bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dissemination of Anesthesia Information During the Coronavirus Disease 2019 Pandemic Through Twitter: An Infodemiology Study
Authors: Gai Nan , So Delvin , Siddiqui Asad , Steinberg Benjamin E. 
Published: April 2021

BACKGROUND:
Twitter is a web-based social media platform that allows instantaneous sharing of user-generated messages (tweets). We performed an infodemiology study of the coronavirus disease 2019 (COVID-19) Twitter conversation related to anesthesiology to describe how Twitter has been used during the pandemic and ways to optimize Twitter use by anesthesiologists.

METHODS:
This was a cross-sectional study of tweets related to the specialty of anesthesiology and COVID-19 tweeted between January 21 and October 13, 2020. A publicly available COVID-19 Twitter dataset was filtered for tweets meeting inclusion criteria (tweets including anesthesiology keywords). Using descriptive statistics, tweets were reviewed for tweet and account characteristics. Tweets were filtered for specific topics of interest likely to be impactful or informative to anesthesiologists of COVID-19 practice (airway management, personal protective equipment, ventilators, COVID testing, and pain management). Tweet activity was also summarized descriptively to show temporal profiles over the pandemic.

RESULTS:
Between January 21 and October 13, 2020, 23,270 of 241,732,881 tweets (0.01%) met inclusion criteria and were generated by 15,770 accounts. The majority (51.9%) of accounts were from the United States. Seven hundred forty-nine (4.8%) of all users self-reported as anesthesiologists. 33.8% of all tweets included at least one word or phrase preceded by the # symbol (hashtag), which functions as a label to search for all tweets including a specific hashtag, with the most frequently used being #anesthesia. About half (52.2%) of all tweets included at least one hyperlink, most frequently linked to other social media, news organizations, medical organizations, or scientific publications. The majority of tweets (67%) were not retweeted. COVID-19 anesthesia tweet activity started before the pandemic was declared. The trend of daily tweet activity was similar to, and preceded, the US daily death count by about 2 weeks.

CONCLUSIONS:
The toll of the pandemic has been reflected in the anesthesiology conversation on Twitter, representing 0.01% of all COVID-19 tweets. Daily tweet activity showed how the Twitter community used the platform to learn about important topics impacting anesthesiology practice during a global pandemic. Twitter is a relevant platform through which to communicate about anesthesiology topics, but further research is required to delineate its effectiveness, benefits, and limitations for anesthesiology discussions.
Regulation of human IGF-II transcription in fetal and adult tissues
Authors: Schofield Paul N. , Tate Valerie E. 
Published: April 2021

ABSTRACT
The insulin-like growth factors are single-chain polypeptides which promote cell multiplication in vitro. Their role in mammalian development is uncertain, although they have been implicated as modulators of cell growth and differentiation. We present evidence that the human IGF-II gene has at least two promoters, and their expression may be developmentally controlled in the liver. Most of the IGF-II transcripts in the fetal organs examined are derived from a promoter which is different to that used for most adult liver IGF-II mRNAs. Steady-state levels of IGF-II transcripts are seen to be dramatically reduced in organs of adult rather than fetal origin. This observation is apparently not linked to promoter usage and therefore suggests a second level of transcriptional control.
In addition, we show that an alternative splicing event at an intron/exon boundary, which results in an mRNA with an altered coding potential, is not developmentally regulated. This variant IGF-II mRNA is coexpressed with the major species of IGF-II at a low, but constant, ratio in all fetal and adult organs examined.
The minor haemoglobins of primitive and definitive erythrocytes of the chicken embryo. Evidence for haemoglobin L
Authors: Cirotto C. , Panara F. , Arangi I. 
Published: April 2021

ABSTRACT
A new minor haemoglobin, L, was isolated from the haemolysates of chicken embryos more than 7 days old. Electrophoresis in denaturing conditions and tryptic peptide maps of the globins show that the β-Mike globin of HbL is identical to that of the minor haemoglobin H(βH) while the α-like globin is very similar to that of the adult haemoglobin D (αD). HbL completes the description of the map of the minor chicken haemoglobins during embryonic development. In early embryos two minor haemoglobins, M and E, are produced which have the same βMike globin (ε) and differ in their α-like globins (αD and αA, respectively). The same two α -like globins will make up the minor haemoglobins of the late embryo, L and H, which differ from HbM and HbE on account of their β -like globin (βH).
The native tetramers L and M are hard to distinguish from each other. However the constituent ε globin can be easily separated from βH by electrophoresis on polyacrylamide gel in formic acid. With this method we found that the switch of the minor haemoglobins in the blood of chicken embryos starts at the 7th incubation day.
The two red cell populations, primitive and definitive, present in the blood of 7-day-old embryos were separated on an albumin gradient and their minor haemoglobins analysed. The haemoglobin couple M/E was found in the primitive erythroid cells whereas the L/H couple was found in the definitive ones. The disappearance of the early haemoglobin couple and its substitution by the late one during embryonic development correlates with the replacement of erythroid lines in the blood.
Patterns of mRNA prevalence and expression of B1 and B2 transcripts in early mouse embryos
Authors: Taylor Kent D. , Pikó Lajos 
Published: April 2021

ABSTRACTConsiderable evidence indicates that the 2-cell stage is a critical period of mouse embryo development when a transition from maternal to zygotic genomic control takes place. The overall changes in the structure of the mRNA population as a result of this transition were explored using a random cDNA library of 69 clones derived from late 2-cell embryos. The prevalence of the cloned sequences was analysed by dot hybridization of the cDNA clones with labelled cDNA probes synthesized to poly(A)+ RNA from different stages of development from 1-cell through blastocyst. The number of copies of individual transcripts was quantitatively estimated by comparison to standard clones of known prevalence. About one half of the transcripts that gave a measurable reaction at the 2-cell and later stages were not represented detectably in egg RNA, suggesting that a large set of zygote-specific genes not included in the maternal gene set becomes transcriptionally active in the 2-cell embryo. Six of the cDNA clones represented Bl and B2 repeat sequences. As measured by hybridization with labelled cDNA, Bl and B2 transcripts were abundantly expressed throughout cleavage, being represented by about 105 to 106 copies per embryo. However, the developmental pattern of prevalence was different for the two transcripts suggesting that their expression is regulated independently. The results of this study corroborate previous evidence derived from protein synthetic patterns and in vitro translation experiments that a major qualitative shift in the mRNA population occurs in the 2-cell embryo.
The organization of mesodermal pattern inXenopus laevis:experiments using aXenopusmesoderm-inducing factor
Authors: Cooke Jonathan , Smith J. C. , Smith Emma J. , Yaqoob M. 
Published: April 2021

ABSTRACTIn this paper, we study the mechanism by which a Xenopus cell line-derived mesoderm-inducing factor (MIF) might establish the spatial-pattern of cellular differentiation in the mesoderm. The effects of the factor on competent animal pole tissue are consistent with it being identical to the natural mesoderm-inducing factor. The signal can only act on those membrane domains of the animal pole that face the blastocoel, but it can be stably recorded there, such that axial mesoderm is formed, after 15 min exposure or less. This exposure can end some hours, or several cell cycles, before the onset of RNA synthesis yet nevertheless be fully effective, although competence to respond also extends well after the onset of transcription.Exposure of the entire blastocoel lining of intact embryos to MIF causes a synchronous and sudden transformation of the behaviour and adhesive properties of all inner animal cap cells. This transformation mimics and is contemporaneous with the involution behaviour of normal mesoderm in the early gastrula marginal zone. Although high concentrations of MIF totally disorganize gastrulation, lower concentrations permit gastrulation to proceed. However, the pattern of mesoderm in these embryos is disrupted and ectopic mesoderm is formed around the blastocoel remnant.When MIF is injected directly into blastomeres, rather than into the blastocoel, it has no effect. This suggests that the molecule is secreted from source cells and affects target cells through an extracellular receptor.Finally, we show that small pieces of animal pole tissue recently exposed to MIF go on to produce morphogenetic signals perhaps distinct from MIF. We discuss the role of these signals in establishing and modifying the spatial pattern of cellular differentiation in the mesoderm of Xenopus.
Genetics of sex determination: what can we learn from Drosophila?
Authors: Nöthiger Rolf , Steinmann-Zwicky Monica 
Published: April 2021

ABSTRACT
The combined efforts of genetics, developmental and molecular biology have revealed the principles of genetic control of sexual differentiation in Drosophila. In combination with maternal components, a quantitative chromosomal signal, provided by the ratio of X chromosomes to sets of autosomes (X:A), regulates a key gene (Sxl). The functional state, ON or OFF, of Sxl, via a few subordinate regulatory genes, controls a switch gene (dsx) that can express two mutually exclusive functions, M or F. These serve to repress either the female or the male set of differentiation genes, thus directing the cells either into the male or into the female sexual pathway.
Investigations of control genes and their regulation show that they have properties of homeotic genes. Their role is to select one of two alternative developmental programs. Their function, or lack of function, is required throughout development to maintain the cells in their respective sexual pathway.
Differentiation genes are under negative control by dsx. We discuss the cis- and trans-regulatory elements that are needed for sex-, tissue- and stage-specific expression of the differentiation genes.
A comparison of Drosophila to other organisms such as Caenorhabditis, mammals and other insects indicates similarities that we interpret as evidence for a basically invariant genetic strategy used by various organisms to regulate sexual development.
Testis-specific transcripts detected by a human Y-DNA-derived probe
Authors: Leroy P. , Seboun E. , Mattei M. G. , Fellous M. , Bishop C. E. 
Published: April 2021

ABSTRACT
A genomic sequence ( 12f3), derived from the long arm of the human Y chromosome, detects a 1-6 kb mRNA, expressed in human and mouse testis, but not in other tissues tested by Northern blot analysis. Using 12f3 as a probe, a mouse cDNA, designated PL5, was isolated from an adult mouse testis cDNA library. The profile obtained by Southern blot analysis using PLS as probe under high-stringency conditions, reveals that 12f3 probably represents a Y-located pseudogene which was derived from an autosomally located gene. Southern blot analysis of different vertebrate species, using probe PL5, shows that this gene has been highly conserved during evolution. Preliminary in situ hybridizations on testis tissue sections indicate that PLS is expressed during the postmeiotic stages of male germ cell differentiation and thus may play a role during spermatogenesis. A second cDNA, also obtained from the testis cDNA library, weakly crossreacts with 12f3. This cDNA, designated PL10, detects a mRNA of approximately 4 kb which is highly expressed in mouse testis, but not in male or female mouse liver. The gene corresponding to this cDNA is also well conserved among vertebrates.
Mapping of testis-determining locus on Yp by the molecular genetic analysis of XX males and XY females
Authors: Müller Ulrich 
Published: April 2021

ABSTRACT
Sex reversal in males with female karyotypes is likely to be caused by the presence of cytogenetically undetectable Y-chromosomal DNA sequences that include the testis-determining gene(s). Studying a total of sixteen 46,XX males and one 47,XXX male, we detected Y-chromosomal DNA in 13 of the XX males (i.e. 80 %) and in the 47,XXX male. The amount of Y-chromosomal DNA present in the patients varied between individuals. This allowed the construction of a molecular map of the Y-chromosome short arm. The putative testis-determining locus was assigned to the more distal portion of Yp, yet proximal to the pseudoautosomal region. Mapping of the testis-determining locus was complemented by molecular findings in 46,XY females. These individuals may carry microdeletions of the portion of Yp that appears to be required for normal male gonadogenesis. The deletions detected in 46,XY females always included those Y-chromosomal DNA sequences that were found in most 46,XX males. Furthermore, the same DNA sequences were missing in a female with a 46,X,dic(Y) karyotype. The observations suggest that some of our DNA probes hybridize with Y-chromosomal DNA sequences within a few million base pairs of the testis locus. Chromosome walking and pulsed-field gel electrophoresis investigations have been initiated in order to isolate those Y-chromosomal DNA sequences that are required for normal testicular development.
Normal and abnormal interchanges between the human X and Y chromosomes
Authors: Weissenbach Jean , Levilliers Jacqueline , Petit Christine , Rouyer François , Simmler Marie-Christine 
Published: April 2021

ABSTRACT
A single obligatory recombination event takes place at male meiosis in the tips of the X- and Y-chromosome short arms (i.e. the pseudoautosomal region). The crossover point is at variable locations and thus allows recombination mapping of the pseudoautosomal loci along a gradient of sex linkage. Recombination at male meiosis in the terminal regions of the short arms of the X and Y chromosomes is 10- to 20-fold higher than between the same regions of the X chromosomes during female meiosis. The human pseudoautosomal region is rich in highly polymorphic loci associated with minisatellites. However, these minisatellites are unrelated to those resembling the bacterial Chi sequence and which possibly represent recombination hotspots. The high recombination activity of the pseudoautosomal region at male meiosis sometimes results in unequal crossover which can generate various sex-reversal syndromes.
Autogenous regulation of tubulin synthesis via RNA stability during sea urchin embryogenesis
Authors: Gong Zhiyuan , Brandhorst Bruce 
Published: April 2021

Abstract
When pluteus embryos of Lytechinus pictus were treated with colcemid, the incorporation of [35S]meth- ionine into tubulin declined by 5- to 15-fold within 4 h. This was mostly accounted for by a rapid decline in the concentration of α- and β-tubulin mRNA in the cytoplasm. Treatment with other microtubule depoly- merizing agents (colchicine, nocodazole, low concen- trations of vinblastine) had similar effects. Treatment of embryos with the microtubule-stabilizing agent, taxol, or high concentrations of vinblastine resulted in increased synthesis of tubulin. The concentration of tubulin mRNA increases during development and becomes increasingly sensitive to colcemid and de- creasingly sensitive to taxol. The transcriptional ac- tivity of tubulin genes, estimated by an RNA run-on assay in isolated nuclei, was not altered after colcemid treatment. On the other hand, the rate of decay of tubulin mRNA in prism embryos treated with actino- mycin D was increased several fold by colcemid treatment, while taxol treatment led to an increased half-life of tubulin mRNA. These observations suggest that tubulin synthesis is autogenously regulated at the level of mRNA stability by the level of unpolymerized tubulin. The increasing polymerization of micro- tubules and declining level of unpolymerized tubulin during embryogenesis would result in a stabilization of tubulin mRNA accounting for the increasing concen- tration of tubulin mRNA and rate of tubulin synthesis, as well as the increasing sensitivity of tubulin synthesis to microtubule-depolymerizing agents. Evidence is also presented for a rapid influence of the level of unpolymerized tubulin on the efficiency of translation of tubulin mRNA.
Intercellular communication in the early embryo of the ascidian Ciona intestinalis
Authors: Serras F. , Baud C. , Moreau M. , Guerrier P. , Biggelaar J. A. M. Van Den 
Published: April 2021

Abstract
We have studied the intercellular communication pathways in early embryos of the ascidian Ciona intestinalis. In two different series of experiments, we injected iontophoretically the dyes Lucifer Yellow and Fluorescein Complexon, and we analysed the spread of fluorescence to the neighbouring cells. We found that before the 32-cell stage no dye spread occurs between nonsister cells, whereas sister cells are dye-coupled, possibly via cytoplasmic bridges. After the 32-cell stage, dye spread occurs throughout the embryo. However, electrophysiological experiments showed that nonsister cells are ionically coupled before the 32-cell stage. We also found that at the 4-cell stage junctional conductance between nonsister cells is voltage dependent, which suggests that conductance is mediated by gap junctions in a way similar to that observed in other embryos.
Proximodistal leg regeneration in Carausius morosus: growth, intercalation and proximalization
Authors: Bart A. 
Published: April 2021

Abstract
The proximodistal epidermal organization of the regenerated insect leg has been studied by grafting between corresponding and noncorresponding levels of the pro- and metathoracic femur and tibia. The results have been studied quantitatively (growth rates of the associated parts and of unsegmented intercalary structures) and qualitatively (nature, length, polarity of intercalary structures). In grafts between equivalent levels, no intercalary structure is formed, but a differential growth has been observed, the distal one fifth of segments growing about 1·5 to 2 times more than the proximal one. In grafts between different levels, unsegmented intercalary structures are formed from the distal part which thereby acquires proximal characteristics (proximalization). However, distal tibial cells do not form femur in this process under an hypothetical femoral influence: there is no ‘dominance’ of femur over tibia. Some segmented intercalary structures have also been observed, but their formation cannot be related clearly to differences in the healing process. To explain proximalization, an hypothesis is presented suggesting that distal cells, which grow faster, would be the first to enter a period when positional value becomes labile and would then adapt to the proximal cells’ value.
Neural cell adhesion molecules during embryonic induction and development of the kidney
Authors: Klein Gerd , Langegger Maria , Goridis Christo , Ekblom Peter 
Published: April 2021

AbstractThe neural cell adhesion molecules (N-CAM) are a family of related glycoproteins with Mr of 180,140 and 120 ×103 (180K etc.). In the embryo, they are often highly sialylated and migrate as a diffuse band of 170250K. N-CAM are found in non-neural tissues and we have now studied the expression of N-CAM in the developing mouse kidney. During kidney development, a unique conversion of a mesenchyme to an epithelium occurs and it is thought that this is mediated by an increase in cell adhesivity. By immunofluorescence, we show that N-CAM is present already at onset of kidney development on the cells of the uninduced nephrogenic mesenchyme. After induction, when the cells convert into an epithelium, they lose N-CAM gradually and instead begin to express uvomorulin, another primary CAM. By using an organ culture model, we could rather precisely show that N-CAM and uvomorulin are coexpressed for a short period, but, when epithelial cell polarization is evident, only uvomorulin is present on the epithelium, whereas N-CAM is confined to the surrounding mesenchyme.Immunoblotting for N-CAM revealed that the ‘embryonic’ form of N-CAM, the broad 170 –250K band was not present in the embryonic kidney, which instead expressed the three distinct 180K, 140K and 120K bands typical of adult neurones. The 180K and 140K bands were gradually lost during development and were no longer detectable in adult kidneys. By using an N-CAM cDNA, we detected three different mRNAs of 7 ·4, 6 ·7 and 4 ·3 kb in the developing kidney, but this expression was restricted to the embryonic and early postnatal stages. No transcripts were detectable in adult kidneys. The studies do not support the hypothesis that N-CAM expression in the kidney is turned on by embryonic induction. Rather, we suggest that N-CAM are important adhesives for the predetermined, but not yet induced, nephrogenic mesenchyme.
An embryonic pineal body as a multipotent system in cell differentiation
Authors: Watanabe Kenji , Aoyama Hirohiko , Tamamaki Nobuaki , Sonomura Takako , Okada T. S. , Eguchi Goro , Nojyo Yoshiaki 
Published: April 2021

Abstract
The differentiating potency of pineal cells from 8-day quail embryos was studied with cell culture. It was found that the differentiation of striated muscle fibres occurred abundantly in the pineal cells cultured in hypertonic culture conditions. Muscle nature of these fibres was confirmed by utilizing the antiserum against the striated muscle type creatine kinase (MM – CK). When CO2, NAHCO3, NaCl, KC1 and MgCl2 were added in hypertonic concentrations, extensive myogenesis occurred in cultured pineal cells. Myogenesis in pineal cultures began as early as 2 days and, after 3 days in the medium with 75 mm additional NaCl, reached 100-fold when compared with that in the isotonic medium. Muscle fibres from pineal cells in culture were similar in morphology to the skeletal muscle fibres of mesodermal origin in situ. Myogenesis of pineal cells under hypertonic conditions was accompanied by the synthesis of a unique 56 × 103Mr protein, which was not found in the intrinsic muscle cells. Clonal cell culture revealed that about 80 % of clonable pineal cells were myogenic precursors. Pineal cells of 8-day quail embryos were not only myogenic but oculopotent (melanogenic and lentoidogenic) in cultures. This study examined whether multipotential progenitor cells with both potentials are present in the pineal or not. The results showed that at least 16 % of all clonable pineal cells were multipotent precursors. The embryonic pineal is considered to be a typical multipotent system in parallel with the pigmented and neural retina, the neural crest and the teratocarcinoma.