetitive sequences at centromeres and the Y chromosome. This complex is up-regulated in Pms2−/− males, but not females, providing an explanation for the sexual dimorphism seen in Pms2−/− mice. The association of MLH3 with repetitive DNA sequences is coincident with MSH2–MSH3 and is decreased in Msh2−/− and Msh3−/− mice, suggesting a novel role for the MMR family in the maintenance of repeat unit integrity during mammalian meiosis

Interaction of Rickettsia felis with histone H2B facilitates the infection of a tick cell line

Haematophagous arthropods are the primary vectors in the transmission of Rickettsia, yet the molecular mechanisms mediating the rickettsial infection of arthropods remain elusive. This study utilized a biotinylated protein pull-down assay together with LC-MS/MS to identify interaction between Ixodes scapularis histone H2B and Rickettsia felis. Co-immunoprecipitation of histone with rickettsial cell lysate demonstrated the association of H2B with R. felis proteins, including outer-membrane protein B (OmpB), a major rickettsial adhesin molecule. The rickettsial infection of tick ISE6 cells was reduced by approximately 25 % via RNA-mediated H2B-depletion or enzymic treatment of histones. The interaction of H2B with the rickettsial adhesin OmpB suggests a role for H2B in mediating R. felis internalization into ISE6 cells

UHRF1 binds G9a and participates in p21 transcriptional regulation in mammalian cells

UHRF1 (ubiquitin-like, containing PHD and RING finger domains 1) is a multi-domain protein associated with cellular proliferation and epigenetic regulation. The UHRF1 binds to methylated CpG dinucleotides and recruits transcriptional repressors DNA methyltransferase 1 (DNMT1) and histone deacetylase 1 (HDAC1) through its distinct domains. However, the molecular basis of UHRF1-mediated transcriptional regulation via chromatin modifications is yet to be fully understood. Here we show that UHRF1 binds histone lysine methyltransferase G9a, and both are co-localized in the nucleus in a cell-cycle-dependent manner. Concurrent with the cell-cycle progression, gradual deposition of UHRF1 and G9a was observed, which mirrored H3K9me2 accumulation on chromatin. Murine Uhrf1-null embryonic stem (ES) cells displayed a reduced amount of G9a and H3K9me2 on chromatin. UHRF1 recruited and cooperated with G9a to inhibit the p21 promoter activity, which correlated with the elevated p21 protein level in both human UHRF1 siRNA-transfected HeLa cells and murine Uhrf1-null ES cells. Furthermore, endogenous p21 promoter remained bound to UHRF1, G9a, DNMT1 and HDAC1, and knockdown of UHRF1 impaired the association of all three chromatin modifiers with the promoter. Thus, our results suggest that UHRF1 may serve as a focal point of transcriptional regulation mediated by G9a and other chromatin modification enzymes

Alzheimer’s-associated upregulation of mitochondria-associated ER membranes after traumatic brain injury

23 p.-5 fig.-3 tab.-1 graph. abst.Traumatic brain injury (TBI) can lead to neurodegenerative diseases such as Alzheimer’s disease (AD) through mechanisms that remain incompletely characterized. Similar to AD, TBI models present with cellular metabolic alterations and modulated cleavage of amyloid precursor protein (APP). Specifically, AD and TBI tissues display increases in amyloid-β as well as its precursor, the APP C-terminal fragment of 99 a.a. (C99). Our recent data in cell models of AD indicate that C99, due to its affinity for cholesterol, induces the formation of transient lipid raft domains in the ER known as mitochondria-associated endoplasmic reticulum (ER) membranes (“MAM” domains). The formation of these domains recruits and activates specific lipid metabolic enzymes that regulate cellular cholesterol trafficking and sphingolipid turnover. Increased C99 levels in AD cell models promote MAM formation and significantly modulate cellular lipid homeostasis. Here, these phenotypes were recapitulated in the controlled cortical impact (CCI) model of TBI in adult mice. Specifically, the injured cortex and hippocampus displayed significant increases in C99 and MAM activity, as measured by phospholipid synthesis, sphingomyelinase activity and cholesterol turnover. In addition, our cell type-specific lipidomics analyses revealed significant changes in microglial lipid composition that are consistent with the observed alterations in MAM-resident enzymes. Altogether, we propose that alterations in the regulation of MAM and relevant lipid metabolic pathways could contribute to the epidemiological connection between TBI and AD.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This work was supported by the U.S. National Institutes of Health (T32-DK007647 to RRA; R21NS125395 to LS; S10-OD016214 and P30-CA013330 to FPM; R01-EB029523 to WM; R01-NS095803 to SGK; R01-NS088197 to RJD; R01-AG056387 to EA-G) and the U.S. Department of Defense (National Defense Science and Engineering Graduate Fellowship, FA9550-11-C-0028, to RRA).Peer reviewe

International genome-wide meta-analysis identifies new primary biliary cirrhosis risk loci and targetable pathogenic pathways.

Primary biliary cirrhosis (PBC) is a classical autoimmune liver disease for which effective immunomodulatory therapy is lacking. Here we perform meta-analyses of discovery data sets from genome-wide association studies of European subjects (n=2,764 cases and 10,475 controls) followed by validation genotyping in an independent cohort (n=3,716 cases and 4,261 controls). We discover and validate six previously unknown risk loci for PBC (Pcombined<5 × 10(-8)) and used pathway analysis to identify JAK-STAT/IL12/IL27 signalling and cytokine-cytokine pathways, for which relevant therapies exist

Biomimetic coating with phosphoserine-tethered poly(epsilon-lysine) dendrons on titanium surfaces enhances Wnt and osteoblastic differentiation

Objectives: Phosphoserine-based functionalization has been proposed as a tool to improve integration of endosseous implants by promoting osteoblast adhesion and differentiation in vitro. The present work investigates whether phosphoserine-tethered poly(epsilon-lysine) dendrons, when applied as a film to titanium surfaces, enhance the differentiation of osteoblastic cells and the activation of Wnt/β-catenin signaling. Materials and methods: These films were tested in a murine model of calvaria-derived MC3T3 osteoblastic cells, primary bone marrow cells and mesenchymal, undifferentiated C2C12 cells. Gene expression was assayed by Real Time PCR, and activation of Wnt signaling pathway was measured with a reporter assay. Results: Dendrons increased expression of alkaline phosphatase and osteocalcin, two osteoblastic markers, in both murine osteoblastic MC3T3 cells and primary bone marrow cells. The expression of osteoprotegerin, a protein opposing osteoclastogenesis was also significantly higher in cells growing on dendron-coated substrates both at 3 and 6 days of culture. Similarly, the mRNA levels of Wisp-2 and of β-catenin, two Wnt target genes, were also markedly increased in this group at day 6. The activation of this signaling pathway in cells growing on the dendron-coated surfaces was confirmed by use of a TCF/β-catenin reporter system in the C2C12 cell line. Conclusions: The findings of the present study show that phosphoserine-tethered poly(epsilon-lysine) dendron films act as stimuli for the activation of specific signal cascades and promote the differentiation of adhering progenitor cells into an osteoblastic phenotype