Femtosecond laser induced synthesis of Au nanoparticles mediated by chitosan.

This paper reports the synthesis of Au nanoparticles by 30-fs pulses irradiation of a sample containing HAuCl4 and chitosan, a biopolymer used as reducing agent and stabilizer. We observed that it is a multi-photon induced process, with a threshold irradiance of 3.8 × 10(11) W/cm2 at 790 nm. By transmission electron microscopy we observed nanoparticles from 8 to 50 nm with distinct shapes. Infrared spectroscopy indicated that the reduction of gold and consequent production of nanoparticles is related to the fs-pulse induced oxidation of hydroxyl to carbonyl groups in chitosan.

Guidelines for safety and quality in anaesthesia practice in the European Union.

Anaesthesia is a medical specialty that is particularly concerned with the safety of the patient who is undergoing a surgical procedure. This is a prerequisite in order to provide quality of care, which is based on good clinical practice, on a sound organization, on an agreement on best practice and on adequate communication with other healthcare workers involved. Providing a safe environment for those working in healthcare is at least as important as other factors serving that objective. A working party on Safety and Quality in Anaesthesiological Practice in the Section and Board of Anaesthesiology of the European Union of Medical Specialists (EUMS/UEMS) has prepared guidelines that were amended and approved recently.

Transitions in the orientational order of liquid crystals induced by periodic patterned substrates.

The orientational order of liquid crystals (LCs) induced by periodic patterned substrates has been investigated with cells coated by azopolymer films that could be photoaligned in a controlled way. Two regimes were observed depending on the period of the patterns: (i) above 3.0 microm the LC follows the direction imposed by the patterned substrate since the energy stored in the surface potential minimizes the elastic energy of the LC medium. (ii) For periods smaller than 1.0 microm a homogeneous in-plane state was induced and the LC did not follow the orientation imposed by the surface. This in-plane transition could be explained qualitatively by a theoretical model based on the competition between the Frank-Oseen elastic energy and the phenomenological surface potential. The results also suggest an out-of-plane transition for the LC director as the period was reduced. These results agree with data in the literature for patterned substrates with completely distinct architectures. This indicates that for a particular LC sample the overall behavior depends basically on the texture period instead of the texture architecture. The textures were characterized with a scanning near-field optical microscope (SNOM), which allowed simultaneous morphological and optical images in the submicrometer range.

Phenomenological analysis of the light intensity dependence of the photoalignment process in azo-containing polymeric films.

A phenomenological model is proposed to analyze the influence of the incident light intensity on the photoinduced anisotropy of an azobenzene-containing polymer film. The optical anisotropy was generated in the films by the incidence of linearly polarized light and monitored by transmittance measurements.

In situ UV-vis absorbance measurements for Langmuir films of poly[4'-[[2-(methacryloyloxy)-ethyl]ethylamino]-2-chloro-4-nitroazobenzene] (HPDR13) azopolymer.

In situ UV-vis absorbance measurements are used to investigate aggregation in Langmuir films from the azopolymer poly[4'-[[2-(methacryloyloxy)-ethyl]ethylamino]-2-chloro-4-nitroazobenzene] (HPDR13), a methacrylate derivative of DR13. The level of aggregation in a Langmuir film is intermediate between that of HPDR13 in chloroform solution and in a deposited LB film, as expected. Absorption is negligible at large areas per monomer, and starts to increase at a critical area that is the same as the one obtained in surface potential isotherms, being close to twice the area per monomer for a condensed film. This indicates that the onset for light absorption coincides with a critical packing density where monolayer structuring occurs and there is a sharp change in the effective dielectric constant of the film/water interface. Consistent with a featureless pressure-area isotherm for HPDR13, denoting no significant molecular rearrangement upon film compression, the UV-vis spectra did not vary with the surface pressure. The intensity of absorbed light increased, though, as the film was compressed owing to a higher density of chromophores. At higher subphase temperatures, larger flexibility of HPDR13 chains led to a more compact arrangement, causing the area per monomer to decrease and the absorbed light to increase-with approximately opposite trends.

Manipulation of anchoring strength in an azo-dye side chain polymer by photoisomerization.

The generation of surface anisotropy by photochemical means has been proposed as an attractive method to align liquid crystals. In this paper, we present an experimental study of the alignment induced on a liquid crystal by a polymer film containing azo-dye groups in the side chain. Optical measurements were performed in nematic liquid crystal cells to determine the azimuthal and zenithal anchoring strengths as a function of the irradiation energy and chromophores concentration. It was observed that the director tends to align perpendicular to the polarization direction of the incident light and the orientation process consists essentially of a rotation of the director in the plane parallel to the boundary surfaces. However, the concentration of azo-dye groups in the polymer film must exceed a minimum value to get a macroscopical effect on the liquid crystal alignment. It is shown that the azimuthal anchoring strength can be varied two orders of magnitude by controlling the irradiation energy and azo-dye concentration.

Surface enhanced fluorescence and Raman imaging of Langmuir-Blodgett azopolymer films.

The spectroscopic properties and surface-enhanced spectra of Langmuir-Blodgett (LB) films of methacrylic homopolymer (HPDR13) are presented. It is shown that LB film displays strong fluorescence attributed to the spatial restrictions imposed by its structure. The emission is observed in conjunction with photoisomerization, a process clearly demonstrated by the formation of surface-relief gratings in the LB film [C.R. Mendonça et al., Macromolecules 32 (1999) 1493]. Surface-enhanced Raman scattering (SERS), Surface-enhanced resonance Raman scattering (SERRS) and surface-enhanced fluorescence (SEF) were observed for LB films of HPDR13 deposited onto silver island films. SERS measurements were also carried out on a sample fabricated with one monolayer LB film deposited onto silver islands followed by one overlayer of silver (LB sandwiched between two layers of silver islands). The polymer interacts very weakly with the metal surface (physisorption), and the enhancement effect is determined by the local electric field enhancement. The strong SERS and SERRS signals were suitable for micro-Raman imaging. Line, area mapping and global images of the LB monolayer on silver island are reported. The transfer ratio in the fabrication of the LB suggests a homogeneous coating of the silver islands, thereby the chemical images show the variation of the SERS intensity due to surface enhancement.

Exogenous neopterin causes cardiac contractile dysfunction in the isolated perfused rat heart.

Neopterin is known in humans as a sensitive marker for diseases associated with increased activity of the cellular immune system. Recent studies report neopterin also to exhibit distinct effects: neopterin induces inducible nitric oxide synthase expression in rat vascular smooth muscle cells and activates translocation of nuclear factor- kappa B. Neopterin may also induce oxidative stress causing apoptotic cell death, or superinduce tumor necrosis factor- alpha -mediated apoptosis. Observing these effects in cell cultures, we were interested in possible consequences of neopterin on cardiac function in the isolated perfused rat heart. The influence of neopterin in three different concentrations (10 micromol/l, 50 micromol/l, 100 micromol/l) on cardiac contractility parameters and coronary vascular resistance were studied in 67 male Sprague-Dawley rats using the temperature-controlled and pressure-constant Langendorff apparatus with retrograde perfusion of the aorta with a Krebs-Henseleit buffer. Treatment with 100 micromol/l neopterin resulted in a significant decrease in coronary flow and cardiac contractility. Coronary flow decreased from 15.2 to 9.5 ml/min (P=0.002), left ventricular pressure from 80 to 52 mmHg (P=0. 002), rate of pressure fall from 1605 to 923 mmHg/s (P=0.001) and rate of pressure rise from 2862 to 1709 mmHg/s (P=0.001). Concentrations lower than 100 micromol/l neopterin had no significant effect on cardiac function. Our study demonstrates a considerable influence of exogenous neopterin on cardiac performance in the Langendorff model of isolated perfused rat hearts. This has to be considered a potential pathogenic factor of cardiac disturbances in diseases in which high concentrations of neopterin are released due to immune activation. At present the exact mechanism remains unclear.

National publication output in medical research.

OBJECTIVE: Both the total number of publications and the number of publications in high-ranking journals determine a country's reputation in scientific research. A predominance of national authors in a country's international high-ranking journals has occasionally been presumed. We therefore analysed the publication output of various countries and the proportion of national authors in international high-ranking journals. METHODS: The database EMBASE (Excerpta Medica) by means of the online service Dialog was used to analyse the national publication output of various countries during the years 1986 to 1990 and 1991 to 1995 and the proportion of national authors in The Lancet and The New England Journal of Medicine (NEJM.). RESULTS: American and British publications played the leading roles in the total number of medical publications from 1986 to 1990 (35.6% and 8.8%, respectively) and also from 1991 to 1995 (34.3% and 9.1%, respectively). A more detailed analysis revealed an unexpectedly high national publication output (publications per million inhabitants) of smaller countries, which exceeded that of larger nations during both periods studied (national publication output 1986-90 vs. 1991-95: Israel: (3386 vs. 3447), Sweden: (3303 vs. 3620), Switzerland: (2930 vs. 3722), Denmark: (2884 vs. 3167), UK: (2186 vs. 2825), USA: (2042 vs. 2388)). Furthermore, the proportion of national authors during both periods (1986-90 vs. 1991-95) studied was 41.8% vs. 34.1% in the case of The Lancet and 77.9% vs. 69.5% in the case of The New England Journal of Medicine. CONCLUSIONS: The present study found an unexpectedly high national publication output of smaller countries as well as a clearly disproportionate number of published articles from national authors in The Lancet and the NEJM during the years 1986 to 1990 and 1991 to 1995.

Effects of a leucocyte depleting arterial line filter on perioperative proteolytic enzyme and oxygen free radical release in patients undergoing aortocoronary bypass surgery.

BACKGROUND: Proteolytic enzymes and oxygen free radicals released from activated leucocytes contribute significantly to the organ dysfunction associated with cardiopulmonary bypass. Leucocyte depletion during extracorporeal circulation should reduce the release of these toxic compounds and thereby improve postbypass myocardial and pulmonary function. Recently, a leucocyte-specific arterial line filter to achieve leucocyte depletion during clinical perfusion has become commercially available. The aim of this study, therefore, was to evaluate the influence of the leucocyte depleting arterial line filter on proteolytic enzyme release, oxygen free radical release and postbypass pulmonary and myocardial function in patients undergoing bypass surgery. METHODS: Forty patients undergoing elective aortocoronary bypass surgery were included into this prospective, randomized clinical study, 20 in the leucocyte depletion (LG-6 group, leucocyte-specific arterial line filter) and 20 in the control group (AV-6 group, standard arterial line filter). White cell count, differential white cell count, plasma elastase concentration, plasma malondialdehyde concentration and C-reactive protein were determined before, twice during and immediately after cardiopulmonary bypass, at the end of surgery and 6 and 20 h thereafter. RESULTS: White cell count, differential white cell count, malondialdehyde and C-reactive protein were not significantly different between LG-6 and control patients. Plasma elastase concentrations were significantly (P < or = 0.03) higher during and immediately after extracorporeal circulation in LG-6 group patients. Need for inotropic support, arterial pO2 after extracorporeal circulation and perioperative CK MB mass and troponin I release were not different between the two groups of patients. CONCLUSION: The use of a leucocyte depleting arterial line filter is associated with an increased release of the proteolytic enzyme elastase, but does not reliably and consistently achieve effective leucocyte depletion during clinical perfusion. In contrast to previous studies, we could not demonstrate any significant difference in postbypass pulmonary or myocardial function between patients perfused with the leucocyte-specific arterial line filter and control patients. Our data do not support the routine use of a leucocyte depleting arterial line filter during clinical perfusion in patients undergoing elective aortocoronary bypass surgery.

A challenge for clinical nurses: a new nursing role.

As a result of difficulties in attracting resident medical officers (RMOs) to the outer western suburbs of Sydney, the intensive care unit at Nepean Hospital created a new nursing position in 1992 called the clinical assistant (CA). This position was trialed and, after a successful period in the intensive care unit, it was expanded to the surgical, pediatric, and mental health divisions. The generic job description of the CA is comprehensive and includes advanced clinical, educational, research, and managerial components. There are a number of variations within the areas of practice. For example, within the clinical component, the intensive care CA is expected to be able to insert central venous and arterial catheters, whereas the mental health CA adopts a full caseload and is responsible for patient assessment and management. A working party was established in 1995 and comprised previous and current CAs, an education manager, a senior nursing administrator, and representatives from personnel and the New South Wales Nursing Association (nursing union). The working party conducted an extensive evaluation of this new nursing role, and the recommendations that followed received a positive response from the hospital management.

DSM-IV Cluster A personality disorder diagnoses among young adults with a 2-7-8 MMPI profile.

The present study evaluated the presence of DSM-IV personality disorders among young adults from a nonclinical setting who produced an MMPI 2-7-8 profile in comparison to a group of MMPI-defined controls. Categorical and dimensional analyses of personality disorders were evaluated. Participants in the 2-7-8 group (n = 20) received significantly more personality disorder diagnoses than did controls (n = 29), and 85% of these individuals received at least one Cluster A (Paranoid, Schizoid, Schizotypal) diagnosis in contrast to only 6.9% of controls (categorical analysis). The 2-7-8 group also received significantly more Cluster A diagnoses than Cluster B or C diagnoses. When dimensional analyses were applied (subclinical diagnoses), 95% of the 2-7-8 group evidenced Cluster A features. Comorbidity patterns were also evaluated; the most frequent comorbid diagnosis for the 2-7-8 group was Avoidant Personality Disorder (n = 8), consistent with Meehl s (1962, 1989, 1990) conceptualization of schizotypy. These results support the use of the MMPI 2-7-8 profile as an indicator of schizophrenia-related pathology within nonclinical samples of young adults.

[Comparative study of propofol emulsions for anesthesia in varicose vein operations]. / Vergleichende Untersuchung zweier Propofol-Emulsionen zur Anästhesie bei Varizenoperationen.

PURPOSE: It is commonly known that propofol-based anaesthesia is easily controlled and well tolerated. These advantages of propofol are partly offset by the comparably high costs of the anaesthetic. The present prospective randomised double-blind cross-over study compared two propofol emulsions with regard to their efficacy and drug safety. METHODS: 30 patients were included in this study. All patients underwent two propofol-based anaesthesias for leg vein surgery on both legs within 2-4 days. The patients were randomised in two treatment groups where Group A (n = 15) received the investigational drug for the 2nd anaesthesia and the control drug for the 1st anaesthesia. The order of drug application was reversed for Group B (n = 15). The propofol induction doses, the maintenance doses, and the side effect profiles were evaluated for the purpose of comparing the two propofol emulsions. RESULTS: The study showed no differences in the efficacy of the two propofol emulsions. Furthermore, the side effect profiles were almost identical and did not reveal any unknown side effects of propofol. CONCLUSIONS: The results clearly demonstrate that both propofol emulsions are comparably well suited for vascular surgery anaesthesia. This study demonstrates a methodological clinical approach to compare the same medication supplied by different manufacturers.

Inhalation injury treated with extracorporeal CO2 elimination.

A 38-year-old male was admitted to the intensive care unit with a full-thickness burn involving 30 per cent of his total body surface area (TBSA) and severe inhalation injury. Respiratory failure developed within 54 h and CO2 could not be eliminated, even by very invasive mechanical ventilation. Because of the patient's age and the minor extent of the burned TBSA, we started extracorporeal CO2 elimination (ECCO2-R) and continued ECCO2-R for 30 days, when the patient was weaned from ECC. The clinical course during ECCO2-R was complicated by major bleeding from a thoracotomy tube, from the site of tangential excision and by four septic episodes. Lung biopsy was performed twice on day 29 (during ECCO2-R) and day 58 (after ECCO2-R) after admission and revealed bronchiolitis obliterans without tendency to recovery. The patient died of sepsis with multiorgan failure on day 81 after trauma.

Augmented release of brain natriuretic peptide during reperfusion of the human heart after cardioplegic cardiac arrest.

The aim of the study was to investigate the release of natriuretic peptides during myocardial ischaemia and reperfusion associated with cardioplegic cardiac arrest. Brain natriuretic peptide (BNP) and atrial natriuretic peptide (ANP) concentrations were measured in paired arterial, central venous and coronary sinus blood samples in 19 patients undergoing elective coronary artery bypass grafting before aortic crossclamping and 1, 5, 10 and 20 min after aortic declamping. Peak myocardial BNP release after aortic declamping was significantly higher than baseline values before aortic crossclamping. Both peak and cumulative BNP release during reperfusion correlated significantly with the severity of ischaemia, as assessed by myocardial lactate production. In 3 patients with perioperative myocardial ischaemia, cumulative and peak myocardial BNP release after aortic unclamping was markedly higher than in the remaining 16 uneventful patients. Myocardial ANP release during reperfusion was not significantly different from baseline values before aortic crossclamping. In conclusion, our data demonstrate a significantly enhanced myocardial BNP release early during reperfusion of the human heart after global ischaemia associated with cardioplegic cardiac arrest.