Broadband, high dynamics and high resolution charge coupled device-based spectrometer in dynamic mode for multi-keV repetitive x-ray sources.

We present a new operating mode, using a charged coupled device as dispersionless spectrometer dedicated to repetitive x-ray sources in the multi-keV domain. This enables to get spectra with high statistics in a short acquisition time and a way compatible with the operation of other diagnostics requiring accumulation. Several reconstruction algorithms for the spreading events are discussed, and a near Fano-limited resolution is demonstrated by using single pixel events. In this case, a method to take into account partial canceling of the events is presented. Experimental characterization and detailed modeling of the detector are performed, which allow to determine absolute number of photon with +/-35% accuracy. Characterization of the 5-25 keV x rays emitted by a short pulse laser-produced plasma is reported, as well as their dependency with the atomic number, the laser duration, and energy.

Observation of subpicosecond x-ray emission from laser-cluster interaction.

We present the first experimental evidence of the subpicosecond duration of x-ray pulses emitted from laser-irradiated clusters, demonstrating the suitability of such a debris free target for ultrafast x-ray science applications. The K-shell emission (approximately 3 keV) from large Ar clusters (6 x 10(5) to 4 x 10(6) atoms) is time resolved, when irradiated by ultrashort (40 fs to 5 ps) and intense laser pulses (10(15-17) W/cm2). The observations are supported by hydrodynamical and collisional-radiative calculations, that reproduce the extremely short x-ray pulse duration.

[Memory symptom exaggeration in a patient with progressive multiple sclerosis outside any medico-legal context]. / Exagération de symptômes mnésiques hors contexte médicolégal chez un patient atteint de sclérose en plaques.

INTRODUCTION: Memory symptom exaggeration or malingering in the forensic neuropsychological evaluation of well-documented brain pathology is seldom described. For some, documented neuropathology and malingering are considered to be mutually exclusive. CASE REPORT: We report an original clinical observation of an amnesic factitious disorder in a patient with progressive multiple sclerosis. This patient, who was seen for a routine comprehensive neuropsychological evaluation, demonstrated a severe memory encoding deficit in a classical standard episodic memory test. This amnesic syndrome was not in agreement with the neurological condition where deficits in retrieval memory processes are essentially observed. Moreover, his performance at two symptom validity tests fell below the admitted cut-off scores. In fact, the patient obtained an accuracy score of 3 (cut-score<10) in the Rey's 15-Items Test, a well known malingered amnesia measure. His performance in the 21-Items Test French adaptation was well below the proposed cut-off score of 15/21 and inferior to the results obtained by an Alzheimer patients group (n=30). A clinical approach of memory symptom exaggeration is described. We discuss the diagnosis of this false disorder. CONCLUSION: This case report demonstrates unequivocally that memory symptom exaggeration or malingering can and does occur in patients seen without litigious contexts and who have a well-documented neurological pathology. Failure to address malingering may compromise neuropsychological clinical findings. Nevertheless, there is a lack of up-to-date standard French-language documentation in this topic.

High dynamic range streak camera for subpicosecond time-resolved x-ray spectroscopy.

The full characterization of a time resolved x-ray spectrometer is presented. It is based on the coupling of a conical crystal with a subpicosecond x-ray streak camera. The detector is designed to operate in accumulation mode at high repetition rate (up to 1 kHz) allowing signal to noise ratio as high as 10(4):1. Optical switches have been used to limit the jitter induced in the subpicosecond range, demonstrating the very long term stability (a few hours) of the entire device. The data analysis have been developed to get the spectral and temporal resolution of an ultrashort laser-plasma-based x-ray source.

Investigation of laser-irradiated Ar cluster dynamics from K-shell x-ray emission measurements.

Intense (up to a few 10(17) W/ cm2) femtosecond (down to 40 fs) laser pulses are focused onto a partially clusterized argon gas jet. The target was previously characterized and optimized in order to get a homogeneous and dense jet of clusters with a well controlled size. The interaction leads to x-ray emission that is absolutely calibrated and spectrally resolved using a high resolution time-integrated spectrometer in the K-shell range (from 2.9 to 4.3 keV). X-ray spectra are investigated as a function of different laser temporal parameters such as the nanosecond prepulse contrast, the laser pulse duration, and the femtosecond delay between two different laser pulses. The cluster size ranges from 180 to 350 angstroms and irradiation by laser pulses with both linear and circular polarization is investigated. The experimental results are discussed in terms of the laser-cluster interaction dynamics. They are compared with the predictions of collision-dominated nanoplasma models. However, further interaction processes are required in order to explain the observed characteristic lines demonstrating highly charged ions up to Ar16+.

Macular pattern dystrophy in patients with deafness and diabetes.

PURPOSE: To report the characteristic findings of a macular pattern dystrophy in patients with diabetes and deafness resulting from the mitochondrial point mutation at position 3243 and to expand the clinical spectrum of this condition by describing functional testing results. METHODS: Four diabetic patients who were referred to the eye department for diabetic fundus examination were found to harbor a macular pattern dystrophy. Further examination of visual fields; color contrast sensitivity; and the ear, nose, and throat; and molecular analysis of the mitochondrial genome were performed. Two of our patients were sisters. Their relatives also were examined. RESULTS: All four patients were found to harbor the mitochondrial point mutation at position 3243 and presented clinically with the phenotype of diabetes and deafness. The macular pattern dystrophy described in these patients seems to be typical for this condition. Results of a 9-year follow-up study of one of the patients showed mild progression of atrophic changes. The overall prognosis of the retinopathy is likely to be good. CONCLUSION: These cases demonstrate the need for further molecular investigations when a macular pattern dystrophy is found in a patient with diabetes and deafness.

Fundus changes in patients with the mitochondrial DNA point mutation at position 3243.

The A3243G transition in the mitochondrial DNA is commonly associated with the syndrome of mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS). Previously, atypical pigmentary retinopathy has been described in patients with this syndrome and in patients with other phenotypes of the same mitochondrial defect. Maternally inherited diabetes mellitus and deafness has been recognized as a distinct clinical presentation of the mitochondrial point mutation at position 3243, and recently a pattern dystrophy has been identified as a characteristic ocular abnormality in these patients. The finding of a macular pattern dystrophy in patients with diabetes should therefore lead to screening for this aberrant mitochondrial genome.

[Lack of sensitivity to per-anesthetic malignant hyperthermia in 32 patients who developed neuroleptic malignant syndrome]. / Absence de sensibilité à l'hyperthermie maligne peranesthésique chez 32 patients ayant développé un syndrome malin des neuroleptiques.

The aim of this study was to verify whether a relationship exists between neuroleptic malignant syndrome (NMS) and anaesthetic-induced malignant hyperthermia (MH) or not. The in vitro halothane-caffeine tests were performed on muscle tissue obtained from 32 patients with documented NMS episodes. The diagnosis of NMS relied on Levenson's criteria. The results, expressed in accordance with the criteria of the European MH Group, defined 29 subjects as MH non-susceptible. Three patients were classified as MH equivocal. These findings demonstrate the lack of any link between NMS and MH. Therefore, patients with a history of NMS are not likely to be at risk of developing MH and special measures against MH are not required for anaesthesia in these patients.

[Cerebellar syndrome after carbon monoxide poisoning. Magnetic resonance imaging and single photon emission tomography]. / Syndrome cérébelleux après intoxication oxycarbonée. Imagerie par résonance magnétique et tomographie d'émission monophotonique.

A 19-year-old woman presented with severe carbon monoxide poisoning resulting in coma, brain stem signs, cerebellar syndrome, anterograde memory disorder and some frontal signs. Nine years later, generalized seizures appeared. At the age of 31, the cerebellar syndrome and memory disorders persisted. MRI showed cerebellar and internal temporal atrophy with high-intensity signals, and hippocampal and callosal atrophy. SPECT (Xe133) showed a low cerebellar blood flow.

Sodium lactate reversal of electrophysiological effects of imipramine in guinea-pig ventricular myocardium.

Overdose cardiac effects of imipramine are due to fast Na channel blockade and are clinically reversed by administration of sodium lactate which induces alkalosis (about pH 7.50) and hypernatremia (about 8 mM). The mechanisms of this beneficial effect of Na lactate were explored in vitro on guinea-pig ventricular myocardium using the microelectrode technique. The time-course effects of the clinically relevant concentration of 10 microM imipramine on action potential characteristics were examined at pH 7.20 and pH 7.50. To test whether alkalinisation per se is important or whether an increase in Na concentration plays a major role in the reversal effect, preparations were exposed to increasing concentrations (1, 3, 10, 30, 100 mM) of either Na lactate, bicarbonate or chloride in the absence or in the presence of 10 microM imipramine at pH 7.50. The influence of elevating osmolality was evaluated with equivalent concentrations of sucrose. Imipramine alone significantly depressed Vmax and shortened action potential duration at all phases of repolarisation. All three high sodium solutions reversed imipramine effects. However the reversal effect was already obvious with 10 mM Na lactate and 10 mM NaHCO3 but not 10 mM NaCl. Osmolality did not reverse the imipramine-induced Vmax depression. The results suggest that at the clinically relevant 10 mM concentration, sodium lactate and bicarbonate may displace imipramine from its receptor site on the Na channel by causing alkalosis at the membrane level without profoundly affecting the driving force of the Na current, whereas at the upper concentrations, the increase in Na ion concentrations is predominantly involved in the reversal of imipramine effects.

Lone atrial fibrillation and stroke.

We studied 21 consecutive patients from the Lausanne Stroke Registry, who had first-ever ischemic stroke and lone atrial fibrillation, with a standard protocol of investigations including brain CT, and non-invasive cardiac and arterial tests. Rarity of associated risk factors and extracranial; arterial disease, presence of distal intracerebral occlusions on early angiography, and topography of cerebral infarct suggested that cardioembolism was the cause of stroke, though echocardiographic evidence for an atrial thrombus was uncommon. There was no recurrence during a post-stroke 14-day phase, during which anticoagulant and antiaggregant therapies were systematically avoided. Though low, the main risk of stroke recurrence was 0.99 per 100 patient-years during a mean follow-up period of 4.8 years, including a mean duration of anticoagulant therapy of 2.3 years in 18 patients. On the other hand, no death, severe cardiac events, or disabling anticoagulation-related hemorrhages occurred.

Conceptualizing community interventions in social service needs of pregnant adolescents.

Traditional approaches to adolescent pregnancy have utilized the paradigm of single cause-single solution and have tended to define it as a pregnancy problem rather than as a parenting problem. The conceptual model presented emphasizes the importance of primary prevention efforts if approaches are to work. This model defines adolescent pregnancy as a parenting problem that is multicausal and thus requires multiple solutions. A community intervention model systematizes a coalition of effort that represent the three helping systems of the health, education, and community environment to ensure interaction among each of the systems to benefit the pregnant adolescent and her family. It uses a cost-effective pool of community volunteers to offer education and advocacy services. Of utmost importance is that it is guided by the belief that parenting is a continuum of experiences that requires the cooperation of all the helping systems to produce positive outcomes.

The association between the neuroleptic malignant syndrome and malignant hyperthermia.

The neuroleptic malignant syndrome (NMS) is an uncommon but dangerous complication of treatment with neuroleptic drugs. A primary defect in skeletal muscle has been suggested in view of similarities in the clinical presentations of NMS and anaesthetic-induced malignant hyperthermia (MH). The in vitro halothane-caffeine contracture tests are the most reliable method of identifying individuals susceptible to MH. The aim of this study was to define if a relationship exists between NMS and MH susceptibility. Hence, the in vitro halothane and caffeine contracture tests were performed on muscle tissue obtained from eight NMS, ten MH-susceptible and ten control patients. The results, which are expressed in accordance with the criteria of the European MH Group, defined the eight NMS subjects as MH non-susceptible. The response to halothane and caffeine exposure of skeletal muscle from NMS and control subjects was the same and significantly different from that of muscle from patients susceptible to MH. Furthermore, muscle from subjects in NMS and control group responded similarly to increasing concentrations of chlorpromazine. These results do not point towards an association between NMS and MH.

[Acute spinal amyotrophy in toxoplasmosis]. / Amyotrophie spinale aiguë au cours d'une toxoplasmose.

A 19 year-old man developed an acute syndrome of the anterior horn of cervical spinal cord during a primo-infection with toxoplasma. The neurological syndrome was completely regressive after treatment with 1 600 mg/day of trimethoprim-sulfamethoxazole for three months.

[Fronto-nasal dysplasia (apropos of 4 cases)]. / La dysplasie fronto-nasale (à propos de quatre observations).

Four cases of frontonasal dysplasia are reported in two boys and two girls. Clinical diagnosis was made at 16 months in one case and sooner in 3 cases (1 month-3 1/2 months) in presence of following features: severe hypertelorism (4/4), paramedian lip and palate cleft (3/4), nose root broadering (4/4), bifid or cleft nose tip (3/4), window's peak (3/4) mediofrontal swelling (4/4), cranium bifidum occultum (2/4). Many abnormalities were associated: conduction deafness (1/4), goldenhar syndrome (1/4), GH deficiency (1/4), etc... In three cases when cerebral investigation was possible, it was pointed out: corpus callosum agenesis (3/3), hydrocephalus (3/3), Dandy-Walker cyst (2/3). Caryotype is normal in whole cases which are sporadic. Two children are dead. The two alive remaining have severe mental impairment.

A field study of the validity of static paper sampling in fluoride pollution surveys.

A field study of fluoride pollution and of its consequences was made over a period of five years in the vicinity of an alumina reduction plant. This study, based upon the use of a static soda impregnated paper sampler, shows that the results obtained are in good agreement with the atmospheric fluoride concentrations obtained with dynamic samplers, especially when fluoride is present in gaseous form (HF). The results suggest that vertically mounted paper samplers are less sensitive to the collection of particulate fluorides. Collection rate is strongly influenced and increases with speed. If this parameter is known, an accurate estimation of the absolute atmospheric concentration is possible; the values shown by this technique are in good correlation with the value (annual mean) of pasture fluoride content. As a correlation exists between pasture fluoride content and the symptoms shown by cattle, the static filter samplers can predict disease in the case of slow chronic fluorosis. The field study agrees with earlier laboratory experiments and shows the validity of these simple and inexpensive types of exposure methods.

[Colonic stenosis following necrotizing enterocolitis in newborn infants. Apropos of 3 cases]. / Stenose colique apres enterocolite necrosante du nouveau-ne. A propos de trois observations.

Three cases of double left colic stenosis revealed at one month of age by subobstruction are reported. Recovery was obtained by surgery. The evolution of radiological data in one case, and of histological changes observed on the resected sigmoid colon in the two other cases favor the assumption that cicatricial stenosis occurred likewise. These cases also confirm the existence of a benign expression of necrotising enterocolitis, most common with a colonic localization. Such stenosis due to submucous connective sclerosis strengthens the hypothesis that a transitory mesenteric ischemia is responsible for the necrotizing enterocolitis in newborns.