Dimethyl Sulfoxide Is Feasible for Plant Tubulin Assembly In vitro： A Comprehensive Analysis

It is much more difficult for tubulin from plant sources to polymerize in vitro than tubulin from animal sources. Taxol, a most widely used reagent in microtubule studies, enhances plant microtubule assembly, but hinders microtubule dynamics. Dimethyl sulfoxide (DMSO), a widely used reagent in animal microtubule studies, is a good candidate for the investigation of plant microtubule assembly in vitro. However, proper investigation is lacking about the effects of DMSO on plant microtubule assembly in vitro. In the present study, DMSO was used to establish optimal conditions for the polymerization of plant tubulin. Tubulin, purified from lily pollen, polymerizes into microtubules at a critical concentration of 1.2 mg/mL in the presence of 10% DMSO. The polymers appear to have a normal microtubule structure, as revealed by electron microscopy. In the presence of 10% DMSO, microtubule polymerization decreases when the pH of the medium is increased from 6.5 to 7.4. Both the polymerization rate and the mass of the polymers increase as temperature increases from 25 to 40 ℃. Tubulin polymerizes and depolymerizes along with cycling of temperature, from 37 to 4 ℃, or following the addition to or the removal of Ca^2 from the medium. When incubated with nuclei isolated from tobacco BY-2 suspension cells, tubulin assembles onto the nuclear surface in the presence of 10% DMSO. Labeling lily pollen tubulin with 5- (and 6-) carboxytetramethyl-rhodamine succinimidyl ester (NHS-rhodamine) was performed successfully in the presence of 10% DMSO. Labeled tubulin assembles into a radial structure on the surface of BY-2 nuclei. The polymerization of lily pollen tubulin is also enhanced by microtubule-associated proteins from animal sources in the presence of 10% DMSO. All the experimental results indicate that plant tubulin functions normally in the presence of DMSO. Therefore, DMSO is an appropriate reagent for plant tubulin polymerization and investigation of plant microtubules in vitro.     

Is there In Vivo Evidence for Amino Acid Shuttles Carrying Ammonia from Neurons to Astrocytes?

Neurochemical Research - The high in vivo flux of the glutamate/glutamine cycle puts a strong demand on the return of ammonia released by phosphate activated glutaminase from the neurons to the...     

Is Redox-Cycling Ubiquinone Involved In Mitochondrial Oxygen Activation?

In most tissues mitochondria consume more than 90% of cellular oxygen. Although the greatest part of it undergoes tetravalent reduction thereby conserving free energy changes in the form of ATP. a great deal of evidence exists in the literature that also univalently reduced dioxygen is released during respiration. Redox-cycling ubiquinone was considered most frequently to be involved in this univalent e^- transfer to oxygen out of sequence however, other components of the respiratory chain could not be excluded. Our investigations on this problem questioned the role of redox-cycling ubiquinone in mitochondrial O^-₂ formation while H₂O₂ is supposed to accept e^- from this source. The paper provides experimental evidence that H₂O₂ in fact may operate as an oxidant of ubisemiquinone while dioxygen requires protons for such a reaction which are not available in the phospholipid bilayer where ubiquinone undergoes one e^-redox-cycling     

Is Lysolecithin an In Vivo Constituent of Chromaffin Granules?

Abstract: It was recently claimed that lysolecithin (lysophosphatidylcholine) in chromaffin granules is a postmortem artefact. We have, therefore, determined catecholamine/lysolecithin ratios in adrenal tissues and isolated chromaffin granules. In rat adrenals and bovine medulla the ratios in both tissues and granules were similar. This indicates that even in rapidly frozen rat adrenal glands, sufficient lysolecithin is present in the total tissue to account for its presence in isolated organelles. Owing to the high cortexhedulla ratios such studies cannot be performed with guinea pig or rabbit adrenals. However, isolated chromafh granules from guinea pig, in contrast to a previous study, do contain lysolecithin. We conclude that lysolecithin is an in vivo constituent of chromaffin granules of all species so far investigated.     

In Vitro and In Vivo Neuronal Electrotaxis: A Potential Mechanism for Restoration?

Electrical brain stimulation used to treat a variety of neurological and psychiatric diseases is entering a new period. The technique is well established and the potential complications are well known and generally manageable. Recent studies demonstrated that electrical fields (EFs) can enhance neuroplasticity-related processes. EFs applied in the physiological range induce migration of different neural cell types from different species in vitro. There are some evidences that also the speed and directedness of cell migration are enhanced by EFs. However, it is still unclear how electrical signals from the extracellular space are translated into intracellular actions resulting in the so-called electrotaxis phenomenon. Here, we aim to provide a comprehensive review of the data on responses of cells to electrical stimulation and the relation to functional recovery.     

Why Don��t People Think Evolution Is True? Implications for Teaching, In and Out of the Classroom

The causes of non-acceptance of evolution are groupable into five categories: inadequate understanding of the empirical evidence and the content of modern evolutionary theory, inadequate understanding of the nature of science, religion, various psychological factors, and political and social factors. This multiplicity of causes is not sufficiently appreciated by many scientists, educators, and journalists, and the widespread rejection of evolution is a much more complicated problem than many of these front-line practitioners think it is. Solutions to the widespread non-acceptance of evolution must therefore involve not just further resolution of the “religion vs. science” controversy. They must also involve better communication of empirical evidence for evolution, more effective explication of the nature of science, and explicitly addressing the numerous significant psychological obstacles that evolution presents to many (perhaps most) people. There is no clear roadmap to how to do all of this, but some practical recommendations include (1) more research on why and when different people accept or do not accept evolution when they are exposed to it, especially the role of “scientific” vs. “affective” causes for non-acceptance, and also on apparently deeply rooted psychological obstacles to acceptance. (2) A more explicit approach to explication and understanding of the causes for non-acceptance of evolution should support the often-stated goal of understanding “where students are” prior to implementing the kind of approaches frequently advocated for teaching evolution. (3) Integration of multiple educational perspectives and academic disciplines to support application of pedagogical strategies in actual educational settings. (4) Increased development and application of approaches to evolution education in settings beyond the K–16 classroom, such as museums, nature centers, zoos, parks, and aquaria.     

Is free halogen necessary for disinfection?

The principle of Le Chatelier was used in demonstrating that 3-chloro-4,4-dimethyl-2-oxazolidinone (compound 1) itself kills Staphylococcus aureus rather than the very small amount of free chlorine in hydrolysis equilibrium with compound 1. On the other hand, when the N-bromo analog of compound 1 (compound 1B) was used as the disinfectant, the mixture of combined compound 1B and free bromine formed in the hydrolysis equilibrium provided disinfection. When the hydrolysis equilibrium for 1B was suppressed to the level at which a negligible amount of free bromine remained in solution, combined compound 1B was much more efficacious than combined compound 1 at killing S. aureus.     

Is there NO help for leptin?

Since the initial identification of leptin as the product of the ob gene in 1994, the signaling pathways by which this hormone alters cell physiology have been the subject of extensive investigations. The fact that leptin can induce nitric oxide (NO) production was first demonstrated in studies of the pituitary gland and pancreatic islets. A large number of additional studies further showed that this adipokine stimulates NO synthesis in multiple tissues. This review article discusses the role of leptin in NO production and its pathophysiological consequences. The role of this gaseous messenger in cell physiology depends on the cell type, the concentration of NO and the duration of exposure. It can be either a potent oxidant or a protector of cell integrity against the formation of reactive oxygen species. Leptin plays two opposing roles on arterial pressure. It exerts a hypertensive effect due to sympathetic activation and a vasorelaxant effect due to NO production. This adipokine acts via NO to produce pro-inflammatory factors in cartilage pathology, potentially contributing to an increased risk for osteoarthritis. Another well-documented role of leptin-induced NO, acting either directly or via the hypothalamus, concerns lipid metabolism in muscle and adipose tissue. In adipocytes, the direct and rapid action of leptin is to activate the nitric oxide synthase III, which favors lipolysis. In contrast, in the long-term, leptin reduces lipolysis. However, both in the short-term and in the long-term, glyceroneogenesis and its key enzyme, the cytosolic phosphoenolpyruvatecarboxykinase (PEPCK-C), are down-regulated by the adipokine, thus favoring fatty acid release. Hence, leptin-induced NO production plays a crucial role in fatty acid metabolism in adipose tissue. The resulting effects are to prevent lipid storage and to improve energy expenditure, with possible improvements of the obese state and its associated diseases.     

Is there a future for GMOs?

Despite strict regulation and a clean safety record, research and development of genetically modified (GM) crops and other organisms has been confronted with tremendous public hostility. Why has this happened, and how can scientists try to guide the debate into more rational channels? The answers may determine the future of GM technology and our ability to provide for a growing world population.     

Is dipalmitoylphosphatidylcholine a substrate for convertase?

Convertase has homology with carboxylesterases, but its substrate(s) is not known. Accordingly, we determined whether dipalmitoylphosphatidylcholine (DPPC), the major phospholipid in surfactant, was a substrate for convertase. We measured [(3)H]choline release during cycling of the heavy subtype containing [(3)H]choline-labeled DPPC with convertase, phospholipases A(2), B, C, and D, liver esterase, and elastase. Cycling with liver esterase or peanut or cabbage phospholipase D produced the characteristic profile of heavy and light peaks observed on cycling with convertase. In contrast, phospholipases A(2), B, and C and yeast phospholipase D produced a broad band of radioactivity across the gradient without distinct peaks. [(3)H]choline was released when natural surfactant containing [(3)H]choline-labeled DPPC was cycled with yeast phospholipase D but not with convertase or peanut and cabbage phospholipases D. Similarly, yeast phospholipase D hydrolyzed [(3)H]choline from [(3)H]choline-labeled DPPC after incubation in vitro, whereas convertase, liver esterase, or peanut and cabbage phospholipases D did not. Thus convertase, liver esterase, and plant phospholipases D did not hydrolyze choline from DPPC either on cycling or during incubation with enzyme in vitro. In conclusion, conversion of heavy to light subtype of surfactant by convertase may require a phospholipase D type hydrolysis of phospholipids, but the substrate in this reaction is not DPPC.     

Flexible Nanopipettes for Minimally Invasive Intracellular Electrophysiology In Vivo

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Is 1,25-dihydroxyvitamin D required for reproduction?

The role of 1,25-dihydroxyvitamin D (1,25-(OH)2D) in avian and mammalian reproduction is examined. 1,25-Dihydroxyvitamin D is required, in both the avian and mammalian species, for maintenance of normocalcemia, adequate intestinal calcium absorption, bone turnover, and mineral homeostasis throughout the reproductive cycle--just as it is required in the nonlaying bird or nonpregnant, nonlactating mammal. In the avian species, 1,25-(OH)2D is required for ovulation and shell formation, transfer of calcium from the egg shell across the chorioallantoic membrane to the fetal circulation, and maintenance of fetal serum calcium, bone metabolism, and mineral homeostasis. In the mammalian species, 1,25-(OH)2D is required for normal ovulation, normal fetal and neonatal bone metabolism, milk production, and maintenance of normocalcemia and mineral homeostasis in the neonate. In the absence of 1,25-(OH)2D, however, embryogenesis (rat and chick) and neonatal development (rat) can proceed in such a way as to produce viable, normal appearing offspring. The classical effects of 1,25-(OH)2D deficiency (hypocacemia, inadequate intestinal calcium absorption, and bone mineralization) become increasingly apparent with advancing age but there are no other apparent major developmental abnormalities.     

Is dose escalation achievable for esophageal carcinoma?

Aim

To investigate the feasibility of dose escalation using rapid arc (RA) and Helical Tomotherapy (HT) for patients with upper, middle and distal esophageal carcinomas, even for large tumor volumes.

Background

In esophageal cancer, for patients with exclusive radio-chemotherapy, local disease control remains poor. Planning study with dose escalation was done for two sophisticated modulated radiotherapy techniques: Rapid arc against Tomotherapy.

Materials and methods

Six patients treated with a RA simultaneous integrated boost (SIB) of 60 Gy were re-planned for RA and HT techniques with a SIB dose escalated to 70 Gy. Dose volume histogram statistics, conformity indices and homogeneity indices were analyzed. For a given set of normal tissue constraints, the capability of each treatment modality to increase the GTV dose to 70 Gy was investigated.

Results

Either HT or VMAT may be used to escalate the dose delivered in esophageal tumors while maintaining the spinal cord, lung and heart doses within tolerance. Adequate target coverage was achieved by both techniques. Typically, HT achieved better lung sparing and PTV coverage than did RA.

Conclusions

Dose escalation for esophageal cancer becomes clinically feasible with the use of RA and HT. This promising result could be explored in a carefully controlled clinical study which considered normal tissue complications and tumor control as endpoints.