Quarantine and the risk of COVID-19 importation.

Using a stochastic model, we assess the risk of importation-induced local transmission chains in locations seeing few or no local transmissions and evaluate the role of quarantine in the mitigation of this risk. We find that the rate of importations plays a critical role in determining the risk that case importations lead to local transmission chains, more so than local transmission characteristics, i.e. strength of social distancing measures (NPI). The latter influences the severity of the outbreaks when they do take place. Quarantine after arrival in a location is an efficacious way to reduce the rate of importations. Locations that see no or low-level local transmission should ensure that the rate of importations remains low. A high level of compliance with post-arrival quarantine followed by testing achieves this objective with less of an impact than travel restrictions or bans.

Development of robust discriminant equations for assessing subtypes of glioblastoma biopsies.

BACKGROUND: In the preceding decade, various studies on glioblastoma (Gb) demonstrated that signatures obtained from gene expression microarrays correlate better with survival than with histopathological classification. However, there is not a universal consensus formula to predict patient survival. METHODS: We developed a gene signature using the expression profile of 47 Gbs through an unsupervised procedure and two groups were obtained. Subsequent to a training procedure through leave-one-out cross-validation, we fitted a discriminant (linear discriminant analysis (LDA)) equation using the four most discriminant probesets. This was repeated for two other published signatures and the performance of LDA equations was evaluated on an independent test set, which contained status of IDH1 mutation, EGFR amplification, MGMT methylation and gene VEGF expression, among other clinical and molecular information. RESULTS: The unsupervised local signature was composed of 69 probesets and clearly defined two Gb groups, which would agree with primary and secondary Gbs. This hypothesis was confirmed by predicting cases from the independent data set using the equations developed by us. The high survival group predicted by equations based on our local and one of the published signatures contained a significantly higher percentage of cases displaying IDH1 mutation and non-amplification of EGFR. In contrast, only the equation based on the published signature showed in the poor survival group a significant high percentage of cases displaying a hypothesised methylation of MGMT gene promoter and overexpression of gene VEGF. CONCLUSION: We have produced a robust equation to confidently discriminate Gb subtypes based in the normalised expression level of only four genes.

Magnetic coupling and spin ordering in bisdithiazolyl, thiaselenazolyl, and bisdiselenazolyl molecular materials.

The use of purely organic materials is a promising approach for the miniaturization of devices due to their interesting optical, electronic and magnetic properties. Bisdithiazolyl-based bisDTA compounds have emerged as promising candidates for radical-based single component conductors exhibiting simultaneously magnetic properties. Our computational work focuses on the intriguing magnetism of 4 isostructural pyridine-bridged bisDTA-multifunctional materials triggered by their magnetic and conducting properties being strongly dependent on the different S/Se ratios in the neutral radical skeleton: specifically, bisdithiazolyl (S,S) displays no magnetic order at low temperatures, thiaselenazolyl (Se,S) exhibits spin-canted antiferromagnetism (AFM), and both (S,Se) and bisdiselenazolyl (Se,Se) behave as bulk ferromagnets (FM). Our results reveal that (1) the magnetic response depends on the existence of an intricate network of both AFM and FM spin exchange JAB couplings between neighbouring radicals; and (2) the structural arrangement of π-stacked pairs of radicals sits on a point in the configurational space that is very close to a crossover region where JAB switches from AFM to FM. Indeed, for bulk FM, the experimental response is only accounted for when considering an ab initio optimised crystal structure able to portray adequately the electronic structure of bisDTAs in the region close to the temperature at which magnetic ordering emerges. Magneto-structural correlation maps show the large sensitivity of JAB to very small structural changes with temperature along the π-stacks that lead to drastic changes in the magnetic properties. Clearly, the understanding of magnetism in the title bisDTA compounds is decisive to rationally tailor the properties of multifunctional materials by subtle structural modifications of their crystal packing.

[The laryngeal tube]. / El tubo laríngeo.

The laryngeal tube (VBM Medizintechnic GmbH, Sulz, Germany) is a supraglottic device designed for airway management in spontaneous or positive-pressure ventilation during anesthesia or in cardiopulmonary resuscitation. Currently, the tube is available in 4 versions: the standard laryngeal tube, the disposable tube (LT-D), the dual-lumen tube (with a tube for suction) (LTS II), and the disposable LTS (LTS-D). The design of the tube has been modified several times. It is easy to insert and the airway seal is more effective than that of the laryngeal mask. The incidence of complications is similar for both devices, though use of the laryngeal tube requires more adjustments. The standard tube is somewhat less effective than the ProSeal laryngeal mask, though the new LTS II has been improved considerably. The laryngeal tube is effective as an aid to management of the difficult airway. We reviewed the literature indexed on MEDLINE through December 2006 using the search terms laryngeal tube, anesthesia, equipment, and airway.

The yeast ser/thr phosphatases sit4 and ppz1 play opposite roles in regulation of the cell cycle.

Yeast cells overexpressing the Ser/Thr protein phosphatase Ppz1 display a slow-growth phenotype. These cells recover slowly from alpha-factor or nutrient depletion-induced G1 arrest, showing a considerable delay in bud emergence as well as in the expression of the G1 cyclins Cln2 and Clb5. Therefore, an excess of the Ppz1 phosphatase interferes with the normal transition from G1 to S phase. The growth defect is rescued by overexpression of the HAL3/SIS2 gene, encoding a negative regulator of Ppz1. High-copy-number expression of HAL3/SIS2 has been reported to improve cell growth and to increase expression of G1 cyclins in sit4 phosphatase mutants. We show here that the described effects of HAL3/SIS2 on sit4 mutants are fully mediated by the Ppz1 phosphatase. The growth defect caused by overexpression of PPZ1 is intensified in strains with low G1 cyclin levels (such as bck2Delta or cln3Delta mutants), whereas mutation of PPZ1 rescues the synthetic lethal phenotype of sit4 cln3 mutants. These results reveal a role for Ppz1 as a regulatory component of the yeast cell cycle, reinforce the notion that Hal3/Sis2 serves as a negative modulator of the biological functions of Ppz1, and indicate that the Sit4 and Ppz1 Ser/Thr phosphatases play opposite roles in control of the G1/S transition.

Rck2 kinase is a substrate for the osmotic stress-activated mitogen-activated protein kinase Hog1.

Exposure of yeast cells to increases in extracellular osmolarity activates the Hog1 mitogen-activated protein kinase (MAPK). Activation of Hog1 MAPK results in induction of a set of osmoadaptive responses, which allow cells to survive in high-osmolarity environments. Little is known about how the MAPK activation results in induction of these responses, mainly because no direct substrates for Hog1 have been reported. We conducted a two-hybrid screening using Hog1 as a bait to identify substrates for the MAPK, and the Rck2 protein kinase was identified as an interactor for Hog1. Both two-hybrid analyses and coprecipitation assays demonstrated that Hog1 binds strongly to the C-terminal region of Rck2. Upon osmotic stress, Rck2 was phosphorylated in vivo in a Hog1-dependent manner. Furthermore, purified Hog1 was able to phosphorylate Rck2 when activated both in vivo and in vitro. Rck2 phosphorylation occurred specifically at Ser519, a residue located within the C-terminal putative autoinhibitory domain. Interestingly, phosphorylation at Ser519 by Hog1 resulted in an increase of Rck2 kinase activity. Overexpression of Rck2 partially suppressed the osmosensitive phenotype of hog1Delta and pbs2Delta cells, suggesting that Rck2 is acting downstream of Hog1. Consistently, growth arrest caused by hyperactivation of the Hog1 MAPK was abolished by deletion of the RCK2 gene. Furthermore, overexpression of a catalytically impaired (presumably dominant inhibitory) Rck2 kinase resulted in a decrease of osmotolerance in wild-type cells but not in hog1Delta cells. Taken together, our data suggest that Rck2 acts downstream of Hog1, controlling a subset of the responses induced by the MAPK upon osmotic stress.

[Pancreatobiliary maljunction. Not only an Eastern disease]. / Unión biliopancreática anómala. Una enfermedad no exclusiva de pacientes orientales.

Pancreatobiliary maljunction, an extramural junction of the pancreatic and biliary ducts in the duodenum, apparently beyond the scope of intramural sphincter function, is thought to be a preferential disease of Eastern people. However, this diagnosis is increasingly being made in other populations. We present a 41-year-old woman who presented with intermittent epigastric pain and mild raise in amylase levels. MRCP did not offer a definitive diagnosis, perhaps because of lack of experience in this disease. Finally, ERCP showed a pancreatobiliary maljunction, type acute angle, but with a complex connection between the choledocus and the pancreatic duct. Fusiform dilation of the common bile duct and of the left main hepatic duct were also present. The patient was referred for extrahepatic biliary resection and a diversion procedure. But also because of lack of experience in this disease, a wait-and-see approach was undertaken. In conclusion, pancreatobiliary maljunction will be increasingly diagnosed in western communities and more diagnostic and therapeutic experience will be needed.

Control of glycogen synthase and phosphorylase in hepatocytes from diabetic rats. Effects of glucagon, vasopressin, and vanadate.

Although glycogen synthase is present in a highly inactivated state in hepatocytes from streptozocin-induced diabetic rats, glucagon, vasopressin, and vanadate are still able to further decrease the basal activity of the enzyme. This inactivation was observed with the low-to-high glucose 6-phosphate activity ratio assay. The inactivation of glycogen synthase occurred concomitantly with the activation of glycogen phosphorylase. When hepatocytes from diabetic rats were incubated with [32P]phosphate and then with the agents and when the 32P-labeled glycogen synthase was immunoprecipitated, we observed that the 32P bound to the 88,000-Mr subunit increased in all cases. All the [32P]phosphate was located in two cyanogen bromide fragments of the enzyme, indicating that the enzyme was phosphorylated at multiple sites. The fragments were precisely those phosphorylated by glycogenolytic hormones in hepatocytes from normal rats. These results demonstrated that hepatic glycogen synthase, although highly inactive, is under potential hormonal control in diabetes and that the enzyme has not reached its maximal level of phosphorylation. Furthermore, they indicated that vanadate behaves as a glycogenolytic agent regarding its effects on glycogen-metabolizing enzymes in hepatocytes from diabetic rats.

Sequence homologies between type 1 and type 2A protein phosphatases.

The Mr = 33,000 catalytic fragment of rabbit skeletal muscle type 1 protein phosphatase was digested with trypsin after reduction and alkylation. The resulting peptides were isolated, subjected to automated Edman degradation, and their sequences compared to the deduced peptide sequence of the bovine type 2A protein phosphatase cDNA. Of 10 tryptic peptides from the type 1 phosphatase that were sequenced, nine showed a high degree of homology with the type 2A phosphatase. This provides the first direct sequence comparison suggesting that the type 1 and type 2 protein phosphatases, distinguished functionally by their substrate specificities and sensitivity to inhibitors, make up part of a family of closely related gene products with similar structures.

Towards the tailored design of benzotriazinyl-based organic radicals displaying a spin transition.

The mechanism of the phase transition of 1-phenyl-3-trifluoromethyl-1,4-dihydrobenzo[e][1,2,4]triazin-4-yl (1), the first reported triazinyl radical to present such a feature, is unveiled. In so doing, we identify the key ingredients that are crucial to enable the phase transition in this family of radicals, and how those can be exploited by a rational design of the spin-carrying units.

New coordination features; a bridging pyridine and the forced shortest non-covalent distance between two CO32- species.

The aerobic reaction of the multidentate ligand 2,6-bis-(3-oxo-3-(2-hydroxyphenyl)-propionyl)-pyridine, H4L, with Co(ii) salts in strong basic conditions produces the clusters [Co4(L)2(OH)(py)7]NO3 (1) and [Co8Na4(L)4(OH)2(CO3)2(py)10](BF4)2 (2). Analysis of their structure unveils unusual coordination features including a very rare bridging pyridine ligand or two trapped carbonate anions within one coordination cage, forced to stay at an extremely close distance (dO···O = 1.946 Å). This unprecedented non-bonding proximity represents a meeting point between long covalent interactions and "intermolecular" contacts. These original motifs have been analysed here through DFT calculations, which have yielded interaction energies and the reduced repulsion energy experimented by both CO32- anions when located in close proximity inside the coordination cage.

Molecular cloning and characterization of two phosphatase 2A catalytic subunit genes from Arabidopsis thaliana.

The plant Arabidopsis thaliana contains five isoforms of the catalytic subunit of protein phosphatase 2A (PP2A) that can be grouped into two families, one composed by isoforms PP2A-1, -2 and -5 and the other composed by isoforms PP2A-3 and PP2A-4. An Arabidopsis genomic library was screened and several clones corresponding to genes PP2A-3 and PP2A-4 were isolated and analysed. Both genes span over approximately 4.5kbp and are composed of 11 exons and 10 introns that show identical organization. Their untranslated regions are also highly conserved, suggesting that the two genes derive from a common ancestral gene. However, the position of intron/exon junctions completely differs from that of the human PP2A genes. Two transcription start sites have been found in the PP2A-3 gene, the major one mapping at nucleotide position -188 from the translation start codon, whereas only one is observed in PP2A-4 (-145). Functional gene promoter analysis reveals that elements required for transient expression of PP2A-3 and PP2A-4 on a protoplast system are contained within a region of about 600bp upstream from the transcription start sites. This is the first report on the cloning and characterization of genes encoding catalytic subunits of Ser/Thr protein phosphatases 2A in higher plants.

Saccharomyces cerevisiae gene SIT4 is involved in the control of glycogen metabolism.

The gene SIT4 of S. cerevisiae, which codes for a protein structurally related to the catalytic subunit of mammalian protein phosphatase 2A, was disrupted in vitro. Analysis of glycogen synthase activity ratio in mutant haploid cells indicated that the enzyme was less active than in wild-type cells. On the contrary, glycogen phosphorylase alpha activity was much higher. The activation of glycogen synthase observed in wild-type cells after incubation with lithium ions was not detected in mutant cells. These results suggest that the product of gene SIT4, a putative protein phosphatase, could be involved in the control of glycogen metabolism in yeast cells.

The PPZ protein phosphatases are involved in the maintenance of osmotic stability of yeast cells.

We have recently reported the existence in the yeast Saccharomyces cerevisiae of a gene named PPZ1, encoding a novel Ser/Thr phosphatase characterized by a large, Ser-rich amino-terminal extension, and suggested the existence of a related gene product that could have overlapping functions. We have now amplified by polymerase chain reaction techniques a genomic fragment of about 600 bp corresponding to this second gene (PPZ2). This fragment hybridizes to an mRNA of about the same size as the PPZ1 message but the amount of PPZ2 mRNA peaks at the stationary phase, when almost no PPZ1 mRNA is found. The PPZ2 fragment was interrupted in vitro and used to transform diploid heterozygous ppz1 PPZ2 cells. Haploid cells carrying the double mutation ppz1 ppz2 were unable to grow in the presence of 5 mM caffeine. However, the mutants did survive when osmotically stabilized in the presence of 1 M sorbitol. The evidence obtained suggests that PPZ1 and PPZ2 may be structurally and functionally related and points to an involvement of these phosphatases in functions related to the maintenance of cell integrity.

Biochemical characterization of recombinant yeast PPZ1, a protein phosphatase involved in salt tolerance.

The Saccharomyces cerevisiae gene PPZ1 codes for a 692-residues protein that shows in its carboxyl-terminal half about 60% identity with the catalytic subunit of mammalian and yeast protein phosphatase-1 and that is involved in salt homeostasis. The complete PPZ1 protein has been successfully expressed as a soluble glutathione-S-transferase fusion protein. The recombinant protein, after purification by a single affinity chromatography step, displayed phosphatase activity towards a number of substrates, including myelin basic protein, histone 2A and casein, but was ineffective in dephosphorylating glycogen phosphorylase. It was also active towards p-nitrophenylphosphate. The activity was severalfold increased by the presence of Mn2+ ions and by limited trypsinolysis. The enzyme was inhibited by okadaic acid and microcystin-LR at concentrations comparable to what is found for type 1 protein phosphatase although it was much less sensitive to inhibitor-2. The recombinant protein was phosphorylated in vitro by cAMP-dependent protein kinase, protein kinase C and casein kinase-2. Phosphorylation affected preferentially sites located in the amino-terminal half of the protein and did not alter the activity of the phosphatase.

Glycogen hyperaccumulation in Saccharomyces cerevisiae ras2 mutant. A biochemical study.

The mechanism by which yeast ras2 mutant hyperaccumulates glycogen has been investigated. Total glycogen synthase activity was between 2.5 and 1.3 times higher in the ras2 mutant than in an isogenic strain. In addition, while in the normal strain the glycogen synthase activation state decreased along the exponential phase, in the mutant strain the opposite behaviour was observed: glycogen synthase activation state rose continuously reaching full activation at the beginning of the stationary phase. Glycogen phosphorylase a activity was up to 40 times higher in the mutant than in the normal strain. Glucose 6-phosphate and fructose 2,6-bisphosphate levels were slightly more elevated in the mutants. The increase in total glycogen synthase and, particularly, the full activation of this enzyme may explain glycogen hyperaccumulation in the ras2 mutant even in the presence of elevated levels of glycogen phosphorylase a.

Identification of the two histidine residues responsible for the inhibition by malonyl-CoA in peroxisomal carnitine octanoyltransferase from rat liver.

Carnitine octanoyltransferase (COT), an enzyme that facilitates the transport of medium chain fatty acids through peroxisomal membranes, is inhibited by malonyl-CoA. cDNAs encoding full-length wild-type COT and one double mutant variant from rat peroxisomal COT were expressed in Saccharomyces cerevisiae. Both expressed forms were expressed similarly in quantitative terms and exhibited full enzyme activity. The wild-type-expressed COT was inhibited by malonyl-CoA like the liver enzyme. The activity of the enzyme encoded by the double mutant H131A/H340A was completely insensitive to malonyl-CoA in the range assayed (2-200 microM). These results indicate that the two histidine residues, H131 and H340, are the sites responsible for inhibition by malonyl-CoA. Another mutant variant, H327A, abolishes the enzyme activity, from which it is concluded that it plays an important role in catalysis.

Hormonal effects on the phosphorylation of glycogen synthase in rat hepatocytes.

The effects of epinephrine and vasopressin on the phosphorylation state of glycogen synthase were studied using rat hepatocytes incubated with 32P. After the incubation with hormones, 32P-labeled glycogen synthase was isolated using antibodies against rat liver enzyme. The immunoprecipitate showed a single radioactive band ( Mapp 88 kDa) when subjected to SDS-gel electrophoresis. Both epinephrine and vasopressin inactivated the enzyme and increased the 32P content of glycogen synthase. Cleavage of the immunoprecipitate with CNBr yielded two major 32P-labeled fragments of Mapp approximately 27 and 12 kDa. Both hormones increased the 32P content of both fragments. These results prove that epinephrine and vasopressin increase the phosphate content of the enzyme promoting its phosphorylation at multiple sites.

The Pzh1 protein phosphatase and the Spm1 protein kinase are involved in the regulation of the plasma membrane H+-ATPase in fission yeast.

We have previously shown that the mutation of the Schizosaccharomyces pombe PPZ-like protein phosphatase encoded by the gene pzh1+ results in increased tolerance to sodium and in hypersensitivity to potassium ions. A similar phenotype has also been reported for deletants in the spm1/pmk1 gene, encoding a mitogen-activated protein (MAP) kinase. We have found that the sodium tolerance phenotype of pzh1 deletants is stronger than that of spm1 mutants, and both effects are additive. Therefore, most probably both gene products mediate different pathways on sodium tolerance. In our hands, mutation of the kinase does not alter the tolerance to potassium, but it yields cells more tolerant to magnesium ions. While in budding yeast the mutations are synthetically lethal, fission yeast cells lacking both the phosphatase and the kinase genes are viable. Interestingly, their ability to export H+ to the medium is greatly impaired (although not that of pzh1 or spm1 single mutants). We have observed that, although the amount of the H+-ATPase in the plasma membrane is not altered, the activity of the enzyme is lower than normal and cannot be induced by glucose. These observations suggest that the activity of the H+-ATPase in fission yeast might be regulated by phospho-dephosphorylation mechanisms that might involve the pzh1+ and spm1+ gene products.