Sensitivity of photoelectron diffraction to conformational changes of adsorbed molecules: Tetra-tert-butyl-azobenzene/Au(111).

Electron diffraction is a standard tool to investigate the atomic structure of surfaces, interfaces, and adsorbate systems. In particular, photoelectron diffraction is a promising candidate for real-time studies of structural dynamics combining the ultimate time resolution of optical pulses and the high scattering cross-sections for electrons. In view of future time-resolved experiments from molecular layers, we studied the sensitivity of photoelectron diffraction to conformational changes of only a small fraction of molecules in a monolayer adsorbed on a metallic substrate. 3,3',5,5'-tetra-tert-butyl-azobenzene served as test case. This molecule can be switched between two isomers, trans and cis, by absorption of ultraviolet light. X-ray photoelectron diffraction patterns were recorded from tetra-tert-butyl-azobenzene/Au(111) in thermal equilibrium at room temperature and compared to patterns taken in the photostationary state obtained by exposing the surface to radiation from a high-intensity helium discharge lamp. Difference patterns were simulated by means of multiple-scattering calculations, which allowed us to determine the fraction of molecules that underwent isomerization.

Light-Matter Interaction at Surfaces in the Spatiotemporal Limit of Macroscopic Models.

What is the spatiotemporal limit of a macroscopic model that describes the optoelectronic interaction at the interface between different media? This fundamental question has become relevant for time-dependent photoemission from solid surfaces using probes that resolve attosecond electron dynamics on an atomic length scale. We address this fundamental question by investigating how ultrafast electron screening affects the infrared field distribution for a noble metal such as Cu(111) at the solid-vacuum interface. Attosecond photoemission delay measurements performed at different angles of incidence of the light allow us to study the detailed spatiotemporal dependence of the electromagnetic field distribution. Surprisingly, comparison with Monte Carlo semiclassical calculations reveals that the macroscopic Fresnel equations still properly describe the observed phase of the IR field on the Cu(111) surface on an atomic length and an attosecond time scale.

Versatile attosecond beamline in a two-foci configuration for simultaneous time-resolved measurements.

We present our attoline which is a versatile attosecond beamline at the Ultrafast Laser Physics Group at ETH Zurich for attosecond spectroscopy in a variety of targets. High-harmonic generation (HHG) in noble gases with an infrared (IR) driving field is employed to generate pulses in the extreme ultraviolet (XUV) spectral regime for XUV-IR cross-correlation measurements. The IR pulse driving the HHG and the pulse involved in the measurements are used in a non-collinear set-up that gives independent access to the different beams. Single attosecond pulses are generated with the polarization gating technique and temporally characterized with attosecond streaking. This attoline contains two target chambers that can be operated simultaneously. A toroidal mirror relay-images the focus from the first chamber into the second one. In the first interaction region a dedicated double-target allows for a simple change between photoelectron/photoion measurements with a time-of-flight spectrometer and transient absorption experiments. Any end station can occupy the second interaction chamber. A surface analysis chamber containing a hemispherical electron analyzer was employed to demonstrate successful operation. Simultaneous RABBITT measurements in two argon jets were recorded for this purpose.

[Magnetic resonance imaging of dilated cardiomyopathy]. / MRT bei dilatativen Kardiomyopathien.

Dilated cardiomyopathy (DCM) is the most common type of cardiomyopathy with a prevalence of 1 out of 2,500 in adults. Due to mild clinical symptoms in the early phase of the disease, the true prevalence is probably even much higher. Patients present with variable clinical symptoms ranging from mild systolic impairment of left ventricular function to congestive heart failure. Even sudden cardiac death may be the first clinical symptom of DCM. The severity of the disease is defined by the degree of impairment of global left ventricular function. Arrhythmias, such as ventricular or supraventricular tachycardia, atrioventricular (AV) block, ventricular extrasystole and atrial fibrillation are common cardiac manifestations of DCM. Magnetic resonance imaging (MRI) plays an important role in the exact quantification of functional impairment of both ventricles and in the evaluation of regional wall motion abnormalities. With its excellent ability for the assessment of myocardial structure, it is becoming increasingly more important for risk stratification and therapy guidance.

[Late gadolinium enhancement in the diagnostics of ischemic heart disease: technical principles, contrast optimization and clinical application]. / Late-Gadolinium-Enhancement in der Diagnostik der koronaren Herzerkrankung : Technische Grundlagen, Kontrastoptimierung und klinische Anwendung.

BACKGROUND: The purpose of the study was to explore a "dark blood" technique and to compare it with a standard inversion recovery gradient echo (IR GRE) sequence in the visualization of myocardial infarction. PATIENTS AND METHODS: A total of 9 patients were examined with standard IR GRE and a "dark blood" sequence 15 mins after contrast medium application (0.2 mmol/kg body weight gadobenate dimeglumine). Contrast-to-noise ratios (CNR) were calculated for each sequence. RESULTS: The CNR(inf-lvc) was significantly higher in the "dark blood" technique compared to the IR GRE sequence, while the CNR(inf-myo) was significantly lower. CONCLUSIONS: Small subendocardial infarctions may be easier to detect with the "dark blood" technique. However, the standard IR GRE sequence is superior in the demarcation of infarctions in relation to the myocardium and cannot be replaced by the "dark blood" technique.

Right ventricular function in patients with severe interstitial lung disease: a Tissue Doppler imaging study.

Tissue Doppler imaging (TDI) can be useful in the evaluation of right ventricular (RV) regional dysfunction due to pulmonary diseases. The aim of the study was to assess RV dysfunction in patients with severe interstitial lung diseases (ILD), using both TDI and conventional transthoracic echocardiography (TTE). The study group consisted of 40 consecutive patients with end-stage ILD referred for lung transplantation (LT). Eighteen of them, mean age 47 +/-12 yr, who fulfilled the ATS/ERS criteria for LT (mean forced vital capacity (FVC) 1.4 +/-0.8 l, mean diffusing capacity for carbon dioxide (DLCO) <50% of predicted) constituted the active group, and 22 age-matched patients (mean age 49 +/-12 yr), who did not fulfill these criteria, were placed in the waiting group for LT. We found that among the TDI parameters, the longitudinal peak systolic strain rate (SR) measured at the RV outflow tract, was significantly more negative (-1.1 +/-0.3 vs. -3.2 +/-1.2 s(-1), P=0.03) and the time to peak velocity (TpVEL) in the medial and apical septal segments were shorter (129.9 +/-47.9 vs. 159.2 +/-38.1 ms, P=0.018 and 126.8 +/-44.3 vs. 154.6 +/-40.9 ms, P=0.019) in the patients from the active than those from the waiting group. TTE showed that patients from the active group had significantly lower values of tricuspid annulus plane systolic excursion (TAPSE) (14.3 +/-3.3 vs. 20.6 +/-6.2 mm, P=0.0003) and pulmonary artery acceleration time (PVAT) (70.3 +/-23.3 vs. 96.9 +/-12.4 ms, P=0.0001)compared with those from the waiting group. No other differences were found for other parameters of RV function between the examined groups. In conclusion, severity of lung disease in patients with ILD influences RV systolic dysfunction, which is reflected in both TDI and conventional echocardiographic parameters.

Patterns in the occurrence of saprophytic fungi carried by arthropods caught in traps baited with rotted wood and dung.

Fungi from approximately 1700 individual arthropods that had been captured in traps set in aspen-dominated woodland in western Canada and baited with coyote dung, moose dung, white-rotted wood, brown-rotted wood and fiberglass were isolated in pure culture and identified. These data were analysed with principal components analysis (PCA) to determine whether different types of substrate attracted specific arthropods and whether these animals carried unique assemblages of fungi with known proclivities for the new habitat. Mycobiotic agar was used to restrict the numbers of fungi isolated and resulted in the recovery of 1687 isolates representing 65 species across 12 orders. Isolates of cosmopolitan fungal taxa such as species of Cladosporium, Penicillium, and Beauveria were the most numerous. Taxa with predilections for specific substrates, such as Myxotrichum and Cryptendoxyla that are known inhabitants of cellulose-rich materials (i.e. rotted wood), and various representatives of the keratinophilic Onygenales were recovered from arthropods attracted respectively to baits rich in cellulose and keratin. When traps were analysed according to the identity and numbers of arthropods captured, there was considerable overlap among clusters representing specific bait types, with traps baited with coyote dung being the most divergent partly because they captured significantly more arthropods than those baited with moose dung or rotted wood. When bait type was examined according to the identity and numbers of fungi on trapped arthropods the degree of overlap was also high although a few trends could be discerned. In particular traps baited with brown-rotted wood and coyote dung diverged slightly indicating that arthropods visiting these bait types were carrying somewhat different suites of fungi.

Respiratory flutter syndrome: an underrecognized cause of respiratory failure in neonates.

We report the clinical and respiratory data of three neonates with flutter of the diaphragm and intercostal muscles, presenting soon after birth with respiratory failure. The breathing pattern was dirhythmic with superimposed frequencies, one regular and slow (60/min) representing the underlying respiratory rate, the other fast (> 300/min) and limited to inspiration. Nasal continuous positive airway pressure immediately normalized the breathing pattern in one infant, and improved ventilation in the two others. Pharmacologic therapy with chlorpromazine terminated the respiratory flutter and permitted weaning of ventilatory support within a few hours. Coexistent dysphagia suggested a disorder of brainstem function, although the children were otherwise developmentally normal at 8, 10, and 26 mo old. Laryngomalacia and gastroesophageal reflux were also present. We propose that the occurrence of respiratory flutter, dysphagia, laryngomalacia, and gastroesophageal reflux in a neonate constitutes a distinct clinical entity, termed the "respiratory flutter syndrome." The diagnosis of three infants with this presentation during an 18-mo period suggests that this may be a more frequent cause of respiratory failure in newborns than previously recognized.

Quantitative neurologic assessment of ataxia-telangiectasia.

BACKGROUND: Ataxia telangiectasia (A-T) is a rare disorder with many distinctive neurologic features. Although there is substantial individual variation in the rate of progression of these features, their relationship to one another or to age has not been characterized. METHODS: We formulated and tested multiple elements that assess different neurologic functions known to be affected by A-T. The overall index was applied to 52 patients with A-T, 2 to 29 years of age. RESULTS: Seven elements items proved to be informative, and three elements were added based on face validity. In a linear regression model of individuals under 19 years of age, controlled for correlation within sibships, age accounted for 87% of the variation in the A-T Index. CONCLUSION: Despite substantial individual variability of the phenotypic elements of A-T, scores on this multidimensional index have a very high correlation with age, indicating that there is a characteristic rate of progression of the disease, although functional domains in the brain are differentially affected. The pattern of scores suggests that a severe and a mild form of A-T may be distinguished by this quantitative measure. With further development this index may become useful as an outcome measure for treatment studies and prognosis.

Oropharyngeal dysphagia and aspiration in patients with ataxia-telangiectasia.

OBJECTIVES: To determine whether patients with ataxia-telangiectasia exhibit oropharyngeal dysphagia with concomitant aspiration and to examine the relationships among swallowing function, age, and nutritional status. STUDY DESIGN: Seventy patients (mean age, 10.7 years; range, 1.8 to 30 years) had feeding/swallowing and nutritional evaluations. Fifty-one patients, in whom there were concerns about swallowing safety, were examined with a standardized videofluoroscopic swallow study. RESULTS: Fourteen of the 51 patients (27%) with histories suggestive of dysphagia demonstrated aspiration. Of these, silent aspiration (aspiration without a cough) occurred in 10 (71%) patients. Aspirators were significantly older than non-aspirators (mean age, 16.9 vs 10.8 years; P =.002). Advancing age was the strongest factor associated with aspiration during continuous drinking (P =.01). In patients with ataxia-telangiectasia, weight and weight/height were abnormally low at all ages and most compromised in older patients. Patients who aspirated had significantly lower mean weight (P <.002) and weight/height z scores (P <.001) than did patients who did not aspirate. CONCLUSIONS: Oropharyngeal dysphagia is common and appears to be progressive in patients with ataxia-telangiectasia. Older patients also have a higher incidence of poorer nutritional status. The relationship between dysphagia and nutritional status deserves further investigation.

Variations in cytokine mRNA expression during normal human pregnancy.

Epidemiological data provide evidence that disease activity of T cell-mediated, organ-specific autoimmune diseases is reduced during pregnancy. Although there are several experimental animal studies on the effect of pregnancy on the immune system, the situation in humans is less clear. We therefore performed a prospective analysis of cytokine mRNA expression in whole blood by a new on-line reverse transcriptase-polymerase chain reaction technique and of serum hormone levels during pregnancy in healthy women. The control group included age-matched non-pregnant healthy women. Quantitativecytokine mRNA expression revealed significantly reduced IL-18, interferon-gamma (IFN-gamma), and IL-2 mRNA levels in the first and second trimester in pregnancy compared with non-pregnant women. No difference between groups was detected for tumour necrosis factor-alpha (TNF-alpha) mRNA. IL-4 and IL-10 mRNA were detected at low levels in only 20% of pregnant women and were reduced to a statistically significant extent in the second and third trimester compared with the control group. Changes in IL-18 mRNA expression correlated inversely with serum values for human choriogonadotropin (HCG) and IL-10 serum levels correlated with increases in serum 17beta-oestradiol levels. These data indicate immunomodulatory effects of pregnancy at the cytokine level which may be related to the variations in the clinical course of organ-specific, T cell-mediated autoimmune diseases during pregnancy.

Microglial/macrophage expression of interleukin 10 in human glioblastomas.

Interleukin 10 (IL-10) expression has been found to be correlated with the extent of malignancy in gliomas. In vitro, IL-10 increases proliferation and migratory capacity in human glioma cell lines. In this study, we localized the site of IL-10 synthesis in gliomas to cells of microglial origin. Biopsy specimens from 11 patients with malignant glioma were processed on native tissues and at early cell culture passages (0-4). IL-10 mRNA was analyzed by RT-PCR and in situ hybridization. Protein was quantitatively assessed by ELISA in cell culture supernatants, and cells expressing IL-10 were determined by a combination of immunohistochemistry for CD68 (specific for microglia/macrophage lineage) and IL-10 in situ hybridization. IL-10 mRNA decreased from passage 0 to 4 in all samples and was undetectable beyond passage 5. Such downregulation of mRNA leads to a steep decrease of IL-10 protein in culture supernatants (below detection level, 0.05 ng/ml, beyond passage 1). The combination of in situ hybridization for IL-10 and CD68 immunostaining revealed that only cells of the microglia/macrophage lineage produced IL-10 mRNA. Our results identify microglia/macrophage cells as the major source of IL-10 expression in gliomas which decreases markedly during early passages of primary cultures of human gliomas due to a progressive reduction of microglia/macrophages present.

Interstrain variation of immediate early DNA sequences and glycoprotein B genotypes in cytomegalovirus clinical isolates.

Cytomegalovirus (CMV) disease is associated with a high mortality in recipients of an allogeneic stem cell transplant. Apparent differences in biological behaviour have been noted among clinical CMV isolates. By amplifying specific functionally relevant regions of the CMV genome [immediate early (IE) exon 3, glycoprotein B (gB)], a possible association of strain variation and clinical symptoms of infection was analysed in 24 patients. A high number of genome mutations of the IE exon 3 region could be documented translating into amino acid changes of viral isolated of 8 out of 15 patients with symptomatic and 2 out of 9 patients with asymptomatic CMV infection. Identical IE mutations and gB types were observed in isolates from two different sites in 6 patients. gB strain 2 was found to be associated with symptomatic CMV infection (P = 0.03). Thus, apart from host factors viral factors might influence the virus-host interaction in severely immunosuppressed patients.

Sperm binding and ultrasound changes after operative repair of varicocele: correlation with fecundity.

The study was conducted to evaluate the changes in sperm binding capacity and ultrasound measurements of the internal spermatic vein, after operative repair of a varicocele. In order to clarify the effect of a varicocele on fertility, these changes were correlated to pregnancy achievement. Twelve infertile males with subnormal semen parameters and varicocele, underwent operative repair. Pre- and post-operatively, all had semen analysis, hemizona assay and ultrasound of the internal spermatic veins. The patients were divided into three subgroups according to pregnancy outcome, and the changes in the different evaluation tests after the operation were compared. Sperm concentration and motility improved post-operatively in all three subgroups, whereas the hemizona index and ultrasonographic measurements improved significantly only in the subgroup that achieved early pregnancies (the mean post-operative percentage of normal morphology was significantly higher), compared to the subgroup without pregnancies. Unlike sperm parameters which improve after operative repair of the varicocele, but have no correlation to conception, sperm binding and ultrasound measurements of the internal spermatic veins improve significantly in cases that achieve early pregnancies. The use of these tests, as well as measuring the percentage of normal morphology, are recommended in all cases of infertility-related varicocele.

Pediatric feeding/swallowing teams.

A team approach is advocated for the evaluation and management of children with impairments in deglutition. The complexity of their needs requires the coordination of evaluation and management efforts so that the impact of a child's feeding/swallowing impairment on general health, development, and overall well-being may be addressed. This article reviews the rationale supporting the use of a team approach, the organizational structures of teams, and the challenges of using a team model of service delivery to meet the needs of this population.

Ethical considerations in pediatric dysphagia.

Speech-language pathologists (SLPs) are bound by ethical codes that reflect professional and institutional commitments. When professional activities involve working with children with dysphagia and other complex medical issues, SLPs frequently must make judgments that have bioethical implications. This article reviews general ethical theories and principles, examines SLPs' ethical commitments, and presents an approach for ethical decision making and reasoning. Case studies of children with dysphagia are presented to illustrate ethical dilemmas.

Anatomy, physiology, and development of feeding.

Dysphagia in infants and children is usually only one part of a broad spectrum of complex medical, health, and developmental problems. As etiologies vary, so do prognoses. Increased survival rates of infants in recent years have been accompanied by an increased prevalence of neurologic, cardiorespiratory, and structural impairments that can affect nutritional status and feeding function. Knowledge of anatomy, physiology, and normal development of feeding skills is basic to the assessment and management of pediatric dysphagia.

Specialized studies in pediatric dysphagia.

The evaluation and management of the pediatric patient with a feeding and swallowing disorder may require the use of specialized studies to evaluate specific aspects of swallowing function; to judge the consequences of the swallowing dysfunction; and to assess factors that may be contributing to swallowing dysfunction. Instrumental assessment of swallowing function may include upper gastrointestinal studies, videofluoroscopy or videofluoroscopic swallow studies, ultrasonography, radionuclide imaging, fiberoptic endoscopy of swallowing, and cervical auscultation. Procedures that assess the consequences and/or identify factors contributing to swallowing dysfunction may include pulse oximetry, chest x-rays, laryngoscopy and/or bronchoscopy, and pulmonary function tests. The use of such specialized procedures to evaluate children with dysphagia is the focus of this article.

Long-lasting exocytosis and massive structural reorganisation in the egg periphery during cortical reaction in Platynereis dumerilii (Annelida, Polychaeta).

The course of the cortical reaction in the Platynereis dumerilii egg is described from live observation and from sectioned fixed material and is found to differ in several aspects from the course of cortical reactions in better-known systems. Cortical granules are unusually numerous. They are discharged by exocytosis during a period of about 25 min following fertilisation (18 degrees C). Most of the surplus membrane material brought to the egg surface by exocytosis is set free into the perivitelline space. Swelling of egg jelly precursor secreted by cortical granule exocytosis may be causal for the detachment of the vitelline envelope from the egg cell surface which, however, remains attached punctately to the vitelline envelope by about 30,000 microvilli. Under the strain of the distending vitelline envelope, the bases of the microvilli move and line up, pulling the cell surface into a network of ridges. The grooves in between the ridges are the sites of exocytoses. Cytochalasin B, generally destabilising actin filaments, induces rupture of the microvilli and exaggerated distension of the vitelline envelope during the cortical reaction. In a final phase of the cortical reaction the vitelline envelope wrinkles and falls back onto the egg cell surface, the microvilli shorten and the egg cell transiently becomes deformed by local contractions. The cortical reaction in the nereid egg is discussed as a process of distortion and reorganisation of the egg cortex and plasmalemma. The abundance of cortical granules accommodating egg jelly precursor in the Platynereis oocyte is attributed to the mode of so-called diffuse oogenesis characteristic of nereids, i.e. of differentiation of oocytes freely suspended in the coelomic fluid. In nereids, egg jelly therefore forms after fertilisation as opposed to ovulation.