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N Guérin

Publications and source records attributed to N Guérin.

At least 37 records · Page 2Linked to original sources
PubMed1998

Multiresolution texture based adaptive clustering algorithm for breast lesion segmentation.

OBJECTIVE: A specific algorithm is presented for the automatic extraction of breast tumors in ultrasonic imaging. METHOD: The algorithm involves two-dimensional adaptive K-means clustering of the gray scale and textural feature images. The segmentation problem is formulated as a maximum a posteriori (MAP) estimation problem. The MAP estimation is achieved using Besag's iterated conditional modes algorithm for the minimization of an energy function. This function has three components: the first constrains the region to be close to the data; the second imposes spatial continuity; and the third takes into consideration the texture of the various regions. A multiresolution implementation of the algorithm is performed using a waveless basis. RESULTS: Experiments were carried out on synthetic images and on in vivo breast ultrasound images. Various parameters involved in the algorithm are discussed to evaluate the robustness and accuracy of the segmentation method. CONCLUSION: Including textural features in the segmentation of ultrasonic data improves the robustness of the algorithm and makes the segmentation result less parameter dependent.

Adenocarcinoma↗
PubMed1998

[Expanded program of vaccination. Results and prospects].

The expanded program on immunization, jointly launched by WHO and UNICEF in 1974 aimed in the beginning at immunizing 80% of the children of the world against measles, tetanus, pertussis, poliomyelitis, diphtheria and tuberculosis. After reaching the objectives in 1990, countries have been urged towards eradication of poliomyelitis, elimination of neonatal tetanus, and measles control. Immunization against hepatitis B and yellow fever were also proposed according to local epidemiology. Tremendous results have been already delivered: the American continent has eliminated poliomyelitis since August 1991, it has reduced dramatically the incidence of measles. All the countries, including those from Africa, are organizing campaigns aiming at polio eradication. Active surveillance systems have been implemented. But financial and operational constraints persist, linked to vaccines prices, their heat sensitivity, injection techniques, and to the sterilisation and waste disposal. Major efforts are still needed.

Adolescent↗
PubMed1997

[Lingual thyroid and intra-lingual thyroglossal cyst. Apropos of 2 cases].

Lingual thyroid and intra lingual thyro-glossal cyst are two benign tumours of similar embryological pathogenesis respectively with the arrest in the ectopic position of the thyroid gland during its downward migration and from abnormal persistence of the thyro-glossal tract for the cyst. The occurrence of lingual thyroid is rare 1/100,000 patients and outnumbers the incidence of intra-lingual cyst which represents an estimated 2.1% of the thyro-glossal cysts or fistulas. Both lesions are a rare cause of dysphagia and dyspnoea due to oropharyngeal obstruction, and radionuclide scintigraphy combined with CT and/or MRI will establish the diagnosis. Surgical pharyngotomy with an infra-hyoid approach provides excellent access to the lesions and complete removal of the tumours.

Adolescent↗
PubMed1996

[Osteoma of the mastoid: apropos of 2 cases].

The authors report two cases of mastoid osteoma: it is a rare benign tumor attached to the cortex of the mastoid bone, approximatively fifty cases have been described in the english language literature and eight in the french literature. The clinical and radiological characteristics combined with histopathologic evidence demonstrate the diagnosis of mastoid osteoma, the most common type being the compact osteoma. Differential diagnosis should be considered with others benign bone-forming lesions (osteochondroma, chondroma, osteoblastoma, exostosis, fibrous dysplasia...) and with malignant lesions (osteosarcoma...). Surgical removal proposed for cosmetic deformity is a simple procedure for the vast majority of small osteomas. Early surgical intervention is recommended to avoid the evolution toward giant osteoma with potential risks of surgical complications.

Adult↗
PubMed1996

[Stereotaxic mammary microbiopsy. I. Technical aspects].

The authors present a review of the literature about the procedure of stereotactic core breast biopsy. Developed since the beginning of the 1990s, this histopathological sampling technique presents numerous advantages. Its low cost, its simplicity and its diagnostic efficacy are the main arguments for its development. The diagnostic efficacy confirmed on clinical trials (see 2nd part of article) must be preserved if core biopsy is performed routinely. This means avoiding wrong choices in indications and respecting evaluated procedures.

Biopsy, Needle↗
PubMed1995

Efficacy of BCG vaccination of the newborn: evaluation by a follow-up study of contacts in Bangui.

BACKGROUND: The efficacy of Bacillus of Calmette and Guérin (BCG) vaccination given at birth is still controversial. We therefore conducted a study in Bangui (Central African Republic) to estimate the protection afforded over the first seven years of life by BCG administered at birth. METHODS: One thousand children who had lived in contact with a recently diagnosed case of contagious tuberculosis were followed up for a period of 6 months in order to detect the occurrence of tuberculosis. Diagnosis of tuberculosis was made through a scoring system. Vaccine efficacy (VE) was calculated on the basis of the relative risk of contracting tuberculosis according to vaccination status. RESULTS: The efficacy of BCG was estimated to be 71% (95% confidence interval: 56-81%). This result remained practically the same after changing the definition used for tuberculosis cases (VE = 75% for a threshold with a score of 15 instead of 6, VE = 74% when only confirmed cases were considered). There was no difference between the two groups in the variables measuring intensity of contact with the source of contamination, but there was a difference in age distribution. Vaccine efficacy adjusted for this factor was the same as the crude VE. CONCLUSION: This study, based on a methodology that controls for most of the risks of bias inherent to field efficacy measurement, confirms the protective capacity of neonatal BCG against childhood tuberculosis. Therefore BCG vaccination at birth must remain a public health priority especially in countries with high incidence of the disease.

BCG Vaccine↗
PubMed1993

Weekly changes in psychophysiological variables of 8- to 10-year-old school girls.

Three groups of schoolgirls 8, 9, and 10 years of age, respectively, self assessed sleep onset/offset and duration, as well as oral temperature and a set of cognitive measures, at school at 09:00, 11:00, 14:00, and 16:00 h on Mondays, Tuesdays, Thursdays, and Fridays (and/or Saturday) for 2 consecutive weeks (spring 1987 and 1989). The scores of a letter cancellation test exhibited neither daily nor weekly temporal variation at the age of 8 years [analysis of variance (ANOVA), p > 0.05]. In contrast, in the 10-year-olds, changes as a function of both time of day (peak time 14:00-16:00 h) and day of week (peak day Tuesday-Friday) were substantiated. Moreover, the time of best performance on the letter cancellation test varied systematically according to the day of the week (ANOVA, p = 0.000). Day of the week changes in the observed duration of sleep, self-rated fatigue, drowsiness, and attention changes were not detected in any of the age groups. It is hypothesized that temporal performance variations in the girls during the 7-day period was age related.

Age Factors↗
PubMed1992

[The prophylaxis of tuberculosis and vaccination with BCG. A recent study].

The efficacy of BCG immunization for the prevention of tuberculosis was prospectively studied in Togo in 705 infants and children aged 1 month to 6 years (319 boys and 386 girls). Five-hundred and four subjects had received the BCG vaccine and 201 had not. All the subjects were exposed to an adult with tuberculosis. Studied subjects were followed up for the development of tuberculosis with physical evaluations, simple biologic tests (blood cell counts and ESR), roentgenograms, and sputum analyses. WHO scores were used to establish the diagnosis of tuberculosis. Tuberculosis was identified in 53.4% of unvaccinated subjects versus 5.3% of vaccinated subjects. Close contact with the index case (e.g., tuberculosis in the mother) was associated with an increased likelihood of tuberculosis. These findings clearly demonstrate the incomplete but substantial protective effect of the BCG vaccine in subjects exposed to tuberculous patients and provide further support for use of the BCG vaccine.

BCG Vaccine↗
PubMed1991

Determination of circulating antibodies directed to pertussis toxin and of agglutinogens in children vaccinated with either the whole cell or component pertussis vaccine in France, Japan and Senegal.

The antibody response to pertussis toxin (PT) and agglutinogens of children vaccinated in Japan, France and Senegal with either whole cell or component pertussis vaccine was determined at various times after immunization. Agglutinin titres were almost similar in sera of Japanese children vaccinated with either whole cell or component pertussis vaccine whereas anti-PT antibody levels were found to be higher after vaccination with whole cell vaccine than with component vaccine. The geometric mean (GM) agglutinin titres in sera of Japanese children amounted to 45.0 and 45.7, respectively, and neutralization GM titres to 71.6 and 22.6, respectively, following vaccination with the whole cell and component pertussis vaccines. Sera of French children receiving three doses of whole cell vaccine exhibited a GM agglutinin titre of 17.8, whereas only 16% of sera contained neutralizing antibodies against PT. Following the booster dose the GM agglutinin titre rose to 213.5 and 68% of the sera contained neutralizing antibodies to PT (GM titre 48.0). Sera of Senegalese children receiving three doses of whole cell vaccine exhibited a GM agglutinin titre of 18.7, whereas anti-PT neutralizing antibodies were hardly detected. Agglutinins and anti-PT antibody in sera of French and Senegalese children turned out to be lower than were found 25 years ago in sera of children immunized with the French whole cell pertussis vaccine.

Adolescent↗
PubMed1991

Diurnal changes in psychophysiological variables of school girls: comparison with regard to age and teacher's appreciation of learning.

Ninety-five nonresident girls of a private school volunteered for the study with the teachers' help as well as parental consent. Ages were approximately 8, 9, and 10 years. They were synchronized with diurnal activity from 0730 to 2100 h and nocturnal rest. Fatigue, drowsiness, and attention were self-rated using visual analogue scales; oral temperature was self-measured and a letter cancellation test was performed. Each of these variables was measured at school at 0900, 1100, 1400, and 1600 h on Mondays, Thursdays, Fridays, and Saturdays for two consecutive weeks in 1987 (March 30-April 11) and again in 1989 (March 13-25) when the youngest group had become 10 years old. According to conventional teacher evaluation of learning (learning performance) within each group, three subgroups were formed: top third, middle third, and bottom third. Time series (more than 50,000 data) were analyzed according to several statistical methods, but mainly chronograms with ANOVA. Similar diurnal changes in oral temperature were validated for each group and subgroups. The occurrence of a diurnal change in self-rated variables (fatigue and drowsiness) and score in letter cancellation was age related: no detection in the 8-year-old group (and subgroups) and validation (p less than 0.002) in 9- and 10-year-old groups (and respective subgroups). A good learning performance was associated with a reduced drowsiness in school girls of 9 and 10 years. Age-related, time-of-day differences in drowsiness (when detected) as well as learning performance effect were not associated with observed duration of sleep. Validated changes in self-rated fatigue were close to that of drowsiness. At 0900 h, girls of 9 and 10 years were more tired when belonging to the bottom third than top third subgroup. Whatever the time of day, self-rated attention was greater in the top than in the bottom third for these girls. Differences related to learning performance were validated in each grade. However, best scores were recorded for the bottom third in the 8-year-old group, while best scores were provided by top third subgroups in 10-year-old girls. It seems that in girls around 8 years of age, critical changes can be detected with regard to the (ontogenic?) occurrence of time-of-day differences in a set of psychophysiologic variables as well as influential effects of learning performance on the same variables. Reported finding are compatible with the hypothesis of circadian oscillators working at the level of the cortex of the human brain.

Age Factors↗
PubMed1991

[Role of BCG in the enlarged program of vaccination].

The BCG vaccine is the most given throughout the world, and the immunization coverage is the highest: 72% in 1989 for children under one year of age. Following doubts which appeared in 1980 concerning its efficacy, many epidemiological studies confirmed the protective potency of this immunization against the severe forms of tuberculosis in children. Recent problems of tolerance arose but are now resolved by the adaptation of the vaccine concentration to the routine immunization of newborns. The world wide epidemic of AIDS and the concomitant recent increase in tuberculosis cases encourage to sustain the effort of immunization of infants. However, questions of theoretical interest have been shelved on this subject: is it reasonable to immunize HIV positive children in absence of clinical signs in countries with high prevalence? Is the vaccine effective in these special cases? Is it safe? In any case, it is the only effective and cheap way, and probably with no risk, of preventing child tuberculosis meningitis in endemic disease countries.

Acquired Immunodeficiency Syndrome↗
PubMed1991

[Comparative serological efficacy of the measles vaccine strains Edmonston-Zagreb, Schwarz and AIK-C in Togolese infants of 4-5 months and 8-10 months].

To examine the value of vaccinating children against measles at age 4-5 months three groups of children in Togo were randomly assigned to receive high-dose Edmonston-Zagreb, high-dose Schwarz, or AIK-C vaccines at that age. Two other groups were vaccinated at age 8-10 months, with either the standard Schwarz vaccine or the same batch of AIK-C as for early immunization. For the 55% of children who were seronegative before vaccination at age 4-5 months, the seroconversion rates were 96% with the AIK-C, 94% with the Edmonston-Zagreb, and 50% with the high-dose Schwarz. The immune response rates for children who were seropositive before vaccination were estimated to be around 50% with the high-dose Edmonston-Zagreb and AIK-C strains and 10% with the Schwarz strain. The seroconversion rates for vaccination at 8-10 months were 87% for the AIK-C and 68% for the Schwarz strains. Thus vaccinations with the high-dose Edmonston-Zagreb or the AIK-C strain at 4-5 months as good as vaccination with the AIK-C strain at 8-10 months better than vaccination with the standard dose Schwarz strain at 8-10 months. These findings require confirmation by further investigations, particularly epidemiological studies, but they already provide evidence that administration of AIK-C and high-dose Edmonston-Zagreb strains at 4-5 months is at least as effective as vaccination with the standard strains at 8-10 months.

Age Factors↗
PubMed1990

[Legal time shifting and biologic rhythms: summer hour in question?].

In France daylight saving time is set on last sunday of march (legal time becomes GMT + 2 h instead of GMT + 1h) and set off last sunday of september. Fifteen years ago when it was established this change of time was generally welcomed by the public. Since then strong rejection reflexes have appeared and an association against the summer daylight saving time has been founded. The arguments sustained by the oponents to this system are based on economical, agricultural and/or health considerations. A growing number of individuals claim they cannot withstand the change of legal time and suffer from various troubles mainly fatigue and sleep disturbances. An alteration of biologic rhythms has been put forward by some to explain these troubles. We will here discuss the problems related to the change of legal time and especially those in the field of health. For the latter we will show that troubles when they are present can not ascribed to a desynchronization.

Biological Clocks↗