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1.
Phys Rev Lett ; 118(13): 130503, 2017 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-28409950

RESUMO

A boson-sampling device is a quantum machine expected to perform tasks intractable for a classical computer, yet requiring minimal nonclassical resources as compared to full-scale quantum computers. Photonic implementations to date employed sources based on inefficient processes that only simulate heralded single-photon statistics when strongly reducing emission probabilities. Boson sampling with only single-photon input has thus never been realized. Here, we report on a boson-sampling device operated with a bright solid-state source of single-photon Fock states with high photon-number purity: the emission from an efficient and deterministic quantum dot-micropillar system is demultiplexed into three partially indistinguishable single photons, with a single-photon purity 1-g^{(2)}(0) of 0.990±0.001, interfering in a linear optics network. Our demultiplexed source is between 1 and 2 orders of magnitude more efficient than current heralded multiphoton sources based on spontaneous parametric down-conversion, allowing us to complete the boson-sampling experiment faster than previous equivalent implementations.

2.
Nature ; 451(7179): 694-8, 2008 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-18256667

RESUMO

Holographic three-dimensional (3D) displays provide realistic images without the need for special eyewear, making them valuable tools for applications that require situational awareness, such as medical, industrial and military imaging. Currently commercially available holographic 3D displays use photopolymers that lack image-updating capability, resulting in restricted use and high cost. Photorefractive polymers are dynamic holographic recording materials that allow updating of images and have a wide range of applications, including optical correlation, imaging through scattering media and optical communication. To be suitable for 3D displays, photorefractive polymers need to have nearly 100% diffraction efficiency, fast writing time, hours of image persistence, rapid erasure, and large area-a combination of properties that has not been shown before. Here, we report an updatable holographic 3D display based on photorefractive polymers with such properties, capable of recording and displaying new images every few minutes. This is the largest photorefractive 3D display to date (4 x 4 inches in size); it can be recorded within a few minutes, viewed for several hours without the need for refreshing, and can be completely erased and updated with new images when desired.

3.
Pathol Biol (Paris) ; 62(5): 241-51, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25179115

RESUMO

Sleep misperception is often observed in insomnia individuals (INS). The extent of misperception varies between different types of INS. The following paper comprised sections which will be aimed at studying the sleep EEG and compares it to subjective reports of sleep in individuals suffering from either psychophysiological insomnia or paradoxical insomnia and good sleeper controls. The EEG can be studied without any intervention (thus using the raw data) via either PSG or fine quantitative EEG analyses (power spectral analysis [PSA]), identifying EEG patterns as in the case of cyclic alternating patterns (CAPs) or by decorticating the EEG while scoring the different transient or phasic events (K-Complexes or sleep spindles). One can also act on the on-going EEG by delivering stimuli so to study their impact on cortical measures as in the case of event-related potential studies (ERPs). From the paucity of studies available using these different techniques, a general conclusion can be reached: sleep misperception is not an easy phenomenon to quantify and its clinical value is not well recognized. Still, while none of the techniques or EEG measures defined in the paper is available and/or recommended to diagnose insomnia, ERPs might be the most indicated technique to study hyperarousal and sleep quality in different types of INS. More research shall also be dedicated to EEG patterns and transient phasic events as these EEG scoring techniques can offer a unique insight of sleep misperception.


Assuntos
Percepção/fisiologia , Distúrbios do Início e da Manutenção do Sono/psicologia , Sono , Ondas Encefálicas/fisiologia , Diagnóstico Diferencial , Eletroencefalografia/métodos , Eletroencefalografia/estatística & dados numéricos , Potenciais Evocados , Análise de Fourier , Humanos , Prontuários Médicos , Polissonografia , Transtornos Psicofisiológicos/diagnóstico , Transtornos Psicofisiológicos/fisiopatologia , Transtornos Psicofisiológicos/psicologia , Distúrbios do Início e da Manutenção do Sono/classificação , Distúrbios do Início e da Manutenção do Sono/diagnóstico , Distúrbios do Início e da Manutenção do Sono/fisiopatologia , Fases do Sono/fisiologia , Vigília/fisiologia
4.
Opt Lett ; 36(17): 3377-9, 2011 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-21886216

RESUMO

Organic photorefractive polymer composites can be made to exhibit near 100% diffraction efficiency and fast writing times, though large external slants are needed to project the applied field onto the grating vector. We show here that the use of interdigitated electrodes on a single plane provides similar performance to these standard devices and geometries but without a external slant angle. This new device's structure also greatly improves the diffraction efficiency and sensitivity compared to less slanted standard devices necessary for some real applications, such as holographic displays, optical coherence imaging, and in-plane switching.

6.
Nat Commun ; 11(1): 5501, 2020 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-33127924

RESUMO

Light states composed of multiple entangled photons-such as cluster states-are essential for developing and scaling-up quantum computing networks. Photonic cluster states can be obtained from single-photon sources and entangling gates, but so far this has only been done with probabilistic sources constrained to intrinsically low efficiencies, and an increasing hardware overhead. Here, we report the resource-efficient generation of polarization-encoded, individually-addressable photons in linear cluster states occupying a single spatial mode. We employ a single entangling-gate in a fiber loop configuration to sequentially entangle an ever-growing stream of photons originating from the currently most efficient single-photon source technology-a semiconductor quantum dot. With this apparatus, we demonstrate the generation of linear cluster states up to four photons in a single-mode fiber. The reported architecture can be programmed for linear-cluster states of any number of photons, that are required for photonic one-way quantum computing schemes.

7.
Curr Opin Chem Biol ; 1(4): 552-63, 1997 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-9667891

RESUMO

The technology of glycopeptide synthesis has recently developed into a fully mature science capable of creating diverse glycopeptides of biological interest, even in combinatorial displays. This has allowed biochemists to investigate substrate specificity in the biosynthetic processing and immunology of various protein glycoforms. The construction of all the mucin core structures and a variety of cancer-related glycopeptides has facilitated detailed analysis of the interaction between MHC-bound glycopeptides and T cell receptors. Novel dendritic neoglycopeptide ligands have been shown to demonstrate high affinity for carbohydrate receptors and these interactions are highly dendrimer specific. Large complex N-linked oligosaccharides have been introduced into glycopeptides using synthetic or chemoenzymatic procedures, both methods affording pure glycopeptides corresponding to a single glycoform in preparative quantities. The improved availability of glycosyl transferases has led to increased use of chemoenzymatic synthesis. Chemical ligation has been introduced as a method of attaching glycans to peptide templates. Combinatorial synthesis and the analysis of resin-bound glycopeptide libraries have been successfully carried out by applying the ladder synthesis principle. Direct quantitative glycosylation of peptide templates on solid phase has paved the way for the synthesis of templated glycopeptide mixtures as libraries of libraries.


Assuntos
Glicopeptídeos/química , Glicopeptídeos/síntese química , Sequência de Aminoácidos , Animais , Configuração de Carboidratos , Sequência de Carboidratos , Glicopeptídeos/metabolismo , Antígenos de Histocompatibilidade Classe II/química , Antígenos de Histocompatibilidade Classe II/metabolismo , Humanos , Complexo Principal de Histocompatibilidade , Modelos Moleculares , Dados de Sequência Molecular , Oligossacarídeos/síntese química , Oligossacarídeos/química , Biblioteca de Peptídeos , Receptores de Antígenos de Linfócitos T/metabolismo , Sialoglicoproteínas/química
8.
J Invest Dermatol ; 97(2): 298-304, 1991 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-2071940

RESUMO

Retinol circulates in the plasma bound to retinol-binding protein (RBP), but the mechanism by which retinol is transferred from RBP to target cells is not known. To study retinol delivery, human keratinocytes (HKc) were incubated with [3H]retinol added directly to the culture medium or bound to RBP and the uptake of [3H]retinol was determined at various times. During the first hour of incubation, the rate of [3H]retinol accumulation by HKc was about 40 times greater when the vitamin was added directly to the media rather than bound to RBP. Although maximal uptake of [3H]retinol added directly to the culture medium occurred at 3 h, the uptake of [3H]retinol from RBP was linear with time for at least 72 h. By 57 h, cell-associated [3H]retinol was the same whether it was added directly to the culture medium or bound to RBP. Excess unlabeled retinol or pretreatment of HKc with retinol had no effect on the uptake of [3H]retinol added directly to the culture medium or bound to RBP. Apo- but not holo-RBP was capable of competing with HKc for the uptake of [3H]retinol from RBP. No specific or saturable binding of 125I-labeled RBP to HKc cultured in the absence or the presence of retinol was found. The dose response of retinol inhibition of cholesterol sulfate synthesis and phorbol ester-induced ornithine decarboxylase activity or retinol modulation of keratin expression was the same whether the retinol was delivered to HKc bound to RBP or added directly to the medium. Our data support a mechanism for retinol delivery from RBP to HKc that does not involve cell-surface RBP receptors but instead suggest that the vitamin is first slowly released from RBP and then becomes cell-associated from the aqueous phase. This mechanism is consistent with the finding that HKc respond identically to retinol whether or not it is delivered to them bound to RBP.


Assuntos
Queratinócitos/metabolismo , Proteínas de Ligação ao Retinol/metabolismo , Vitamina A/farmacocinética , Células Cultivadas , Meios de Cultura , Humanos , Queratinócitos/citologia , Proteínas Plasmáticas de Ligação ao Retinol , Trítio , Vitamina A/farmacologia
9.
Mol Biochem Parasitol ; 114(1): 81-8, 2001 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-11356516

RESUMO

We have identified peptides that are relatively resistant to hydrolysis by a recombinant cysteine proteinase, CPB2.8DeltaCTE, of Leishmania mexicana, and yet exhibit inhibition constant (K(i)) values in the nanomolar range. Common to these peptides is a basic-hydrophobic-hydrophobic motif in the P3-P1 sites, which is also present in the pro-region of the enzyme. A nine-amino acid stretch, FAARYLNGA, which has good homology to the pro-region of mammalian cathepsin L was identified as the part of the pro-region most likely to interact with the active site of the parasite enzyme. This peptide is not hydrolyzed by CPB2.8DeltaCTE and inhibited it with a K(i) of 4 microM. Extension of this sequence at both the N- and C-termini and the introduction of ortho-aminobenzoic acid at the N-terminal site reduced the K(i) value to 30 nM. The best substrate for CPB2.8DeltaCTE was also well hydrolyzed by cathepsin L, however the best inhibitor of the parasite enzyme inhibit poorly cathepsin L, with K(i) value two order of magnitude higher than against the parasite enzyme. These promising data provide insights into the peculiar specificity of the parasite enzyme and will aid the design of antiparasitic drugs directed against the leishmanial enzyme.


Assuntos
Cisteína Endopeptidases/química , Inibidores de Cisteína Proteinase/farmacologia , Leishmania mexicana/enzimologia , Oligopeptídeos/farmacologia , Proteínas de Protozoários/antagonistas & inibidores , Sequência de Aminoácidos , Animais , Catepsina L , Catepsinas/química , Cisteína Endopeptidases/genética , Inibidores de Cisteína Proteinase/química , Humanos , Cinética , Mamíferos , Dados de Sequência Molecular , Oligopeptídeos/química , Fragmentos de Peptídeos/química , Proteínas de Protozoários/química , Proteínas Recombinantes/antagonistas & inibidores , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Especificidade por Substrato
10.
Mol Biochem Parasitol ; 116(1): 1-9, 2001 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-11463460

RESUMO

The primary S(1) subsite specificity of a recombinant cysteine proteinase, CPB2.8 Delta CTE, of Leishmania mexicana was investigated in a systematic way using a series of peptides derived from Abz-KLRFSKQ-EDDnp in which Arg was substituted by all natural amino acids (where Abz is ortho-amino-benzoyl and EDDnp is N-[2,4-dinitrophenyl]-ethylenediamine). The peptides from this series with charged side chain amino acids, Cys, Cys(SBzl), and Thr(OBzl) were well hydrolysed. All other substitutions resulted in peptides that were resistant or hydrolysed very slowly and inhibited the enzyme with K(i) values in the range of 9--400 nM. Looking for natural substrates for CPB2.8, we observed that the recombinant enzyme failed to release kinin from human kininogen, an activity earlier observed with cruzipain from Trypanosoma cruzi (Del Nery et al., J. Biol. Chem. 272 (1997) 25713.). This lack of activity seems to be a result of the resistance to hydrolysis of the sequence at the N-terminal site of bradykinin in the human kininogen. The preferences for the S(3), S(2) and S(1)'-S(3)' for some amino acids were also examined using substrates derived from Abz-KLRFSKQ-EDDnp with variations at Lys, Leu, Phe, Ser and Lys, using the amino acids Ala, Phe, Leu, His or Pro. Peptides with Phe at P(1)' presented the highest affinity to the leishmanial enzyme. For comparison, some of the obtained peptides were also assayed with recombinant human cathepsin L and cruzain. The best substrates for CPB2.8 Delta CTE were also well hydrolysed by cathepsin L, however, the best inhibitors of the parasite enzyme have low affinity to cathepsin L. These promising data provide leads for the design of anti-parasitic drugs directed against the leishmanial enzyme.


Assuntos
Cisteína Endopeptidases/metabolismo , Leishmania mexicana/enzimologia , Sequência de Aminoácidos , Animais , Catepsina L , Catepsinas/metabolismo , Cisteína Endopeptidases/genética , Inibidores de Cisteína Proteinase/farmacologia , Humanos , Cininogênios/metabolismo , Leishmania mexicana/genética , Dados de Sequência Molecular , Fragmentos de Peptídeos/metabolismo , Proteínas de Protozoários/metabolismo , Proteínas Recombinantes/metabolismo , Especificidade por Substrato
11.
Acta Cytol ; 42(3): 725-8, 1998.
Artigo em Inglês | MEDLINE | ID: mdl-9622695

RESUMO

BACKGROUND: Solid papillary carcinoma of the breast was recently described. This tumor display distinctive clinical and morphologic features. It is an intraductal papillary carcinoma frequently associated with mucinous carcinoma and infiltrating ductal carcinoma not otherwise specified. CASE: Fine needle aspiration cytology (FNAC) of a solid papillary carcinoma of the right breast in an 82-year-old female, demonstrated a cellular specimen of discohesive, small, uniform and ovoid tumor cells, with occasional loose cluster. The cytoplasm was abundant and finely granular. The nuclei were round, without marked atypia. The nucleoli were inconspicuous. SCant mucinous material was present. The diagnosis was confirmed histologically and immunohistochemically. CONCLUSION: The cytologic aspects of solid papillary carcinoma of the breast suggest a carcinoma with endocrine differentiation and a weak mucinous component.


Assuntos
Biópsia por Agulha , Neoplasias da Mama/patologia , Mama/patologia , Carcinoma Papilar/patologia , Idoso , Idoso de 80 Anos ou mais , Neoplasias da Mama/química , Neoplasias da Mama/diagnóstico , Carcinoma Papilar/química , Carcinoma Papilar/diagnóstico , Diferenciação Celular , Feminino , Humanos , Mucinas/análise , Proteínas de Neoplasias/análise , Células-Tronco Neoplásicas/patologia
12.
J Gynecol Obstet Biol Reprod (Paris) ; 29(7): 680-3, 2000 Nov.
Artigo em Francês | MEDLINE | ID: mdl-11119041

RESUMO

Abdominal wall metastasis to laparoscopic trochar sites after preoperative staging procedure is rare for uterine cervix cancer. Prognosis is unfavorable. We report a case of metastasis to a laparoscopic trochar site in a patient with a stage IIB cervical cancer with no nodal involvement who is alive four and a half years after radical surgery and radiotherapy.


Assuntos
Músculos Abdominais , Neoplasias Musculares/patologia , Inoculação de Neoplasia , Instrumentos Cirúrgicos/efeitos adversos , Neoplasias do Colo do Útero/patologia , Adulto , Feminino , Humanos , Indução de Remissão
13.
Artigo em Francês | MEDLINE | ID: mdl-8568176

RESUMO

OBJECTIVE: Evaluate the reliability, safety and performance of hysterosonographic assessment of the uterine cavity. MATERIALS AND METHODS: Hysterosonography was performed in 220 patients with injection of sterile saline into the uterine with a novel catheter. Among these patients, 132 patients then underwent a hysteroscopy or hysterectomy with a histology examination. RESULTS: There were 8 failures: 2 synechiae, 3 atresias of the cervix, and massive reflux in 3 cases. No other complication occurring. Hysterosonography appeared to give more information on the uterine cavity than standard vaginal sonography. In cases with metrorrhage before menopause, the diagnosis was correct in 75.4% of the cases. Errors were related to confusion between polyp and hyperplasia. In post-menopausal metrorrhagia, there was 92% agreement between sonography and histological results. Agreement was 86.3% in cases of infertility. CONCLUSION: Hysterosonography using saline solution injected with a novel catheter can be an excellent means of evaluating the uterine cavity and can completely replace classical hysterography, thus avoiding many exploratory hysterocopies.


Assuntos
Histeroscopia/métodos , Ultrassonografia de Intervenção/métodos , Doenças Uterinas/diagnóstico por imagem , Viés , Diagnóstico Diferencial , Estudos de Viabilidade , Feminino , Humanos , Histerectomia , Histeroscópios , Injeções , Reprodutibilidade dos Testes , Cloreto de Sódio/administração & dosagem , Ultrassonografia de Intervenção/instrumentação , Doenças Uterinas/patologia , Doenças Uterinas/cirurgia
14.
J Gynecol Obstet Biol Reprod (Paris) ; 42(5): 458-63, 2013 Sep.
Artigo em Francês | MEDLINE | ID: mdl-23790970

RESUMO

OBJECTIVE: In present study, we are assessing the efficiency of endometrial ablation by radiofrequency (Novasure(®)) for the treatment of abnormal uterine bleeding. MATERIAL AND METHODS: A total of 90 patients underwent an endometrial ablation by radiofrequency for uterine bleeding between 2009 and 2012. For the postoperative follow-up, symptoms amelioration and eventual adverse-events were evaluated by a self-administered questionnaire given to all patients after the surgery. RESULT: Sixty-five patients (74%) responded to the questionnaire with an average of 17.5 months. Among them, endometrial bleeding decreased in 92% of the cases (IC 95%; 86-99). The amenorrhea rate was 55% (IC 95%; 43-67) and 36% of the patients presented a diminution of menstrual bleeding after treatment. Thirty-two patients (36%) presented dysmenorrhea before the radiofrequency and 78% of them experienced an amelioration of the symptoms after treatment (IC 95%; 64-93). In 19 patients (21%), the cause of uterine bleeding was adenomyosis, among them, bleeding decreased in 84% of the cases (IC 95%; 71-98) and dysmenorrhea in 70%. (IC 95%; 41-97). Finally, 84% of the patients were satisfied with the result of the treatment. CONCLUSION: Our findings suggest that endometrial radiofrequency is effective for the treatment of menometrorrhagia, dysmenorrhea and also adenomyosis.


Assuntos
Ablação por Cateter/métodos , Técnicas de Ablação Endometrial/métodos , Pré-Menopausa , Ablação por Cateter/efeitos adversos , Cesárea/estatística & dados numéricos , Feminino , Humanos , Metrorragia/epidemiologia , Metrorragia/cirurgia , Pessoa de Meia-Idade , Paridade , Complicações Pós-Operatórias/epidemiologia , Gravidez , Estudos Retrospectivos , Resultado do Tratamento
15.
J Gynecol Obstet Biol Reprod (Paris) ; 41(3): 227-34, 2012 May.
Artigo em Francês | MEDLINE | ID: mdl-22464015

RESUMO

UNLABELLED: Various statistic predictive models have been developed to predict the status of the non-sentinel lymph nodes (NSLN) when the sentinel one was invaded by tumor cells in the case of breast invasive carcinoma. The objective of this study was to compare the accuracy of three of these statistic models: the MSKCC nomogram, the Tenon score and the MDA score. The study was conducted at Croix Rousse Hospital, Lyon, France. OBJECTIVE: When sentinel lymph node is invaded by metastasis, complete lymph node dissection of the axilla can be avoided using statistic predictive models especially when talking about micrometastases and moreover about isolated tumor cells in the sentinel lymph node. Over the different existing models, we tested the three most used ones to determine the model that is most adapted to our everyday practice. METHOD: The study population consisted of 77 women with an invasive breast cancer treated by complete axillary lymph node dissection for metastatic sentinel lymph node. Over the nine models already published, we focused on three of them due to their ease to use as well as their good preliminary results: the Memorial Sloan-Kettering Cancer Center nomogram (MSKCC), the Tenon score and the M.D Anderson score (MDA). Different criteria are used by these models, but all of them take in consideration: tumor size, multifocality, tumor type, lymphovascular invasion, hormonal receptors, number of sentinel lymph node resected, degree of sentinel lymph node invasion (i.e. macrometastasis, micrometastasis or isolated tumor cells) and histologic method used to diagnose sentinel lymph node invasion. These scores are validated depending on their false negative ratio as well as the proportion of patient selected as having a low risk of non-sentinel lymph node invasion. The major criterion for the MSKCC score is the calibration that compares the predicted likelihood of invasion and the histologically proved one. RESULTS: The rate of non-sentinel lymph node invasion was 37.6%. The discrimination of the three models was good with an AUC of 0.74 for both MSKCC nomogram and Tenon score and of 0.72% for MDA score. MSKCC nomogram was well calibrated (P=0.23). The false negative ratio was 0 (CI 95%: 0-18.1%) for MSKCC nomogram, 16.7% (CI 95%: 8.6%-27.8%) for Tenon score and 16% (CI 95%: 6.8-31%) for MDA score. The percentage of patients considered as having a low risk of invasion of the non-sentinel lymph node was 20.5% for MSKCC nomogram, 34.7% for MDA score and 47.4% for Tenon score. CONCLUSION: MSKCC nomogram seems to be the statistic model that is most adapted to the population we studied. To validate the Tenon and MDA score, we should have a most important population.


Assuntos
Neoplasias da Mama/patologia , Metástase Linfática/diagnóstico , Biópsia de Linfonodo Sentinela , Axila , Feminino , França , Humanos , Excisão de Linfonodo , Invasividade Neoplásica , Micrometástase de Neoplasia , Nomogramas , Estudos Retrospectivos
16.
Science ; 335(6066): 324-8, 2012 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-22267810

RESUMO

Observations of comets in Sun-grazing orbits that survive solar insolation long enough to penetrate into the Sun's inner corona provide information on the solar atmosphere and magnetic field as well as on the makeup of the comet. On 6 July 2011, the Solar Dynamics Observatory (SDO) observed the demise of comet C/2011 N3 (SOHO) within the low solar corona in five wavelength bands in the extreme ultraviolet (EUV). The comet penetrated to within 0.146 solar radius (~100,000 kilometers) of the solar surface before its EUV signal disappeared. Before that, material released into the coma--at first seen in absorption--formed a variable EUV-bright tail. During the final 10 minutes of observation by SDO's Atmospheric Imaging Assembly, ~6 × 10(8) to 6 × 10(10) grams of total mass was lost (corresponding to an effective nucleus diameter of ~10 to 50 meters), as estimated from the tail's deceleration due to interaction with the surrounding coronal material; the EUV absorption by the comet and the brightness of the tail suggest that the mass was at the high end of this range. These observations provide evidence that the nucleus had broken up into a family of fragments, resulting in accelerated sublimation in the Sun's intense radiation field.

18.
Appl Opt ; 33(5): 768-74, 1994 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-20862073

RESUMO

The modulation transfer function characteristics of image-plane holographic stereograms are calculated, and the behavior of the modulation transfer function with respect to factors such as image depth, resolution, and perspective window size is described. The expression for the modulation transfer function is then used to determine the optimum stereogram parameters, and it is shown how this approach can lead to significant computational economies in the display of three-dimensional data.

19.
J Nutr ; 123(2 Suppl): 356-61, 1993 02.
Artigo em Inglês | MEDLINE | ID: mdl-8429387

RESUMO

In response to body demands, retinol (ROL) is secreted from the liver into the circulation bound to serum retinol-binding protein (RBP). The mechanism by which ROL is transferred from RBP to target cells remains controversial. To study ROL delivery, we have used a model system of cultured human foreskin keratinocytes (HKc) to compare the uptake, metabolism and biologic effects of ROL added either directly to the medium or bound to RBP. [3H]ROL added directly to the medium was rapidly taken up by HKc, and maximal accumulation of [3H]ROL occurred by 3 h. In contrast, [3H]ROL delivered bound to RBP was taken up very slowly but at a linear rate for at least 72 h. Several experimental approaches indicated that ROL uptake from RBP was not mediated by a cell surface receptor for RBP. The rate and extent of [3H]ROL metabolism to retinyl esters was the same whether the ROL was added directly to the medium or bound to RBP. In addition, several biologic responses by HKc to ROL showed the same dose response curves whether the ROL was added directly to the medium or bound to RBP. Overall, the results support a model of ROL uptake from RBP in which the vitamin is first slowly released from RBP into the aqueous phase and then becomes cell associated. In this manner, the cells are provided with a slow but constant supply of ROL and are protected from the rapid and potentially toxic accumulation of ROL that occurs in the absence of RBP.


Assuntos
Queratinócitos/metabolismo , Proteínas de Ligação ao Retinol/metabolismo , Vitamina A/farmacocinética , Células Cultivadas , Ésteres do Colesterol/análise , Meios de Cultura Livres de Soro , Humanos , Recém-Nascido , Inibidores da Ornitina Descarboxilase , Trítio , Vitamina A/farmacologia
20.
Rev Fr Gynecol Obstet ; 87(11): 527-32, 1992 Nov.
Artigo em Francês | MEDLINE | ID: mdl-1480921

RESUMO

An analysis of the limits, risks and difficulties of interpreting trophocentesis leads to the conclusion that the method is effective and free from maternal risk. The unsuccessful cases and the "fetal losses" are however more numerous than for amniocentesis.


Assuntos
Amostra da Vilosidade Coriônica/normas , Síndrome de Down/diagnóstico , Amostra da Vilosidade Coriônica/efeitos adversos , Amostra da Vilosidade Coriônica/métodos , Síndrome de Down/epidemiologia , Estudos de Avaliação como Assunto , Feminino , Humanos , Cariotipagem , Gravidez , Resultado da Gravidez
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