Basics of CANDU Reactor Physics

Nuclear fission is the splitting of a (large) nucleus, with the release of energy. The nuclei of some heavy elements, such as U-238, do exhibit spontaneous fission in nature. However, the rate of such fissions is extremely low. The half-life of uranium is longer than 100 million years, and most of its decay is by alpha emission, so spontaneous fission is not a practical source of energy. Spontaneous fission is not of much use to us as an energy source!

HPV Infection Significantly Accelerates Glycogen Metabolism in Cervical Cells with Large Nuclei: Raman Microscopic Study with Subcellular Resolution

Using Raman microscopy, we investigated epithelial cervical cells collected from 96 women with squamous cell carcinoma (SCC) or belonging to groups I, IIa, IIID-1 and IIID-2 according to Munich III classification (IIID-1 and IIID-2 corresponding to Bethesda LSIL and HSIL groups, respectively). All women were tested for human papillomavirus (HPV) infection using PCR. Subcellular resolution of Raman microscopy enabled to understand phenotypic differences in a heterogeneous population of cervical cells in the following groups: I/HPV−, IIa/HPV−, IIa/HPV−, LSIL/HPV−, LSIL/HPV+, HSIL/HPV−, HSIL/HPV+ and cancer cells (SCC/HPV+). We showed for the first time that the glycogen content in the cytoplasm decreased with the nucleus size of cervical cells in all studied groups apart from the cancer group. For the subpopulation of large-nucleus cells HPV infection resulted in considerable glycogen depletion compared to HPV negative cells in IIa, LSIL (for both statistical significance, ca. 45%) and HSIL (trend, 37%) groups. We hypothesize that accelerated glycogenolysis in large-nucleus cells may be associated with the increased protein metabolism for HPV positive cells. Our work underlines unique capabilities of Raman microscopy in single cell studies and demonstrate potential of Raman-based methods in HPV diagnostics.

The relationship between genome size and metabolic rate in extant vertebrates

Genome size has long been hypothesized to affect the metabolic rate in various groups of animals. The mechanism behind this proposed association is the nucleotypic effect, in which large nucleus and cell sizes influence cellular metabolism through surface area-to-volume ratios. Here, we provide a review of the recent literature on the relationship between genome size and metabolic rate. We also conduct an analysis using phylogenetic comparative methods and a large sample of extant vertebrates. We find no evidence that the effect of genome size improves upon models in explaining metabolic rate variation. Not surprisingly, our results show a strong positive relationship between metabolic rate and body mass, as well as a substantial difference in metabolic rate between endothermic and ectothermic vertebrates, controlling for body mass. The presence of endothermy can also explain elevated rate shifts in metabolic rate whereas genome size cannot. We further find no evidence for a punctuated model of evolution for metabolic rate. Our results do not rule out the possibility that genome size affects cellular physiology in some tissues, but they are consistent with previous research suggesting little support for a direct functional connection between genome size and basal metabolic rate in extant vertebrates. This article is part of the theme issue ‘Vertebrate palaeophysiology’.

Diagnostics of collateral circulation during revascularization of cerebral arteries

54 patients with acute stroke were examined and treated: 12 patients were treated by thrombolytic therapy and/or thrombectomy, 22 patients were treated by endarterectomy from the internal carotid artery, and 20 patients were treated by anticoagulant, nootropic and antiplatelet therapy. Collateral blood circulation of blood vessels and foci of cerebral ischemia in ischemic stroke were examined in all patients to select a treatment method. The effect of collateral circulation in patients with recanalization of the carotid and cerebral arteries on the outcome of acute stroke treatment was analyzed. According to such parameters of neuroimaging as a large nucleus and poor collaterals, 25 out of 54 patients did not respond to revascularizing therapy, which was proved by CT data and a slight regression of neurological deficit within 14 days. Patients with a large nucleus and poor collateral circulation do not respond to revascularization surgery. Compared groups of patients according to CT data. It was found that the level of development of collaterals was associated with better clinical results. Adequate collateral circulation can help maintain tissue viability in the absence of recanalization. The choice of revascularization method depends on the state of collateral circulation, the size of the ischemic focus (according to CT, MRI) and the duration of treatment from the onset of stroke. Diagnosis of ischemia should begin with MRI angiography on the first day or CT angiography from the second day, which will allow assessing the level of collaterals, giving an idea of ​​collateral perfusion in patients and the size of the lesion.

SGK regulates pH increase and cyclin B–Cdk1 activation to resume meiosis in starfish ovarian oocytes

Tight regulation of intracellular pH (pHi) is essential for biological processes. Fully grown oocytes, having a large nucleus called the germinal vesicle, arrest at meiotic prophase I. Upon hormonal stimulus, oocytes resume meiosis to become fertilizable. At this time, the pHi increases via Na+/H+ exchanger activity, although the regulation and function of this change remain obscure. Here, we show that in starfish oocytes, serum- and glucocorticoid-regulated kinase (SGK) is activated via PI3K/TORC2/PDK1 signaling after hormonal stimulus and that SGK is required for this pHi increase and cyclin B–Cdk1 activation. When we clamped the pHi at 6.7, corresponding to the pHi of unstimulated ovarian oocytes, hormonal stimulation induced cyclin B–Cdk1 activation; thereafter, oocytes failed in actin-dependent chromosome transport and spindle assembly after germinal vesicle breakdown. Thus, this SGK-dependent pHi increase is likely a prerequisite for these events in ovarian oocytes. We propose a model that SGK drives meiotic resumption via concomitant regulation of the pHi and cell cycle machinery.

The Relationship Between Genome Size and Metabolic Rate in Extant Vertebrates

Genome size has long been hypothesized to affect metabolic rate in various groups of animals. The mechanism behind this proposed association is the nucleotypic effect, in which large nucleus and cell sizes influence cellular metabolism through surface area-to-volume ratios. Here, we provide a review of the recent literature on the relationship between genome size and metabolic rate. We also conduct an analysis using phylogenetic comparative methods and a large sample of extant vertebrates. We find no evidence that the effect of genome size improves upon models in explaining metabolic rate variation. Not surprisingly, our results show a strong positive relationship between metabolic rate and body mass, as well as a substantial difference in metabolic rate between endothermic and ectothermic vertebrates, controlling for body mass. The presence of endothermy can also explain elevated rate shifts in metabolic rate whereas genome size cannot. We further find no evidence for a punctuated model of evolution for metabolic rate. Our results do not rule out the possibility that genome size affects cellular physiology in some tissues, but they are consistent with previous research suggesting little support for a direct functional connection between genome size and basal metabolic rate in extant vertebrates.

SGK regulates pH increase and cyclin B-Cdk1 activation to resume meiosis in starfish ovarian oocytes

Tight regulation of intracellular pH (pHi) is essential for biological processes. Fully-grown oocytes, having a large nucleus called the germinal vesicle, arrest at meiotic prophase-I. Upon hormonal stimulus, oocytes resume meiosis to acquire fertilizability. At this time, pHi increases through Na+/H+ exchanger activity. However, regulation and function of this change remains obscure. Here we show that in starfish oocytes, serum- and glucocorticoid-regulated kinase (SGK) is activated by the PI3K/TORC2/PDK1 signaling after hormonal stimulus, and is required for the pHi increase and cyclin B–Cdk1 activation. Furthermore, when we clamped pHi at 6.7, corresponding to the pHi of unstimulated ovarian oocytes, hormonal stimulus normally induced cyclin B–Cdk1 activation; thereafter, oocytes initiated germinal vesicle breakdown (GVBD), but failed to complete it. Thus, SGK-dependent pHi increase is likely prerequisite for completion of GVBD in ovarian oocytes. We propose a model that SGK drives meiotic resumption through concomitant regulation of pHi and the cell-cycle machinery.

Baseline CTC subtype to predict outcomes on mCRPC patients (pts) receiving enzalutamide (E) compared to abiraterone (A).

5070 Background: Prior response to A or E does not predict sensitivity to E following A or A following E. The detection of AR-V7 predicts insensitivity to either drug, but identifies only a portion of non-responders. We previously identified 15 CTC subtypes based on unique phenotypic features in mCRPC pts, each with unique biology and different degree of likelihood of predicting resistance to either drug. Here we explored the relationship between individual subtypes and sensitivity to A vs. E, but not both. Methods: 107 pre-treatment blood samples from mCRPC pts starting A (n = 47) or E (n = 60) as a 1st or 2nd line of Tx were analyzed for CTCs utilizing the Epic Sciences platform. Samples were assayed for CTC subtypes based upon 15 pre-defined phenotypic CTC classifiers (Type A-O). Treatment outcomes were assessed by serial PSA changes and landmarked percent time of therapy progression on radiographs, and overall survival following either A or E. Cell type prevalence was also analyzed in relation to clinical outcomes, and subsets of the CTC subtypes subject to single cell NGS to ascertain genomic drivers common to each subtype. Results: CTCs were identified in 94% (101/107) of pt samples. One, cell Type K, found in 25% (27/107) of pts, was associated with a statistically significant inferior outcomes on E for all measures. Whereas similar outcomes were seen between K+ & K- pts treated with A. The distinct features of Cell Type K include a large nucleus, high nuclear entropy and high Nuclear/cytoplasmic AR terminal ratio; and a unique genomic profile enriched for cell cycle and DNA repair alterations relative to other CTC subtypes. Conclusions: The presence of specific CTC subtypes in pre-Rx phlebotomy samples associated with outcomes on A or E. A CTC subtype (Cell Type K) helped to identify pts with poor outcomes on E but not A vs. those without the cell type. Further biologic interrogation of K cells and ongoing clincial validation of the CTC subtype is planned. [Table: see text]

Biología celular de Lacondonia schismatica. Análisis por microscopía electrónica y de fuerza atómica

We have previously described the cell nucleus of Lacandonia schismatica by transmission electron microscopy. In this paper, the ultrastructure of the cytoplasm of L. schismatica and photosynthesis activity were studied. In addition, atomic force microscopy was used to generate images of cell structure. Samples were prepared for standard electron microscopy using glutaraldehyde-paraformaldehyde fixation. Cells from tegument or receptacle show 1-3 Golgi apparatus. They have 3-7 cisternae, 0.81 μm width. 0.04 μm in diameter vesicles were also observed associated to cisternae. Mitochondria were 0.9 μm long and 0.35 μm width. Double membrane earphones-like plastids were observed with lipid inclusions but no developed tilacoids. No photosynthesis activity was detected in these cellular structures. Rough endoplasmic reticulum is similar to that of other eukaryotes and associated ribosomes are around 15 nm in diameter. A large nucleus and one o several vacuoles are present in cells of L. schismatica, therefore, leaving a very restricted portion for cytoplasm and organelles.