Osteoblastic and Vascular Endothelial Niches, Their Control on Normal Hematopoietic Stem Cells, and Their Consequences on the Development of Leukemia

Stem cell self-renewal is regulated by intrinsic mechanisms and extrinsic signals mediated via specialized microenvironments called “niches.” The best-characterized stem cell is the hematopoietic stem cell (HSC). Self-renewal and differentiation ability of HSC are regulated by two major elements: endosteal and vascular regulatory elements. The osteoblastic niche localized at the inner surface of the bone cavity might serve as a reservoir for long-term HSC storage in a quiescent state. Whereas the vascular niche, which consists of sinusoidal endothelial cell lining blood vessel, provides an environment for short-term HSC proliferation and differentiation. Both niches act together to maintain hematopoietic homeostasis. In this paper, we provide some principles applying to the hematopoietic niches, which will be useful in the study and understanding of other stem cell niches. We will discuss altered microenvironment signaling leading to myeloid lineage disease. And finally, we will review some data on the development of acute myeloid leukemia from a subpopulation called leukemia-initiating cells (LIC), and we will discuss on the emerging evidences supporting the influence of the microenvironment on chemotherapy resistance

Nitric oxide synthase activity in human trophoblast, term placenta and pregnant myometrium

To investigate the possible role of nitric oxide (NO) produced locally or intramurally in the quiescence of the pregnant myometrium, nitric oxide synthase (NOS) activity was measured in samples from first trimester (villous, and non villous-trophoblast), term placenta and pregnant myometrium. Trophoblast tissue was obtained from psychosocial termination of pregnancy (9 – 12 weeks' gestation) whereas placenta and myometrium, from the same patient, at deliveries by Caesarean section. NOS activity was measured in both cytosolic and particulate fractions by the formation of (14)C-citrulline from (14)C-arginine. Western immunoblotting was used to identify the endothelial NOS (eNOS) and neuronal (nNOS) isoforms. The activity of NOS in particulate fractions from all preparations was considerably higher than the cytosolic fractions. Activity in all fractions except the myometrium was highly Ca-dependent. More than 50% of particulate NOS from the myometrium was Ca-independent. NOS activity was highest in the villous trophoblast and there was a significant difference between the villous and non-villous trophoblast. In placenta and myometrium, NOS was 2–4 fold and 20–28-fold lower than the villous trophoblast, respectively. Western blot analysis showed clearly eNOS in the particulate fraction and a weak eNOS band in the cytosolic fractions, whereas nNOS was not detectable in any of the fractions. In view of the marginal activity of NOS in the myometrium, NO produced by the trophoblast and placenta could play a significant role in maintaining uterine quiescence by paracrine effect

Digital ethics in education: An examination of Omani information studies students’ ethical competencies during e-learning

Shifting to an e-learning style forced students to learn many skills and competencies to benefit from their experience in an e-learning environment. Ethical competencies play a crucial role in ensuring the fairness of students' assessments and the overall educational process. During the COVID-19 pandemic, the research used   a questionnaire to evaluate the ethical understanding of students enrolled in Sultan Qaboos University's Information Studies Department using a quantitative methodology. The findings of this study reveal a significant lack of basic ethical competencies among students in the e-learning environment which negatively impacts their educational experience. The responses obtained indicate a low level of awareness regarding ethical practices in e-learning   as well as a lack of knowledge concerning learning misconduct practices. The study suggests the implementation of an educational program that addresses academic ethical practices and e-learning misconduct across all educational levels. The outcomes of this research contribute to a better understanding of current e-learning practices among students, raise awareness about the importance of ethical competencies in e-learning   and provide guidance for students to develop ethical digital competencies

Important differences in nitric oxide synthase activity and predominant isoform in reproductive tissues from human and rat

For the extrapolation of data obtained from experimental animals to the human situation, it is important to know the similarities and differences between human and animal species. Some important characteristics of nitric oxide synthase (NOS) in myometrium and vagina from human and rat were compared. NOS-activity was measured by the formation of (14)C-citrulline from (14)C-arginine and the expression of NOS isoforms was examined by Western blotting. NOS activity in human uterus and vagina was significantly lower than in the tissues from rat. In contrast to the rat where NOS activity was predominantly found in the cytosolic fractions, NOS activity in particulate and cytosolic fractions from both human myometrium and vagina was similar. Data from Western blots confirmed that eNOS and nNOS isoforms were concentrated in the particulate and cytosolic fractions, respectively. Estrogen treatment of rats resulted in a down regulation of uterine cytosolic NOS activity. A down regulation of NOS in the cytosolic fraction was also seen in the human pregnant myometrium as compared with the nonpregnant myometrium. The vaginal NOS activity was considerably higher than the uterus in both species. In spite of some clear-cut qualitative and other differences between human and rat tissues, there are some interesting similarities. Downregulation in pregnancy of human uterine NOS is probably due to, at least in part, the influence of estrogen and progesterone

Natural Dyes in Cyanide and Anion Sensing

Cyanide is one of anions of concern due to its high toxicity. It causes death at a low dosage (2.6 mM) and the allowable level should be lower than 1.9 mmolar according to World health Organization (WHO). Cyanide contamination in the environment comes from many sources as metallurgy, gold mining, cyanide fishing, manufacturing acrylonitriles and related polymers, and natural sources. Cyanide also is present in some foods and food products such as cassava, bitter almonds, apple seeds, and some beans. The wide spread of cyanide in these food is of concern and the levels should be monitored and evaluated. In addition cyanide, may leak and get into water bodies or soil accidentally or intentionally, therefore, developing an easy, simple method for its detection is a priority. Many methods have been developed for detection of cyanide and anions such as titrations, distillations, GC-ECD, and spectrophotometrically. Colorimetric methods have been developed which are easy and simple that can give qualitative results visually and quantitatively using absorption or fluorescence spectroscopy. We have tuned into using dyes and natural dyes that are none toxic and available to use as visual (colorimetric) using both absorption and fluorescence techniques. Curcumin [1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione] is obtained from dry rhizomes of Curcuma longa, as the main yellow pigment used as spices, cosmetic and traditional medicine. It has been reported that curcumin also has many pharmacological functions like antioxygenation, antibiosis and antitumor. Despite the fact that extensive colorimetric and related photophysical studies of curcumin has been extensively studied, less study has done on its potentiality in application as a colorimetric and naked eye sensor of biologically and environmentally important anions like fluoride, acetate and phosphate. Some studies reported interaction of curcumin with cyclodextrin based on changes in basicity in acetonitrile which showed its importance in supramolecular chemistry. We herein describe a simple and efficient visible colorimeric cyanide and fluoride ions detection using commercially available curcumin as a receptor. The method could allow application in detection of curcumin, fluoride and cyanide, important chemical and biological species The choice of curcumin as a sensor for anion was mainly based on the fact that curcumin is a phenol and therefore exist in a equilibrium between its protonated and deprotonated forms in relatively basic media. It also contains a carbonyl group succeptable to nucleophilic addition, this will make it have two anion receptors., hydroxyl for hydrogen bonding to associate with basic anions. The carbonyl is areceptor for nucleophilc anions such as cyanide. Due to this reason curcumin can interact differently with different anions and enhance its selectivity based on the sovent choice. It will behave as a chemodosimeter. Acetonitrile, a polar aprotic solvent is is a good media for the analysis, it does not compete with anion in the recognition sites of curcumin. Variation in color changes of curcumin in acetonitrile was done by addition of aliquots of various anions as tetrabutylammonium salts. Addition of fluoride and cyanide ions induced color change from yellow, purple, blue to deep blue with intensity at every level dependent on the fluoride ion concentration. Acetate ion changed the color of solution to light purple, while dihydrogen phosphate induced only a tinge of color enhancement. Chloride, bromide and perchlorate were found to show no effect on the solution of curcumin. In an aquaeous acetonitrile solution the effect was observed only for cyanide only with a clear color change from yellow to red. While other anions had no significant effect. This indicates that the mechanism of interaction is based on nucleophilic addition in the case of cyanide in aqueous media and hydrogen bonding in nonpeotoc solvents. The stoichiometry was determinned to be 1:1 for cyanide and 1:2 for fluoride. The binding constants and detection limits were calculated form the UV-vis absorption titrations. In this presentation the method, structures of dye and complexes, the titration curves, color changes, binding constants and aplication will be discussed.qscienc

Effect of Carbamate Insecticide, Lannate, on the Gonads of Mice

The effect of the carbamate insecticide, lannate, on the gonads of mice was studied. Treating mice with lannate at a dose level of 10mg/kg body weight daily for 3-6 weeks had induced degenerative effects in the gonads, as follows, first in testis, a significant reduction in the diameter of the seminiferous tubules and germinal epithelial height. Histological examination of the testis showed that the seminiferous tubules were elongated and contained reduced spermatogenic cells. The number, of mature sperms was markedly reduced and after 3 weeks the sperm bundles were completely absent. On the other hand, the effect on the ovarian structure showed that, decrease in the number of secondary ovarian follicles and corpora lutea was recorded, while, the number of atretic follicles showed a significant increase. It is speculated that it may be resulted from the inhibition of RNA synthesis due to the effect of lannate

Acquired pure megakaryocytic aplasia successfully treated with cyclosporine

Acquired pure megakaryocytic aplasia is a rare hematological disorder characterized by thrombocytopenia with absent or markedly reduced megakaryocytes in the bone marrow. We report a case of a 25-year-old male diagnosed as acquired pure megakaryocytic aplasia. Treatment with prednisone and intravenous immunoglobulin failed, but he was successfully treated with cyclosporine, with complete remission after 90 days and normal platelet count maintained thereafter

Effect of Carbamate Insecticide, Lannate, on the Gonads of Mice

The effect of the carbamate insecticide, lannate, on the gonads of mice was studied. Treating mice with lannate at a dose level of 10mg/kg body weight daily for 3-6 weeks had induced degenerative effects in the gonads, as follows, first in testis, a significant reduction in the diameter of the seminiferous tubules and germinal epithelial height. Histological examination of the testis showed that the seminiferous tubules were elongated and contained reduced spermatogenic cells. The number, of mature sperms was markedly reduced and after 3 weeks the sperm bundles were completely absent. On the other hand, the effect on the ovarian structure showed that, decrease in the number of secondary ovarian follicles and corpora lutea was recorded, while, the number of atretic follicles showed a significant increase. It is speculated that it may be resulted from the inhibition of RNA synthesis due to the effect of lannate

Blockchain-based secure and intelligent data dissemination framework for UAVs in battlefield applications

The modern warfare scenario has immense challenges that can risk personnel's lives, highlighting the need for data acquisition to win a military operation successfully. In this context, unmanned aerial vehicles (UAVs) play a significant role by covertly acquiring reconnaissance data from an enemy location to make the friendly troops aware. The acquired data is mission-critical and needs to be secured from the intruders, which can implicitly manipulate it for their benefit. Moreover, UAVs collect a large amount of data, including high-definition images and surveillance videos; handling such a massive amount of data is a bottleneck on traditional communication networks. To mitigate these issues, this article proposes a blockchain and machine learning (ML)-based secure and intelligent UAV communication underlying sixth-generation (6G) networks, that is, Block-USB. The proposed system refrain the disclosure of highly-sensitive military operations from intruders (either a rogue UAV or a malicious controller). The proposed system uses off-chain storage, that is, Interplanetary file system (IPFS), to improve the blockchain storage capacity. We also present a case study on securing UAV-based military operations by considering multiple scenarios considering controller/UAV malicious. The performance of the proposed system outperforms the traditional baseline 4G/5G and non IPFS-based systems in terms of classification accuracy, communication latency, and data scalability