Four cases of direct ion channel gating by cyclic nucleotides

Four different nucleotide-gated ion channels are discussed in terms of their biophysical properties and their importance in cell physiology. Channels activated directly by cGMP are present in vertebrate and invertebrate photoreceptors. In both cases cGMP increases the fraction of time the channel remains in the open state. At least three cGMP molecules are involved in channel opening in vertebrate photoreceptors and the concentration of the cyclic nucleotide to obtain the half maximal effect is about 15 µM. The light-dependent channel of both vertebrates and invertebrates is poorly cation selective. The vertebrate channel allows divalent cations to pass through 10–15-fold more easily than monovalent ions. In agreement with their preference for divalent cations, this channel is blocked byl-cis Dialtazem, a molecule that blocks certain types of calcium channels. In olfactory neurons a channel activated by both cAMP and cGMP is found and, as in the light-dependent channel, several molecules of the nucleotide are needed to open the channel with a half maximal effect obtained in the range of 1–40 µM. The channel is poorly cationic selective. A K⁺ channel directly and specifically activated by cAMP is found inDrosophila larval muscle. At least three cAMP molecules are involved in the opening reaction. Half-maximal effect is obtained at about 50 µM. This channel is blocked by micromolar amount of tetraethylammonium applied internally. Interestingly, this channel has a probability of opening 10–20-fold larger in the mutantdunce, a mutant that possesses abnormally elevated intracellular cAMP level, than in the wild type.     

Ashworthius Patriciapilittae n. sp. (Trichostrongyloidea: Haemonchinae), an abomasal nematode in Odocoileus virginianus from Costa Rica,and a new record for species of the genus in the Western Hemisphere

A species of Ashworthius is reported for the first time in the Western Hemisphere, and A. patriciapilittae n. sp. is described on the basis of specimens in white-tailed deer Odocoileus virginianus from Costa Rica. Among 8 known species, A. patriciapilittae is morphologically similar to A. tuyenquangi in red muntjac Muntjacas muntjak from northern Vietnam. The synlophe in A. patriciapilittae is composed of 26 ridges in the cervical zone and is continuous to the caudal extremity in males and females. Males are characterized by a complex dorsal ray and narrow trifurcate spicules (351-356 microm long) lacking an "eyelet." with dissimilar ventral and dorsal processes; the gubernaculum is 45-48% of the spicule length. Females have a prominent linguiform flap at the vulva and large eggs (108-142 microm long). The presence of A. patriciapilittae in Costa Rica is examined in the context of competing hypotheses for cospeciation or contemporary host-switching in cervids: either A. patriciapilittae is a component of an endemic Central and South American fauna that has diversified through coevolution of Ashworthius and cervid hosts or it has been introduced. Among haemonchines in the Western Hemisphere, specimens of A. patriciapilittae may be confused with 3 species of Haemonchus, including H. contortus, H. placei, and H. similis, that occur in both domestic and wild ruminants. Discovery of A. patriciapilittae emphasizes the continued need for survey and inventory to define the structure and distribution of parasite faunas in wild and domestic ruminants from the Nearctic and Neotropical regions.     

Synthesis of Copper-64 and Technetium-99M Labeled Oligonucleotides with Macrocyclic Ligands

Abstract

An efficient procedure for the preparation of oligonucleotides carrying a mono-N-substituted azamacrocycle and its radiolabeled complex with Cu-64 and Tc-99m is reported. The new derivatives are of potential interest for Positron Emission Tomography and Single Photon Emission Tomography.     

Kinetic model of BiP- and PDI-mediated protein folding and assembly

A mechanism for heavy chain binding protein (BiP)- and protein disulfide isomerase (PDI)- mediated protein folding and assembly has been proposed. It considers BiP chaperoning action and PDI catalytic activity. A kinetic model has been developed based on the proposed mechanism. The model was used for quantifying the influence of polypeptide concentration and ratio, and the effect of BiP and PDI concentration on the kinetics of folding and assembly. An optimum value for polypeptide concentration that minimizes assembly times was found, and different kinetic behaviors were identified for polypeptide concentrations higher or lower than the optimum. Pulse-chase experiments and the dependence of assembly time on unassembled polypeptides ratio predicted by the model are similar to those found during in vitro and in vivo folding and assembly of antibodies and human chorionic gonadotropin (hCG), as well as bovine pancreatic trypsin inhibitor (BPTI) folding. The model also explains the increase in folding and assembly rates during overexpression of BiP and PDI.     

Improvement of catalytic properties of Escherichia coli penicillin G acylase immobilized on glyoxyl agarose by addition of a six-amino-acid tag

A tag of three lysines alternating with three glycines was added to the C-terminal end of the beta chain of penicillin G acylase (PGA). This modification improved the immobilization efficiency of PGA on glyoxyl agarose and the catalytic properties of the PGA derivative, although it impaired the posttranslational steps of overexpressed protein maturation.     

Fertilizing Methods and Nutrient Balance at the End of Traditional Organic Agriculture in the Mediterranean Bioregion: Catalonia (Spain) in the 1860s

By reconstructing the nutrient balance of a Catalan village circa 1861–65 we examine the sustainability of organic agricultural systems in the northwest Mediterranean bioregion prior to the green revolution and the question of whether the nutrients extracted from the soil were replenished. With a population density of 59 inhabitants per square km, similar to other northern European rural areas at that time, and a lower livestock density per cropland unit, this village experienced a manure shortage. The gap was filled by other labour-intensive ways of transferring nutrients from uncultivated areas into the cropland. Key elements in this agricultural system were vineyards because they have few nutrient requirements, and woodland and scrublands as sources of relevant amounts of nutrients collected in several ways.     

San Francisco Syncope Rule to predict short-term serious outcomes: a systematic review

Background:

The San Francisco Syncope Rule has been proposed as a clinical decision rule for risk stratification of patients presenting to the emergency department with syncope. It has been validated across various populations and settings. We undertook a systematic review of its accuracy in predicting short-term serious outcomes.

Methods:

We identified studies by means of systematic searches in seven electronic databases from inception to January 2011. We extracted study data in duplicate and used a bivariate random-effects model to assess the predictive accuracy and test characteristics.

Results:

We included 12 studies with a total of 5316 patients, of whom 596 (11%) experienced a serious outcome. The prevalence of serious outcomes across the studies varied between 5% and 26%. The pooled estimate of sensitivity of the San Francisco Syncope Rule was 0.87 (95% confidence interval [CI] 0.79–0.93), and the pooled estimate of specificity was 0.52 (95% CI 0.43–0.62). There was substantial between-study heterogeneity (resulting in a 95% prediction interval for sensitivity of 0.55–0.98). The probability of a serious outcome given a negative score with the San Francisco Syncope Rule was 5% or lower, and the probability was 2% or lower when the rule was applied only to patients for whom no cause of syncope was identified after initial evaluation in the emergency department. The most common cause of false-negative classification for a serious outcome was cardiac arrhythmia.

Interpretation:

The San Francisco Syncope Rule should be applied only for patients in whom no cause of syncope is evident after initial evaluation in the emergency department. Consideration of all available electrocardiograms, as well as arrhythmia monitoring, should be included in application of the San Francisco Syncope Rule. Between-study heterogeneity was likely due to inconsistent classification of arrhythmia.Syncope is defined as sudden, transient loss of consciousness with the inability to maintain postural tone, followed by spontaneous recovery and return to pre-existing neurologic function.^1–5 It represents a common clinical problem, accounting for 1%–3% of visits to the emergency department and up to 6% of admissions to acute care hospitals.^6,7Assessment of syncope in patients presenting to the emergency department is challenging because of the heterogeneity of underlying pathophysiologic processes and diseases. Although many underlying causes of syncope are benign, others are associated with substantial morbidity or mortality, including cardiac arrhythmia, myocardial infarction, pulmonary embolism and occult hemorrhage.^4,8–10 Consequently, a considerable proportion of patients with benign causes of syncope are admitted for inpatient evaluation.^11,12 Therefore, risk stratification that allows for the safe discharge of patients at low risk of a serious outcome is important for efficient management of patients in emergency departments and for reduction of costs associated with unnecessary diagnostic workup.^12,13In recent years, various prediction rules based on the probability of an adverse outcome after an episode of syncope have been proposed.^3,14–16 However, the San Francisco Syncope Rule, derived by Quinn and colleagues in 2004,³ is the only prediction rule for serious outcomes that has been validated in a variety of populations and settings. This simple, five-step clinical decision rule is intended to identify patients at low risk of short-term serious outcomes^3,17 (Box 1).

Box 1:

San Francisco Syncope Rule³

AimPrediction of short-term (within 30 days) serious outcomes in patients presenting to the emergency department with syncope.DefinitionsSyncope: Transient loss of consciousness with return to baseline neurologic function. Trauma-associated and alcohol- or drug-related loss of consciousness excluded, as is definite seizure or altered mental status.Serious outcome: Death, myocardial infarction, arrhythmia, pulmonary embolism, stroke, subarachnoid hemorrhage, significant hemorrhage or any condition causing or likely to cause a return visit to the emergency department and admission to hospital for a related event.Selection of predictors in multivariable analysis: Fifty predictor variables were evaluated for significant associations with a serious outcome and combined to create a minimal set of predictors that are highly sensitive and specific for prediction of a serious outcome.Clinical decision ruleFive risk factors, indicated by the mnemonic “CHESS,” were identified to predict patients at high risk of a serious outcome:

• C – History of congestive heart failure
• H – Hematocrit < 30%
• E – Abnormal findings on 12-lead ECG or cardiac monitoring¹⁷ (new changes or nonsinus rhythm)
• S – History of shortness of breath
• S – Systolic blood pressure < 90 mm Hg at triage

Note: ECG = electrocardiogram.The aim of this study was to conduct a systematic review and meta-analysis of the accuracy of the San Francisco Syncope Rule in predicting short-term serious outcome for patients presenting to the emergency department with syncope.     

Overexpression of csc1-1. A plausible strategy to obtain wine yeast strains undergoing accelerated autolysis

The potential of several alternative genetic engineering based strategies in order to accelerate Saccharomyces cerevisiae autolysis for wine production has been studied. Both constitutively autophagic and defective in autophagy strains have been studied. Although both alternatives lead to impaired survival under starvation conditions, only constitutively autophagic strains, carrying a multicopy plasmid with the csc1-1 allele under the control of the TDH3 promoter, undergo accelerated autolysis in the experimental conditions tested. Fermentation performance is impaired in the autolytic strains, but industrial strains carrying the above-mentioned construction are still able to complete second fermentation of a model base wine. We suggest the construction of industrial yeasts showing a constitutive autophagic phenotype as a way to obtain second fermentation yeast strains undergoing accelerated autolysis.     

The freshwater planarian Dugesia (G.) tigrina contains a great diversity of homeobox genes

To identify potential pattern control and cell determination and/or differentiation genes in the freshwater planarian Dugesial (G.) tigrina, we searched for homeobox genes of different types in the genome of this primitive metazoan. We applied two basic approaches: 1) Screening the cDNA library with degenerate oligonucleotides corresponding to the most conserved amino acid sequence from helix-3 of the homeodomain of each family; and 2) PCR amplification of genomic DNA or cDNA, using two sets of degenerated oligonucleotides corresponding to helices 1 and 3 of the homeodomain or two specific domains of the POU family. Using the first strategy we have identified and characterized two tissue-specific cell determination and/or differentiation NK-type homeobox genes. Using the second strategy we have identified several homeobox genes that belong to the HOM/Hox, paired (prd) or POU families.