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Biomedical subjects

M Collet

Publications and source records attributed to M Collet.

At least 19 recordsLinked to original sources
PubMed2005

Detection of an unexpected subtelomeric 15q26.2 --> qter deletion in a little girl: clinical and cytogenetic studies.

Unlike the small proximal 15q deletions causing Prader-Willi and/or Angelman syndrome, distal deletions of the terminal long arm of chromosome 15 have rarely been described. To the best of our knowledge, only four patients with a pure terminal 15q deletion have been documented in the literature. We report here on an unexpected abnormal hybridization pattern for the 15q specific subtelomeric control probe (clone 154P1) of the commercial SNRPN probe in a girl referred for suspicion of Angelman syndrome. Investigation by fluorescent in situ hybridization (FISH) using bacterial artificial chromosome (BAC) clones defined a partial monosomy 15q26.2 --> 15qter for a minimal critical region of approximately 5.7 Mb, which is the most distal de novo 15qter deletion reported to date. All the de novo 15qter deletion cases, including ours, presented with pre- and post-natal growth retardation related to the loss of one copy of the IGF1R gene. Based on the comparaison with the previous published cases and owing to the clinical phenotype of our patient, we define a new subtelomeric 15qter syndrome which would be characterized by intrauterine growth retardation and global post-natal growth failure, variable mental retardation, facial anomalies including relative micrognathia and triangular facies and minor malformations of the extremities including proximally placed thumbs, cubitus valgus, and brachydactyly with tappering of the digits.

Abnormalities, Multiple↗
PubMed2005

[Consequences of smoking on fetal development and risk of intra-uterine growth retardation or in utero fetal death].

Active and passive smoking constitutes one of the most serious public health problems due to the deleterious effect on the expected infant and the mother. These effects are dose dependent as illustrated by intra-uterine growth retardation, where the effect worsens with duration of smoking during pregnancy, and also by other conditions such as abrutio placentae or placenta praevia, premature rupture of the membranes and preterm birth, where the risk is multiplied by two (or even three)! In utero death is the ultimate sanction. Studies on the consequences of maternal smoking on fetal development have demonstrated the cardiovascular effect (CO and nicotine) and the respiratory effect (CO) which can be aggravated after birth by passive smoking. Teratogenic and cancerogenic effects have also been clearly demonstrated. Maternal smoking would also affect fetal brain development with negative effects on the major neurotransmitter systems (domaminergic, serotinergic, noradrenergic) and on the development of key structures such as the prefrontal cortex, certain limbic structures including the hippocampus and other structures implicated in motor function such as the ventral striatum. These development anomalies of the brain could give rise, after birth, to psychological, behavioral, attention and cognitive disorders, further arguments in favor of an effective anti-smoking policy including appropriate care for smoking pregnant mothers in both hospital and outpatient settings.

Female↗
PubMed2005

[Preliminary results of an herpetology investigation in sugar cane plantation in Democratic Republic of Congo].

Out of the 3,000 species of snakes described in the world, 163 are currently known from D.R. of Congo. We performed a systematic survey in sugar-cane plantations of the Sugar Company of Kwilu-Ngongo (Bas-Congo), located at 160 km South-West from Kinshasa and exploiting nearly 10,000 ha. The plantation is divided into 3 sectors in the middle of which we deposited barrels filled of formaldehyde. All the employees of the Sugar Company of Kwilu-Ngongo were requested to collect encountered snakes and put them in the nearest barrel. Between August 9th and September 21st, 2004, we collected 36 snakes in two different sites, revealing the presence of 3 families and 12 species. The most abundant species in Causus maculatus (47% in the first site--Point 8--and 29% in the second site--Point 13). The most poisonous and dangerous species were captured only in the first site--point 8, and were Dendroaspis jamesoni and Naja melanoleuca, both young.

Agriculture↗
PubMed2003

[Breastfeeding and drugs].

Breastfeeding offers several advantages for the mother and infant. Taking drugs while breastfeeding however creates a dilemma for practitioners and often leads to a contraindication or interruption of breastfeeding. There are however very few drugs which present clinically significant risk for the breastfed child. When the mother has to take drugs, the decision to initiate or continue breastfeeding or not must be made with special care after evaluating the individual benefit/risk ratio resulting from breastfeeding and drug exposure. Evidence-based medicine is the key. The purpose of the present review is 1) to present the epidemiological data available concerning undesirable effects in infants breastfed by mothers taking drugs and on the attitude of prescribers and patients in the event of exposure to drugs while breastfeeding; 2) to analyze the pharmacokinetic data to determine the appropriate management approach in particular clinical situations; 3) to present data concerning certain drugs and sources of information useful for further study.

Breast Feeding↗
PubMed1998

Evidence of bacterial biofilm in tubing from hydraulic pathway of hemodialysis system.

Biofilms consist of microorganisms immobilized at a substratum surface embedded in an organic polymer matrix of bacterial origin. Tubing drawn from the fluid pathways within dialysis machines of various models were investigated for biofilm. Scanning electron microscopy (SEM), performed on approximately 2 cm2 samples of the tubing inner surfaces revealed that the inner surfaces of the tubing were covered with biofilms consisting of numerous deposits and glycocalix at different stages of formation with components containing bacteria and algae. Evaluations of biomass were performed from tubing sections of various lengths and inner diameters put in tubes containing water for injection and immersed in an ultrasound washtub for 1 h to ensure sloughing of the biofilm. Living bacteria were identified by plating on nutrient agar media and incubation for 48 h at 37 degrees C. Epifluorescent stains were used for the total bacteria count. Lipopolysaccharide levels were determined by the endotoxin activity measurements. Polyoside contents were determined by the colometric method, and the chemical oxygen demand was measured to evaluate the amount of organic substance. Biofilms detached from tubing samples drawn from the water path, bicarbonate path, and fresh dialysate path within dialysis machines contained approximately 1.10(3)-1.10(6) total bacteria/cm2, yet only some living bacteria were found. Endotoxin levels ranged from 1 to 12 EU/cm2. In contrast in the dialysate fluid, no bacteria were found, and the endotoxin content was under the detection level of the method. The polyoside content and chemical oxygen demand of the biomass ranged from 11 to 83 microg/cm2 and from 53 to 234 mg/cm2, respectively. It is concluded that a germ- and endotoxin-free dialysate does not exclude the risks and hazards of bacteria and endotoxin discharge from biofilm developed on the fluid pathway tubing, acting as a reservoir for continuous contamination, and efforts in the optimization of cleaning and disinfection procedures used for hemodialysis systems should aim to detach and neutralize biofilm when necessary.

Bacillus↗
PubMed1997

[Transitory hyperinsulinism with hypoglycemia in asphyxia neonatorum].

BACKGROUND: Hypoglycemia is a well-known complication in neonates small for gestational age and in those with diabetic mothers. Birth asphyxiated infants can develop severe hypoglycemia due to reduced glycogen stores. CASE REPORTS: The first patient was born at 41 weeks, weighing 3,780 g by emergency cesarean section because of fetal distress. He developed a pneumothorax and hypoglycemia. He was given glucose infusion (at day 4: 20 mg/kg/d). Hyperinsulinism was confirmed: blood levels at 18.3 mU/L on day 1 and 11.7 mU/L on day 2. The infusion rate was gradually decreased. The second patient was born at 39 weeks, weighing 2,780 g by emergency cesarean section because of fetal distress. She needed glucose infusion (24 g/kg/d) because of hypoglycemia with hyperinsulinism (12.8 mU/L on day 2 and 11.7 mU/L on day 3). After 5 days, the infusion of glucose was replaced by oral feeding only. CONCLUSION: Transient hypoglycemia in asphyxiated newborn infants with hyperinsulinism must be considered even when hypoglycemia may be difficult to prove.

Asphyxia Neonatorum↗
PubMed1997

Analysis of the mutations induced in the E. coli lac Z gene by a psoralen analog.

A psoralen in which intracyclic oxygen atoms were replaced by sulfur (7H-thieno [3,2-g]-[1]-[benzothiopyran-7-one) [PSO(S-S)]) was recently synthesized and its photobiological properties were investigated. M13mp19 DNA photosensitization mediated by PSO (S-S) followed by transfection into competent E. coli gave rise to a very low phage progeny showing the high aptitude of this compound to modify DNA. In order to characterize the role of oxidative damages in the photosensitized reaction mediated by PSO(S-S), plasmid bearing the gene encoding the formamidopyrimidine DNA glycosylase (Fpg) under the control of the inducible lac Z promoter was transfected in E. coli. Overexpression of Fpg was induced by addition of isopropyl-beta-D-thio-galactopyranoside (IPTG) to the cells and monitored by western blot analysis. Fpg overexpression did not influence the rate of M13mp19 DNA photoinactivation by PSO(S-S) neither the mutation frequency measured by the expression of beta-galactosidase encoded by the lac Z gene beared by M13mp19. Analysis of the mutation patterns recorded with or without Fpg overexpression showed that several G to T transversions due to oxidative damages were repaired by Fpg. These data show that oxidative DNA damages generated during PSO(S-S) photosensitization have only limited biological implications measured in terms of DNA photoinactivation.

Bacteriophage M13↗
PubMed1997

Photoreaction of new psoralen analogs with DNA: sequence and mutation specificity in the Escherichia coli lacZ gene.

New thio- and seleno-analogs of psoralen were synthesized and analyzed for their photoreactivity toward DNA. Using oligonucleotides of defined sequence, we first showed that these derivatives predominantly generated interstrand crosslinks at 5'-TpA sites. We also observed a surprisingly high reactivity of 7H-thiopyrano[3,2-f][1]benzofuran-7-one (PSO[O-S]) with the BamHI and PstI oligomers, giving rise to the formation of crosslinks at 5'-ApT sites and of the thymidine-psoralen-cytosine type. Next, the sequence specificity in the photochemical binding of all the compounds was investigated in two DNA fragments encompassing the lacZ gene of Escherichia coli, using the T4 DNA polymerase sequencing methodology. Resulting maps demonstrated that thio- and seleno-analogs of psoralen preferentially photoreacted with thymine and cytosine residues. The AT-rich sequences proved to be particularly reactive sites as did adjacent thymines, especially at C-surrounding residues. Likewise, photoaddition at cytosines in CA/AC context was observed. It was highly significant that all of the derivatives exhibited similar sequence specificities with only minor differences. However, PSO(O-S) differed from the other heteropsoralens. Photoadducts occurred with a higher frequency at AC and CA dinucleotides, and new sites were detected. A comparison with 8-methoxypsoralen photobinding is also reported. Finally, the mutagenic consequences of photoadducts induced in M13mp19 DNA by PSO(O-S) were determined in a forward system that detects all classes of mutagenic events. The high phototoxicity exhibited by PSO(O-S) could be attributed to crosslinks, and the comparison of the observed mutational specificity with the photoadduct distribution within the same gene showed that mutations were targeted at potential monoadduct sites where photolesions were detected in our footprinting experiments.

DNA Adducts↗
PubMed1994

[Abdominal emergencies and pregnancy].

The authors report the principal abdominal surgical emergencies which may occur during pregnancy. Missed diagnosis of these acute abdomens forms the basis of their gravity in terms of both maternal and fetal prognosis.

Abdomen, Acute↗
PubMed1994

[Prenatal diagnosis of congenital cystic adenomatoid malformation of lung: perinatal management. Apropos of 4 cases].

BACKGROUND: Cystic adenomatoid malformation of the lung can be seen by ultrasonography during pregnancy. Surgical excision of the affected lobe is indicated during the first days of life. CASES REPORT: Four neonates were admitted to an intensive care unit from March 1988 to February 1992, due to cystic adenomatoid malformation of the lung, that had been diagnosed by ultrasonography at 19, 22, 34 and 37 weeks of gestational age, respectively. These malformations were not associated with other abnormalities and were type I (three cases) and II (one case) according to Stocker's classification. Only one patient became symptomatic, requiring intubation by 72 hours of age. Surgical excision of the affected lobe was performed in three patients at 4 hours, 2 and 7 days of life, respectively, with a normal long-term survival. A segmental resection was performed at 5 days of life in the remaining symptomatic patient but persistence of cystic lesions required lobectomy at 10 months. CONCLUSIONS: Early perinatal management of cystic adenomatoid malformations of the lung is necessary as surgical excision is indicated as soon as possible, even in asymptomatic patients.

Cystic Adenomatoid Malformation of Lung, Congenita↗
PubMed1993

Prenatal diagnosis of a fetus with partial monosomy 7(q34-->qter) and partial trisomy 18(q21-->qter).

Ultrasound examination of a 31-year-old woman at 27 weeks' gestation revealed fetal growth retardation, a bilateral cleft lip and palate, and the absence of median cerebral structures. Chromosome analysis after cordocentesis showed an abnormal karyotype with a structural abnormality of the long arm of chromosome 7: 46,XX,-7,+der(7),t(7;18) (q34;q21.3)mat. The pregnancy was terminated at week 29. The ultrasound findings were confirmed by post-mortem examination, which also revealed a semilobar holoprosencephaly.

Abnormalities, Multiple↗
PubMed1993

Analysis of mutations induced by 4'-hydroxymethyl-4,5',8-trimethylpsoralen and UVA in Escherichia coli lac Z gene and its regulatory region.

The mutagenic consequences of covalent adducts induced in M13mp19 DNA by 4'-hydroxymethyl-4,5',8-trimethylpsoralen (HMT) and UVA have been determined in a forward mutational system capable of detecting all classes of mutagenic events. The photoreaction mediated by HMT has been carried out at a very low molar ratio of HMT to DNA which favours the induction of cross-links between high affinity reaction sites. When damaged M13mp19 DNA is used to transfect competent Escherichia coli K12 JM105 cells, a five-fold increase in mutation frequency is observed at 3.5% survivors when measured as a loss of beta-galactosidase alpha-complementation. The enhanced mutation frequency is largely due to base substitutions, frameshift events and large deletions. The single nucleotide substitutions occur both in the lac Z coding sequence and in its regulatory region. Transversion and transition have been detected with a predominant form consisting of A.T-to-G.C transversion at position +159. Frameshift mutations have been observed at five positions while three large deletions removing either part of the coding sequence or both the coding and the regulatory regions have been detected with a higher frequency. The spectrum of base substitutions detected between the M13 lac Z- phages surviving to the treatment is totally different from those appearing spontaneously whereas several frameshift events or deletions can already be detected between the spontaneous mutations. Despite the presence of these spontaneous hot spots, the spectrum of mutations recovered after HMT photoaddition appears to be unique and a detailed analysis of the different classes of mutations indicates an important role of cross-links in the production of mutations.

Bacteriophage M13↗
PubMed1993

[Osteogenesis imperfecta. Reflections after the prenatal diagnosis of 2 cases].

The authors report two cases of prenatal diagnosis of osteogenesis imperfecta (OI) of type II according to the classification of Sillence. When dwarfism had been discovered with deformities, fractures and low bone density, the diagnosis was made in one case at 24 and the second at 20 weeks of amenorrhoea. A recent review of the literature shows that the ideas concerning OI have changed markedly recently. All agree that within the framework of classification of diseases that there is a single entity. A dominant autosome genetic transmission is increasingly considered to be the cause for all forms of the condition. The physiopathology of collagen makes it easier to understand why these should be clinical forms. The ability to localise deleterious genes by using molecular biology makes it likely a very early antenatal diagnosis will be possible. All the same, this optimism has to be tempered with the frequent discovery in this illness of mosaicism which still leaves a large place for ultrasound.

Abortion, Therapeutic↗
PubMed1991

[Peridural obstetrical analgesia and the cicatricial uterus. A 4-year evaluation].

191 women with previous cesarean section in 291 indexed between October 1985 and September 1989 underwent a trial of labor. 146 patients received epidural analgesia in the course of labor. Vaginal delivery occurred in 126 patients (86.3%). Duration for epidural analgesia in labour was 163 +/- 110 min. The intrauterine pressure for monitoring continuous was 51.00 +/- 15.40 mmHg. We report four uterine dehiscences and one rupture. In no case, epidural analgesia did not delay the diagnosis. The use of epidural analgesia for trial of labor in previous cesarean section did not increase maternal or fetal risk.

Analgesia, Epidural↗