934 resultados para Crack initiation
Resumo:
Background. The ability to inhibit inappropriate or unwanted actions is a key element of executive control. The existence OF executive function deficits in schizophrenia is consistent with frontal lobe theories of the disorder. Relatively few Studies have examined response inhibition in schizophrenia, and none in adolescent patients with early-onset schizophrenia (EOS). Methods. Twenty-one adolescents with (lie onset of clinically impairing psychosis before 19 years of age and 16 matched controls performed a stop-signal task to assess response inhibition. The patients with EOS were categorized Lis paranoid (n= 10) and Undifferentiated subtypes (n= 11). The undifferentiated group had higher levels of negative symptomatology. Stop-signal reaction time (SSRT) and go-signal reaction time (Go-RT) were analysed with respect to hand of response. Results. The Undifferentiated early-onset patients had significantly longer SSRTs, indicative of poor response inhibition, for the left hand compared to the paranoid early-onset patients and control participants. No differences existed for inhibitory control with the right hand. The three groups did not differ in Go-RT. Conclusions. Our results indicate a specific lateralized impairment of response inhibition in patients With Undifferentiated, but not paranoid, EOS. These findings are consistent with reports of immature frontostriatal networks in EOS and implicate areas such as the pre-motor cortex and Supplementary motor area (SMA) that are thought to play a role in both voluntary initiation and inhibition of movement.
Resumo:
This paper examines upper-body movement kinematics in individuals with high-functioning autism (HFA) and Asperger's disorder (AD). In general, the results indicate that HFA is more consistently associated with impaired motoric preparation/initiation than AD. The data further suggest that this quantitative difference in motor impairment is not necessarily underpinned by greater executive dysfunction vulnerability in autism relative to AD. Quantitative motoric dissociation between autism and AD may have down-stream effects on later stages of movement resulting in qualitative differences between these disorder groups, e.g. motor clumsiness in AD versus abnormal posturing in autism. It will be important for future research to map the developmental trajectory of motor abnormalities in these disorder groups.
Resumo:
Acute kidney injury (AKI) is now well recognized as an independent risk factor for increased morbidity and mortality particularly when dialysis is needed. Although renal replacement therapy (RRT) has been used in AKI for more than five decades, there is no standard methodology to predict which AKI patients will need dialysis and who will recover renal function without requiring dialysis. The lack of consensus on what parameters should guide the decision to start dialysis has led to a wide variation in dialysis utilization. A contributing factor is the lack of studies in the modern era evaluating the relationship of timing of dialysis initiation and outcomes. Although listed as one of the top priorities in research on AKI, timing of dialysis initiation has not been included as a factor in large, randomized controlled trials in this area. In this review we will discuss the criteria that have been used to define early vs. late initiation in previous studies on dialysis initiation. In addition, we propose a patient-centered approach to define early and late initiation that could serve as framework for managing patients and for future studies in this area.
Resumo:
Mixed connective tissue disease (MCTD) is a rare disease that includes clinical and laboratorial manifestations of systemic lupus erythematosus, scleroderma and polymyositis that is associated with high titers of anti-U1RNP antibodies. In general, muscle involvement is subclinical, usually appearing as an increase in muscle enzyme levels that tends to be a characteristic of the initial phases of the disease. Severe clinical muscle weakness is not observed in this disease. The objective of this study is to report a rare case of a patient who presented a severe onset of myositis characterized by dysphagia, an increase in myopathy and a weakening of the cervical musculature. While there was no response to the administration of an initial dose of corticosteroids, improvement was observed after increasing the dose of corticosteroids, in addition to the initiation of pulse therapy with methylprednisolone accompanied by methotrexate treatment. The authors emphasize that there is only one previously reported case regarding a child with MCTD and severe clinical myopathy on electromyography and muscle biopsy, and they report in this article one adult female patient who presented severe myositis and was refractive to corticotherapy. Lupus (2010) 19, 1659-1661.
Resumo:
Prophylactic vaccines for genital human papillomavirus (HPV) infection have been shown to be feasible in animal models, and suitable vaccine material based on virus-like particles can be produced in bulk at reasonable cost. Initiation of phase III clinical trials will follow definition of trial outcome measures through further epidemiological studies, and development-of assays of host protective immunity. Vaccines could in principle eliminate HPV-related disease, as the human race is the only natural host for the relevant papillomaviruses (PVs). Therapeutic vaccines for genital HPV infection are also possible, but have not yet been demonstrated as feasible in practice because the choice of vaccine antigens is difficult, the method of their optimal delivery is uncertain, and the nature of the relevant antiviral immunity is unknown. PV species specificity will require trials to be conducted in man, which will slow definition of an ideal vaccine.
Resumo:
Cells of the mononuclear phagocyte lineage possess receptors for macrophage colony-stimulating factor (CSF-1) encoded by the c-fms protooncogene and respond to CSF-1 with increased survival, growth, differentiation, and reversible changes in function. The c-fms gene is itself a macrophage differentiation marker. In whole mount analyses of mRNA expression in embryos, c-fms is expressed at very high levels on placental trophoblasts. It is detectable on individual cells in the yolk sac around 8.5 to 9 days postcoitus, appears on isolated cells in the head of the embryo around 9.5 dpc, and appears on numerous cells throughout the embryo by day 10.5. The extent of c-fms expression is much greater than for other macrophage-specific genes including lysozyme and a macrophage-specific protein tyrosine phosphatase. Our studies of the cis-acting elements of the c-fms promoter have indicated a key role for collaboration between the macrophage-specific transcription factor, Pu.1, which functions in determining the site of transcription initiation, and other members of the Ets transcription factor family. This is emerging as a common pattern in macrophage-specific promoters. We have shown that two PU box elements alone can function as a macrophage-specific promoter. The activity of both the artifical promoter and the c-fms promoter is activated synergistically by coexpression of Pu.1 and another Ets factor, c-Ets-2. A 3.5kb c-fms exon 2 promoter (but not the 300bp proximal promoter) is also active in a wide diversity of tumor cell lines. The interesting exception is the melanoma cell line K1735, in which the promoter is completely shut down and expression of c-fms causes growth arrest and cell death. The activity of the exon 2 promoter in these nonmacrophages is at least as serum responsive as the classic serum-responsive promoter of the c-fos gene. It is further inducible in nonmacrophages by coexpression of the c-fms product. Unlike other CSF-1/c-fms-responsive promoters, the c-fms promoter is not responsive to activated Ras even when c-Ets-2 is coexpressed. In most lines, production of full length c-fms is prevented by a downstream intronic terminator, but in Lewis lung carcinoma, read-through does occur, and expression of both c-fms and other macrophage-specific genes such as lysozyme and urokinase becomes detectable in conditions of serum deprivation. (C) 1997 Wiley-Liss, Inc.
Resumo:
An experimental white cast iron with the unprecedented fracture tough ness of 40 MPa m(1/2) is currently being studied to determine the mechanisms of toughening. This paper reports the investigation of the role of strain-induced martensitic (SIM) transformation. The dendritic microconstituent in the toughened alloy consists primarily of retained austenite, with precipitated M(7)C(3) carbides and some martensite. Refrigeration experiments and differential scanning calorimetry (DSC) were used to demonstrate, firstly, that this retained austenite has an ''effective'' sub-ambient M(S) temperature and, secondly, that SIM transformation can occur at ambient temperatures. Comparison between room temperature and elevated temperature K-Ic tests showed that the observed SIM produces a transformation toughening response in the alloy, contributing to, but not fully accounting for, its high tough ness. SIM as a mechanism for transformation toughening has not previously been reported for white cast irons. Microhardness traverses on crack paths and X-ray diffraction (XRD) on fracture surfaces confirmed the interpretation of the K-Ic experiments. Further DSC and quantitative XRD showed that, as heat-treatment temperature is varied, there is a correlation between fracture toughness and the volume fraction of unstable retained austenite.
Resumo:
We examined the role of cytokinins (CKs) in release of apical dominance in lateral buds of chickpea (Cicer arietinum L.). Shoot decapitation or application of CKs (benzyladenine, zeatin or dihydrozeatin) stimulated rapid bud growth. Time-lapse video recording revealed growth initiation within 2 h of application of 200 pmol benzyladenine or within 3 h of decapitation. Endogenous CK content in buds changed little in the first 2 h after shoot decapitation, but significantly increased by 6 h, somewhat later than the initiation of bud growth. The main elevated CK was zeatin riboside, whose content per bud increased 7-fold by 6 h and 25-fold by 24 h. Lesser changes were found in amounts of zeatin and isopentenyl adenine CKs. We have yet to distinguish whether these CKs are imported from the roots via the xylem stream or are synthesised in situ in the buds, but CKs may be part of an endogenous signal involved in lateral bud growth stimulation following shoot decapitation. To our knowledge, this is the first detailed report of CK levels in buds themselves during release of apical dominance.
Resumo:
Background/Aim: Galectin-3 has been associated with activated Wnt pathway, translocating beta-catenin into the nucleus. However, it is still unknown whether this lectin drives the Wnt signaling activation in lesions from galectin-3-deficient (Gal3(-/-)) mice. The purpose was to study beta-catenin expression in tongue lesions from Gal3(-/-) and wildtype (Gal3(+/+)) mice and the status of Wnt signaling. Materials and Methods: Twenty Gal3(-/-) and Gal3(+/+) male mice were challenged with 4-nitroquinolin-1-oxide and killed at week 16 and 32. Tongues were processed and stained with H&E to detect dysplasias and carcinomas. An imunohistochemical assay was performed to evaluate beta-catenin expression. Results: Carcinomas were more evident in Gal3(+/+) than Gal3(-/-) mice (55.5% vs. 28.5%, respectively; p>0.05). Elevated expression of non-membranous beta-catenin was observed in dysplasias and carcinomas from both groups (p>0.05). Conclusion: Absence of galectin-3 does not interfere in the pattern of beta-catenin expression and therefore in the mediation of the Wnt signaling pathway.
Resumo:
Sepsis remains a major cause of morbidity and mortality mainly because of sepsis-induced multiple organ dysfunction. In contrast to preclinical studies, most clinical trials of promising new treatment strategies for sepsis have failed to demonstrate efficacy. Although many reasons could account for this discrepancy, the misinterpretation of preclinical data obtained from experimental studies and especially the use of animal models that do not adequately mimic human sepsis may have been contributing factors. In this review, the potentials and limitations of various animal models of sepsis are discussed to clarify to which extent these findings are relevant to human sepsis. Such models include intravascular infusion of endotoxin or live bacteria, bacterial peritonitis, cecal ligation and perforation, soft tissue infection, pneumonia or meningitis models using different animal species including rats, mice, rabbits, dogs, pigs, sheep, and nonhuman primates. Despite several limitations, animal models remain essential in the development of all new therapies for sepsis and septic shock because they provide fundamental information about the pharmacokinetics, toxicity, and mechanism of drug action that cannot be replaced by other methods. New therapeutic agents should be studied in infection models, even after the initiation of the septic process. Furthermore, debility conditions need to be reproduced to avoid the exclusive use of healthy animals, which often do not represent the human septic patient.
Resumo:
The solution conformation of a peptide LYS(11-36), which corresponds to the beta-sheet region in T4 lysozyme, has been examined in aqueous solution, TFE, and SDS micelles by CD and H-1 NMR spectroscopy. Secondary structure predictions suggest some beta-sheet and turn character in aqueous solution but predict a helical conformation in a more hydrophobic environment. The predictions were supported by the CD and NMR studies which showed the peptide to be relatively unstructured in aqueous solution, although there was some evidence of a beta-turn conformer which was maintained in 200 mM SDS and, to a lesser extent, in 50% TFE. The peptide was significantly helical in the presence of either 50% TFE or 200 mM SDS. TFE and SDS titrations showed that the peptide could form helical, sheet, or extended structure depending on the TFE or SDS concentration. The studies indicate that peptide environment is the determining factor in secondary structure adopted by LYS(11-36).
Resumo:
Introduction: No study so far has tested a beverage containing glutamine 2 h before anesthesia in patients undergoing surgery. Objectives: The aim of the study was to investigate: 1) the safety of the abbreviation of preoperative fasting to 2 h with a carbohydrate-L-glutamine-rich drink; and 2) the residual gastric volume (RGV) measured after the induction of anesthesia for laparoscopic cholecystectomies. Methods: Randomized controlled trial with 56 women (42 (17-65) years-old) submitted to elective laparoscopic cholecystectomy. Patients were randomized to receive either conventional preoperative fasting of 8 hours (fasted group, n = 12) or one of three different beverages drunk in the evening before surgery (400 mL) and 2 hours before the initiation of anesthesia (200 mL). The beverages were water (placebo group, n = 12), 12.5% (240 mOsm/L) maltodextrine (carbohydrate group, n = 12) or the latter in addition to 50 g (40 g in the evening drink and 10g in the morning drink) of L-glutamine (glutamine group, n = 14). A 20 F nasogastric tube was inserted immediately after the induction of general anesthesia to aspirate and measure the RGV. Results: Fifty patients completed the study. None of the patients had either regurgitation during the induction of anesthesia or postoperative complications. The median (range) of RGV was 6 (0-80) mL. The RGV was similar (p = 0.29) between glutamine group (4.5 [0-15] mL), carbohydrate group (7.0 [0-80] mL), placebo group (8.5 [0-50] mL), and fasted group (5.0 [0-50] mL). Conclusion: The abbreviation of preoperative fasting to 2 h with carbohydrate and L-glutamine is safe and does not increase the RGV during induction of anesthesia. (Nutr Hosp. 2011;26:86-90) DOI:10.3305/nh.2011.26.1.4993
Resumo:
We have investigated molecular mechanisms of the embryonic development of an ascidian, a primitive chordate which shares features of both invertebrates and vertebrates, with a view to identifying genes involved in development and metamorphosis, We isolated 12 partial cDNA sequences which were expressed in a stage-specific manner using differential display, We report here the isolation of a full-length cDNA sequence for one of these genes which was specifically expressed during the tailbud and larval stages of ascidian development, This cDNA, 1213 bp in length, is predicted to encode a protein of 337 amino acids containing four epidermal growth factor (EGF)-like repeats and three novel cysteine-rich repeats, Characterization of its spatial expression pattern by in situ hybridisation in late tailbud and larval embryos demonstrated strong expression localised throughout the papillae and anteriormost trunk and weaker expression in the epidermis of the remainder of the embryo, As recent evidence indicates that the signal for metamorphosis originates in the anterior trunk region, these results suggest that this gene may have a role in signalling the initiation of metamorphosis. (C) 1997 Wiley-Liss, Inc.
Resumo:
Non-astringent persimmon is rapidly expanding as a new fruit crop in warm subtropical regions of the world, Most research and development of this fruit crop has occurred in Japan, where there is a considerable amount of published literature on its performance. Much of this information is not readily accessible to other countries and needs to be interpreted and modified for other climatic regions. This paper reviews reproductive events from floral initiation to the completion of fruit growth. The timing and significance of these events is described in relation to the phenological cycle. Method of improving flowering, reducing fruit drop and altering the fruit maturity period are discussed. (C) 1997 Elsevier Science B.V.
Resumo:
The objective of this study was to find very early viral kinetic markers to predict nonresponse to hepatitis C virus (HCV) therapy in a group of human immunodeficiency virus (HIV)/HCV-coinfected patients. Twenty-six patients (15 HCV genotype-1 and 11 genotype-3) were treated with a 48-week regimen of peginterferon-alfa-2a (PEG-IFN) (180 mu g/week) and weight-based ribavirin (11 mg/kg/day). Samples were collected at baseline; 4, 8, 12, 18, 24, 30, 36 and 42 h; days 2, 3, 4, 7, 8, 15, 22, 29, 43 and 57 then weekly and monthly. Five patients discontinued treatment. Seven patients (27%) achieved a sustained virological response (SVR). Nadir HCV RNA levels were observed 1.6 +/- 0.3 days after initiation of therapy, followed by a 0.3- to 12.9-fold viral rebound until the administration of the second dose of PEG-IFN, which were not associated with SVR or HCV genotype. A viral decline < 1.19 log for genotype-1 and < 0.97 log for genotype-3, 2 days after starting therapy, had a negative predictive value (NPV) of 100% for SVR. The day 2 virological response had a similar positive predictive value for SVR as a rapid virological response at week 4. In addition, a second-phase viral decline slope (i.e., measured from day 2 to 29) < 0.3 log/week had a NPV = 100% for SVR. We conclude that first-phase viral decline at day 2 and second-phase viral decline slope (< 0.3 log/week) are excellent predictors of nonresponse. Further studies are needed to validate these viral kinetic parameters as early on-treatment prognosticators of nonresponse in patients with HCV and HIV.