Fragmentation pathways of tungsten hexacarbonyl clusters upon electron ionization.

Electron ionization of neat tungsten hexacarbonyl (W(CO)6) clusters has been investigated in a crossed electron-molecular beam experiment coupled with a mass spectrometer system. The molecule is used for nanofabrication processes through electron beam induced deposition and ion beam induced deposition techniques. Positive ion mass spectra of W(CO)6 clusters formed by electron ionization at 70 eV contain the ion series of the type W(CO)n (+) (0 ≤ n ≤ 6) and W2(CO)n (+) (0 ≤ n ≤ 12). In addition, a series of peaks are observed and have been assigned to WC(CO)n (+) (0 ≤ n ≤ 3) and W2C(CO)n (+) (0 ≤ n ≤ 10). A distinct change of relative fragment ion intensity can be observed for clusters compared to the single molecule. The characteristic fragmentation pattern obtained in the mass spectra can be explained by a sequential decay of the ionized organometallic, which is also supported by the study of the clusters when embedded in helium nanodroplets. In addition, appearance energies for the dissociative ionization channels for singly charged ions have been estimated from experimental ion efficiency curves.

[Cutaneous nodular lesions and antiphospholipid syndrome]. / Nodules cutanés douloureux et syndrome des antiphospholipides.

BACKGROUND: Antiphospholipid antibodies are a group of autoimmune antibodies directed against a broad panel of phospholipids and their cofactors. Antiphospholipid antibody syndrome is defined by the presence of a hypercoagulable clinical state associated with antiphospholipid antibodies. We report a case with very unusual cutaneous nodular lesions. PATIENTS AND METHODS: A 37-year-old man presented with painful recurrent cutaneous lesions of the nape of the neck. The lesions appeared four years earlier and regressed with oral prednisone. The previous year, cerebral ischaemia revealed antiphospholipid syndrome and anticoagulant therapy was initiated. The patient's cerebral ischaemia was successfully treated but the skin lesions recurred in spite of good anticoagulation therapy. The nodules were strictly confined to the back of the neck. Histopathological examination of a nodular lesion from this patient revealed dilated arterioles and venules with luminal blockage due to fibrinoid thrombosis consistent with the thrombotic microangiopathy seen in antiphospholipid syndrome. DISCUSSION: We describe a case of primary antiphospholipid syndrome with cutaneous lesions as the initial sign of the disease. These "Sweet-like" lesions have been described only once in the literature. Therapeutic strategy in the event of failure of anticoagulants is not well codified.

Magnetic resonance imaging of intestinal necrosis in preterm infants.

BACKGROUND AND OBJECTIVE: Noninvasive diagnosis of intestinal necrosis is important in planning surgery in preterm infants with necrotizing enterocolitis (NEC). We aimed to assess the potential of magnetic resonance imaging (MRI) for the diagnosis of intestinal necrosis. STUDY PARTICIPANTS AND METHODS: Abdominal MRI scans were performed in a group of preterm infants with suspected NEC and compared with surgical findings and to MRI results in a group of control infants. In addition, MRI was performed in 2 preterm infants with suspected NEC who did not require surgery. RESULTS: Six infants with a median birth weight of 1220 g (range, 760-1770 g) and median gestational age at birth of 30 weeks (range, 28-34 weeks) were studied at a median postnatal age of 10 days (range, 4-19 days). Four infants had a bubble-like appearance in part of the intestinal wall, intramural gas, and an abnormal fluid level within bowel lumen. At surgery, NEC was found in 5 infants and sigmoid volvulus in 1. The site of the bubble-like appearance corresponded to the site of intestinal necrosis at surgery. Four control infants with a median birth weight of 1500 g (range, 730-2130 g) and a median gestational age of 31 weeks (range, 26-36 weeks) had abdominal MRI at a median postnatal age of 8 days (range, 4-70 days). None of the above findings were seen in any control infant. The bubble-like appearance was not seen in the 2 infants with suspected NEC who did not require surgery. CONCLUSION: Abdominal MRI allows the noninvasive diagnosis of bowel necrosis. This may aid the timing of surgical intervention in preterm infants with a clinical diagnosis of NEC.gangrene, ischemia, MRI, necrotizing enterocolitis.

Relationship between MR imaging and histopathologic findings of the brain in extremely sick preterm infants.

BACKGROUND AND PURPOSE: MR imaging can now be used safely in extremely preterm infants. The aim of this study was to compare the MR imaging appearance of the immature brain with neuropathologic findings at postmortem examination. METHODS: Seven extremely sick preterm infants, born at a median of 24 weeks' gestation, were studied using T1- and T2-weighted MR sequences. Infants died at a median of 3 days after initial MR imaging, and postmortem examinations were carried out. RESULTS: The cortex and germinal matrix were seen as areas of low signal intensity on T2-weighted images, which corresponded to their highly cellular histologic appearance. The periventricular and subcortical layers of white matter had a high signal intensity, corresponding to high fiber and relatively low cellular density; the intermediate layer of low signal intensity corresponded to a dense band of migrating cells. Regions of acute hemorrhage were seen as low signal intensity and regions of infarction as high signal intensity on T2-weighted images. One infant with mild periventricular leukomalacia had some low signal intensity on T1-weighted images, but no focal changes on T2-weighted images. Regions of neuronal mineralization, seen in association with infarction and capillary proliferation, within the basal ganglia and thalami were characterized by very low signal intensity on T2-weighted images and by very high signal intensity on T1-weighted images. There were no imaging abnormalities detected in regions with more subtle histologic abnormalities, such as increased glial or apoptotic cells. CONCLUSION: MR imaging can be used to observe normal developing brain anatomy in extremely premature infants; it can detect areas of hemorrhage and infarction within the developing brain, but conventional MR imaging may not detect more subtle histologic abnormalities.

Arthrogryposis multiplex congenita and bilateral mid-brain infarction following maternal overdose of co-proxamol.

We report a case of arthrogryposis multiplex congenita secondary to fetal hypokinesia in a 41-week gestation infant following antenatal central nervous system injury. The mother's pregnancy was complicated by an episode of attempted self harm, with an overdose of co-proxamol at 22 weeks of gestational age, and by the use of cocaine in combination with excess alcohol intake. Magnetic resonance imaging showed bilateral mid-brain cysts and marked atrophy of the basal ganglia and thalami.

Periventricular haemorrhagic infarct in a preterm neonate.

Magnetic resonance imaging (MRI) was performed on an infant born, at 28 weeks gestational age who suffered a sudden episode of bradycardia and desaturation on the 3rd day of life. Imaging demonstrated bilateral germinal layer haemorrhage and intraventricular haemorrhage, with parenchymal involvement in a fan-shaped pattern in the periventricular white matter on the left. These appearances are consistent with a combination of intravascular thrombi and perivascular haemorrhage along the course of the medullary veins. We believe that this is the first report of the MRI appearance of an acute periventricular haemorrhagic infarct associated with a germinal layer haemorrhage/intraventricular haemorrhage in a preterm neonate.

Physiological stability of preterm infants during magnetic resonance imaging.

AIM: This study looked for evidence of physiological disturbance in preterm infants undergoing magnetic resonance imaging (MRI). METHODS: Intensive care was continued, as appropriate, throughout scanning in each infant. The heart rate, oxygen saturation (SaO2), temperature and mean arterial blood pressure (BP) was monitored during MRI in preterm infants, median gestational age at birth 27 (range 23-32) weeks and median postnatal age at initial MRI, 3 days (range 1-42). The acoustic noise level during imaging was also measured. RESULTS: 2087 min of data were obtained from 39 examinations in 23 infants. The median heart rate was 159 and no bradycardia < 100 or tachycardia > 200 bpm occurred. Although 42 episodes of desaturation < 90% were detected only three were < 80, and these occurred in one infant due to endotracheal tube blockage. The median axillary temperature was 36.9 degrees C (range 35.7-37.8) and median BP (n = 6) was 37 mmHg (24-48). The ambient noise level in the MR system during scanning was 67-72 dBA. CONCLUSION: In preterm infants who required intensive care during scanning, MRI could be performed without major physiological instability.

Neonatal hypopituitarism presenting with poor feeding, hypoglycemia and prolonged unconjugated hyperbilirubinemia.

The association between neonatal hypopituitarism and unconjugated hyperbilirubinemia has rarely been documented. We report a female infant who presented with persistent poor feeding, episodic borderline hypoglycemia and prolonged unconjugated hyperbilirubinemia; investigation revealed hypopituitarism. The diagnosis of hypopituitarism should therefore be considered in neonates presenting with prolonged unconjugated hyperbilirubinemia.

Jejunal atresia in an infant with triple-X syndrome.

A 33-year-old woman presented at 31 weeks' gestation with polyhydramnios that required repeated amniodrainage. An antenatal scan at 32 weeks showed dilated fetal bowel loops, which were not confirmed on subsequent scans. The amniotic fluid karyotype confirmed 47,XXX. After birth, jejunal obstruction was confirmed. To our knowledge, this is the first report of an association of triple-X syndrome and jejunal atresia.

Magnetic resonance imaging of the neonatal brain.

Advances in magnetic resonance technology have revolutionized our ability to obtain detailed images of the neonatal brain without the use of ionizing radiation. Magnetic resonance imaging has now become the modality of choice for the in-vivo assessment of brain development, myelination and pathology.

Biological perspectives on the non-surgical endodontic management of periradicular pathosis.

Differential radiographic criteria are unreliable for the histological diagnosis of periradicular lesions of pulpal origin. It should not, therefore, be assumed that large lesions or lesions with an opaque border are cystic. Even if cystic, or if strands of epithelium are present, the literature supports repair following the removal of the source of the pathosis. In most cases, the aetiological factors are oral contamination through the root canal or degenerating pulpal tissue. Therefore, the mere surgical removal of lesions of pulpal origin without removing the causes through proper root canal cleaning, shaping and obturation, will not result in the healing of the periradicular tissues. In addition to removing effectively the causative factors, environmental changes in the periradicular tissues caused by the process of canal debridement may inherently aid in the demise of epithelium, when present. The salient issues are discussed in light of thorough debridement of the root canal system, coupled with postulated mechanisms for the resolution of lesions displaying epithelial stands or cavities. Likewise, the role of calcium hydroxide and its potential role in the alteration of the periradicular environment is addressed, with support for the repair of large periradicular lesions without surgical intervention.

[The Thermafil obturator in endodontics: preliminary study]. / "L'obturateur Thermafil" en endodontie: étude préliminaire.

A clinical study involving 25 patients and a total number of 42 canals was carried out in the department of Endodontics at the Saint-Joseph University of Beirut and in private practice. The use of the Thermafil device seems to be safe due to the carrier manufactured with a stainless steel medical grade, covered with a layer of gutta-percha alpha phase. The clinical results are satisfactory, the technique is simple, fast and efficient, which confirms the results published in the literature. More investigations are necessary to a better evaluation of the system.

[Clinical evaluation of 160 degrees C thermoplasticized gutta-percha]. / Evaluation clinique de la gutta-percha thermoplastifiée à 160 degrees C.

A clinical study involving 30 patients randomly selected in the department of endodontics at the Saint Joseph University of Beirut and in private practice was carried out. The use of "Obtura", a high-heat thermoplasticized gutta-percha system seems to be satisfactory, the findings stressed the advantages and the disadvantages of the technique and the material. Some suggestions are advanced in order to make the use of the technique easier and more efficient.

In utero nephropathy, Denys-Drash syndrome and Potter phenotype.

We report an unusual case of Denys-Drash syndrome presenting in a newborn infant with end-stage renal failure of antenatal origin and Potter phenotype. DNA analysis showed a novel missense change in arginine 394 of zinc finger 3 of the WT1 gene. This mutation may lead to an earlier and more severe presentation of Denys-Drash syndrome. It may be of interest to look for this mutation in other Potter phenotype cases.

Magnetic resonance imaging of the brain in a cohort of extremely preterm infants.

To define magnetic resonance imaging (MRI) appearances of the brain in extremely preterm infants between birth and term, a sequential cohort of infants born at a gestational age <30 weeks was studied with a dedicated neonatal magnetic resonance scanner. Images of infants (n = 41) with a median gestational age of 27 weeks (range 23 to 29 weeks) were initially obtained at a median age of 2 days (range 1 to 20 days) and then repeatedly studied; 29 (71%) infants had MRI at a median gestational age of 43 weeks (range 38 to 52 weeks) (term MRI). On the initial MRI scan 28 of 41 infants had abnormalities: either intraventricular hemorrhage, germinal layer hemorrhage, ventricular dilatation, or diffuse and excessive high signal intensity in the white matter on T(2)-weighted images. When magnetic resonance images for preterm infants at term gestation were compared with those of infants in the control group born at term, 22 of 29 infants had dilatation of the lateral ventricles, 24 of 29 had squaring of the anterior or posterior horns of the lateral ventricles, 11 of 29 had a widened interhemispheric fissure or extracerebral space, and 22 of 29 had diffuse and excessive high signal intensity in the white matter. There were no cases of cystic periventricular leukomalacia. We conclude that MRI abnormalities are commonly seen in the brain of preterm infants on whom images are obtained within 48 hours of birth and that further abnormalities develop between birth and term. A characteristic appearance of diffuse and excessive high signal intensity in the white matter on T(2)-weighted images is associated with the development of cerebral atrophy and may be a sign of white matter disease. These MRI appearances may help account for the high incidence of neurodevelopmental impairment in extremely preterm infants.

Magnetic resonance imaging of the brain in very preterm infants: visualization of the germinal matrix, early myelination, and cortical folding.

OBJECTIVE: To investigate preterm infants, we have installed in our neonatal intensive care unit a dedicated magnetic resonance (MR) imaging system which was specifically designed for neonatal use. The aim of this study was to describe the MR appearances of the brain in preterm infants who were first scanned between 25 and 32 weeks gestational age (GA) and to outline changes to the brains of these infants between their first scan and term. METHODS: Preterm infants of 25 to 32 weeks GA were imaged using the 1T neonatal MR system (Oxford Magnet Technology, Eyensham, Oxfordshire, England/Picker International, Cleveland, OH). The scanning protocol included T1-weighted conventional spin echo (repetition time [TR], 600; echo time, 20 ms), inversion recovery fast spin echo (TR, 3530; effective echo time, 30; inversion time, 950 ms), and T2-weighted fast spin echo (TR, 3500; effective echo time, 208 ms) sequences. RESULTS: Seventeen infants of median 28 weeks GA (range, 24 to 31 weeks) at birth were imaged a total of 53 times between birth and term. The median number of images per infant was two (range, 1 to 9). In infants of < 30 weeks GA, the germinal matrix was visualized at the margins of the lateral ventricles. It had a short T1 and short T2 and the bulk of it involuted at between 30 and 32 weeks GA. The white matter had a relatively homogeneous low signal except for bands of altered signal (probably originating from regions containing radial glia and migrating cells) which were most apparent anterolateral and posterolateral to the lateral ventricles. Myelination was seen in the posterior brainstem, cerebellum, and region of the ventrolateral nuclei of the thalamus. Infants had very little cortical folding at 25 weeks GA but this developed later in an orderly fashion. CONCLUSION: The neonatal MR system allowed extremely preterm infants to be studied safely with MR imaging. The images acquired demonstrated the germinal matrix, early myelination, and early cortical folding. Evolution of these features was demonstrated with serial studies.