Influence of clinical usage of GT and GTX files on cyclic fatigue resistance.

AIM: To compare static cyclic fatigue resistance of unused, unused and sterilized and clinically used conventional NiTi GT and M-Wire GTX files. METHODOLOGY: One hundred and sixty new files (80 GT and 80 GT series X) were divided into four control groups and four experimental groups (n = 20 each). Control groups were new unused files and new sterilized files. In the experimental groups, instruments were used in three (GT1 and GTX1 groups) or four molars (GT2 and GTX2 groups). Cyclic fatigue resistance was tested in stainless steel curved canals (60°, r = 3 mm). Each file was rotated until fracture (300 rpm, 2 N cm torque). Time-to-fracture (s) was registered. Mean life, eta and beta parameters of their Weibull distributions were calculated. RESULTS: Unused and sterilized GTX files will last significantly longer than GT files with a probability of 75% and 65%, respectively; whilst mean life was significantly longer for GT than for GTX in used files with a probability of 68%. Sterilized GT files will last longer than unused files with a probability of 66%. In both brands, unused and sterilized files will last significantly longer than files used clinically with a probability higher than 98%. The probability that GT will last longer after being used in three rather than four molars was 62% (statistically significant) and 52% (not statistically significant) for GTX. CONCLUSIONS: GTX files had an extended cyclic fatigue life when compared with GT when they were unused or unused and sterilized, but GT were significantly more resistant to cyclic fatigue after clinical usage than GT series X files 3 mm from the tip. Sterilization of files enhanced the cyclic fatigue resistance of GT instruments. Clinical use of files diminished cyclic fatigue resistance.

[Sistematic review on the influence of leadership style on job satisfaction of health professionals]. / Revisión sistemática sobre la influencia del estilo de liderazgo en la satisfacción laboral de los profesionales de la salud.

INTRODUCTION AND OBJECTIVES: Healthcare organisations are highly complex entities that live with a high risk of instability. In order to minimise this instability, interactions and personal relationships play a major role and accordingly the figure of the leader gains full significance. The leadership style used can produce different reactions and lead to multiple outcomes, including job satisfaction. The aim of the present review is to correlate leadership style with job satisfaction in healthcare professionals. MATERIAL AND METHODS: A systematic review was carried out in BVS, Cochrane plus, CINAHL, ApaPsycinfo and Pubmed, selecting publications that mentioned leadership styles and job satisfaction in healthcare professionals. Publications search strategy were limited for the 5-10last years, full text availability and language of writing: English, French and Spanish. Review-type publications were excluded. Of the 1566 initial titles, 15 were selected for analysis. RESULTS AND CONCLUSIONS: The transformational style showed the highest number of positive correlations, followed by the authentic and transactional styles. On the other hand, the passive and laissez-faire styles showed a negative correlation regardless of the professional category to which they belonged. The results of this study provide a starting point for adopting effective leadership styles to optimise the recruitment and training processes of staff in management and coordination roles.

The effect of the AKT1 gene and cannabis use on cognitive performance in healthy subjects.

BACKGROUND: Evidence suggests that the AKT1 gene may modulate the degree to which cannabis use induces cognitive alterations in patients with a psychotic disorder. AIM: To examine the interplay between AKT1 and cannabis use in terms of the cognitive performance of the general population. METHODS: Our sample consisted of 389 Spanish university students. Sustained attention was measured via the Continuous Performance Test-Identical Pairs, immediate and delayed verbal memory with the Logical Memory subtest of the Wechsler Memory Scale, and working memory with the Wisconsin Card Sorting Test. Lifetime cannabis use frequency was assessed and individuals were classified as cannabis users or non-users. Two single nucleotide polymorphisms of the AKT1 gene were genotyped and, according to previous studies, each subject was defined as a carrier of two, one or no copies of the haplotype (rs2494732(C)-rs1130233(A)). Multiple linear regressions were conducted to test the effect of the genetic variability and cannabis use (and their interaction) on cognitive performance. RESULTS: An effect of the AKT1 haplotype was found on attention scores: individuals with two copies of the haplotype performed better (ß=0.18, p<0.001 (adjusted for false discovery rate)), while neither cannabis nor the AKT1-cannabis interaction was associated with attention. No effect of AKT1, cannabis or the AKT1-cannabis interaction was found on verbal memory or working memory. CONCLUSIONS: Our study provides additional evidence that AKT1 modulates cognitive performance. However, in our non-clinical sample, the previously reported interaction between cannabis use and the AKT1 gene was not replicated.

Evidence of an epistatic effect between Dysbindin-1 and Neuritin-1 genes on the risk for schizophrenia spectrum disorders.

BACKGROUND: The interest in studying gene-gene interactions is increasing for psychiatric diseases such as schizophrenia-spectrum disorders (SSD), where multiple genes are involved. Dysbindin-1 (DTNBP1) and Neuritin-1 (NRN1) genes have been previously associated with SSD and both are involved in synaptic plasticity. We aimed to study whether these genes show an epistatic effect on the risk for SSD. METHODS: The sample comprised 388 SSD patients and 397 healthy subjects. Interaction was tested between: (i) three DTNBP1 SNPs (rs2619537, rs2743864, rs1047631) related to changes in gene expression; and (ii) an haplotype in NRN1 previously associated with the risk for SSD (rs645649-rs582262: HAP-risk C-C). RESULTS: An interaction between DTNBP1 rs2743864 and NRN1 HAP-risk was detected by using the model based multifactor dimensionality reduction (MB-MDR) approach (P=0.0049, after permutation procedure), meaning that the risk for SSD is significantly higher in those subjects carrying both the A allele of rs2743864 and the HAP-risk C-C. This interaction was confirmed by using a logistic regression model (P=0.033, OR (95%CI)=2.699 (1.08-6.71), R2=0.162). DISCUSSION: Our results suggest that DTNBP1 and NRN1 genes show a joint effect on the risk for SSD. Although the precise mechanism underlying this effect is unclear, the fact that these genes have been involved in synaptic maturation, connectivity and glutamate signalling suggests that our findings could be of value as a link to the schizophrenia aetiology.

Halothane inhibits endothelium-dependent relaxation elicited by acetylcholine in human isolated pulmonary arteries.

This study examined whether a clinically relevant concentration of the volatile anaesthetic halothane modifies the endothelium-dependent relaxation produced by acetylcholine (3 nM-10 microM), histamine (1 pM-0.1 microM) and anti-human immunoglobulin E (1:1000) in human isolated pulmonary arteries submaximally precontracted with noradrenaline. An inhibitor of nitric oxide formation, N(G)-nitro-L-arginine (100 microM), attenuated acetylcholine-induced relaxation but failed to inhibit histamine- and anti-human immunoglobulin E-induced relaxation. Indomethacin (2.8 microM, a cyclooxygenase inhibitor) preferentially reduced the relaxation to histamine and anti-human IgE. Halothane (2%) significantly attenuated the relaxation to acetylcholine but had no significant effect on the relaxation elicited by histamine and anti-human IgE. Halothane (2%) enhanced the basal release of prostaglandin I2 by human pulmonary arteries (control 0.31 +/- 0.04 ng mg(-1); treated tissues 0.50 +/- 0.06 ng mg(-1); n = 5; P < 0.05). Halothane (2%) did not alter the responsiveness and sensitivity of preparations to relaxants acting through activation of adenylyl cyclase (forskolin) or guanylyl cyclase (sodium nitroprusside) or by the opening of K(ATP) channels (cromakalim). In conclusion, halothane inhibits the endothelium-dependent relaxation of human pulmonary arteries to acetylcholine by interfering with the nitric oxide pathway at a site before activation of soluble guanylyl cyclase in vascular smooth muscle.

Plasma lipid composition in an elderly population: correlation with dietary fat.

The effects of dietary fat on plasma lipid composition were studied in a population of 51 elderly subjects (19 men, 32 women) who lived in a retirement home in the province of Jaén (southern Spain). Dietary intake of fat was elevated (106 and 115 g/day in men and women respectively), and fatty acid intake consisted of 40% oleic acid, 17% linoleic acid and 0.7% linolenic acid. Cholesterol intake was 506 and 518 mg/day in men and women respectively, whereas the plasma level of cholesterol was approximately 250 mg/dl in both sexes. In men and women, HDL-cholesterol levels were 71.5 and 62.2 mg/dl, and LDL-cholesterol levels were 153.5 and 152.3 mg/dl. The most abundant circulating fatty acid was palmitic acid (25%) in both sexes, followed by oleic (23%) and linoleic acid (15-16%), whereas linolenic acid represented only 0.3% of the plasma fatty acids. To determine whether plasma levels of fatty acids served as reliable biological markers of dietary fatty acid intake, we compared the two sets of values, and found that higher intake was reflected in higher plasma levels, although a significant linear correlation (p < 0.05) was found only for linolenic acid.

Acceptance and commissioning of a treatment planning system based on Monte Carlo calculations.

The Monaco Treatment Planning System (TPS), based on a virtual energy fluence model of the photon beam head components of the linac and a dose computation engine made with Monte Carlo (MC) algorithm X-Ray Voxel MC (XVMC), has been tested before being put into clinical use. An Elekta Synergy with 6 MV was characterized using routine equipment. After the machine's model was installed, a set of functionality, geometric, dosimetric and data transfer tests were performed. The dosimetric tests included dose calculations in water, heterogeneous phantoms and Intensity Modulated Radiation Therapy (IMRT) verifications. Data transfer tests were run for every imaging device, TPS and the electronic medical record linked to Monaco. Functionality and geometric tests were run properly. Dose calculations in water were in accordance with measurements so that, in 95% of cases, differences were up to 1.9%. Dose calculation in heterogeneous media showed expected results found in the literature. IMRT verification results with an ionization chamber led to dose differences lower than 2.5% for points inside a standard gradient. When an 2-D array was used, all the fields passed the g (3%, 3 mm) test with a percentage of succeeding points between 90% and 95%, of which the majority of the mentioned fields had a percentage of succeeding points between 95% and 100%. Data transfer caused problems that had to be solved by means of changing our workflow. In general, tests led to satisfactory results. Monaco performance complied with published international recommendations and scored highly in the dosimetric ambit. However, the problems detected when the TPS was put to work together with our current equipment showed that this kind of product must be completely commissioned, without neglecting data workflow, before treating the first patient.

Uncertainties and CTV to PTV margins quantitative assessment using cone-beam CT technique in clinical application for prostate, and head and neck irradiation tumours.

PURPOSE To evaluate the magnitude of systematic and random errors from a subset of 100 prostate and 26 head and neck (H&N) cancer patients treated with conventional conformal radiotherapy and using image-guided radiotherapy (IGRT). After treatment, the uncertainties involved and the CTV to PTV margin were evaluated. MATERIAL AND METHODS An Elekta Synergy® linear accelerator was used, taking advantage of 3D on-board computed tomography. IGRT with no-action level (NAL) protocol was applied, reporting the 3D translation and rotation corrections. A statistical study was performed to analyse systematic, random and interobserver uncertainties, and, finally, to obtain the CTV to PTV margins. RESULTS The H&N patients' uncertainties found were smaller than those of prostate patients. The CTV to PTV margins assessed, following the guidelines found in the literature, in the three dimensions of space (right-left, superior-inferior, anterior-posterior) were (5.3, 3.5, 3.2) mm for H&N and (7.3, 7.0, 9.0) mm for prostate cancer treatments. CONCLUSIONS It was found that assessing all the involved uncertainties within radiation treatments was very revealing; their quality improves using IGRT techniques and performing extensive data analysis.

Drug provocation tests in children: Indications and interpretation.

Drug provocation tests in children are always a problematic task. In the present article the most important aspects of this technique are reviewed, including the differences between children and adults; the main mechanisms involved in drug reaction; how to perform the different tests; and when they are indicated.

Insights on plant chromosome structure provided by the FPG technique.

The high resolution afforded by the fluorescence plus Giemsa (FPG) labelling method has allowed us to visualize three main features in BrdU-substituted A. cepa chromosomes. These are (1) exchanged segments smaller than the width of the chromatid detected after BrdU substitution for two S periods; (2) late-replicated chromosome segments (LRS) of similar characteristics; (3) discontinuous or 'step-wise' exchanges (SWE). A variation in longitudinal dimension has not been observed in any case; all these features have a roughly constant longitudinal dimension of about 0.5 microns. These results suggest that arrangements of the chromatin fibres having a diameter detectable under the light microscope following a longitudinal pattern can be ignored. In addition, our observations seem to support the model of a coiled structure of metaphase chromosomes. On the other hand, the analysis of the morphological pattern shown by the SWE along a chromatid and in sister chromatids has provided us with what could be evidence of a direction of the hypothetical gyres.