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1.
Phys Rev Lett ; 125(16): 163601, 2020 Oct 16.
Artículo en Inglés | MEDLINE | ID: mdl-33124851

RESUMEN

Phase matching refers to a process in which atom-field interactions lead to the creation of an output field that propagates coherently through the interaction volume. By studying light scattering from arrays of cold atoms, we show that conditions for phase matching change as the dimensionality of the system decreases. In particular, for a single atomic chain, there is phase-matched reflective scattering in a cone about the symmetry axis of the array that scales as the square of the number of atoms in the chain. For two chains of atoms, the phase-matched reflective scattering can be enhanced or diminished as a result of Bragg scattering. Such scattering can be used for mapping collective states within an array of neutral atoms onto propagating light fields and for establishing quantum links between separated arrays.

2.
Phys Rev Lett ; 123(20): 203603, 2019 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-31809095

RESUMEN

Hanbury Brown-Twiss interference and stimulated emission, two fundamental processes in atomic physics, have been studied in a wide range of applications in science and technology. We study interference effects that occur when a weak probe is sent through a gas of two-level atoms that are prepared in a singly excited collective (Dicke or "superatom") state and for atoms prepared in a factorized state. We measure the time-integrated second-order correlation function g^{(2)} of the output field as a function of the delay τ between the input probe field and radiation emitted by the atoms and find that, for the Dicke state, g^{(2)} is twice as large for τ=0 as it is for γ_{e}τ≫1 (γ_{e} is an excited state decay rate), while for the product state, this ratio is equal to 3/2. The results agree with those of a theoretical model in which any effects related to stimulated emission are totally neglected-the coincidence counts measured in our experiment arise from Hanbury Brown-Twiss interference between the input field and the field radiated by the atoms.

3.
Phys Rev Lett ; 120(13): 132505, 2018 Mar 30.
Artículo en Inglés | MEDLINE | ID: mdl-29694189

RESUMEN

We report on the first observation of γ rays emitted from an sd-shell hypernucleus, _{Λ}^{19}F. The energy spacing between the ground state doublet, 1/2^{+} and 3/2^{+} states, of _{Λ}^{19}F is determined to be 315.5±0.4(stat)_{-0.5}^{+0.6}(syst) keV by measuring the γ-ray energy of the M1(3/2^{+}→1/2^{+}) transition. In addition, three γ-ray peaks are observed and assigned as E2(5/2^{+}→1/2^{+}), E1(1/2^{-}→1/2^{+}), and E1(1/2^{-}→3/2^{+}) transitions. The excitation energies of the 5/2^{+} and 1/2^{-} states are determined to be 895.2±0.3(stat)±0.5(syst) and 1265.6±1.2(stat)_{-0.5}^{+0.7}(syst) keV, respectively. It is found that the ground state doublet spacing is well described by theoretical models based on existing s- and p-shell hypernuclear data.

4.
Phys Rev Lett ; 115(22): 222501, 2015 Nov 27.
Artículo en Inglés | MEDLINE | ID: mdl-26650298

RESUMEN

The energy spacing between the spin-doublet bound state of _{Λ}^{4}He(1^{+},0^{+}) was determined to be 1406±2±2 keV, by measuring γ rays for the 1^{+}→0^{+} transition with a high efficiency germanium detector array in coincidence with the ^{4}He(K^{-},π^{-})_{Λ}^{4}He reaction at J-PARC. In comparison to the corresponding energy spacing in the mirror hypernucleus _{Λ}^{4}H, the present result clearly indicates the existence of charge symmetry breaking (CSB) in ΛN interaction. By combining the energy spacings with the known ground-state binding energies, it is also found that the CSB effect is large in the 0^{+} ground state but is vanishingly small in the 1^{+} excited state, demonstrating that the ΛN CSB interaction has spin dependence.

5.
J Radiol Prot ; 34(3): 675-98, 2014 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-25125455

RESUMEN

Data related to radioactivity released from the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident on 15 March 2011 gathered by residents of Miharu, Fukushima Prefecture, and by Tohoku University are presented. These data sets consist of (1) the earliest radiation monitoring by a Geiger counter in the town, (2) ratios of radioactivity between (132)Te and (137)Cs for a wide area between Fukushima and Tokyo, (3) radiation measurement of soil samples collected from 18 school grounds, and (4) external radiation exposure of 1400 students using OSL badges. By combining and analysing these various data sets, a curve for the cumulative total external exposure as a function of time, with 16 : 00 h on 15 March 2011 being time zero, is obtained. The average cumulative external dosage is estimated to be 10 mSv (σ = 4.2 mSv) over 10 years. In addition, the initiative that the residents of Miharu took in response to the FDNPP accident, which became known as The Misho Project (MP), is documented; in particular, the time at which the municipality instructed the immediate ingestion of iodine tablets by those under the age of 40, 13 : 00 h on 15 March 2011, is assessed.


Asunto(s)
Accidente Nuclear de Fukushima , Plantas de Energía Nuclear , Radiación Ionizante , Radiometría/estadística & datos numéricos , Japón
6.
Br J Cancer ; 109(5): 1100-8, 2013 Sep 03.
Artículo en Inglés | MEDLINE | ID: mdl-23922113

RESUMEN

BACKGROUND: Chemokines and chemokine receptors not only have significant roles in cancer metastasis and tumorigenesis but also act as antitumour agents. The interaction between the Crk-like adaptor protein (CrkL), which is encoded by the CRKL gene, and non-receptor tyrosine kinase c-ABL is reported to transform many cells into malignant cells. We examined the effects of CC chemokine receptor 7 (CCR7), CCR7 ligands and CrkL and c-ABL in lung adenocarcinoma. METHODS: One hundred and twenty patients with lung adenocarcinoma were included in this historical cohort analysis. We examined CCR7 and CCR7 ligands and CrkL and c-ABL mRNA expressions in surgically resected lung adenocarcinoma specimens and evaluated their contribution to prognosis, and the relationship with epidermal growth factor receptor (EGFR) and TP53 mutations. RESULTS: High CCR7 mRNA expressions indicated better prognoses than those of the groups with low CCR7 mRNA expressions (P=0.007, HR=2.00, 95% CI of ratio: 1.22 -3.31). In lung adenocarcinoma, CrkL and c-ABL mRNAs were related to CCR7 mRNA expression (P<0.0001). CrkL and c-ABL mRNA expressions were influenced by EGFR mutations. A high expression of CCL19 was a good prognostic factor of lung adenocarcinoma. CONCLUSION: We propose that CCR7 and CCL19 are clinically good prognostic factors and that CCR7 is strongly related to CrkL and c-ABL kinase mRNA expression in lung adenocarcinoma.


Asunto(s)
Adenocarcinoma/metabolismo , Adenocarcinoma/mortalidad , Biomarcadores de Tumor/metabolismo , Quimiocina CCL19/biosíntesis , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/mortalidad , Receptores CCR7/metabolismo , Proteínas Adaptadoras Transductoras de Señales/genética , Adenocarcinoma/cirugía , Adenocarcinoma del Pulmón , Adulto , Anciano , Anciano de 80 o más Años , Biomarcadores de Tumor/genética , Quimiocina CCL19/genética , Receptores ErbB/genética , Femenino , Humanos , Neoplasias Pulmonares/cirugía , Metástasis Linfática , Masculino , Persona de Mediana Edad , Proteínas Nucleares/genética , Pronóstico , Proteínas Proto-Oncogénicas c-abl/genética , ARN Mensajero/biosíntesis , Receptores CCR7/genética , Tasa de Supervivencia , Proteína p53 Supresora de Tumor/genética
7.
Diabetes Obes Metab ; 15(5): 455-62, 2013 May.
Artículo en Inglés | MEDLINE | ID: mdl-23279373

RESUMEN

AIMS: To compare the efficacy and safety of these two agents and the impact on surrogate markers related to diabetic complications in Japanese type 2 diabetic patients. METHODS: In a multicenter, open-label trial, 130 patients whose diabetes had been inadequately controlled (HbA1c, 6.9-9.5%) with metformin and/or sulphonylurea were randomly assigned to a sitagliptin group (50 mg/day) or a pioglitazone group (15 mg/day) and were followed up for 24 weeks. At 16 weeks, if the patient's HbA1c level was ≥6.5%, the dose of sitagliptin or pioglitazone was increased up to 100 or 30 mg/day, respectively. Main outcome measure was the difference in the mean changes in the HbA1c level from baseline at 24 weeks between these two groups. RESULTS: Of the 130 patients who were enrolled, 115 subjects (sitagliptin group: 58 patients, pioglitazone group: 57 patients) completed this trial. At 0 weeks, the mean HbA1c level was 7.47 ± 0.66% in the sitagliptin group and 7.40 ± 0.61% in the pioglitazone group. At 24 weeks, the mean changes in the HbA1c level from baseline were -0.86 ± 0.63% versus -0.58 ± 0.68% (p = 0.024). Hypoglycaemia (2 patients, 3.4% vs. 2 patients, 3.5%), gastrointestinal symptoms (3 patients, 5.2% vs. 1 patient, 1.8%) and pretibial oedema (0 patients, 0% vs. 39 patients, 68.4%, p < 0.001) were observed for 24 weeks. CONCLUSIONS: Sitagliptin was not only more tolerable, but also more effective than pioglitazone in Japanese type 2 diabetic patients who had been treated with metformin and/or sulphonylurea.


Asunto(s)
Glucemia/efectos de los fármacos , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Hemoglobina Glucada/efectos de los fármacos , Hipoglucemiantes/uso terapéutico , Pirazinas/uso terapéutico , Tiazolidinedionas/uso terapéutico , Triazoles/uso terapéutico , Adulto , Anciano , Pueblo Asiatico/estadística & datos numéricos , Glucemia/metabolismo , Diabetes Mellitus Tipo 2/sangre , Diabetes Mellitus Tipo 2/epidemiología , Quimioterapia Combinada , Femenino , Hemoglobina Glucada/metabolismo , Humanos , Japón/epidemiología , Masculino , Metformina/uso terapéutico , Persona de Mediana Edad , Pioglitazona , Fosfato de Sitagliptina , Compuestos de Sulfonilurea/uso terapéutico , Resultado del Tratamiento
8.
Phys Rev Lett ; 107(25): 256803, 2011 Dec 16.
Artículo en Inglés | MEDLINE | ID: mdl-22243101

RESUMEN

We report on the mapping of quantum-Hall edge states by quasiresonant photovoltage measurements using a near-field scanning optical microscope. We have observed fine structures near sample edges that shift inward with an increase in magnetic field in accordance with the shift of the positions of the quantum-Hall edge states. We have found a transition from the weak disorder regime where compressible-incompressble strips are visible to the strong disorder regime where fluctuations smear out incompressible strips.

9.
Br J Dermatol ; 163(3): 466-75, 2010 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-20500798

RESUMEN

BACKGROUND: Hyperkeratosis and acanthosis occur in inflamed skin. Proliferation and differentiation of keratinocytes are important processes during epidermal repair after inflammation. Neuropsin and its human homologue kallikrein-related peptidase 8 (KLK8) have been reported to be involved in epidermal proliferation and differentiation, but the involved molecular mechanisms are obscure. OBJECTIVES: To explore the molecular mechanism of KLK8/neuropsin-induced hyperkeratosis and acanthosis in inflamed skin. METHODS: The molecular mechanism involved in KLK8/neuropsin-induced hyperkeratosis and acanthosis in inflamed skin was investigated both in vivo and in vitro using neuropsin knockout mice and KLK8 knockdown human keratinocytes. Neuropsin-related genes were identified by differential gene display. The localization and functional relationship of the molecules affected downstream of KLK8/neuropsin in normal and inflamed skin were analysed by in situ hybridization and immunohistochemistry. RESULTS: Hyperkeratosis and acanthosis in sodium lauryl sulphate-stimulated skin were markedly inhibited in neuropsin knockout mice. Knockdown of KLK8/neuropsin increased transcription factor activator protein-2α (AP-2α) expression and decreased keratin 10 expression in human keratinocytes and mouse skin, respectively. AP-2α has been reported to inhibit epidermal proliferation and keratin 10 expression. Distributional analysis showed that KLK8/neuropsin was expressed in the stratum spinosum, AP-2α was expressed in the stratum basale and the lower part of the stratum spinosum, and keratin 10 was expressed throughout the stratum spinosum. CONCLUSIONS: The above findings suggest the following mechanism of events underlying KLK8/neuropsin-induced hyperkeratosis: (i) skin inflammation increases KLK8/neuropsin expression in the stratum spinosum; (ii) the released KLK8/neuropsin inhibits AP-2α expression in the cells of the stratum basale and stratum spinosum; (iii) the decrease in AP-2α results in cell proliferation in the stratum basale and cell differentiation in the stratum spinosum, with an increase in keratin 10 expression.


Asunto(s)
Acantosis Nigricans/metabolismo , Dermatitis/metabolismo , Hiperqueratosis Epidermolítica/metabolismo , Calicreínas/genética , Queratinocitos/metabolismo , Factor de Transcripción AP-2/antagonistas & inhibidores , Acantosis Nigricans/etiología , Acantosis Nigricans/genética , Animales , Dermatitis/genética , Modelos Animales de Enfermedad , Humanos , Hiperqueratosis Epidermolítica/etiología , Hiperqueratosis Epidermolítica/genética , Inmunohistoquímica , Queratina-10/metabolismo , Ratones , Ratones Noqueados , Reacción en Cadena de la Polimerasa/métodos , Piel/química , Piel/metabolismo , Dodecil Sulfato de Sodio/metabolismo , Factor de Transcripción AP-2/metabolismo , Regulación hacia Arriba
10.
J Mater Sci Mater Med ; 21(2): 807-13, 2010 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-19802687

RESUMEN

Antibiotic resistance of microorganisms is one of the major problems faced in the field of wound care and management resulting in complications like infection and delayed wound healing. Currently a lot of research is focused on developing newer antimicrobials to treat wounds infected with antibiotic resistant microorganisms. Silver has been used as an antimicrobial agent for a long time in the form of metallic silver and silver sulfadiazine ointments. Recently silver nanoparticles have come up as a potent antimicrobial agent and are finding diverse medical applications ranging from silver based dressings to silver coated medical devices. Chitin is a natural biopolymer with properties like biocompatibility and biodegradability. It is widely used as a scaffold for tissue engineering applications. In this work, we developed and characterized novel chitin/nanosilver composite scaffolds for wound healing applications. The antibacterial, blood clotting and cytotoxicity of the prepared composite scaffolds were also studied. These chitin/nanosilver composite scaffolds were found to be bactericidal against S. aureus and E. coli and good blood clotting ability. These results suggested that these chitin/nanosilver composite scaffolds could be used for wound healing applications.


Asunto(s)
Bacterias/efectos de los fármacos , Vendajes , Quitina/química , Nanoestructuras/química , Plata/química , Plata/farmacología , Andamios del Tejido , Antibacterianos/química , Antibacterianos/farmacología , Diseño de Equipo , Ensayo de Materiales , Nanoestructuras/administración & dosificación , Cicatrización de Heridas/efectos de los fármacos
11.
Phys Rev Lett ; 103(26): 266806, 2009 Dec 31.
Artículo en Inglés | MEDLINE | ID: mdl-20366333

RESUMEN

We investigate low-temperature transport characteristics of a side-coupled double quantum dot where only one of the dots is directly connected to the leads. We observe Fano resonances, which arise from interference between discrete levels in one dot and the Kondo effect, or cotunneling in general, in the other dot, playing the role of a continuum. The Kondo resonance is partially suppressed by destructive Fano interference, reflecting novel Fano-Kondo competition. We also present a theoretical calculation based on the tight-binding model with the slave boson mean field approximation, which qualitatively reproduces the experimental findings.

12.
Phys Rev Lett ; 103(18): 182502, 2009 Oct 30.
Artículo en Inglés | MEDLINE | ID: mdl-19905801

RESUMEN

We have measured the branching ratio of the three-body process in the nonmesonic weak decay of Lambda12C to be 0.29+/-0.13. This result was obtained by reproducing the nucleon and the nucleon pair yields introducing a measured final state interaction. At the same time, we have determined the absolute decay widths, Gamma(n) and Gamma(p), along with Gamma2N, whose relative ratio has been a long-standing puzzle. Including the three-body process, we have successfully reproduced the nucleon energy distribution, the coincidence two-nucleon angular correlation, and the momentum sum distribution simultaneously.

13.
Int J Biol Macromol ; 44(1): 107-11, 2009 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-19026679

RESUMEN

Alginate/phosphorylated chitin (P-chitin) blend films were prepared by mixing of 2% of alginate and P-chitin in water and then cross-linked with 4% CaCl2 solution. The blended films were characterized by FT-IR. Then, the bioactivity of blend films was studied by biomimetic method in simulated body fluid solution (SBF) for 7, 14 and 21 days. After 7, 14 and 21 days and films were characterized by FT-IR and SEM studies. The SEM and FT-IR studies showed that the hydroxyapatite was formed on the surface of the blend films after 7, 14 and 21 days in the SBF solution. These studies confirmed that the alginate/P-chitin blend films are bioactive. Furthermore, the adsorption of Ni2+, Zn2+ and Cu2+ onto alginate/P-chitin blend films has been investigated. The parameters studied include the pH, contact time, and initial metal ion concentrations. The maximum adsorption capacity of alginate/P-chitin blend films for Ni2+, Zn2+ and Cu2+ at pH 5.0 was found to be 5.67, 2.85 and 11.7 mg/g, respectively. These results suggest that alginate/P-chitin blend films-based technologies may be developed for water purification and metal ions separation and enrichment.


Asunto(s)
Alginatos/química , Quitina/química , Sustancias Macromoleculares/síntesis química , Adsorción , Biomimética , Ácido Glucurónico/química , Ácidos Hexurónicos/química , Cinética , Sustancias Macromoleculares/química , Ensayo de Materiales , Metales Pesados/química , Microscopía Electrónica de Rastreo , Fosforilación , Espectrofotometría Infrarroja , Espectroscopía Infrarroja por Transformada de Fourier
14.
Int J Biol Macromol ; 44(1): 1-5, 2009 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-18940197

RESUMEN

Beta-chitin is a biopolymer principally found in shells of squid pen. It has the properties of biodegradability, biocompatibility, chemical inertness, wound healing, antibacterial and anti-inflammatory activities. Hydroxyapatite (HAp) is a natural inorganic component of bone and teeth and has osteoconductive property. In this work, beta-chitin-HAp composite membranes were prepared by alternate soaking of beta-chitin membranes in CaCl2 (pH 7.4) and Na2HPO4 solutions for 2 h in each solution. After 1, 3 and 5 cycles of immersion, beta-chitin membranes were characterized using the SEM, FT-IR, EDS and XRD analyses. The results showed the presence of apatite layer on surface of beta-chitin membranes, and the amounts of size and deposition of apatite layers were increased with increasing number of immersion cycles. Human mesenchymal stem cells (hMSCs) were used for evaluation of the biocompatibility of pristine as well as composite membranes for tissue engineering applications. The presence of apatite layers on the surface of beta-chitin membranes increased the cell attachment and spreading suggesting that beta-chitin-HAp composite membranes can be used for tissue engineering applications.


Asunto(s)
Quitina/química , Durapatita/química , Membranas Artificiales , Ingeniería de Tejidos/métodos , Adhesión Celular/fisiología , Ensayo de Materiales , Células Madre Mesenquimatosas/metabolismo , Microscopía Electrónica de Rastreo , Espectroscopía Infrarroja por Transformada de Fourier , Difracción de Rayos X
15.
Eur J Gynaecol Oncol ; 30(2): 216-9, 2009.
Artículo en Inglés | MEDLINE | ID: mdl-19480261

RESUMEN

We report a case of uterine angiomyolipoma confirmed with molecular-genetic analysis by fluorescence in situ hybridization (FISH). A 25-year-old nulliparous woman visited Yamaguchi University Hospital with a complaint of lower abdominal pain. Magnetic resonance imaging demonstrated an ill-bordered uterine tumor and exploratory laparotomy revealed a myometrial elastic-soft tumor at the anterior wall of the uterine corpus. Histopathologically, the tumor consisted of fascicles of smooth muscle cells with intermingled adipocytes and small to medium-sized arterial blood vessels surrounded by epithelioid cells of clear cytoplasm. FISH examination revealed chromosome X trisomy, which was comparable to a previously reported molecular-genetic finding of PEComa family tumors including angiomyolipoma. Although the tumor was immunohistochemically negative for HMB-45 antigen, the histological and FISH findings were compatible with angiomyolipoma.


Asunto(s)
Antígenos de Neoplasias/análisis , Biomarcadores de Tumor/análisis , Proteínas de Neoplasias/análisis , Neoplasias de Células Epitelioides Perivasculares/diagnóstico , Neoplasias Uterinas/diagnóstico , Adulto , Angiomiolipoma/diagnóstico , Angiomiolipoma/inmunología , Angiomiolipoma/patología , Cromosomas Humanos X/genética , Análisis Citogenético , Femenino , Humanos , Hibridación Fluorescente in Situ , Antígenos Específicos del Melanoma , Neoplasias de Células Epitelioides Perivasculares/inmunología , Neoplasias de Células Epitelioides Perivasculares/patología , Trisomía , Neoplasias Uterinas/inmunología , Neoplasias Uterinas/patología
16.
Transplant Proc ; 51(3): 676-683, 2019 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-30979450

RESUMEN

OBJECTIVES: Living donor kidney transplant relieves the disease burden of patients with end-stage renal disease but may shorten donor life expectancy; however, their quality of life (QOL) is preserved. Nevertheless, the magnitude of the net gain of this procedure is unknown. We evaluated the QOL of both donors and recipients concurrently and calculated the net utility gain. METHODS: We recruited 210 subjects who visited the kidney transplantation clinic of a university hospital. Subjects were asked to complete the 5-level EQ-5D-based questionnaire, and patient characteristics were extracted from their medical records. We performed multivariate tobit models analysis to evaluate the QOL change caused by transplant surgery and subsequently ran computational simulations to determine the net utility gains of donors and recipients. We also performed sensitivity analyses. RESULTS: After excluding 16 answers with missing data, we analyzed 203 answers in total. After the transplant surgery, recipients gained 0.07 in utility value while donors lost 0.04. In the net utility analysis, we found that the quality-adjusted life years gained ranged from 7.2 to 7.8 in the most favorable case observed in the combination of middle-aged recipients and elderly donors. Assuming no utility discount, the most favorable combination was that with older donors and younger recipients. CONCLUSIONS: These findings indicated that the QOL improvement in recipients was larger than the loss among donors. When calculating the net utilities, a combination of middle-aged recipients and elderly donors yielded the largest net utility, but this was likely derived from assumption in the discount of QOL.


Asunto(s)
Trasplante de Riñón/métodos , Trasplante de Riñón/psicología , Donadores Vivos/psicología , Calidad de Vida , Adulto , Anciano , Femenino , Humanos , Fallo Renal Crónico/epidemiología , Fallo Renal Crónico/etiología , Masculino , Persona de Mediana Edad , Encuestas y Cuestionarios , Obtención de Tejidos y Órganos
17.
Hum Reprod ; 23(2): 285-9, 2008 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-18037605

RESUMEN

BACKGROUND: Changes in blood flow impedance of the uterine artery (UA) and uterine radial artery (RA) which is in the lower-extremity of the UA were examined during early pregnancy. METHODS: Blood flow impedance was assessed by transvaginal color-pulsed-Doppler-ultrasonography in 72 women from weeks 4-16 of pregnancy and expressed as a resistance index (RI). RESULTS: RA-RI remained at the late-luteal phase level until the 5th week of pregnancy, decreased until the 7th week, and remained low until the 10th week. UA-RI remained at the late-luteal phase level until the 10th week, and then gradually decreased until the 16th week. In nine women with spontaneous abortion, five out of six women with impaired growth of the gestational sac showed high RA-RI at the 6th week of pregnancy, whereas all three women with loss of fetal heart beat at the 8th week showed normal changes in RA-RI. CONCLUSIONS: Our results show different changes in blood flow impedance between the UA and RA during early pregnancy. A significant decrease of RA-RI after the 5th week may reflect vascular remodeling in the maternal-fetal interface at placentation, whereas a significant decrease of UA-RI after the 10th week may reflect changes of the whole uterine blood flow associated with uterine growth.


Asunto(s)
Embarazo , Útero/irrigación sanguínea , Resistencia Vascular , Aborto Espontáneo/fisiopatología , Adulto , Arterias/diagnóstico por imagen , Femenino , Muerte Fetal , Humanos , Fase Luteínica , Complicaciones del Embarazo/fisiopatología , Primer Trimestre del Embarazo , Segundo Trimestre del Embarazo , Flujo Sanguíneo Regional , Ultrasonografía Doppler en Color , Ultrasonografía Doppler de Pulso
18.
Acta Radiol ; 49(7): 816-26, 2008 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-18608014

RESUMEN

BACKGROUND: Much attention has been directed toward identifying early signs of cerebral ischemia on computed tomography (CT) images. Hypoattenuation of ischemic brain parenchyma has been found to be the most frequent early sign. PURPOSE: To evaluate the effect of a previously proposed adaptive smoothing filter for improving detection of parenchymal hypoattenuation of acute ischemic stroke on unenhanced CT images. MATERIAL AND METHODS: Twenty-six patients with parenchymal hypoattenuation and 49 control subjects without hypoattenuation were retrospectively selected in this study. The adaptive partial median filter (APMF) designed for improving detectability of hypoattenuation areas on unenhanced CT images was applied. Seven radiologists, including four certified radiologists and three radiology residents, indicated their confidence level regarding the presence (or absence) of hypoattenuation on CT images, first without and then with the APMF processed images. Their performances without and with the APMF processed images were evaluated by receiver operating characteristic (ROC) analysis. RESULTS: The mean areas under the ROC curves (AUC) for all observers increased from 0.875 to 0.929 (P = 0.002) when the radiologists observed with the APMF processed images. The mean sensitivity in the detection of hypoattenuation significantly improved, from 69% (126 of 182 observations) to 89% (151 of 182 observations), when employing the APMF (P = 0.012). The specificity, however, was unaffected by the APMF (P = 0.41). CONCLUSION: The APMF has the potential to improve the detection of parenchymal hypoattenuation of acute ischemic stroke on unenhanced CT images.


Asunto(s)
Isquemia Encefálica/diagnóstico por imagen , Interpretación de Imagen Radiográfica Asistida por Computador/métodos , Accidente Cerebrovascular/diagnóstico por imagen , Tomografía Computarizada por Rayos X/métodos , Adulto , Anciano , Anciano de 80 o más Años , Algoritmos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Curva ROC , Sensibilidad y Especificidad
19.
Int J Biol Macromol ; 43(1): 32-6, 2008 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-17950453

RESUMEN

Chitin is known to be natural polymer and it is non-toxic, biodegradable and biocompatible. The chitin-g-poly(epsilon-caprolactone) (chitin-g-PCL) copolymer was prepared by the ring-opening polymerization of epsilon-caprolactone onto chitin gel in the presence of tin(II) 2-ethylhexanoate catalyst by bulk polymerization method under homogeneous system. The prepared copolymer were characterized by FT-IR, (13)C NMR, thermogravimetric analysis (TGA), differential thermal analysis (DTA), scanning electron microscopy (SEM), solubility and X-ray diffraction (XRD). The degree of substitution of chitin-g-PCL copolymer was found to be 0.48. The TGA analysis showed that chitin-g-PCL was slightly less thermal stability than original chitin. It was due to the grafting of PCL reduced the crystalline structure of chitin. DTA analysis of chitin-g-PCL showed the two exothermic peaks between 300 and 400 degrees C. The first peak at 342 degrees C was due to chitin peak and the second peak was due to PCL. These results suggested that chitin and PCL chains were mixed well at a molecular level. The XRD pattern analysis of chitin-g-PCL showed a weak and broader peak, which demonstrated that the conjugation of PCL with chitin suppressed the crystallization of both chitin and PCL to some extent. The SEM studies showed that the chitin gel seems have a smooth surface morphology, but the chitin-g-PCL showed slightly rough morphology due to the grafting of PCL into chitin. The surface morphology studies also confirmed the grafting reaction.


Asunto(s)
Quitina/química , Poliésteres/síntesis química , Temperatura , Quitina/ultraestructura , Geles/química , Espectroscopía de Resonancia Magnética , Microscopía Electrónica de Rastreo , Estructura Molecular , Poliésteres/química , Solubilidad , Espectroscopía Infrarroja por Transformada de Fourier , Difracción de Rayos X
20.
Int J Biol Macromol ; 42(4): 335-9, 2008 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-18279950

RESUMEN

Chitosan a natural based polymer is non-toxic, biocompatible and biodegradable. Chemical modification of chitosan to generate new bifunctional materials and finally would bring new properties depending on the nature of the group introduced. In our present study, we prepared phosphorylated chitosan (P-chitosan) by using H(3)PO(4)/P(2)O(5)/Et(3)PO(4)/hexanol method. From our present method, we got high yield and high degree of substitution (DS). The prepared P-chitosan (DS-1.18) was characterized by FT IR, (13)C NMR, (31)P NMR, elemental, XRD, TGA, DTA and SEM studies. After the phosphorylation, the solubility of the polymer was improved. The P-chitosan showed less thermal stability and crystallinity than the chitosan. It was due to the phosphorylation.


Asunto(s)
Quitosano/química , Quitosano/síntesis química , Materiales Biocompatibles/química , Hexanoles/química , Calor , Espectroscopía de Resonancia Magnética , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Conformación Molecular , Fosforilación , Polímeros/química , Solubilidad , Espectroscopía Infrarroja por Transformada de Fourier , Propiedades de Superficie , Temperatura , Difracción de Rayos X
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