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1.
Eur Rev Med Pharmacol Sci ; 25(5): 2415-2417, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33755985

RESUMO

Coronavirus Disease 2019 (COVID-19) pandemic has made more awful effect on wellbeing and economy worldwide on an extraordinary scale. Angiotensin I Converting Enzyme 2 (ACE2), the principal receptor of SARS-CoV2, has been found to be communicated with Dopa decarboxylase in unwinding the connection of catecholamines with COVID-19 infection. Cardiovascular (CV) sickness, diabetes, hypertension, and related conditions cause significant risks during the current situation and the affected people are under basic observation around the world. The hypertension and diabetes are related with alterations in the degrees of catecholamines associated with renal gland. The naive form of renal dopaminergic framework is related with the expanded reabsorption of sodium resulting in downregulation of the ACE2 expression. Catecholamine biosynthesis is managed by counter-controlling angiotensin type 1R (AT1R) and angiotensin type 2R (AT2R), incitement of AT2 lessens catecholamine biosynthesis by means of a diminishing in cGMP levels likewise incitement of AT1 initiate catecholamine biosynthesis. This audit sums up the conceivable contribution of catecholamines in intense COVID-19 contamination and furthermore featured possible restorative adequacy of catecholamine flagging pathways against the incessant SARS-CoV-2.


Assuntos
COVID-19/terapia , Catecolaminas/metabolismo , Enzima de Conversão de Angiotensina 2 , Diabetes Mellitus/metabolismo , Hormônios , Humanos , Hipertensão/metabolismo , Pandemias , Receptores Virais , SARS-CoV-2
2.
Zhonghua Yi Xue Za Zhi ; 100(3): 178-181, 2020 Jan 21.
Artigo em Chinês | MEDLINE | ID: mdl-32008282

RESUMO

Objective: To evaluate the classification of the types of pediatric posterior fossa brain tumors based on routine MRI (T(1)WI, T(2)WI and ADC) using wavelet transformation analysis of whole tumor. Methods: MRI images of medulloblastoma (n=59), ependymoma (n=13) and pilocytic astrocytoma (n=27) confirmed by pathology before treatments in Children's Hospital of Nanjing Medical University from January 2014 to February 2019 were enrolled in this retrospective study as well as the clinical data of age, gender and symptoms. Registration was performed among the three sequences and wavelet features of ROI were acquired. Afterwards, the top ten features were ranked and trained among groups by using random forest classifier. Finally, the results were compared and analyzed according to the classification. Results: The top ten contribution three sequences and wavelet features of ROI were acquired from the ADC sequence. The random forest classifier achieved 100% accuracy on training data and was validated best accuracy (86.8%) when combined of first and third wavelet features. The sensitivity was 100%, 94.8%, 76.9%, and the specificity was 97.6%, 88.0%, 98.8% respectively. Conclusions: Features based on wavelet transformation of ADC sequence of entire tumor can provide more quantitative information, which could provide help in the differential diagnosis of pediatric posterior fossa brain tumors. The optimum combination to distinguish three pediatric posterior fossa brain tumors is sixth and twelfth wavelet features of ADC sequence.


Assuntos
Astrocitoma/classificação , Neoplasias Cerebelares/patologia , Neoplasias Infratentoriais/patologia , Imageamento por Ressonância Magnética/métodos , Meduloblastoma/classificação , Astrocitoma/patologia , Neoplasias Encefálicas/patologia , Criança , Humanos , Meduloblastoma/patologia , Estudos Retrospectivos
3.
Zhonghua Er Ke Za Zhi ; 56(5): 369-372, 2018 May 02.
Artigo em Chinês | MEDLINE | ID: mdl-29783824

RESUMO

Objective: To summarize the clinical features of 7 rare cases of hemolytic disease of newborn (HDN), and to improve the understanding of rare HDN. Methods: Data of clinical information, laboratory findings, treatments and outcomes were collected and analyzed for four cases with HDN due to anti-M, two cases due to anti-Kidd, and one case due to anti-Duffy. All of them were admitted to the Department of Neonatology, Beijing Children's Hospital Affiliated to Capital Medial University from July 2007 to June 2017. Results: Among the four MN hemolytic babies, two were males and two were females. Jaundice was found in three cases. Two cases had hyperbilirubinemia, one of them had severe hyperbilirubinemia. All the four cases developed anemia, including severe anemia in three cases. Two cases of Kidd hemolytic disease and 1 case of Duffy hemolytic disease had jaundice and anemia, but did not reach the level of severe hyperbilirubinemia and severe anemia. MN hemolytic disease babies got negative results in direct antiglobulin test, whereas the Kidd and Duffy hemolytic disease babies had positive findings in direct antiglobulin test. None of the babies had blood transfusion, and they were discharged from the hospital. Conclusions: Without maternal and fetal blood group incompatibility (ABO or Rh blood-group system), for early onset of jaundice, severe jaundice or anemia, antiglobulin test to mother and child earlier should be administered, and MN, Kidd, Duffy and other rare hemolytic disease of the newborn should be pay attention to.


Assuntos
Sistema ABO de Grupos Sanguíneos , Incompatibilidade de Grupos Sanguíneos , Eritroblastose Fetal , Criança , Teste de Coombs , Eritroblastose Fetal/diagnóstico , Feminino , Humanos , Hiperbilirrubinemia/etiologia , Recém-Nascido , Masculino
4.
Physiol Res ; 63(6): 801-5, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25535647

RESUMO

Hypoxia-inducible factor-1alpha (HIF-1alpha) transcriptionally regulates expression of several target genes in protecting tissues against hypoxia. With hypoxic stress, vascular endothelial growth factor (VEGF) is a signal protein produced by cells and further contributes to improvement of vascular functions and restoring the oxygen supply to tissues. In this current study, we first hypothesized that the protein levels of HIF-1alpha and VEGF are reduced in skeletal muscles of plateau animals [China Qinghai-Tibetan plateau pikas (ochotona curzoniae)] in response to hypoxia as compared with control animals [normal lowland Sprague-Dawley (SD) rats]. We further hypothesized that HIF-1alpha plays a role in regulating expression of VEGF in skeletal muscle. Note that HIF-1alpha and VEGF were determined by using two-site immunoenzymatic assay (ELISA) methods. Our results demonstrated that hypoxic stress induced by exposure of lower O(2) (6 h) significantly increased the levels of HIF-1alpha and VEGF in the oxidative and glycolytic muscles of SD rats and pikas (P<0.05 vs. normoxic conditions). Notably, the increases in HIF-1alpha and VEGF were significantly less in pikas (P<0.05, vs. SD controls) than in SD rats. In addition, a linear relationship was observed between amplified HIF-1alpha and VEGF in oxidative muscle (r=0.76 and P<0.01) and glycolytic muscle (r=0.72 and P<0.01) and inhibiting HIF-1alpha significantly decreased expression of VEGF induced by hypoxic stress in skeletal muscles (P<0.05). Overall, our findings suggest that (1) responsiveness of HIF-1alpha and VEGF in skeletal muscles to hypoxic stress is blunted in plateau animals, and (2) HIF-1alpha has a regulatory effect on VEGF under hypoxic environment.


Assuntos
Subunidade alfa do Fator 1 Induzível por Hipóxia/biossíntese , Hipóxia/metabolismo , Lagomorpha/metabolismo , Músculo Esquelético/metabolismo , Fator A de Crescimento do Endotélio Vascular/biossíntese , Animais , Masculino , Ratos , Ratos Sprague-Dawley
5.
Genet Mol Res ; 13(2): 3859-68, 2014 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-24938474

RESUMO

This study aimed to examine olfactory mucosal changes in a rat model of acute rhinosinusitis and to determine how acute rhinosinusitis induces dysosmia. Total 100 rats were divided into the experimental (N = 80) and control (N = 20) groups. An acute rhinosinusitis model was established in the experimental rats. From the experimental group, 20 rats each were sacrificed at 1, 2, 3, or 4 weeks. The control group was sacrificed at 1 week without inoculation. Olfaction was tested by the buried food pellet test before killing the rats, and the duration until the pellet was recorded and analyzed by a statistical software program. Mature olfactory receptor neurons (ORNs) and olfactory ensheathing cells (OECs) were examined. The durations spent by the experimental group in the BFPT were 402.9 ± 9.3, 453.7 ± 7.3, 351.9 ± 8.9, and 278.7 ± 8.1 s at 1, 2, 3, and 4 weeks, respectively. These durations were greater than that of the control group (178.3 ± 6.6 s), and the difference was statistically significant (P < 0.01). A reduction in ORNs and thinning of the epithelium were detected in the experimental group, most notably in the 2nd week and less in the fourth week. OECs were reduced in the 1st week, increased in the 2nd week, and almost completely recovered in the fourth week. In addition, some growing OECs were detected in the experimental group. Acute rhinosinusitis decreased both the mature ORNs and OECs, but OECs increased faster than the ORNs.


Assuntos
Transtornos do Olfato/patologia , Mucosa Olfatória/metabolismo , Neurônios Receptores Olfatórios/metabolismo , Sinusite/patologia , Animais , Células Cultivadas , Humanos , Regeneração Nervosa/genética , Transtornos do Olfato/etiologia , Mucosa Olfatória/patologia , Ratos , Sinusite/complicações
6.
Sleep Med ; 15(5): 530-5, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24780136

RESUMO

OBJECTIVES: We aimed to describe and report the initial validity of a newly developed structured interview for sleep disorders (Diagnostic Interview for Sleep Patterns and Disorders [DISP]) administered by trained lay interviewers. METHODS: A total of 225 patients with various sleep disorders were recruited from two nationally recognized sleep centers in the United States. The International Classification of Sleep Disorders, second edition (ICSD-2) criteria, were used to classify sleep disorders (e.g., delayed sleep phase disorder, hypersomnia, narcolepsy with cataplexy [NC], restless legs syndrome [RLS], periodic limb movement disorder [PLMD], insomnia, rapid eye movement sleep behavior disorder [RBD], and obstructive sleep apnea [OSA]). Interview diagnoses were compared with final diagnoses by sleep specialists (reference diagnosis based on clinical history, examination, and polysomnography [PSG] when indicated). RESULTS: DISP diagnoses had fair to substantial concordance with clinician diagnoses for various sleep disorders, with area under the receiver operator characteristic curves (AUC) ranging from 0.65 to 0.84. Participants classified by the clinician as having a sleep disorder were moderately well-detected (sensitivity ranging from 0.50 for RBD disorder to 0.87 for insomnia). Substantial specificity (>0.8) also was seen for five of the eight sleep disorders (i.e., delayed sleep phase, hypersomnia, NC, PLMD, and RBD). Interviews were more likely than clinicians to detect disorders secondary to the primary sleep problem. CONCLUSIONS: The DISP provides an important tool for the detection of a wide range of sleep disorders in clinical settings and is particularly valuable in the detection of secondary disorders that were not the primary referral diagnosis.


Assuntos
Entrevista Psicológica/métodos , Transtornos do Sono-Vigília/diagnóstico , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Entrevista Psicológica/normas , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Sono , Adulto Jovem
7.
Psychol Med ; 44(11): 2351-62, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24384401

RESUMO

BACKGROUND: Threshold and subthreshold forms of generalized anxiety disorder (GAD) are highly prevalent and impairing conditions among adults. However, there are few general population studies that have examined these conditions during the early life course. The primary objectives of this study were to: (1) examine the prevalence, and sociodemographic and clinical characteristics of threshold and subthreshold forms of GAD in a nationally representative sample of US youth; and (2) test differences in sociodemographic and clinical characteristics between threshold and subthreshold forms of the disorder. METHOD: The National Comorbidity Survey-Adolescent Supplement is a nationally representative face-to-face survey of 10,123 adolescents 13 to 18 years of age in the continental USA. RESULTS: Approximately 3% of adolescents met criteria for threshold GAD. Reducing the required duration from 6 months to 3 months resulted in a 65.7% increase in prevalence (5.0%); further relaxing the uncontrollability criterion led to an additional 20.7% increase in prevalence (6.1%). Adolescents with all forms of GAD displayed a recurrent clinical course marked by substantial impairment and co-morbidity with other psychiatric disorders. There were few significant differences in sociodemographic and clinical characteristics between threshold and subthreshold cases of GAD. Results also revealed age-related differences in the associated symptoms and clinical course of GAD. CONCLUSIONS: Findings demonstrate the clinical significance of subthreshold forms of GAD among adolescent youth, highlighting the continuous nature of the GAD construct. Age-related differences in the associated symptoms and clinical course of GAD provide further support for criteria that capture variation in clinical features across development.


Assuntos
Transtornos de Ansiedade/epidemiologia , Adolescente , Feminino , Humanos , Masculino , Prevalência , Estados Unidos/epidemiologia
8.
Oncogene ; 31(23): 2876-87, 2012 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-22002310

RESUMO

Pin1 regulates a subset of phosphoproteins by isomerizing phospho-Ser/Thr-Pro motifs via a 'post-phosphorylation' mechanism. Here, we characterize TR3 as a novel Pin1 substrate, and the mitogenic function of TR3 depends on Pin1-induced isomerization. There are at least three phospho-Ser-Pro motifs on TR3 that bind to Pin1. The Ser95-Pro motif of TR3 is the key site through which Pin1 enhances TR3 stability by retarding its degradation. Pin1 can also catalyze TR3 through phospho-Ser431-Pro motif, which is phosphorylated by extracellular signal-regulated kinase 2 (ERK2), resulting in enhanced TR3 transactivation. Furthermore, Pin1 not only facilitates TR3 targeting to the promoter of cyclin D2, a novel downstream target of TR3, but also promotes TR3 to recruit p300, thereby inducing cell proliferation. Importantly, we found that Pin1 is indispensable for TR3 to promote tumor growth both in vitro and in vivo. Our study thus suggests that Pin1 has an important role in cell proliferation by isomerizing TR3.


Assuntos
Proliferação de Células , Dipeptídeos/química , Mitose/fisiologia , Membro 1 do Grupo A da Subfamília 4 de Receptores Nucleares/química , Membro 1 do Grupo A da Subfamília 4 de Receptores Nucleares/metabolismo , Peptidilprolil Isomerase/metabolismo , Animais , Western Blotting , Imunoprecipitação da Cromatina , Ciclina D2/metabolismo , Fator de Transcrição E2F1/metabolismo , Ensaio de Desvio de Mobilidade Eletroforética , Células HeLa , Humanos , Imunoprecipitação , Luciferases/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Peptidilprolil Isomerase de Interação com NIMA , Membro 1 do Grupo A da Subfamília 4 de Receptores Nucleares/genética , Peptidilprolil Isomerase/genética , Fosforilação , RNA Interferente Pequeno/genética , Transdução de Sinais , Estereoisomerismo , Fatores de Transcrição de p300-CBP/metabolismo
9.
Andrologia ; 43(4): 254-60, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21486406

RESUMO

The expression and localisation of downstream signalling molecules of transforming growth factor beta superfamily, Smad2 and Smad4 proteins, was investigated in immature and mature dog testis. Cellular localisation of Smad2 and Smad4 proteins was examined using immunohistochemistry. Quantitative analysis of immunostaining was determined by the image analysis system. The specificity of the antibodies was examined using Western blotting assay. Smad2 and Smad4 were widely expressed in the testes, mainly immunolocalised in the cytoplasm of gonocytes, Leydig cells and Sertoli cells of immature testes, and Leydig cells and Sertoli cells of mature testes. At the same time, the expression levels for both proteins were different between immature and mature age groups: the expression of Smad2 and Smad4 proteins in the Sertoli cells of mature testis was higher than in the immature group (P < 0.05), but the expression of these two proteins in Leydig cells of mature testis was weaker than that seen in immature stage (P < 0.05). The temporospatial distribution of Smad2 and Smad4 proteins in testicular cells suggests that these two signalling molecules may play an important role in specific stages of testicular development and spermatogenesis, thus providing direct evidences for transforming growth factor beta action in the dog testis.


Assuntos
Proteína Smad2/metabolismo , Proteína Smad4/metabolismo , Testículo/metabolismo , Animais , Cães , Imuno-Histoquímica , Células Intersticiais do Testículo/metabolismo , Masculino , Células de Sertoli/metabolismo , Testículo/crescimento & desenvolvimento
10.
Phys Rev Lett ; 99(5): 057208, 2007 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-17930789

RESUMO

The local spectroscopic signatures of metamagnetic criticality in Sr(3)Ru(2)O(7) were explored using scanning tunneling microscopy (STM). Singular features in the tunneling spectrum were found close to the Fermi level, as would be expected in a Stoner picture of itinerant electron metamagnetism. These features showed a pronounced magnetic field dependence across the metamagnetic critical point, which cannot be understood in terms of a naive Stoner theory. In addition, a pseudogap structure was observed over several tens of meV, accompanied by a c(2 x 2) superstructure in STM images. This result represents a new electronic ordering at the surface in the absence of any measurable surface reconstruction.

11.
J Phys Condens Matter ; 19(17): 172203, 2007 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-21690937

RESUMO

Changes in the charge/orbital ordering (CO/OO) structure with the bandwidth of the e(g) band and quenched disorder were investigated in doped manganites RE(0.5)(Ca(1-y)Sr(y))(1.5)MnO(4)(RE = Pr,Eu) with a single-layer perovskite structure. A systematic study of the modulation structure associated with the CO/OO phase demonstrated that the long-range commensurate structure changes to a short-range incommensurate structure with increasing Sr content through the enhancement of the bandwidth and quenched disorder in these systems. At the same time, the transition temperature of CO/OO (T(CO/OO)) decreases. Changes in structure and T(CO/OO) with different A-site combinations reveal that the CO/OO phase is strongly suppressed by the widening of the e(g) band and the stronger quenched disorder in these layered manganites.

12.
Phys Rev Lett ; 97(7): 077203, 2006 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-17026270

RESUMO

We report on the in-plane anisotropy of the electronic response in the spin-, charge-, and orbital-ordered phase of a half-doped layered-structure manganite. The optical conductivity spectra for a single domain of Eu1/2Ca3/2MnO4 unambiguously show the anisotropic charge dynamics which well corresponds to the theoretical calculation: the optical conductivity with the polarization along the zigzag ferromagnetic chain direction exhibits a smaller gap and a larger intensity at lower energies than that of the perpendicular polarization mostly due to the charge and orbital ordering and the associated quantum interference effect.

13.
Phys Rev Lett ; 96(20): 207204, 2006 May 26.
Artigo em Inglês | MEDLINE | ID: mdl-16803202

RESUMO

Ferroelectric transition has been detected in a ferrimagnetic spinel oxide of CoCr2O4 upon the transition to the conical spin order below 25 K. The direction [110] of the spontaneous polarization is normal to both the magnetization easy axis [001] and to the propagation axis [110] of the transverse spiral component, in accord with the prediction based on the spin-current model. The reversal of the spontaneous magnetization by a small magnetic field (approximately 0.1 T) induces the reversal of the spontaneous polarization, indicating the clamping of the ferromagnetic and ferroelectric domain walls.

14.
Phys Rev Lett ; 96(16): 167202, 2006 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-16712266

RESUMO

A simple method to dramatically enhance the optical magnetoelectric (ME) effect, i.e., nonreciprocal directional birefringence, is proposed and demonstrated for a polar ferrimagnet GaFeO3 as a typical example. We patterned a simple grating with a period of 4 microm on a surface of GaFeO3 crystal and used the diffracted light as a probe. The optical ME modulation signal for the Bragg spot of the order n=1 becomes gigantic in the photon energy 1-4 eV and reaches 1-2% of the bare diffracted light intensity in a magnetic field of 500 Oe. This is amplified by more than 3 orders of magnitude compared to that for the reflection of bulk GaFeO3. Fabricating a photonic crystal will make it possible to lead the way for the practical use of the optical ME effect.

15.
Phys Rev Lett ; 93(3): 037403, 2004 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-15323868

RESUMO

The optical magnetoelectric (ME) effect, i.e., the change of optical absorption upon the reversal of the light propagation direction, has been investigated for a polar ferrimagnet GaFeO3. For dipole- and spin-forbidden d-d transition bands located at 1.2-2.3 eV, a clear signal of the optical ME effect (Deltaalphat approximately 3x10(-3)) is observed with an applied magnetic field as low as 500 Oe and a sample thickness (t) of 50 microm. The observation of a large ME effect in the present compound suggests a possible route to magnification of this novel phenomenon for application.

16.
Z Geburtshilfe Neonatol ; 208(4): 141-9, 2004 Aug.
Artigo em Alemão | MEDLINE | ID: mdl-15326556

RESUMO

UNLABELLED: BACKGROUND/PATIENTS: A reverse flow in the umbilical artery and/or fetal aorta is associated with a higher perinatal and neonatal mortality. 30 fetuses showed a reverse flow using pulsed wave Doppler sonography (group I). A matched-pair control group including 30 fetuses with the same gestational age as well as a normal Doppler flow pattern in the umbilical artery and/or fetal aorta was taken for comparison (group II). RESULTS: In the group with reverse flow the rates of pregnancies with pre-eclampsia (n = 19/30, p < 0.0001), intrauterine growth retardation (n = 25/30, p < 0.0001), oligohydramnios (n = 21/30, p < 0.0001) and nicotine abuse (n = 15/30, p < 0.01) were significantly higher compared to the control group. Postnatal data showed significantly lower pH values in group I (p < 0.01). 40 % of the fetuses with reverse flow died in utero whereas in 67 % the reverse flow was accompanied by an insufficiency of the placenta (IUGR, oligohydramnios, histopathological abnormalities of the placenta). None of the fetuses in the control group died in utero. The incidence of IUGR (< 5ht percentile) was 83 % in group I but only 3 % in group II. The perinatal and overall mortality (including neonatal mortality 7 - 28 days after birth) amounted to 27 % and 53 % in group I, respectively, compared to 3 % and 0 % in the control group (p < 0.001). In addition cerebral anomalies could be found by ultrasound in 50 % of the neonates who presented a reverse flow prenatally. In 28 % of the surviving newborns an intracerebral hemorrhage (ICH) could be detected. None of the newborns of group II developed an ICH. CONCLUSIONS: Pregnancies with a reverse flow in the umbilical artery and/or fetal aorta have to be considered as a high risk group with a poor prognosis. The reverse flow is mainly caused by chronic placental insufficiency with IUGR. With respect to the further neuromotor development the incidence and severity of cerebral lesions in affected fetuses should be considered when discussing the perinatal situation with the parents.


Assuntos
Aorta/diagnóstico por imagem , Feto/irrigação sanguínea , Resultado da Gravidez , Gravidez de Alto Risco/fisiologia , Ultrassonografia Doppler de Pulso , Ultrassonografia Pré-Natal , Artérias Umbilicais/diagnóstico por imagem , Adulto , Aorta/embriologia , Hemorragia Cerebral/diagnóstico por imagem , Hemorragia Cerebral/mortalidade , Feminino , Morte Fetal/diagnóstico por imagem , Morte Fetal/fisiopatologia , Retardo do Crescimento Fetal/diagnóstico por imagem , Retardo do Crescimento Fetal/mortalidade , Humanos , Recém-Nascido , Análise por Pareamento , Oligo-Hidrâmnio/diagnóstico por imagem , Oligo-Hidrâmnio/mortalidade , Insuficiência Placentária/diagnóstico por imagem , Insuficiência Placentária/mortalidade , Pré-Eclâmpsia/diagnóstico por imagem , Pré-Eclâmpsia/mortalidade , Gravidez , Fatores de Risco , Análise de Sobrevida , Tabagismo/diagnóstico por imagem , Tabagismo/mortalidade
17.
Phys Rev Lett ; 92(13): 137401, 2004 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-15089643

RESUMO

In a polar ferrimagnet GaFeO3, we have found a novel magneto-optical effect, termed x-ray nonreciprocal directional dichroism (XNDD), that the x-ray absorption at around the K edge of an Fe ion depends on whether the x-ray propagation vector is parallel or antiparallel to the outer product of the magnetization and electric-polarization vectors. The XNDD spectroscopy as demonstrated here can be a useful tool to probe the local magnetism in noncentrosymmetric systems such as magnetic interfaces and nanostructures.

18.
Phys Rev Lett ; 92(4): 047401, 2004 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-14995401

RESUMO

Second harmonic generation (SHG) induced by spontaneous magnetization has been investigated for a polar ferromagnetic crystal of GaFeO3. The Kerr rotation of the second harmonic light becomes gigantic with decreasing temperature below the magnetic transition temperature (approximately =205 K), e.g., as large as 73 degrees at 100 K. The magnetic domains can be visualized by using that large nonlinear Kerr rotation. The spectrum of the magnetization-induced SHG as measured indicates the two-photon resonant electronic process on a Fe3+ ion in the crystal.

19.
Z Geburtshilfe Neonatol ; 207(5): 173-8, 2003.
Artigo em Alemão | MEDLINE | ID: mdl-14600851

RESUMO

BACKGROUND: Fetuses with a reversed enddiastolic flow in the umbilical artery and/or aorta are at risk pregnancies and show a higher incidence of perinatal morbidity and mortality. The aim of this study was to evaluate the pathological changes in the terminal villous tree in fetuses with a reverse flow in the fetal aorta or umbilical artery. MATERIALS AND METHODS: In this retrospective study, 16 cases with a reverse flow in the fetal aorta or umbilical artery (Gr. 1) were compared with gestational age matched 16 healthy pregnant women (Gr. 2). The following morphometric parameters were evaluated in 50 sections in each placenta (1600 measurements): mean vessel diameter, volume density of the villous tissue, stem villi and terminal villi. Measurements were performed using a computerized Video Image Analysis system. RESULTS: The mean gestational age at birth was similar in both groups (30 + 4 weeks gestation vs. 30 + 6 weeks gestation, respectively, for Gr. 1 and Gr. 2). The birth weights (985 g vs. 1780 g) and the placental weights (216 g vs. 385 g) were significantly lower in the reverse flow group. There was a significant reduction in the proportion of total villous tissue (19 % versus 45 %) and in the diameter of tissue at the terminal villi (2.1 % versus 7.6 %) in the reverse flow group. Although the mean number of vessels at the terminal villi was lower than the control group (4.1 versus 5.6), the mean and total areas of the vessels were not different. CONCLUSION: Our observations showed a significant association between the placental morphometric parameters and reversed enddiastolic flow in the umbilical artery or fetal aorta. The reduced number of functional placental units is responsible for the diminished exchange function of the placental vessels in "reverse flow" cases. This could partially explain the adverse outcome in this clinical situation.


Assuntos
Aorta/diagnóstico por imagem , Vilosidades Coriônicas/irrigação sanguínea , Vilosidades Coriônicas/patologia , Retardo do Crescimento Fetal/diagnóstico por imagem , Retardo do Crescimento Fetal/patologia , Hipóxia Fetal/diagnóstico por imagem , Hipóxia Fetal/patologia , Feto/irrigação sanguínea , Recém-Nascido Pequeno para a Idade Gestacional , Insuficiência Placentária/diagnóstico por imagem , Insuficiência Placentária/patologia , Gravidez de Alto Risco , Ultrassonografia Doppler , Ultrassonografia Pré-Natal , Artérias Umbilicais/diagnóstico por imagem , Adulto , Aorta/embriologia , Peso ao Nascer/fisiologia , Velocidade do Fluxo Sanguíneo/fisiologia , Feminino , Humanos , Recém-Nascido , Tamanho do Órgão/fisiologia , Placenta/irrigação sanguínea , Placenta/patologia , Gravidez , Artérias Umbilicais/embriologia , Resistência Vascular/fisiologia
20.
Phys Rev Lett ; 91(5): 056403, 2003 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-12906613

RESUMO

Optical conductivity spectra sigma(omega) were used to investigate the effect of orbital ordering on the electronic structure of Ca2RuO4. Our LDA+U calculation predicts Ru 4d(xy) ferro-orbital ordering at the ground state, and well explains the present sigma(omega) as well as the reported O 1s x-ray absorption spectra. Variation of temperature (T) causes a large change of spectral weight over several eV as well as collapse of a charge gap accompanied by elongation of the c-axis Ru-O bond length. These results clearly indicate that the d(xy) orbital ordering plays a crucial role in the metal-insulator transition and the T-dependent electronic structure on a large energy scale.

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