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Biomedical subjects

A Collignon

Publications and source records attributed to A Collignon.

At least 37 records · Page 2Linked to original sources
PubMed1997

Multimodality image registration by maximization of mutual information.

A new approach to the problem of multimodality medical image registration is proposed, using a basic concept from information theory, mutual information (MI), or relative entropy, as a new matching criterion. The method presented in this paper applies MI to measure the statistical dependence or information redundancy between the image intensities of corresponding voxels in both images, which is assumed to be maximal if the images are geometrically aligned. Maximization of MI is a very general and powerful criterion, because no assumptions are made regarding the nature of this dependence and no limiting constraints are imposed on the image content of the modalities involved. The accuracy of the MI criterion is validated for rigid body registration of computed tomography (CT), magnetic resonance (MR), and photon emission tomography (PET) images by comparison with the stereotactic registration solution, while robustness is evaluated with respect to implementation issues, such as interpolation and optimization, and image content, including partial overlap and image degradation. Our results demonstrate that subvoxel accuracy with respect to the stereotactic reference solution can be achieved completely automatically and without any prior segmentation, feature extraction, or other preprocessing steps which makes this method very well suited for clinical applications.

Algorithms↗
PubMed1997

[Evaluation of a tool for developmental disorder screening in 4-year-old children].

With the aim of helping physicians working in a "Mother and Infant Protection Service" (PMI) in their mission of children's development difficulties screening, authors tried to assess performances of a clinical tool including parental informations and standardized tests. The whole four years old children going at school in a canton of Calvados department were independently examined by a PMI doctor using the tool to be estimated and by a specialized service working from a beforehand established protocol. For the language disorders on the one hand and the adaptation on the other hand, this evaluation shows a significant correlation between the PMI screening and the specialists one's: the sensitivity of the PMI examination is about 70% for those two types of difficulties with a positive predictive value respectively 28% and 57%. However the tool appears less reliable for the psychomotor disorders screening: only one quarter of the children who require a specialized investigation about these problems have been detected by the PMI screening. A filing and a selection of the questionnaire items should permit to improve the efficiency of this tool.

Child, Preschool↗
PubMed1996

Prevalence and pathogenicity of Clostridium difficile in hospitalized patients. A French multicenter study.

BACKGROUND: Although Clostridium difficile is the main agent responsible for nosocomial diarrhea in adults, its prevalence in stool cultures sent to hospital microbiology laboratories is not clearly established. OBJECTIVES: To determine the prevalence of C difficile in inpatient stools sent to hospital microbiology laboratories and to assess the relationship between serotypes and toxigenicity of the strains isolated and the clinical data. METHODS: From January 18, 1993, to July 31, 1993, the presence of C difficile was systematically investigated in a case-control study on 3921 stool samples sent for stool culture to 11 French hospital microbiology laboratories. The prevalence of C difficile in this population (cases) was compared with that of a group of 229 random hospital controls matched for age, department, and length of stay (controls). Stool culture from controls was requested by the laboratory although not prescribed by the clinical staff. Serotype and toxigenesis of the strains isolated were compared. RESULTS: The overall prevalence of C difficile in the cases was twice the prevalence in the controls (9.7% vs 4.8%; P < .001) and was approximately 4 times as high in diarrheal stools (ie, soft or liquid) as in normally formed stools from controls (11.5% vs 3.3%; P < .001). The strains isolated from diarrheal stools were more frequently toxigenic than those isolated from normally formed stools. Serogroup D was never toxigenic, and its proportion was statistically greater in the controls than in the cases (45% vs 18%; chi 2 = 5.2; P < .05). Conversely, serogroup C was isolated only from the cases. Clostridium difficile was mainly found in older patients ( > 65 years), suffering from a severe disabling disease, who had been treated with antibiotics and hospitalized for more than 1 week in long-stay wards or in intensive care. CONCLUSIONS: This multicenter period prevalence study clearly supports the hypothesis of a common role of C difficile in infectious diarrhea in hospitalized patients. Disease associated with C difficile should therefore be systematically evaluated in diarrheal stools from inpatients.

Anti-Bacterial Agents↗
PubMed1995

Evaluation of a rapid agglutination test for detection of group B streptococci in the gastric aspirates of neonates.

A rapid commercial agglutination test (Bactigen Strepto B) for detection of group B streptococci in gastric aspirates of neonates was evaluated. One hundred and sixty-one gastric samples were analyzed with conventional bacteriological techniques and with the commercial test after modification of the extraction technique. The sensitivity of the test relative to the culture technique was 90.4%, the specificity 94.2%, the positive predictive value 70.3% and the negative predictive value 98.5%. The commercial test could be performed in one hour and showed good sensitivity and specificity. If a test result was negative colonization could be excluded, obviating the need for empirical antibiotic therapy, whereas a positive result suggested colonization or neonatal infection with group B streptococci.

Agglutination Tests↗
PubMed1995

Corynebacterium diphtheriae osteomyelitis in an immunocompetent child: a case report.

UNLABELLED: Septic osteomyelitis of the hip in a previously healthy child is described. A weakly toxigenic Corynebacterium diphtheriae strain was isolated from the bone aspirate. The results of the treatment were rapidly satisfactory, after surgical drainage and antibiotic therapy with pristinamycin. CONCLUSION: This case report shows that C. diphtheriae has not disappeared in the developed world and can be responsible of systemic infections.

Child, Preschool↗
PubMed1995

Value of routine stool cultures in hospitalized patients with diarrhea.

In a prospective study conducted over a six-month period, the relative yield of 721 routine cultures of stool from adult inpatients as a function of the time after hospital admission was assessed. Salmonella, Campylobacter, Shigella or Yersinia spp. were recovered from 10.9% (41/377) of patients within three days of hospitalization and from only 1.5% (5/344) after three days. However, a review of these patients' charts did not suggest nosocomial transmission but rather a delay in stool collection or asymptomatic carriage. Clostridium difficile was isolated with a high frequency in patients both within and after three days of hospitalization (10.3% and 10.2%, respectively). Thus, stool specimens from adults hospitalized for more than three days should not be cultured except for Clostridium difficile unless there are plausible clinical or epidemiological reasons to do so.

Adult↗
PubMed1994

Effects of early chronic diazepam treatment on incorporation of glucose and beta-hydroxybutyrate into cerebral amino acids: relation to undernutrition.

The effects of early chronic diazepam (DZP) exposure on blood glucose and ketone body concentration and glucose and beta-hydroxybutyrate (beta HB) utilization for regional cerebral amino acid biosynthesis were studied in suckling rats. The animals were treated from postnatal day 2 (P2) to 21 (P21) by a daily subcutaneous injection of 10 mg/kg DZP or of the dissolution vehicle and studied at P5, P10, P14 and P21, together with an additional group of food-restricted rats obtained by an increase in litter size. DZP treatment induced a 9-26% decrease in body and brain weight. Undernutrition decreased body weight by 20-24% at all ages whereas brain weight was relatively spared. DZP and N-desmethyldiazepam concentrations decreased with age and were cleared from brain and plasma by 6-8 hrs after the injection. DZP decreased plasma glucose concentrations by 6-12% at P5, P14 and P21, whereas undernutrition did not change plasma glucose concentrations, except for a 7% decrease at P14. DZP treatment had no consequences on circulating concentrations of both ketone bodies while undernutrition increased their concentration by 45-362% at all ages. The conversion of [14C]glucose into cerebral amino acids was reduced by DZP at P5 and P10. The cerebral concentration of neurotransmitter amino acids was not affected by DZP treatment which only increased the amount of neutral amino acids mainly in the cerebellum at P5 and P10. After [U-14C]glucose injection, specific radioactivities of cerebral amino acids were mostly decreased by DZP from P5 to P14 and significantly increased at P21. With [3-14C] beta HB as a precursor, specific radioactivities of neurotransmitter amino acids were increased by DZP. In conclusion, P5 and P10 rats appear to be most sensitive to DZP effects whereas some tolerance to the drug seems to develop by P21. The lack of effects of DZP on blood ketone body concentrations compared to food restriction as well as the relative sparing of brain weight in undernourished rats confirms that the cerebral metabolic consequences of early DZP exposure on brain energy metabolism are mostly direct effects not mediated by sedation-induced undernutrition.

3-Hydroxybutyric Acid↗
PubMed1994

Cloning of a genetic determinant from Clostridium difficile involved in adherence to tissue culture cells and mucus.

Our laboratory has previously shown that Clostridium difficile adherence to Caco-2 cells is greatly enhanced after heat shock at 60 degrees C and that it is mediated by a proteinaceous surface component. The experiments described here show that C. difficile could adhere to several types of tissue culture cells (Vero, HeLa, and KB) after heat shock. The type of culture medium (liquid or solid, with or without blood) had little effect on adhesion. To clone the adhesin gene, polyclonal antibodies against C. difficile heated at 60 degrees C were used to screen a genomic library of C. difficile constructed in lambda ZapII. Ten positive clones were identified in the library, one of which (pCL6) agglutinated several types of erythrocytes in the presence of mannose. In Western blots (immunoblots), this clone expressed in Escherichia coli a 40- and a 27-kDa protein; a 27-kDa protein has been previously identified in the surface extracts of heat-shocked C. difficile as a possible adhesin. The clone adhered to Vero, Caco-2, KB, and HeLa cells; the adherence was blocked by anti-C. difficile antibodies, by a surface extract of C. difficile, and by mucus isolated from axenic mice. Furthermore, the clone could attach ex vivo to intestinal mucus isolated from axenic mice. Preliminary studies on the receptor moieties implicated in C. difficile adhesion revealed that glucose and galactose could partially block adhesion to tissue culture cells, as did di- or trisaccharides containing these sugars, suggesting that the adhesin is a lectin. In addition, N-acetylgalactosamine, a component of mucus, and gelatin partially impeded cell attachment.

Animals↗
PubMed1993

Heterogeneity of Clostridium difficile isolates from infants.

In order to improve our understanding of the role of Clostridium difficile in infants we characterised the strains isolated from this population. The production of toxin A and toxin B was studied. The toxin A, playing a major role in the disease, was searched for in faecal samples. The serogroup of the isolates was determined because some serogroups have been shown to be more pathogenic than others. Over a 9-month period, 102 faecal samples from 102 hospitalised infants (0-12 months) were analysed and 26% of the children were colonised with C. difficile. Fifteen isolates secreted neither toxin A nor B (62.5%). Nine isolates were toxigenic and secreted both toxins (37.5%). Of the eight toxigenic strains tested, six were from serogroup H and two serogroup K. Of the 13 nontoxigenic strains tested, 8 belonged to serogroup D, 2 to serogroup X, and 1 each to serogroup A, serogroup B and serogroup C. Three infants out of 102 studied had toxin A in their faeces. In summary, the infants can be colonised by (1) nontoxigenic strains, most of them from nonpathogenic serogroup D, without toxin A in the faeces; (2) toxigenic strains of virulent serogroups H and K, with or without toxin A in the faeces. Although some infants had diarrhoea, none needed a specific treatment for C. difficile. No specific C. difficile pathology could be retained and different mechanisms are advanced to explain this absence of pathogenicity.

Bacterial Toxins↗
PubMed1993

Enterobacter cloacae cross-colonization in neonates demonstrated by ribotyping.

The intestinal colonization by Enterobacter cloacae strains with a derepressed cephalosporinase was studied in a paediatric ward between February 1990 and January 1991. Environmental sampling was performed simultaneously. Fifty-two isolates were recovered from 200 neonates (stool, blood) and 14 strains were isolated from the neonatal environment. An epidemiological study based on the typing of 36 Enterobacter cloacae isolates was carried out using antibiotyping, biotyping and ribotyping methods. The isolates selected were from 21 neonates (24 isolates), the neonatal ward environment (8 isolates) and from other wards (4 isolates). Thirty-two isolates had the same antibiotic resistance pattern, corresponding to a derepressed cephalosporinase and resistance to the following aminoglycosides: kanamycin, gentamicin, tobramycin and netilmicin. No predominant biotyping pattern could be established. Ribotyping done with two endonucleases (EcoRI and BamHI) showed 28 Enterobacter cloacae isolates to have a single pattern. Ribotyping was the most discriminating method used in this study, permitting identification of cross-contamination with Enterobacter cloacae in the paediatric ward.

Bacteremia↗
PubMed1993

[Prevalence of Clostridium difficile and toxin A in feces of HIV infected patients].

Patients with AIDS are immunodeficient, receive multiple antibiotic treatments, occasionally anti-cancer chemotherapy and are often hospitalised; thus they are susceptible to develop a Clostridium difficile infection. The aim of this study was to evaluate the role of C. difficile in diarrhoea in this patient population. Therefore, C. difficile and toxin A which plays a major role in pathogenicity were examined in faecal samples of HIV infected patients. Between January 1991 and June 1992, 102 stool samples from 67 patients were studied. Ninety p. cent of these patients were hospitalised (length > 3 days), 80% had a diagnosis of AIDS stage IV, and 66% had diarrhoea. Nineteen point four p. cent of the patients were carriers of C. difficile. Different associations were found: 1) presence of non toxigenic strains and absence of toxin A in stool samples (6 patients), 2) presence of toxigenic strains and absence of toxin A in stool samples (6 patients), 3) presence of toxigenic strains and toxin A in stool samples (2 patients). None of the patients developed a colitis or pseudomembranous colitis. The carrier rate was identical to those found in other hospitalised populations without AIDS. The prevalence of C. difficile diarrhoea or colitis is low. In this study, AIDS patients do not seem to constitute a risk group for C. difficile intestinal pathology. However, carriers of C. difficile were subjected to strict hygiene rules to prevent nosocomial spread.

AIDS-Related Opportunistic Infections↗
PubMed1992

Effects of antibiotics and other drugs on toxin production in Clostridium difficile in vitro and in vivo.

In an attempt to understand more completely why patients treated with phenothiazines (chlorpromazine and cyamemazine), methotrexate, and certain antibiotics such as clindamycin have an increased risk of developing pseudomembranous colitis, the production of toxins A and B by Clostridium difficile in the presence of these drugs was measured in vitro as well as in vivo by using axenic mice. None of the drugs tested increased the production of toxins either in vitro or in vivo.

Animals↗
PubMed1990

Incidence of juvenile type 1 (insulin-dependent) diabetes mellitus in France.

The incidence rate of juvenile Type 1 (insulin-dependent) diabetes in France was reported as the lowest in Europe 13 years ago, but during the recent years increasing rates have been observed in different European countries. A prospective programme has been designed to study the incidence rate of Type 1 diabetes in patients up to 20 years of age in four regions located in the north and south of France (population less than 20 years = 2.31 million inhabitants; 15% of the French population). All cases were independently identified by four specially trained research assistants through hospital admission files, paediatricians, diabetologists and general practitioners. A specific questionnaire was filled out for each newly diagnosed case. Degree of ascertainment was 96% with the data from Sécurité Sociale, the French National Health Insurance. In 1988, 166 cases of juvenile Type 1 diabetes were identified. The incidence rate was 7.17 cases per 10(5) children (95% confidence interval = 6.1-8.2/10(5). The values were not statistically different among the four regions. Age specific incidence rates were as follows: 0-4 years = 3.8; 5-9 years = 8.0; 10-14 years = 9.7 and 15-19 years = 7.3/10(5). Sex ratio was 1.2 (male/female). These data indicate that incidence of juvenile Type 1 diabetes in France was higher in 1988 than previously reported but remains lower than in Northern Europe. This is consistent with the concept of a north to south gradient of the disease.

Adolescent↗
PubMed1989

[Yersinia enterocolitica infections and thalassemia major in children].

We report two cases of severe Yersinia enterocolitica infection in children with homozygous thalassemia. One patient had septicemia and the other had mesenteric adenitis. Two factors can enhance the infectivity of Yersinia enterocolitica in children with thalassemia: iron overload and deferoxamine therapy. Laparotomy and cefotaxime-netilmicin therapy were successful in the patient with mesenteric adenitis. In the patient with septicemia, cefotaxime-netilmicin, then doxycycline-netilmicin failed, and recovery was finally achieved under rifampicin-netilmicin. Because of the possibility of septicemic dissemination secondary to digestive Yersinia enterocolitica infection in children with thalassemia, we advocate immediate discontinuation of deferoxamine and prescription of oral antimicrobial therapy (trimethoprim-sulfamethoxazole for instance) in every thalassemic patient with febrile diarrhea.

Adolescent↗
PubMed1989

[Cancer incidence in the department of la Manche: heterogeneity and geographic autocorrelation].

In order to demonstrate systematic spatial variations of cancer morbidity in the French "department of la Manche" (1979-1981), heterogeneity and spatial autocorrelation tests are performed. The "canton" (electoral ward of around 10,000 inhabitants) is retained as the statistical unit and the standardized incidence ratio (SIR) in each ward for the most frequent cancer sites, as morbidity rate. For males, three cancers show organized patterns: upper respiratory and digestive tract cancers with a North/South gradient; lung and other respiratory cancers mainly in the urban wards; and cancer of the skin with a high incidence on the West coast and a low incidence in the northern area. For females, cancer of the skin is the only one to show significant spatial variation characterized by a pronounced South/North gradient. The possible etiological factors involved are discussed for each cancer site.

Female↗
PubMed1988

Comparative effects of caffeine and L-phenylisopropyladenosine on local cerebral glucose utilization in the rat.

The quantitative [14C]2-deoxyglucose autoradiographic method was used to study the effects of the acute administration of 10 mg/kg of caffeine and 0.1 mg/kg of L-phenylisopropyladenosine (LPIA) given separately or in combination. After an injection of caffeine, the local cerebral metabolic rates for glucose (LCMRglu) were increased in 34 out of 61 structures studied, mainly in monoaminergic cell groupings, the thalamus and structures belonging to the extrapyramidal motor system. The administration of LPIA decreased the LCMRglu in 30 out of 61 structures studied. These areas were essentially monoaminergic cell groupings, structures of the extrapyramidal motor system and all hypothalamic areas. After a combined injection of caffeine and LPIA, the LCMRglu was either increased or not changed in structures affected by caffeine or LPIA given alone. The results of the present study indicate that, even if caffeine and LPIA compete for the occupation of adenosine receptors, the effects of these two substances on the energy metabolism of the brain are partly mediated by peripheral mechanisms.

Adenosine↗
PubMed1988

Specific binding characteristics of high affinity monoclonal antidigitoxin antibodies.

The specificity of various monoclonal antidigitoxin antibodies was characterized using 6 cardiac glycoside analogs. Spleen cells from BALB/c mice, immunized with BSA- or KLH-digitoxin conjugates, were fused with NS1 myeloma cells, and antibody-producing hybrids were identified by radioimmunoassay. Twenty-one monoclonal antidigitoxin-specific antibodies were obtained, 10 of which were cloned and characterized for affinity and specificity. All the antibodies had a high affinity constant, ranging from 8.10(8) to 2.5.10(10) 1/M. On the basis of their binding specificities, the antibodies could be classified into 3 groups: the first contained 7 antibodies exhibiting high cross reactivity (42-100%) with digitoxigenin, whereas the second and third groups did not recognize this analog (cross-reactivity of 1%). In the former group, the absence of the sugar moiety only slightly affected the binding reaction, although for the two other groups, this structure did appear to be involved in antibody recognition. Changes in the functional groups of the hapten molecule led to considerable changes in the antibody-antigen reaction. For all the antibodies except one, saturation of the lactone ring considerably affected binding. These results demonstrated that monoclonal antibodies of different specificities with respect to both the steroid backbone and the sugar moiety of digitoxin can be induced using a digitoxin-protein conjugate.

Animals↗