Perda de carga em mangueiras gotejadoras novas, usadas e com emissores entupidos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

LOCAL HEAD LOSS OF NON-COAXIAL EMITTERS INSERTED IN POLYETHYLENE PIPE

The design of a lateral line for drip irrigation requires accurate evaluation of head losses in not only the pipe but in the emitters as well. A procedure was developed to determine localized head losses within the emitters by the formulation of a mathematical model that accounts for the obstruction caused by the insertion point. These localized losses can be significant when compared with tire total head losses within the system due to the large number of emitters typically installed along the lateral line. Air experiment was carried out by altering flow characteristics to create Reynolds numbers (R) from 7,480 to 32,597 to provide turbulent flow and a maximum velocity of 2.0 m s(-1). The geometry of the emitter was determined by an optical projector and sensor An equation was formulated to facilitate the localized head loss calculation using the geometric characteristics of the emitter (emitter length, obstruction ratio, and contraction coefficient). The mathematical model was tested using laboratory measurements on four emitters. The local head loss was accurately estimated for the Uniram (difference of +13.6%) and Drip Net (difference of +7.7%) emitters, while appreciable deviations were found for the Twin Plus (-21.8%) and Tiran (+50%) emitters. The head loss estimated by the model was sensitive to the variations in the obstruction area of the emitter However, the variations in the local head loss did not result in significant variations in the maximum length of the lateral lines. In general, for all the analyzed emitters, a 50% increase in the local head loss for the emitters resulted in less than an 8% reduction in the maximum lateral length.

Loss of Y-chromosome does not correlate with age at onset of head and neck carcinoma: a case-control study

Loss of Y-chromosome has been correlated with older age in males. Furthermore, current evidence indicates that Y-chromosome loss also occurs in several human tumors, including head and neck carcinomas. However, the association between Y nullisomy and the occurrence of neoplasias in elderly men has not been well established. In the present study, the association between Y-chromosome loss and head and neck carcinomas was evaluated by comparison to cells from peripheral blood lymphocytes and normal mucosa of cancer-free individuals matched for age using dual-color fluorescence in situ hybridization. Twenty-one patients ranging in age from 28 to 68 years were divided into five-year groups for comparison with 16 cancer-free individuals matched for age. The medical records of all patients were examined to obtain clinical and histopathological data. None of the patients had undergone radiotherapy or chemotherapy before surgery. In all groups, the frequency of Y-chromosome loss was higher among patients than among normal reference subjects (P < 0.0001) and was not age-dependent. These data suggest that Y-chromosome loss is a tumor-specific alteration not associated with advanced age in head and neck carcinomas.

Loss of Y-chromosome does not correlate with age at onset of head and neck carcinoma: a case-control study

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Loss of imprinting and loss of heterozygosity on 11p15.5 in head and neck squamous cell carcinomas

Background. IGF2 and H19 are reciprocal imprinted genes with paternal and maternal monoallelic expression, respectively. This is interesting, because IGF2 is known as a growth factor, and H19 encodes a RNA with putative tumor suppressor action. Furthermore, IGF2 and H19 are linked genes located on chromosome 11p15.5, a common site of loss of heterozygosity in human cancers.Methods. We performed an allelic-typing assay using a PCR-RFLP-based method for identification of heterozygous Informative cases in head and neck squamous cell carcinomas. Tumoral total RNA was extracted from each of the heterozygotes and further studied by RT-PCR analysis.Results. We detected the expression of the IGF2 gene in 10 of 10 informative cases. Two cases exhibited LOI of the IGF2 gene as evidenced by biallelic expression, and in another case, LOH was coupled with monoallelic expression of this growth factor. LOI for the H19 gene was observed in 1 of 14 informative samples analyzed. In this case, we also detected parallel mono-allelic expression of the IGF2 gene. Down-regulation of the H19 gene was observed in 10 of 14 cases.Conclusion. These findings support the hypothesis that H19 may be a tumor suppressor gene involved In head and neck carcinogenesis. Furthermore, our data showed that genetic and epigenetic chances at 11p15.5 could lead to abnormal expression of imprinted genes in HNSCC. (C) 2001 John Wiley & Sons, Inc.

Distinct regions of loss of heterozygosity on 22q at different sites of head and neck squamous cell carcinomas

Background: Frequent loss of heterozygosity (LOH) has been reported in many types of cancer, including head and neck carcinomas. Somatic deletions involving specific chromosomal regions are strongly associated with inactivation of the allele of a tumor suppressor gene located within the deleted region. In most studies concerning LOH in head and neck squamous cell carcinomas (HNSCC) the different anatomical sites are not distinguished. The behavior of tumors arising at various sites differs significantly, however, suggesting different intrinsic tumor properties. In this study we compared the LOH on 22q and its relationship to clinicopathological parameters at the three major sites of HNSCC: oral cavity, larynx and pharynx. Material/Methods: LOH and microsatellite instability (MSI) were studied using seven polymorphic microsatellite markers mapped to the 22q11-q13.3 region in 37 oral, 32 laryngeal, and 31 pharyngeal carcinomas. Results: Two separate regions of LOH were identified in the laryngeal (22q11.2-12.1) and oral cavity (22q13.1-13.31) tumors. When the different anatomical sites were compared, a statistically significant difference was found between the presence of LOH at D22S421 (p<0.001), D22S315 (p=0.014) and D22S929 (p=0.026) in the laryngeal tumors. Conclusions: These data suggest that distinct regions on 22q are involved in LOH in oral cavity and laryngeal tumorigenesis but do not support a similar association between the development of pharyngeal tumors and genes located on 22q. These findings implicate the presence of different tumor suppressor genes mapping to distinct regions on chromosome 22q in oral and laryngeal carcinomas.

Loss of Y-chromosome does not correlate with age at onset of head and neck carcinoma: a case-control study

Loss of Y-chromosome has been correlated with older age in males. Furthermore, current evidence indicates that Y-chromosome loss also occurs in several human tumors, including head and neck carcinomas. However, the association between Y nullisomy and the occurrence of neoplasias in elderly men has not been well established. In the present study, the association between Y-chromosome loss and head and neck carcinomas was evaluated by comparison to cells from peripheral blood lymphocytes and normal mucosa of cancer-free individuals matched for age using dual-color fluorescence in situ hybridization. Twenty-one patients ranging in age from 28 to 68 years were divided into five-year groups for comparison with 16 cancer-free individuals matched for age. The medical records of all patients were examined to obtain clinical and histopathological data. None of the patients had undergone radiotherapy or chemotherapy before surgery. In all groups, the frequency of Y-chromosome loss was higher among patients than among normal reference subjects (P < 0.0001) and was not age-dependent. These data suggest that Y-chromosome loss is a tumor-specific alteration not associated with advanced age in head and neck carcinomas.

Accident Management Actions In An Upper-Head Small-Break Loss-Of-Coolant Accident With High-Pressure Safety Injection Failed

Since the Three Mile Island accident, an important focus of pressurized water reactor (PWR) transient analyses has been a small-break loss-of-coolant accident (SBLOCA). In 2002, the discovery of thinning of the vessel head wall at the Davis Besse nuclear power plant reactor indicated the possibility of an SBLOCA in the upper head of the reactor vessel as a result of circumferential cracking of a control rod drive mechanism penetration nozzle - which has cast even greater importance on the study of SBLOCAs. Several experimental tests have been performed at the Large Scale Test Facility to simulate the behavior of a PWR during an upper-head SBLOCA. The last of these tests, Organisation for Economic Co-operation and Development Nuclear Energy Agency Rig of Safety Assessment (OECD/NEA ROSA) Test 6.1, was performed in 2005. This test was simulated with the TRACE 5.0 code, and good agreement with the experimental results was obtained. Additionally, a broad analysis of an upper-head SBLOCA with high-pressure safety injection failed in a Westinghouse PWR was performed taking into account different accident management actions and conditions in order to check their suitability. This issue has been analyzed also in the framework of the OECD/NEA ROSA project and the Code Applications and Maintenance Program (CAMP). The main conclusion is that the current emergency operating procedures for Westinghouse reactor design are adequate for these kinds of sequences, and they do not need to be modified.

Delayed loss of cholesterol from a localized lipoprotein depot in apolipoprotein A-I-deficient mice

The anti-atherogenic role of high density lipoprotein is well known even though the mechanism has not been established. In this study, we have used a novel model system to test whether removal of lipoprotein cholesterol from a localized depot will be affected by apolipoprotein A-I (apo A-I) deficiency. We compared the egress of cholesterol injected in the form of cationized low density lipoprotein into the rectus femoris muscle of apo A-I K-O and control mice. When the injected lipoprotein had been labeled with [3H]cholesterol, the t½ of labeled cholesterol loss from the muscle was about 4 days in controls and more than 7 days in apo A-I K-O mice. The loss of cholesterol mass had an initial slow (about 4 days) and a later more rapid component; after day 4, the disappearance curves for apo A-I K-O and controls began to diverge, and by day 7, the loss of injected cholesterol was significantly slower in apo A-I K-O than in controls. The injected lipoprotein cholesterol is about 70% in esterified form and undergoes hydrolysis, which by day 4 was similar in control and apo A-I K-O mice. The efflux potential of serum from control and apo A-I K-O mice was studied using media containing 2% native or delipidated serum. A significantly lower efflux of [3H]cholesterol from macrophages was found with native and delipidated serum from apo A-I K-O mice. In conclusion, these findings show that lack of apo A-I results in a delay in cholesterol loss from a localized depot in vivo and from macrophages in culture. These results provide support for the thesis that anti-atherogenicity of high density lipoprotein is related in part to its role in cholesterol removal.

Loss of heterozygosity of the APC gene in oral squamous cell carcinoma

The aim of this study was to investigate loss of heterozygosity (LOH) of the APC tumor suppressor gene loci, using restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR) in 40 cases of oral squamous cell carcinoma (OSCC). Observed informativity was 72.5% for APC exon 11 and 82.5% for APC exon 15. LOH at APC exon 11 was observed in 2 (6.9%) of 29 informative cases, and no LOH was observed for APC exon 15. Our results suggest that inactivation of the APC gene plays a minor role in the carcinogenesis of OSCC. (C) 2008 Elsevier GmbH. All rights reserved.

Complete loss of vision caused by a giant mucocele of the frontal sinus.

The authors report the case of a 75-year-old man presenting with an exceptionally large giant posttraumatic mucocele of the frontal sinus years after a gunshot blast to the head. The lesion had grown so extensively that the right eye had shrunk and calcified, resulting in total monocular blindness, a complication that has been reported only once. To the best of our knowledge, it is the first time that a giant mucocele of such a large size is reported. We describe how the patient underwent surgical removal of this massive lesion, cranial base reconstruction, and a cosmetic oculoplastic procedure. The etiology, clinical presentation, and possible complications are reviewed, as well as the importance of a regular clinical follow-up and early surgical cure. Although the diagnosis and management of mucoceles are nowadays considered quite standard, the exceptional size of the lesion illustrated here emphasizes the destructive potential of such seemingly indolent lesions. Despite the benign histology of mucoceles, one should never underestimate their morbid potential or be lulled in delaying surgical cure. Large mucoceles should be removed as quickly as possible to prevent such unacceptable complications as permanent visual loss.

Radiothérapie externe accélérée postopératoire des carcinomes épidermoïdes localement évolués de la sphère ORL: étude prospective de phase II [Prospective study of accelerated postoperative radiation therapy in patients with squamous-cell carcinoma of the head and neck]

PURPOSE: To assess the feasibility and efficacy of accelerated postoperative radiation therapy (RT) in patients with squamous-cell carcinoma of the head and neck (SCCHN). PATIENTS AND METHODS: Between December 1997 and July 2001, 68 patients (male to female ratio: 52/16; median age: 60-years (range: 43-81) with pT1-pT4 and/or pN0-pN3 SCCHN (24 oropharynx, 19 oral cavity, 13 hypopharynx, 5 larynx, 3 unknown primary, 2 maxillary sinus, and 2 salivary gland) were included in this prospective study. Postoperative RT was indicated because extracapsular infiltration (ECI) was observed in 20 (29%), positive surgical margins (PSM) in 20 (29%) or both in 23 patients (34%). Treatment consisted of external beam RT 66 Gy in 5 weeks and 3 days. Median follow-up was 15 months. RESULTS: According to CTC 2.0, acute morbidity was acceptable: grade 3 mucositis was observed in 15 (22%) patients, grade 3 dysphagia in 19 (28%) patients, grade 3 skin erythema in 21 (31%) patients with a median weight loss of 3.1 kg (range: 0-16). No grade 4 toxicity was observed. Median time to relapse was 13 months; we observed only three (4%) local and four (6%) regional relapses, whereas eight (12%) patients developed distant metastases without any evidence of locoregional recurrence. The 2 years overall-, disease-free survival, and actuarial locoregional control rates were 85, 73 and 83% respectively. CONCLUSION: The reduction of the overall treatment time using postoperative accelerated RT with weekly concomitant boost (six fractions per week) is feasible with local control rates comparable to that of published data. Acute RT-related morbidity is acceptable.

Loss of Expression and Function of SOCS3 Is an Early Event in HNSCC: Altered Subcellular Localization as a Possible Mechanism Involved in Proliferation, Migration and Invasion

Background: Suppressor of cytokine signaling 3 (SOCS3) is an inducible endogenous negative regulator of signal transduction and activator of transcription 3 (STAT3). Epigenetic silencing of SOCS3 has been shown in head and neck squamous cell carcinoma (HNSCC), which is associated with increased activation of STAT3. There is scarce information on the functional role of the reduction of SOCS3 expression and no information on altered subcellular localization of SOCS3 in HNSCC.Methodology/Principal Findings: We assessed endogenous SOCS3 expression in different HNSCC cell lines by RT-qPCR and western blot. Immunofluorescence and western blot were used to study the subcellular localization of endogenous SOCS3 induced by IL-6. Overexpression of SOCS3 by CMV-driven plasmids and siRNA-mediated inhibition of endogenous SOCS3 were used to verify the role of SOCS3 on tumor cell proliferation, viability, invasion and migration in vitro. In vivo relevance of SOCS3 expression in HNSCC was studied by quantitative immunohistochemistry of commercially-available tissue microarrays. Endogenous expression of SOCS3 was heterogeneous in four HNSCC cell lines and surprisingly preserved in most of these cell lines. Subcellular localization of endogenous SOCS3 in the HNSCC cell lines was predominantly nuclear as opposed to cytoplasmic in non-neoplasic epithelial cells. Overexpression of SOCS3 produced a relative increase of the protein in the cytoplasmic compartment and significantly inhibited proliferation, migration and invasion, whereas inhibition of endogenous nuclear SOCS3 did not affect these events. Analysis of tissue microarrays indicated that loss of SOCS3 is an early event in HNSCC and was correlated with tumor size and histological grade of dysplasia, but a considerable proportion of cases presented detectable expression of SOCS3.Conclusion: Our data support a role for SOCS3 as a tumor suppressor gene in HNSCC with relevance on proliferation and invasion processes and suggests that abnormal subcellular localization impairs SOCS3 function in HNSCC cells.

Study of the Influence of Localized Vibrational Modes in Charge Transport Properties at Nanoscale Systems.

In molecular and atomic devices the interaction between electrons and ionic vibrations has an important role in electronic transport. The electron-phonon coupling can cause the loss of the electron's phase coherence, the opening of new conductance channels and the suppression of purely elastic ones. From the technological viewpoint phonons might restrict the efficiency of electronic devices by energy dissipation, causing heating, power loss and instability. The state of the art in electron transport calculations consists in combining ab initio calculations via Density Functional Theory (DFT) with Non-Equilibrium Green's Function formalism (NEGF). In order to include electron-phonon interactions, one needs in principle to include a self-energy scattering term in the open system Hamiltonian which takes into account the effect of the phonons over the electrons and vice versa. Nevertheless this term could be obtained approximately by perturbative methods. In the First Born Approximation one considers only the first order terms of the electronic Green's function expansion. In the Self-Consistent Born Approximation, the interaction self-energy is calculated with the perturbed electronic Green's function in a self-consistent way. In this work we describe how to incorporate the electron-phonon interaction to the SMEAGOL program (Spin and Molecular Electronics in Atomically Generated Orbital Landscapes), an ab initio code for electronic transport based on the combination of DFT + NEGF. This provides a tool for calculating the transport properties of materials' specific system, particularly in molecular electronics. Preliminary results will be presented, showing the effects produced by considering the electron-phonon interaction in nanoscale devices.

The silent loss of neuronavigation accuracy: a systematic retrospective analysis of factors influencing the mismatch of frameless stereotactic systems in cranial neurosurgery

BACKGROUND Neuronavigation has become an intrinsic part of preoperative surgical planning and surgical procedures. However, many surgeons have the impression that accuracy decreases during surgery. OBJECTIVE To quantify the decrease of neuronavigation accuracy and identify possible origins, we performed a retrospective quality-control study. METHODS Between April and July 2011, a neuronavigation system was used in conjunction with a specially prepared head holder in 55 consecutive patients. Two different neuronavigation systems were investigated separately. Coregistration was performed with laser-surface matching, paired-point matching using skin fiducials, anatomic landmarks, or bone screws. The initial target registration error (TRE1) was measured using the nasion as the anatomic landmark. Then, after draping and during surgery, the accuracy was checked at predefined procedural landmark steps (Mayfield measurement point and bone measurement point), and deviations were recorded. RESULTS After initial coregistration, the mean (SD) TRE1 was 2.9 (3.3) mm. The TRE1 was significantly dependent on patient positioning, lesion localization, type of neuroimaging, and coregistration method. The following procedures decreased neuronavigation accuracy: attachment of surgical drapes (DTRE2 = 2.7 [1.7] mm), skin retractor attachment (DTRE3 = 1.2 [1.0] mm), craniotomy (DTRE3 = 1.0 [1.4] mm), and Halo ring installation (DTRE3 = 0.5 [0.5] mm). Surgery duration was a significant factor also; the overall DTRE was 1.3 [1.5] mm after 30 minutes and increased to 4.4 [1.8] mm after 5.5 hours of surgery. CONCLUSION After registration, there is an ongoing loss of neuronavigation accuracy. The major factors were draping, attachment of skin retractors, and duration of surgery. Surgeons should be aware of this silent loss of accuracy when using neuronavigation.