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1.
Vet Res ; 48(1): 52, 2017 09 19.
Artigo em Inglês | MEDLINE | ID: mdl-28927447

RESUMO

Breeding towards genetic resistance to prion disease is effective in eliminating scrapie. In sheep, classical forms of scrapie have been eradicated almost completely in several countries by breeding programs using a prion protein (PrP) gene (PRNP) amino acid polymorphism. For goats, field and experimental studies have provided evidence for several amino acid polymorphisms that are associated with resistance to scrapie, but only limited data are available concerning the susceptibility of caprine PRNP genotypes to BSE. In this study, goat kids representing five PRNP genotypes based on three polymorphisms (M142, Q211 and K222 and the wild type I142, R211 and Q222) were orally challenged with bovine or goat BSE. Wild type goats were killed with clinical signs between 24-28 months post inoculation (mpi) to both challenges, and goats with genotype R/Q211 succumbed between 29-36 mpi. I/M142 goats developed clinical signs at 44-45 mpi and M/M142 goats remained healthy until euthanasia at 48 mpi. None of the Q/K222 goats showed definite clinical signs. Taken together the highest attack ratios were seen in wild type and R/Q211 goats, and the lowest in I/M142, M/M142 and Q/K222. In all genotype groups, one or more goats remained healthy within the incubation period in both challenges and without detectable PrP deposition in the tissues. Our data show that both the K222 and M142 polymorphisms lengthen the incubation period significantly compared to wild type animals, but only K222 was associated with a significant increase in resistance to BSE infection after oral exposure to both BSE sources.


Assuntos
Resistência à Doença/genética , Encefalopatia Espongiforme Bovina/prevenção & controle , Doenças das Cabras/prevenção & controle , Príons/efeitos adversos , Animais , Cruzamento , Bovinos , Códon/genética , Encefalopatia Espongiforme Bovina/genética , Feminino , Doenças das Cabras/genética , Doenças das Cabras/patologia , Cabras , Masculino , Proteínas Priônicas
2.
J Laryngol Otol ; 136(7): 649-653, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35000623

RESUMO

OBJECTIVE: The main objective was to assess the prevalence of dysphagia in the intensive care unit in patients with coronavirus disease 2019.Methods. A cohort, observational, retrospective study was conducted of patients admitted to the intensive care unit for severe acute respiratory syndrome coronavirus 2 pneumonia at the University Hospital of Rouen in France. RESULTS: Over 4 months, 58 patients were intubated and ventilated, 43 of whom were evaluated. Screening revealed post-extubation dysphagia in 62.7 per cent of patients. In univariate analysis, a significant association was found between the presence of dysphagia and: the severity of the initial pathology, the duration of intubation, the duration of curare use, the degree of muscle weakness and the severity indicated on the initial scan. At the end of intensive care unit treatment, 22 per cent of the dysphagic patients had a normal diet, 56 per cent had an adapted diet and 22 per cent still received exclusive tube feeding. CONCLUSION: Post-extubation dysphagia is frequent and needs to be investigated.


Assuntos
COVID-19 , Transtornos de Deglutição , COVID-19/complicações , COVID-19/epidemiologia , Estudos de Coortes , Transtornos de Deglutição/complicações , Transtornos de Deglutição/etiologia , Humanos , Unidades de Terapia Intensiva , Prevalência , Estudos Retrospectivos
3.
Open Biol ; 11(11): 210117, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34784793

RESUMO

Poultry are the main source of human infection by Salmonella. As infected poultry are asymptomatic, identifying infected poultry farms is difficult, thus controlling animal infections is of primary importance. As cell tropism is known to govern disease, our aim was therefore to identify infected host-cell types in the organs of chicks known to be involved in Salmonella infection and investigate the role of the three known invasion factors in this process (T3SS-1, Rck and PagN). Chicks were inoculated with wild-type or isogenic fluorescent Salmonella Typhimurium mutants via the intracoelomic route. Our results show that liver, spleen, gall bladder and aortic vessels could be foci of infection, and that phagocytic and non-phagocytic cells, including immune, epithelial and endothelial cells, are invaded in vivo in each organ. Moreover, a mutant defective for the T3SS-1, Rck and PagN remained able to colonize organs like the wild-type strain and invaded non-phagocytic cells in each organ studied. As the infection of the gall bladder had not previously been described in chicks, invasion of gall bladder cells was confirmed by immunohistochemistry and infection was shown to last several weeks after inoculation. Altogether, for the first time these findings provide insights into cell tropism of Salmonella in relevant organs involved in Salmonella infection in chicks and also demonstrate that the known invasion factors are not required for entry into these cell types.


Assuntos
Proteínas de Bactérias/genética , Galinhas/microbiologia , Mutação , Salmonelose Animal/microbiologia , Salmonella typhimurium/patogenicidade , Animais , Aorta/microbiologia , Carga Bacteriana , Vesícula Biliar/microbiologia , Fígado/microbiologia , Salmonella typhimurium/genética , Baço/microbiologia , Tropismo Viral
4.
Chem Commun (Camb) ; 51(78): 14574-7, 2015 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-26083202

RESUMO

Electrospun carbon nanofibres (CNFs) containing CNTs were produced by electrospinning and subsequent thermal treatment. This material was evaluated as a bioelectrode for biofuel cell applications after covalent grafting of laccase. Bis-pyrene-modified ABTS was used as a plug to wire laccase to the nanofibres leading to a maximum current density of 100 µA cm(-2).

5.
J Clin Endocrinol Metab ; 83(10): 3563-8, 1998 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-9768665

RESUMO

An association between vitamin D receptor (VDR) gene polymorphism and body size has been observed in infants. We hypothesized that the estradiol receptor (ER) gene is another determinant of infant growth and that the effects of the VDR and ER genotypes may interact with each other. The ER genotype (PvuII and XbaI sites), VDR genotype (BsmI site), and body size during the first 2 yr of life were analyzed in 161 healthy Caucasian full-term babies homozygous for the BsmI polymorphism of the VDR gene (BB or bb). There was no significant association between ER polymorphism and 1) body weight in boys and girls, 2) body length in girls, or 3) body length in boys with a bb genotype. In contrast, ER polymorphism and body length were significantly associated in BB boys. Boys with the BBpp genotype were shorter at birth (P < 0.005) and at 10 months of age (P < 0.001) than boys with other genotypes. They were even shorter than girls with the same genotype. These results indicate some degree of interaction between the effects of the VDR and ER genes, leading to significant variations in body growth during infancy, especially in boys.


Assuntos
Desenvolvimento Infantil/fisiologia , Polimorfismo Genético/fisiologia , Receptores de Calcitriol/genética , Receptores de Estradiol/genética , Antropometria , Constituição Corporal/fisiologia , Estatura/fisiologia , Peso Corporal/fisiologia , Pré-Escolar , Feminino , Genótipo , Homozigoto , Humanos , Lactente , Masculino
6.
J Clin Endocrinol Metab ; 82(9): 2966-70, 1997 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-9284728

RESUMO

An association between vitamin D receptor (VDR) gene polymorphisms and bone mass variance has been observed in adult populations. To analyze possible association between VDR genotype and growth, we studied 589 healthy infants who were homogeneous for age, diet, and vitamin D status. The Bsm I, TaqI, and ApaI alleles' frequencies and genotypes were similar to those reported for Caucasian populations. Variations in Bsm I polymorphism were not associated with calcium intakes nor with serum levels of calcium, 25-hydroxyvitamin D, 1, 25-dihydroxyvitamin D, or alkaline phosphatase activity. But, they were associated with differences in body size. At 2 yr, homozygote BB (BsmI site absent) girls had higher length, weight and body surface area, and inversely, BB boys had lower weight, body mass index and body surface area, than their respective bb counterparts. As a result, gender-related differences were observed in Bb and bb, but not in BB populations. This VDR genotypic effect was observed also at birth and at 10 months in the longitudinal analysis of 145 selected full-term babies homozygous for the Bsm I polymorphism. These findings provide support for the hypothesis that VDR genotype influences intrauterine and early postnatal growth, directly or via interactions with gender-related growth regulators.


Assuntos
Desenvolvimento Infantil , Polimorfismo Genético , Receptores de Calcitriol/genética , Caracteres Sexuais , Alelos , Antropometria , Constituição Corporal , Pré-Escolar , Estudos de Coortes , Estudos Transversais , Feminino , Frequência do Gene , Genótipo , Humanos , Lactente , Estudos Longitudinais , Masculino
7.
J Clin Endocrinol Metab ; 82(9): 2971-7, 1997 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-9284729

RESUMO

The correlations among age, gender, body size parameters, and type I collagen metabolism were evaluated in 183 healthy infants, aged 8.5-27.5 months. Collagen formation was assessed by measuring serum type I collagen carboxy-terminal propeptide, and degradation was determined by urinary pyridinoline and deoxypyridinoline (measured by high performance liquid chromatography) and cross-linked N- and C-terminal telopeptides of type I collagen (measured by NTx and CrossLaps assays). A new RIA specific for deoxypyridinoline was also evaluated. The results provide reference values at 10 months and 2 yr of age, including cross-linked C-terminal telopeptides (1492 +/- 685 and 1510 +/- 446 in boys; 1705 +/- 612 and 1849 +/- 611 micrograms/mmol creatinine in girls; mean +/- 1 SD). There was a good correlation between the high performance liquid chromatography and RIA data for deoxypyridinoline, showing that the RIA method is suitable for use in healthy children. Some correlations were found among peptide-bound cross-links, serum type I collagen carboxy-terminal propeptide, and the anthropometric parameters, suggesting that these peptides reflect bone resorption and also overall body type I collagen. Finally, there were age- and sex-related differences in the urinary excretion of the collagen degradation markers, suggesting that, unlike boys, girls maintain a high degree of collagen degradation up to the age of 24 months despite a decrease in their rate of collagen formation.


Assuntos
Envelhecimento/metabolismo , Colágeno/metabolismo , Peptídeos/metabolismo , Caracteres Sexuais , Envelhecimento/urina , Biomarcadores/urina , Pré-Escolar , Colágeno Tipo I , Feminino , Humanos , Lactente , Masculino , Valores de Referência
8.
Physiol Behav ; 59(3): 403-7, 1996 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-8700939

RESUMO

Individual patterns of food intake development have been investigated on the basis of a longitudinal study of nutrition and growth carried out in 112 children at the ages of 10 months, and 2, 4, 6, and 8 years. On the average, energy intake increased steadily with age. However, individual subjects sometimes followed a different pattern. Approximately 1 out of 5 subjects decreased their intake between two examinations. Besides, less than half the children (43%) were in the same category of energy intake (defined as tertiles) at 10 months and 8 years of age. Similarly, 47% of the children were in the same weight/height (BMI) category at 10 months and 8 years. Correlations computed between early intakes (10 months, and 2, 4, and 6 years) and intakes at 8 years were better for energy and protein intake than for fat and carbohydrates (CHO), showing that intake of energy or protein early in life has a better predictive value of intake at later ages. Energy intake development has been examined in those children who were found to be lean, medium, and fat at the age of 8 years; it increased more between the ages of 4 and 6 years, in children who were fat at 8 years. Individual variations of anthropometric measurements during growth are well documented. The present study points out that similar individual variations of intake also exists. These variations could reflect regulatory processes acting during growth and should be taken into account in investigating the child's appetite.


Assuntos
Ingestão de Alimentos , Preferências Alimentares/psicologia , Crescimento/fisiologia , Fenômenos Fisiológicos da Nutrição/fisiologia , Composição Corporal , Estatura/fisiologia , Peso Corporal/fisiologia , Criança , Pré-Escolar , Dieta , Carboidratos da Dieta/administração & dosagem , Gorduras na Dieta/administração & dosagem , Proteínas Alimentares/administração & dosagem , Metabolismo Energético , Seguimentos , Humanos , Lactente , Estudos Longitudinais
9.
Eur J Clin Nutr ; 48(1): 54-9, 1994 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-8200329

RESUMO

Urinary iodine excretion was assessed in 1222 healthy children aged 10 months (n = 456), 2 years (n = 368) and 4 years (n = 398) living in the Paris area and originating from continental France (55.2%), North Africa (15.7%), the West Indies (9.7%), West Africa (8.2%), Southeast Asia (5.5%), and southern Europe (5.7%). Iodine excretions (median values) were, respectively, 18.1, 13.4 and 11.6 micrograms/100 ml at 10 months, 2 years and 4 years, and risk of mild to moderate iodine deficiency (< 10 micrograms/100 ml) was 18.0%, 32.3% and 37.2% for the same age groups. Urinary iodine excretion was highest among Southeast Asian children, and lowest among West Africans. Hearing acuity was measured either by conventional mono-aural pure-tone audiometry or by binaural free field testing depending on the child's age. Hearing loss at 4000 Hz and average hearing impairment at speech frequencies (500, 1000 and 2000 Hz) were more severe among children at risk of mild to moderate iodine deficiency (less than 10 micrograms/100 ml) compared with those with urinary excretion above 10 micrograms/100 ml.


Assuntos
Transtornos da Audição/urina , Iodo/deficiência , Antropometria , Audiometria de Tons Puros , Estatura , Peso Corporal , Pré-Escolar , Transtornos da Audição/diagnóstico , Transtornos da Audição/etiologia , Transtornos da Audição/fisiopatologia , Humanos , Lactente , Iodo/urina , Fatores de Risco
10.
Eur J Clin Nutr ; 45(1): 13-21, 1991 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-1855495

RESUMO

This report provides Body Mass Index (weight/height2) values for the French population from birth to the age of 87 years. BMI curves increase during the first year, decrease until the age of 6, increase again up to 65 years and decrease thereafter. These variations reflect the total changes of fat body mass during life. The 50th centile values of Wt/Ht2 at the ages of 20, 40, 60, 80 years are 21.5, 24.6, 25.4, 24.4 kg/m2 for men and 20.6, 22.6, 24.1, 23.4 kg/m2 for women. The values for the 3rd, 50th and 97th centiles in the middle years are approximately 18, 24 and 32 kg/m2. Graphs for these and four other percentiles are plotted against age, and two other graphs summarising the variation and skewness of the Wt/Ht2 distribution are provided to calculate exact percentiles and Z-scores for individuals.


Assuntos
Envelhecimento/fisiologia , Índice de Massa Corporal , Estado Nutricional , Feminino , França , Humanos , Estudos Longitudinais , Masculino , Valores de Referência , Fatores Sexuais
11.
In Vitro Cell Dev Biol Anim ; 29A(10): 773-81, 1993 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-8118612

RESUMO

In the avian embryo, vascular smooth muscle cells (VSMC) in the aortic arch (elastic) arteries originate in the neural crest, whereas other VSMC develop from local mesoderm. These two lineages have been shown previously to be significantly different in the timing and expression of the smooth muscle phenotype and in their respective abilities to produce an orderly elastic matrix. Two differing kinds of VSMC also have been shown in mammals. In the experimental absence of neural crest (NC) in the avian embryo, the matrix is spatially disordered. The molecular basis of the difference between the normal NC-VSMC and the surrogate mesodermal (MDM)-VSMC has not previously been investigated. In this study the expression of vascular smooth muscle alpha-actin, tropoelastin, c-fos and c-jun were examined via immunoblotting, immunohistochemistry, Northern blot, and/or transcription run-on assays. Control avian VSMC of NC origin were compared with experimental MDM-derived VSMC that populate the cardiac outflow after surgical ablation of the NC. The results show that, when they are grown under identical conditions in vitro or freshly removed from an embryonic vessel, surrogate MDM-VSMC express about 10 times more alpha-actin and tropoelastin than the normal NC-VSMC; and MDM-VSMC express up to 15 times more c-jun, whereas c-fos was not different. These results show profound heterogeneity in the regulation of VSMC-specific genes that is based in the embryonic lineage of the cells.


Assuntos
Actinas/biossíntese , Elastina/biossíntese , Músculo Liso Vascular/metabolismo , Proteínas Proto-Oncogênicas c-jun/biossíntese , Actinas/genética , Animais , Northern Blotting , Células Cultivadas , Embrião de Galinha , Elastina/genética , Imunofluorescência , Músculo Liso Vascular/citologia , Músculo Liso Vascular/embriologia , Proteínas Proto-Oncogênicas c-fos/biossíntese , Proteínas Proto-Oncogênicas c-fos/genética , Proteínas Proto-Oncogênicas c-jun/genética , RNA Mensageiro/metabolismo
12.
Biol Trace Elem Res ; 32: 259-66, 1992.
Artigo em Inglês | MEDLINE | ID: mdl-1375063

RESUMO

Urinary iodine excretion was assessed in 642 healthy children aged 10 mo (n = 243), 2 yr (n = 183), and 4 yr (n = 216) living in the Paris area and originating from continental France (60.3%), North Africa (13.8%), the West Indies (9.1%), West Africa (8.3%), Southeast Asia (4.8%), and southern Europe (3.8%). Mild impairment of neurological (reflexes, tone, audiometry) and intellectual development (Brunet-Lézine scale) was assessed in relation to iodine status. Iodine excretions (median values) were 18.4, 11.9, and 10.9 micrograms/100 mL at 10 mo, 2 yr, and 4 yr, respectively, and risk of mild iodine deficiency (5-10 micrograms/100 mL) was 18.1%, 34.8%, and 38.3% for the same age groups. No relationship was found between anthropometry, global development quotient, and iodine status. High hearing thresholds were more commonly associated with lower iodine excretion, suggesting mild hearing defects. In spite of iodine prophylaxis, the risk of mild to moderate iodine deficiency still exists in France and in a number of European countries. Evaluation of neurological sequels of borderline iodine status is a major public health problem in European communities.


Assuntos
Envelhecimento/urina , Dieta , Iodo/urina , Pré-Escolar , Deficiências Nutricionais/complicações , Deficiências Nutricionais/etiologia , Deficiências Nutricionais/urina , França , Perda Auditiva/etiologia , Humanos , Lactente , Iodo/deficiência
13.
J Fr Ophtalmol ; 8(8-9): 549-54, 1985.
Artigo em Francês | MEDLINE | ID: mdl-4086730

RESUMO

Ophthalmological examination is part of a comprehensive examination in children under 4 years of age. Screening priorities are: strabismus examination at 10 months and 2 years of age; assessment of distant visual acuity at 2 years of age; assessment of monocular far and near acuity in association with colored vision screening at 4 years of age. Out of 130 000 check ups carried out by ophthalmologists in the Bilan de Santé de l'Enfant: At 10 months and 2 years of age: one child out of five presented ophthalmological anomalies of various degrees; At 4 years of age, one child out of four. One anomaly out of five required immediate treatment. Strabismus was noted in one child out of 28 for all ages considered. In the first year of age, the risk factors for ophthalmological anomalies were: prematurity, dysmaturity, neo-natal pathology, a familial past history of ophthalmic anomalies. These children must be routinely examined prior to the age of 2 years by an ophthalmologist trained in the examination of young children. The decision to refer to the ophthalmologist is the pediatrician's responsibility.


Assuntos
Programas de Rastreamento/métodos , Transtornos da Visão/epidemiologia , Ambliopia/prevenção & controle , Pré-Escolar , Oftalmopatias/genética , Humanos , Lactente , Recém-Nascido de Baixo Peso , Recém-Nascido , Recém-Nascido Prematuro , Erros de Refração/epidemiologia , Risco , Estrabismo/epidemiologia , Estrabismo/terapia , Fatores de Tempo
14.
Presse Med ; 21(22): 1017-21, 1992 Jun 13.
Artigo em Francês | MEDLINE | ID: mdl-1387214

RESUMO

Between April 1988 and February 1990, 3,007 cases of female breast cancer were recorded among people insured by CANAM*; 118 cancers were bilateral from the start and 2,889 were unilateral. At the time of diagnosis the patients' age ranged from 24 to 101 years (median: 60 years), and 35.6 percent of the tumours were virtually subclinical. Lymph node involvement was clinically absent in 75 percent of the cases and histologically absent in 57 percent. In women under 50 the proportion of small TO-T1 tumours was greater than 40 percent, which pleaded for detection before the age of 50 years. Conversely, in economically weak populations and in women who were followed up for cancerous disease, breast cancer was diagnosed at a later stage. In older (retired) women (median age: 74), who accounted for 44 percent of the whole population, the proportion of advanced tumours was practically doubled (T4: 11 percent versus 6 percent), and the probability of metastases at the time of diagnosis had risen from 4.2 to 6.1 percent. In these patients, clinical examination once a year should contribute to an earlier diagnosis.


Assuntos
Neoplasias da Mama/diagnóstico , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Neoplasias da Mama/epidemiologia , Neoplasias da Mama/patologia , Feminino , França , Humanos , Mamografia , Pessoa de Meia-Idade , Fatores Socioeconômicos
15.
Bull Acad Natl Med ; 174(6): 719-29; discussion 729-30, 1990.
Artigo em Francês | MEDLINE | ID: mdl-2271981

RESUMO

Since its creation, the Medical Service of Health Insurance has known an important evolution. Initially, its essential role was to control the allowances paid to the insured persons of the regimes of Health Insurance. Its aspect was rather coercive. But since 1960 a change has been outlined with the creation of the "Haut Comité Médical de la Sécurité Sociale": the Medical Control left its place to the Medical Service. With this denomination, its functions never stopped expanding. The Medical Service maintained its tasks of control devolved by the different regulations, and that is how it falls to it to express a view about long term diseases, disability occupational injuries, etc. It is also responsible for setting up "selective" controls with regard to some of medical or ancillary medical acts. But this taskwork is coupled with an important activity: the counsel. This responsibility is orientated in three directions: the Health Insurance Associations, the insured persons, and the Health Professions particularly as a part of the conventions binding them to the organizations of the French social protection system. During these last years new date intervened in health insurance matters in consequence of the economical crisis. Henceforward, it suits to find just a balance between a social protection of a high standard and adapted care of quality for the best cost. New opportunities are offered to the Medical Service to face this situation and gave it also a fresh impulse. This new evolution fits into an activity of public health considering the progress of the medicine. This activity must be orientated to a better knowledge of dispensed care and its good employment. Several orientations must be detained. In disease matters, informations in possession of the medical services are to be operated and, thanks to the data processing, a balance sheet of expenses will be drawn up, comparing them with diagnostic and therapeutic means. These studies, whose results will be published, must be guided with an exemplary scientific strictness and be supported by uncontested leading people in the medical world. Hospitalization is the other field where the role of the medical service must be essential. It certainly charges to continue the individual controls. But it must go further and be interested in the hospital working, as well as in the aggregate as by hospital service. This permits to get indispensable informations for useful decisions in view of a better hospitalisation.(ABSTRACT TRUNCATED AT 400 WORDS)


Assuntos
Serviços de Saúde/tendências , Seguro Saúde/tendências , Custos e Análise de Custo , Previsões , França , Serviços de Saúde/economia , Administração de Serviços de Saúde , Humanos , Seguro Saúde/economia , Seguro Saúde/organização & administração , Qualidade da Assistência à Saúde , Previdência Social
16.
Bull Acad Natl Med ; 178(1): 85-94; discussion 94-6, 1994 Jan.
Artigo em Francês | MEDLINE | ID: mdl-8038997

RESUMO

Since 1970, the "Caisse Primaire d'Assurance Maladie de Paris" carries out free periodic health examinations of apparently healthy children aged 10 months, 2 years and 4 years. Routine medical check-up last 3.50 hours, and included 800 items recorded on computerized forms. Of the 15,000 children annually screened, 21% were found to be normal, and unsuspected medical diagnosis were made in 11,500 of these children (79%), despite one or more previous evaluations by a physician. Altogether 27,400 abnormalities were detected (mean: 2.2) with a high rate of missed diagnosis (87%). The majour risks of medical problems were, in the four-year age group: 1/ abnormal vision (32%) 2/ abnormal audiological examination (13%), 3/ abnormal behavior and delayed development test performance (22%), 4/ poor nutritional status, 43% being reported as iron-deficient anemic children. These results warrant the use of selected screening tests to determine the type of injuries amenable to future early preventive measures of Public Health.


Assuntos
Triagem Multifásica , Pediatria , Prevenção Primária , Pré-Escolar , Estudos de Avaliação como Assunto , Humanos , Lactente , Seguro Saúde , Paris
17.
Ultrasonics ; 50(2): 202-7, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19879618

RESUMO

A 100 fs laser pulse passes through a single transparent cell and is absorbed at the surface of a metallic substrate. Picosecond acoustic waves are generated and propagate through the cell in contact with the metal. Interaction of the high frequency acoustic pulse with a probe laser light gives rise to Brillouin oscillations. The measurements are thus made with lasers for both the opto-acoustic generation and the acousto-optic detection, and acoustic frequencies as high as 11 GHz can be detected, as reported in this paper. The technique offers perspectives for single cell imaging. The in-plane resolution is limited by the pump and probe spot sizes, i.e. approximately 1 microm, and the in-depth resolution is provided by the acoustic frequencies, typically in the GHz range. The effect of the technique on cell safety is discussed. Experiments achieved in vegetal cells illustrate the reproducibility and sensitivity of the measurements. The acoustic responses of cell organelles are significantly different. The results support the potentialities of the hypersonic non-invasive technique in the fields of bio-engineering and medicine.


Assuntos
Acústica/instrumentação , Allium , Células/efeitos da radiação , Óptica e Fotônica/instrumentação , Absorção , Técnicas In Vitro , Lasers , Reprodutibilidade dos Testes , Espalhamento de Radiação , Temperatura , Titânio
19.
Ultrasonics ; 48(6-7): 574-7, 2008 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-18790512

RESUMO

In this paper, acute focusing of the laser pump beam ( approximately 0.5 microm) on the sample surface allows picosecond acoustic diffraction in thin metallic films. The resulting wavefronts propagate at a group velocity which differs from phase velocities in anisotropic films. Waveforms have been experimentally recorded in a gold layer (2.1 microm thick) for several distances between pump and probe on the sample surface. A specified signal processing based on a Synthetic Focalization Technique allows analyzing the space repartition of the acoustic wave vectors for both longitudinal and shear waves. Stiffness coefficients of the gold layer are then identified from wave arrival times.

20.
Ultrasonics ; 44 Suppl 1: e1249-53, 2006 Dec 22.
Artigo em Inglês | MEDLINE | ID: mdl-16806352

RESUMO

A theoretical solution is presented to identify laser-generated ultrasounds in the transient response over time and space of a cylinder impacted by a laser line pulse. Theoretical radial displacements at various observation angles are obtained for an aluminum cylinder under thermoelastic regime. The corresponding displacements are observed experimentally by the laser ultrasonic technique. Good agreement is found in the time arrival, shape and relative amplitude of surface waves and various longitudinal and transverse bulk waves. These laser-generated ultrasounds are further identified by the ray trajectory analysis. This work will be helpful for the inverse problem of the nondestructive evaluation of cylinder parts.

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