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31.
32.
Moore ST Clément G Raphan T Cohen B 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2001,137(3-4):323-335
During the 1998 Neurolab mission (STS-90), four astronauts were exposed to interaural centripetal accelerations (Gy centrifugation)
of 0.5g and 1g during rotation on a centrifuge, both on Earth and during orbital space flight. Subjects were oriented either left-ear out
or right-ear out, facing or back to motion. Binocular eye movements were measured in three dimensions using a video technique.
On Earth, tangential centrifugation that produces 1g of interaural linear acceleration combines with gravity to tilt the gravitoinertial acceleration (GIA) vector 45° in the
roll plane relative to the head vertical, generating a summed vector of 1.4g. Before flight, this elicited mean ocular counterrolling (OCR) of 5.7°. Due to the relative absence of gravity during flight,
there was no linear acceleration along the dorsoventral axis of the head. As a result, during in-flight centrifugation, gravitoinertial
acceleration was strictly aligned with the centripetal acceleration along the interaural axis. There was a small but significant
decrease (mean 10%) in the magnitude of OCR in space (5.1°). The magnitude of OCR during postflight 1g centrifugation was not significantly different from preflight OCR (5.9°). Findings were similar for 0.5g centrifugation, but the OCR magnitude was approximately 60% of that induced by centrifugation at 1g. OCR during pre- and postflight static tilt was not significantly different and was always less than OCR elicited by centrifugation
on Earth for an equivalent interaural linear acceleration. In contrast, there was no difference between the OCR generated
by in-flight centrifugation and by static tilt on Earth at equivalent interaural linear accelerations. These data support
the following conclusions: (1) OCR is generated predominantly in response to interaural linear acceleration; (2) the increased
OCR during centrifugation on Earth is a response to the head dorsoventral 1g linear acceleration component, which was absent in microgravity. The dorsoventral linear acceleration could have activated
either the otoliths or body-tilt receptors that responded to the larger GIA magnitude (1.4g), to generate the increased OCR during centrifugation on Earth. A striking finding was that magnitude of OCR was maintained
throughout and after flight. This is in contrast to most previous postflight OCR studies, which have generally registered
decreases in OCR. We postulate that intermittent exposure to artificial gravity, in the form of the centripetal acceleration
experienced during centrifugation, acted as a countermeasure to deconditioning of this otolith-ocular orienting reflex during
the 16-day mission.
Electronic Publication 相似文献
33.
Claudio Gustavo Stefanoff Rocío Hassan Ana Carolina Gonzalez Luiz Ant?nio B Andrade Daniel G Tabak Sérgio Romano Ilana R Zalcberg 《Diagnostic molecular pathology》2003,12(2):79-87
We herein present a technical strategy to optimize DNA isolation from paraffin-embedded tissue (PET). This includes the choice of adequate buffers for proteinase K digestion and multiplex PCR amplifications for assessing the appropriateness of DNA extracts for subsequent PCR assays for detecting clonality. We found that the association of proteinase K digestion in nonionic buffer and subsequent extract dilutions accounted for 79% of successful amplifications. A final efficiency of 88% was achieved by additional organic extractions and/or re-extractions. Comparisons were carried out with control DNA extracts from fresh samples to assess the efficiency of each clonality assay. Immunoglobulin CDRIII rearranged region amplification was more efficient for pregerminal center B-cell lymphomas in contrast to CDRII rearrangement detection, which was more effective for germinal and postgerminal lymphomas. T-cell clonality detection by TCRgamma PCR was less efficient in PET samples than in fresh tissues showing that DNA integrity is more critical for TCR than for IGH amplification. Two inconclusive cases without phenotypic markers and two other atypical lymphoproliferations masked by reactive T cells were diagnosed as plasmablastic lymphomas and as monoclonal B-proliferations, respectively, due to IGH rearrangements. 相似文献
34.
35.
Gil LH Alves FP Zieler H Salcedo JM Durlacher RR Cunha RP Tada MS Camargo LM Camargo EP Pereira-da-Silva LH 《Journal of medical entomology》2003,40(5):636-641
Studies on seasonal anopheline fauna variation were performed in two distinct settlements in the State of Rond?nia, Brazil: one at the Madeira River banks (Portuchuelo) with stable native Amazonian population; the other at an inland lumber-extracting farm (Urupá) in dry land, in which adults are mostly migrants. During a 6-yr period (1994-2000), 8,638 adult anophelines were collected: 2,684 in Urupá and 5,954 in Portuchuelo. Anopheles darlingi represented >95% of total mosquitoes caught. Dissection of 4,424 A. darlingi females yielded a very low sporozoite infection index below 0.1%. Oocysts were found in both localities in approximately 0.1% of dissected mosquitoes. Determination of the hour biting rates disclosed seasonal variations in both localities. However, in Portuchuelo, mosquito density peaked at the acme of the rainy season, whereas at Urupá it peaked in the dry season. The increase in mosquito density and incidence of malaria cases were coincident. The high mosquito densities observed in the riverine settlement of Portochuelo sector B, which permits evaluation in > 10,000 mosquitoes' bites/person/year, could explain, in spite of the low mosquito's infection index, the previously described development of natural immunity in the local population that is not observed in the dry land agroindustrial settlement of Urupá. 相似文献
36.
Cláudia M Coutinho-Camillo M Mitzi Brentani Ossamu Butugan Humberto Torloni Maria A Nagai 《Diagnostic molecular pathology》2003,12(1):57-62
IGFII and H19 genes are expressed only from one allele due to genomic imprinting, biallelic expression (loss of imprinting) being associated with the tumorigenic process of different types of tumors. The mechanism responsible for genomic imprinting is not yet determined, although DNA methylation has been considered the main genetic event for an imprinted mark. In the current study, the authors analyzed the imprinting status and expression levels of the IGFII and H19 genes in 27 cases of Juvenile Nasopharyngeal Angiofibroma (JNA) using RFLPs, RT-PCR, and Southern and Northern Blots. The authors found that four out of eight informative cases (50%) for ApaI/IFGII polymorphism showed biallelic expression of IFGII whereas none of the nine informative cases for the polymorphism showed biallelic expression of the H19 gene. Overexpression of IFGII was observed in 8 out of 22 cases (36.4%), and 7 out of 19 cases (36.8%) showed H19 overexpression. Hypomethylation was found only in the H19 gene in six out of eight cases analyzed. Therefore, our results demonstrate that alterations in the IFGII/H19 imprinted region occur in JNA. 相似文献
37.
Clément G. Magnin M. 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1983,52(3):429-438
Experimental Brain Research - The influence of horizontal optokinetic stimulation on posture and postural readjustments, induced by horizontal rotation of a turntable, were studied in the cat.... 相似文献
38.
Superantigens induce clonal deletion of reactive T cells in the thymus and clonal deletion and anergy in the periphery of euthymic mice. In this report we have assessed the ability of Staphylococcal enterotoxin B (SEB) to induce peripheral tolerance in nude mice reconstituted with normal, syngeneic T cells. Immunization of reconstituted nude mice with SEB resulted in lethal toxic shock in a large fraction of the animals. Such lethality was never observed in the normal donor mouse strain. Analysis of lymphokine production in response to SEB showed that reconstituted nude mice produced higher levels of interleukin-2 and tumor necrosis factor-α, but lower levels of interleukin-4, than euthymic control mice. Furthermore, SEB was unable to promote either clonal elimination or induction of anergy in the SEB-responsive peripheral T cells, despite the fact that reconstituted nude mice did produce high levels of corticosterone upon treatment with SEB. These results imply a lack of control over immune responses to superantigen in T cell-reconstituted athymic mice. 相似文献
39.
G. Clément F. Lestienne 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1988,72(2):381-389
Summary Adaptation of static posture was studied before, during, and after a 7-day space flight. Body segment orientations, body stability, and muscle activity underlying the reproduction of several postural attitudes were examined in various visual situations either with the shoes attached to the floor or during free floating. In standing or relaxed subjects whose shoes were attached to the floor, the tonic activity of the ankle flexor was enhanced relative to that in the same posture on earth, whereas the extensor activity disappeared. Errors in attempting to reproduce the normal terrestrial upright posture and a forward-leaning posture were accompanied by major changes in the synergies between neck, hip, knee, and ankle joints. These changes are mainly attributed to cumulative adjustments in response to nonvestibular signals such as tactile, articular, and proprioceptive cues. 相似文献
40.
Chimello-Sousa Daniela Thomazatti Lavez Geovane Praxedes Fernandes Roger Rodrigo Tavares Milla Sprone Rosa Adalberto Luiz Siessere Selma Regalo Simone Cecílio Hallak Bombonato-Prado Karina Fittipaldi 《Lasers in medical science》2021,36(9):1979-1988
Lasers in Medical Science - The purpose of this study is to analyze the influence of InGaAlP diode laser (660 nm) with or without an odontogenic medium (OM) in the functional activity of... 相似文献