bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preoperative oral melatonin can reduce preoperative anxiety and postoperative analgesia in a dose-dependent manner
Authors: Lotfy Mohamed , Ayaad Mohamad 
Published: April 2021

Abstract
Background
Preoperative anxiety has deleterious effects on patients’ outcome through its influence on intraoperative requirements of anesthetics and analgesics (Bayrak et al., J Coll Physicians Surg Pak 29:868–873, 2019), postoperative (PO) pain intensity, and analgesia requirement, and may even increase PO morbidity and mortality after certain types of surgery. Melatonin is a methoxyindole synthesized and secreted principally by the pineal gland at night under control of an endogenous rhythm of secretion generated by the suprachiasmatic nuclei. The current study hypothesized that preoperative melatonin could reduce patients’ anxiety and reduce intraoperative (IO) and postoperative (PO) analgesic in a dose-dependent manner.

Results
Preoperative consultation was, to some extent, effective in reducing patients’ anxiety and apprehension. At 1 h after receiving premedication, Anxiety Specific to Surgery Questionnaire (ASSQ) scores were significantly lower in study groups in comparison to baseline scores and at 1 h scores of P group patients (patients who received 3 ml of plain distilled water), and this significant effect extended for 3-h PO. The reported ∆∆ASSQ between study groups was 25.9% between M2 (melatonin) and Z (midazolam) groups and 36.9% between groups M1 (received melatonin in a dose of 3 mg) and M2 (received melatonin in a dose of 6 mg). Preoperative anxiolytic therapy allowed reduction of PO pain scores and analgesia consumption with prolongation of duration till 1st request of rescue analgesia, and these effects were more pronounced with melatonin 6 mg in comparison to placebo, melatonin 3mg, or midazolam.

Conclusion
Preoperative melatonin is an appropriate policy for reduction of preoperative anxiety and provided reduction of PO anxiety, pain scores, and consumption of analgesia thus promoting early recovery and short PO hospital stay. Dose dependency was evident, and preoperative melatonin 6-mg dose provided satisfactory effect.
Enhancing the resolving ability of electrical resistivity tomography for imaging saltwater intrusion through improvements in inversion methods: A laboratory and numerical study
Authors: Goebel Meredith , Knight Rosemary , Kang Seogi 
Published: April 2021

Mapping and monitoring saltwater intrusion are critical for the sustainable management of groundwater in coastal aquifers around the world. Increasingly, geophysical methods, such as electrical resistivity tomography (ERT), have been used to address these needs. We identify methods for the inversion of ERT data that would most accurately map the location and geometry of an intrusion wedge. This is accomplished using laboratory and synthetic experiments, with the classic representation of an intrusion wedge perpendicular to the coast. The laboratory experiments allow us to collect ERT data on a saltwater intrusion wedge in an environment in which we have supporting data that provided (1) the distribution of salinity within the tank with which to verify our inversion results, (2) the resistivity, porosity, and permeability of the porous medium, and (3) the transform between resistivity and salinity. The synthetic experiments allow exploration of issues of specific interest related to the presence of lithologic heterogeneity at a field site: the role of lithologic heterogeneity in introducing complexity into the resistivity-salinity relationship and the geometry of the saltwater intrusion wedge. We find that using a reference model with a good approximation of the wedge to inform the inversion greatly improves the ability of the resulting resistivity profile to map the wedge. Where there is no, or limited, lithologic heterogeneity, a parametric approach, which constrains the range of possible solutions by solving for a sharp interface between the saltwater and freshwater regions, is very effective at capturing the wedge location and geometry. Where there is lithologic heterogeneity, a hybrid between the parametric and informed inversion approaches is most effective, resolving the wedge with a high level of accuracy with little a priori information.
Distribution of Antigens in the Developing Newt Embryo
Authors: Clayton R. M. 
Published: April 2021

ABSTRACT
Evidence is presented that a synthesis of antigenic material occurs in Triturus alpestris between the blastula and gastrula stage, before neurulation, and between neurulation and the formation of the tail-bud. During early morphogenesis and well before organogenesis the tissues exhibit a lack of antigenic uniformity. The behaviour of six antigenic fractions found in the gastrula have been studied both in their ontogeny and distribution up to the stage of the neurula. Three of these are to be found only after gastrulation. Ectoderm and archenteron roof contain fractions specific to themselves as well as containing some antigens in common. The ectoderm and neural plate of the neurula have some specificity relative to each other. An antigenic fraction specific to a given tissue type may be detected at a stage earlier than that at which this tissue first appears. Two antigenic fractions later characteristic of distinct tissues may coexist in their common precursor. A possible case of in vitro antigenic transformation is described. Antisera exhibit an irregularly cytotoxic effect when used in culture media. Partially absorbed antisera tend to cause abnormalities rather than death of whole embryos. There are indications that a certain degree of specificity in action of absorbed antisera occurs when used in culture media. Such specificity is more definite in the case of isolates of ectoderm and archenteron roof. A difference is found between the susceptibilities of blastulae and gastrulae to antisera which cannot be attributed to their difference in antigenic constitution but must depend on a change in the location of certain antigens or a change in permeability.
Les Effets de la centrifugation sur la blastula et la gastrula des Amphibiens : II. Étude comparative de la sensibilité en fonction des stades et des espèces
Authors: Pasteels J. 
Published: April 2021

ABSTRACT
Dans le premier mémoire de cette série nous avons analysé le mécanisme par lequel des organes surnuméraires ou des axes embryonnaires secondaires peuvent apparaître aux dépens de l’ectoblaste, à la suite d’une centrifugation de la blastula ou de la gastrula.
Changes in Deoxyribonucleic Acid and Total Nitrogen in Planarian Worms during Starvation
Authors: Hoff-Jørgensen E. , Løvtrup Ebba , Løvtrup S. 
Published: April 2021

ABSTRACT
The changes in total nitrogen and in deoxyribosides (DNA) have been followed during starvation of the planarian worm, Polycelis nigra. It was found that total nitrogen content after 60 days had been reduced to about 14 per cent, of its initial value. It is not possible to exclude with certainty the occurrence of any DNA loss, but it is clear that the loss, if any, is much smaller than the loss in nitrogen. The implications of these results for previous morphological investigations of the effects of starvation on planarian worms are discussed.
An Experimental Study of the Development of the Notochordal Sheath
Authors: Mookerjee Sivatosh 
Published: April 2021

ABSTRACT
Pieces of presumptive notochord of amphibian embryos, carefully cleaned of other mesodermal cells, fail to form notochordal sheath when cultivated in isolation, but a sheath is formed around them when they are transplanted to any other site in the embryo in which they come in contact with mesoblastic cells. The sheath is absent from those regions of transplanted notochords which are in contact with non-mesodermal tissues such as endoderm. No sheath is formed around pieces of human hair placed in the position from which the notochord has been excised. If the presumptive notochord material is excised from late gastrulae of Trituras, a new notochord may be formed by regulation from the more lateral mesoderm. The regulated notochords are always provided with a sheath, and conversely the sheath is absent whenever the notochord is missing. It is concluded that the sheath is laid down by extra-chordal mesoblastic cells, which are induced to carry out this secretion by contact with the notochord. It is pointed out that this contradicts the conventional view held by most comparative anatomists, who have attributed the secretion of the sheath to the external layer of notochord cells (the ‘notochordal epithelium’).
The Development in vitro of the Embryonic Pineal Body of the Fowl
Authors: Vidmar Biserka 
Published: April 2021

ABSTRACT
The pineal bodies of 4 and of 9-12 days old chick embryos were cultivated by Fell’s watchglass technique. The rate of differentiation was almost normal, but the growth-rate was retarded in vitro. The pineal body of 4 and of 9-12 days old embryonic fowl therefore possesses a capacity for self-differentiation which is independent of either bloodsupply or of endocrine stimulation.
The role of the Wolffian ducts in the formation of the sinus vagina: an organ culture study
Authors: Bok Gabriele , Drews Ulrich 
Published: April 2021

ABSTRACTIn mammals formation of a sinus vagina is inhibited in the male by endogenous testosterone from the embryonic testes. To answer the question which morphogenetic events during formation of the vagina are influenced by testosterone, we explanted genital tracts of mouse embryos in the indifferent stage of development in organ culture. Half of the explants were treated with testosterone and therefore developed in male direction. The other half was kept without testosterone and developed constitutively in female direction. Since the antiMüller factor was not present, in both types of cultures the Müllerian ducts were preserved.During female development the Müllerian ducts fused with the dorsolaterally apposed caudal segments of the Wolffian ducts. Thus the caudal segments of the Wolffian ducts were incorporated in the vaginal plate, while cranially the Wolffian ducts degenerated as expected.During male development fusion between Müllerian and Wolffian ducts did not occur. Under the influence of testosterone the respective caudal segments of the Wolffian ducts were surrounded by dense mesenchyme and further male differentiation took place.We conclude that the ‘sinus protrusions’ or ‘sinovaginal bulbs’ observed during development of the vagina, are in fact the caudal segments of the Wolffian ducts. They serve as a link between Müllerian ducts and urogenital sinus. Formation of a sinus vagina is prevented by testosterone simply by induction of male development in this area.
Time-dependent effects of α-amanitin on nuclear maturation and protein synthesis in mammalian oocytes
Authors: Osborn J. C. , Moor R. M. 
Published: April 2021

ABSTRACT
The addition of α-amanitin to extrafollicular, cumulus-enclosed ovine oocytes at explantation inhibits meiotic maturation and prevents many of the changes in protein synthesis that normally accompany maturation. By contrast, these inhibitory effects are considerably reduced by either delaying the addition of the drug for 1-4 h or by denuding the oocytes of all associated cumulus cells at the onset of culture. The observations that the inhibitory effect of cordycepin on nuclear maturation is also time-dependent and cumulus-cell-dependent and that the oocyte is susceptible to cordycepin for longer than its sensitivity to α-amanitin are consistent with the differential effects of these drugs on RNA synthesis.
It is concluded that a transcriptional event at the onset of maturation is essential for the initiation of those changes in protein synthesis required for the regulation of nuclear and cytoplasmic maturation. It is uncertain, however, whether this transcriptional event occurs within the cumulus cells or within the oocyte.
Growth pattern of the sex ducts in foetal mouse hermaphrodites
Authors: Andersen C. Yding , Byskov A. G. , Grinsted J. 
Published: April 2021

ABSTRACT
In this report the morphology of the gonads and the growth of the Wolffian and Müllerian duct in foetal mouse true hermaphrodites (16 days p.c.) have been studied and compared to that of normal mice. The ducts from the hermaphrodites were placed in one of five groups according to the proportion of male and female characteristic of the gonad.
When more than 85 % of the gonadal tissue was masculine, the Wolffian ducts showed the same percentage of cells in mitosis (mitotic index, MI) as normal males. The MI of the Wolffian ducts was lower, but constant, if the gonad contained between 0 and 85 % of testicular tissue. The number of Leydig cells in the gonads showed a linear relationship with the percentage of testicular tissue. Apparently, the MI of the Wolffian duct does not increase with increasing ‘maleness’ and with the number of Leydig cells. Four possibilities are put forward to explain the constant level of MI: (1) The Leydig cells of hermaphrodites may be deficient in producing testosterone. (2) The Leydig cells may produce testosterone at a normal rate but the epithelial cells of the Wolffian duct may not respond to increasing levels of testosterone by increasing their mitotic activity. (3) The presence of female gonadal tissue may directly or indirectly inhibit the mitotic activity of the epithelial cells of the Wolffian duct. (4) The epithelial cells of the Wolffian duct may respond to a low threshold level of testosterone, but maximal response is only triggered by a critical higher hormone level present only in group V.
In hermaphrodites, the Wolffian duct attached to a gonad without testicular tissue and without Leydig cells, has a MI which is significantly higher than in normal females. It is suggested that circulating testosterone from the contralateral gonad is responsible for this high MI.
In the Müllerian duct a mitotic index similar to that of the normal females was only found when the gonad contained from 0 to 15 % of testicular tissue. If a gonad contained more than 15 % of testicular tissue, the MI of the attached Müllerian duct was much lower equalizing that of normal males. No influence on the growth of the Müllerian duct could be observed from the contralateral gonad.
Lentoidogenesis from neural retina cells in culture is affected by interactive relationships between different cell types
Authors: Takagi Shin , Kondoh Hisato , Nomura Kazuya , Okada T. S. 
Published: April 2021

ABSTRACT
By centrifugation in a Percoll gradient, two cell fractions were separated from cell populations harvested from 8-day cultures of neural retina cells of 3-5-day-old quail embryos. The heavy (H-) fraction contained mostly N-cells, which are considered to be putative neuronal cells, while the light (L-) fraction contained both E-cells, putative retinal glial cells, and N-cells. Determination of choline acetyltransferase activity in both fractions suggested that this enzyme is predominantly localised in N-cells. After replating the separated L-fraction for further culturing, frequent lentoidogenesis occurred from clusters of N-cells which, though few in number, were included in this fraction. Addition of H-fraction to L-fraction cells caused a significant increase in lentoidogenesis up to a ratio of N- to E-cells of 3:1. However, addition of excess H-fraction cells beyond this ratio inhibited lens differentiation. This difference in the expression of lens phenotypes resulting from the different ratios of H- and L-fraction was confirmed by monitoring the level of δ-crystallin in cultures. These results are discussed in the light of interactive relationships between N- and E-cells in the transdifferentiation of neural cells into lens in cell culture.
The organization and myofilament array of insect visceral muscles
Authors: Smith D. S. , Gupta B. L. , Smith Una 
Published: April 2021

ABSTRACT
The cytological organization of three insect visceral muscles has been examined in the electron microscope. In each instance, the fibres were found to be striated, and the striation pattern has been shown to reflect the distribution along the sarcomere of two sets of myofilaments. In transverse sections of the fibre at the level of the A band, these muscles have been found to exhibit an unusual myofilament array in which each thick (myosin) filament is surrounded by twelve thin (actin) filaments rather than six, as in insect flight muscle and vertebrate skeletal muscle. The distribution of T-system tubules and cisternae of the sarcoplasmic reticulum in these visceral fibres is described, and compared with the corresponding membrane systems in other striated muscles.
Observations on the secretory processes in the corpus cardiacum of the stick insect, carausius morosus
Authors: Smith Una , Smith D. S. 
Published: April 2021

ABSTRACT
The organization of the corpora cardiaca and of the nerve tracts linking these with the brain of the stick insect has been examined in the electron microscope. Particular attention has been paid to the appearance of neurosecretory products within the axons of the nervi corporis cardiaci, and within the cell processes of the intrinsic secretory neurons of the corpus cardiacum; these observations are considered to be an essential preliminary to a consideration of the mechanism of release of secreted products from the organ into the ambient haemolymph.
The corpus cardiacum contains cells of three main categories: axons of neurons located in the brain, intrinsic secretory neurons, and glial cells. Within the organ the cellular components form a loosely knit tissue incorporating ramifying extracellular spaces confluent with the haemolymph via the peripheral basement-membrane sheath of the organ. The present electron-microscopic account relates particularly to the mode of release of neurosecretory products into the extracellular milieu. This evidence indicates that the corpus cardiacum is the site of release of both extrinsic and intrinsic secretions, but does not support the suggestion that intrinsic neurosecretory materials synthesized within the corpus cardiacum are discharged via axon terminals at sites outside the corpus cardiacum. It is suggested that release of both extrinsic and intrinsic material takes place by fusion of the membrane surrounding the neurosecretory droplet with the plasma membrane of the nerve cell in regions where the glial sheath is absent.
The evidence on the mechanism of extrusion of materials initially secreted and sequestered within nerve cells and their processes is described and discussed in terms of present concepts of the passage of neural and other materials across plasma membrane boundaries.
It is stressed that, in this functionally versatile organ, the electron microscope may reveal the mechanism of release of active neurohumoral materials, but is at present unable to differentiate between the rich variety of these pharmacologically active products which affect numerous target organs throughout the body.
Chromosomes and nucleoli of the axolotl, Ambystoma mexicanum
Authors: Callan H. G. 
Published: April 2021

ABSTRACT
Amongst the axolotl’s haploid complement of fourteen mitotic chromosomes, one of the four largest, with a greater arm asymmetry than the other three, shows a nucleolar constriction subterminally in its shorter arm. Low-temperature treatment causes further secondary constrictions to appear; these constrictions enable most of the mitotic chromosomes to be identified; the constrictions occur at similar sites in the chromosomes of tail-fin epithelial cells, hepatocytes, and brain cells.
Homology between the mitotic and oocyte (lampbrush) nucleolar organizers has been established, and thus the several hundred free nucleoli in oocytes are genetically related to the two nucleoli of diploid somatic interphases. During oocyte development the free nucleoli transform from solid structures to rings and back to solid structures again without detectable increase in number. During the contraction and aggregation of the lampbrush chromosomes within the oocyte nucleus as maturity approaches, in most axolotls the free ring-shaped nucleoli become stretched between the nuclear periphery and central chromosome group, and take on a characteristic beaded appearance. These transformations of the free nucleoli are largely paralleled by forms which nucleoli attached subterminally to the shorter arm of lampbrush chromosome III concurrently assume.
The question as to whether fully developed nucleoli detach from the organizer loci and add to the population of free nucleoli in oocytes remains undecided. It may well be that virtually all the DNA-generators of free nucleoli detach from the organizer loci before starting to carry out nucleolar functions, and before there is any significant accumulation of protein and RNA around them. If so, the variability in quantity of attached nucleolar material may not reflect different states in a nucleolar synthesis and detachment cycle, but rather variation in the number of nucleolar DNA Anlagen which happen to remain attached to the organizer loci after the synthesis and detachment of the great majority of the Anlagen has ceased.
In occasional oocytes the only chromosomal continuity maintained across the organizer locus consists of a nucleolar ‘ double bridge ‘; this indicates that the genetically persistent (i.e. chromosomal) organizer DNA bears the same structural relationship to neighbouring parts of a lampbrush chromosome as any other chromomere with its attendant pair of lateral loops.
The lampbrush chromosomes of the axolotl have been provisionally mapped. The centromeres are represented by short portions of chromosome axis without lateral loops, and there are two spheres close to the centromeres of both chromosome VI and chromosome XIII. Other recognition characters are inconspicuous or not very reliable, and features of the lampbrush chromosomes related to the low-temperature induced secondary constrictions of mitotic chromosomes have not been identified.
Some studies on the chromatin and cell wall of the mycetomal micro organisms of Sitophilus granarius (L.) (Coleoptera)
Authors: Singh S. B. , Musgrave A. J. 
Published: April 2021

ABSTRACT
Cytochemical studies of the outer membranes and chromatinic material in the inherited, supposedly symbiotic mycetomal micro-organisms of Sitophilus granarius have revealed the presence of considerable amounts of DNA occurring as either consolidated dots or a spongy network. There is also evidence that, at times, the organisms are surrounded by cell walls.
Demonstration of extracellular space by freeze-drying in the cerebellar molecular layer
Authors: Harreveld A. Van , Malhotra S. K. 
Published: April 2021

ABSTRACT
In electron micrographs of the molecular layer of the mouse cerebellum frozen within 30 sec of circulatory arrest and subsequently dried at − 79 °C an appreciable extracellular space was found between the axons of the granular cells. Tight junctions were regularly observed between pre- and postsynaptic structures and the enveloping glia cells. In micrographs of cerebellum frozen 8 min after decapitation the space between the axons was absent and tight junctions between the nerve fibres were almost exclusively encountered. The extracellular space of asphyxiated and non-asphyxiated tissue in electron micrographs of frozen-dried material is similar to the space in comparable tissues treated by freeze-substitution. These observations suggest that there is an appreciable amount of extracellular material in oxygenated, living tissue which is taken up by cellular elements during asphyxiation.