Time-resolved x-ray scattering from laser-molten indium antimonide

We demonstrate a concept to study transient liquids with picosecond time-resolved x-ray scattering in a high-repetition-rate configuration. Femtosecond laser excitation of crystalline indium antimonide (InSb) induces ultrafast melting, which leads to a loss of the long-range order. The remaining local correlations of the liquid result in broad x-ray diffraction rings, which are measured as a function of delay time. After 2 ns the liquid structure factor shows close agreement with that of equilibrated liquid InSb. The measured decay of the liquid scattering intensity corresponds to the resolidification rate of 1 m/s in InSb.

The effect of carnitine supplemented total parenteral nutrition on lipid, energy and nitrogen metabolism in severely ill patients

To analyse the effects of L-carnitine supplemented TPN on lipid, energy and nitrogen metabolism, 16 severely injured patients were studied during the first 8 days after trauma. An L-carnitine solution (3g = 18.6mmol) was added to the fat emulsion and infused over 16h in a blind randomised fashion to half of the patients. Plasma triglyceride, free fatty acid and 3-OH-butyrate concentrations increased during the fat infusion, and fell to pre-infusion concentrations within 24h. There were no differences in plasma levels before, during or after infusion between the groups. ATP and phosphocreatine in muscle tissue were not influenced by carnitine supplementation. Glycogen, however, remained unchanged in the carnitine group and fell in the non-carnitine group. A cumulative N-balance measured from day 2 to day 8 was equally negative in both groups. Plasma carnitine levels were significantly higher in the supplemented group from day 3. The mean daily urinary carnitine excretion was increased 15-fold in the supplemented group. Muscle carnitine, however, remained unchanged in both groups and did not differ between them. The present results do not demonstrate any beneficial effects of parenterally administered L-carnitine on lipid, energy or nitrogen metabolism except for maintaining normal muscle glycogen levels in critically ill patients receiving TPN during the early phase after trauma.

Complexity of factors related to outcome of neuropathic and neuroischaemic/ischaemic diabetic foot ulcers: a cohort study

AIMS/HYPOTHESIS

We sought to identify factors related to short-term outcome of foot ulcers in patients with diabetes treated in a multidisciplinary system until healing was achieved.

METHODS

Consecutively presenting patients with diabetes and worst foot ulcer (Wagner grade 1-5, below ankle) (n = 2,511) were prospectively followed and treated according to a standardised protocol until healing was achieved or until death. The number of patients lost to dropout was 31. The characteristics of the remaining 2,480 patients were: 1,465 men, age 68 +/- 15 years (range 18-96), type 1 diabetes 18%, type 2 diabetes 82% and insulin-treated 62%.

RESULTS

The healing rate without major amputation in surviving patients was 90.6% (n = 1,867). Sixty-five per cent (n = 1,617) were healed primarily, 9% (n = 250) after minor amputation and 8% after major amputation; 17% (n = 420) died unhealed. Out of 2,060 surviving patients, 1,007 were neuroischaemic (48.8%). In a multiple regression analysis, primary healing was related to co-morbidity, duration of diabetes, extent of peripheral vascular disease and type of ulcer. In neuropathic ulcers, deep foot infection, site of ulcer and co-morbidity were related to amputation. Amputation in neuroischaemic ulcers was related to co-morbidity, peripheral vascular disease and type of ulcer. Age, sex, duration of diabetes, neuropathy, deformity and duration of ulcer or site of ulcer did not have an evident influence on probability of amputation.

CONCLUSIONS/INTERPRETATION

Patients with diabetic foot ulcer suffer from multi-organ disease. Factors related to outcome are correspondingly complex.

Amount drained at ultrasound-guided thoracentesis and risk of pneumothorax

BACKGROUND

It has been suggested that no upper limit of the fluid amount drained is necessary when performing ultrasound-guided thoracentesis, but the risk of pneumothorax when large amounts of fluid are drained has not been studied in detail.

PURPOSE

To study the amount of drained fluid at ultrasound-guided thoracentesis and the subsequent risk of pneumothorax.

MATERIAL AND METHODS

Prospectively collected information on all ultrasound-guided thoracenteses performed at a county hospital between 2004 and 2006 was evaluated. In total, 735 thoracenteses in 471 patients were included. Chest radiographs performed within 14 days after thoracentesis were identified to obtain cases of pneumothorax and cases treated with tube thoracostomy. Data were analyzed by logistic regression. The study was approved by the regional research ethics committee.

RESULTS

There was a steep increase in risk for pneumothorax when large amounts of fluid were drained. Compared to a thoracentesis of 0.8-1.2 l, drainage of 1.8-2.2 l was associated with a more than threefold increase in risk for pneumothorax (odds ratio [OR] 3.8, 95% confidence interval [CI] 1.28-11.2), and after drainage of 2.3 l or more, the increase in risk was almost sixfold (OR 5.7, 95% CI 1.30-24.7). The association between the amount drained and the risk of pneumothorax was even more pronounced for pneumothoraces requiring tube thoracostomy (P for trend <0.0001). Nine of 11 tube thoracostomies occurred after thoracenteses of 1.8 l or more.

CONCLUSION

Our study suggests that drainage of large amounts of fluid at ultrasound-guided thoracentesis is a risk factor for pneumothorax.

Job satisfaction or production? How staff and leadership understand operating room efficiency: a qualitative study

BACKGROUND

How to increase efficiency in operating departments has been widely studied. However, there is no overall definition of efficiency. Supervisors urging staff to work efficiently may meet strong reactions due to staff believing that demands for efficiency means just stress at work. Differences in how efficiency is understood may constitute an obstacle to supervisors' efforts to promote it. This study aimed to explore how staff and leadership understand operating room efficiency.

METHODS

Twenty-one members of staff and supervisors in an operating department in a Swedish county hospital were interviewed. The analysis was performed with a phenomenographic approach that aims to discover the variations in how a phenomenon is understood by a group of people.

RESULTS

Six categories were found in the understanding of operation room efficiency: (A) having the right qualifications; (B) enjoying work; (C) planning and having good control and overview; (D) each professional performing the correct tasks; (E) completing a work assignment; and (F) producing as much as possible per time unit. The most significant finding was that most of the nurses and assistant nurses understood efficiency as individual knowledge and experience emphasizing the importance of the work process, whereas the supervisors and physicians understood efficiency in terms of production per time unit or completing an assignment.

CONCLUSIONS

The concept 'operating room efficiency' is understood in different ways by leadership and staff members. Supervisors who are aware of this variation will have better prerequisites for defining the concept and for creating a common platform towards becoming efficient.

Effect of dietary supplement on nutritional status and clinical outcome in 501 geriatric patients--a randomised study

The present study was designed to evaluate to the effect of dietary supplements on clinical outcome and nutritional status in a large group of geriatric patients (n = 501). The patients were randomised into an experimental group which received nutritional supplementation (400 kcal) as well as a standard hospital diet, and a control group on hospital diet alone. The nutritional state was measured on admission and after 8 and 26 weeks by anthropometry, serum protein analysis and a delayed hypersensitivity skin test. Protein energy malnutrition was defined as the presence of three or more abnormal parameters. 28.5% of patients showed evidence of malnutrition on admission. Hospitalisation itself resulted in a gradual deterioration in nutritional status. Nutritional supplementation generally improved nutritional state. Among those patients who were well nourished on admission, and subsequently receiving dietary supplementation, 8.3% fulfilled malnutrition criteria after 26 weeks, while 21.1% were considered malnourished in the control group (p < 0.05). The improvement observed in transport proteins was probably related to nutritional support and not just to the reversal of inflammation. In the initially well nourished group of more than 300 patients, the mortality rate was 8.6% in those given nutritional support compared to 18.6% in the control group (p < 0.02).

The correlation between anergy, malnutrition and clinical outcome in an elderly hospital population

The nutritional state of 482 out of 501 newly admitted elderly patients was assessed by anthropometry, serum protein analyses and the delayed hypersensitivity skin test (DH) on admission and after 8 and 26 weeks. The mean age of the women was 81.3 +/- 7.7 and of the men 77.9 +/- 9.3. Protein-energy malnutrition (PEM) was initially defined as three or more subnormal criteria, one in each of the three categories of measurement. The data was then reanalysed excluding anergy and using the two other criteria only. The prevalence of PEM on the first assessment was 28.5% and was 10% higher when anergy was excluded as a criterion. PEM was more common in women and increased with age. The anergic patients had lower mean values in serum protein and anthropometry than those with normal reactivity. Anergic patients had a higher mortality rate and more pressure sores than the reactive group. Nutritional supplementation was associated with an increase in skin reactivity.

X-ray diffuse scattering measurements of nucleation dynamics at femtosecond resolution

Femtosecond time-resolved small and wide angle x-ray diffuse scattering techniques are applied to investigate the ultrafast nucleation processes that occur during the ablation process in semiconducting materials. Following intense optical excitation, a transient liquid state of high compressibility characterized by large-amplitude density fluctuations is observed and the buildup of these fluctuations is measured in real time. Small-angle scattering measurements reveal snapshots of the spontaneous nucleation of nanoscale voids within a metastable liquid and support theoretical predictions of the ablation process.

Dendrin expression in glomerulogenesis and in human minimal change nephrotic syndrome

BACKGROUND

Dendrin is an 81-kD cytosolic protein hitherto described in the brain, where it is associated with the actin cytoskeleton. Recently, we found dendrin in foot processes of mouse glomerular podocytes. Here we describe its expression both during mouse glomerulogenesis and in the normal and diseased human kidney for the first time.

METHODS

Dendrin expression was characterized using RT-PCR and immunohistochemistry and semi-quantified using immunoelectron microscopy.

RESULTS

In glomerulogenesis, dendrin mRNA and protein appeared first at the early capillary loop stage. It was concentrated to the pre-podocytes on the basal side of podocalyxin, an apical cell membrane marker. In human tissue, dendrin transcripts were detected in the brain and kidney. In the mature kidney dendrin localized solely in the podocytes, close to the filtration slit diaphragms. A comparison with the slit-associated protein zonula occludens-1 (ZO-1) was done in minimal change nephrotic syndrome (MCNS). Dendrin and ZO-1 were re-distributed from slit regions to the podocyte cytoplasm in areas with foot process effacement (FPE). In areas without FPE, dendrin and ZO-1 distributions were unchanged compared to controls. The total amounts of dendrin or ZO-1 markers were unchanged. This differs from nephrin that, according to our previous results, is also decreased in non-effaced areas.

CONCLUSIONS

The expression of dendrin during glomerulogenesis and in the normal human kidney is similar to that previously shown for nephrin, which suggests that dendrin associates with the slit diaphragm complex. In MCNS patients, dendrin and ZO-1 are re-distributed within the podocytes. Whether this is a cause or a consequence of FPE remains unclear.

A Multipurpose receptor composed of promiscuous proteins. Analyte detection through pattern recognition

A multipurpose receptor akin to the "electronic nose" was composed of coumarin-labeled mutants of human glutathione transferase A1. We have previously constructed a kit for site-specific modification of a lysine residue (A216K) using a thiol ester of glutathione (GSC-Cou bio) as a modifying reagent. In the present investigation, we scrambled the hydrophobic binding site (H-site) of the protein scaffold through mutations at position M208 via random mutagenesis and isolated a representative library of 11 A216K/M208X mutants. All of the double mutants could be site-specifically labeled to form the K216 Cou conjugates. The labeled proteins responded to the addition of different analytes with signature changes in their fluorescence spectra resulting in a matrix of 96 data points per analyte. Ligands as diverse as n-valeric acid, fumaric acid monoethyl ester, lithocholic acid, 1-chloro-2,4-dinitrobenzene (CDNB), glutathione (GSH), S-methyl-GSH, S-hexyl-GSH, and GS-DNB all gave rise to signals that potentially can be interpreted through pattern recognition. The measured K d values range from low micromolar to low millimolar. The cysteine residue C112 was used to anchor the coumarin-labeled protein to a PEG-based hydrogel chip in order to develop surface-based biosensing systems. We have thus initiated the development of a multipurpose, artificial receptor composed of an array of promiscuous proteins where detection of the analyte occurs through pattern recognition of fluorescence signals. In this system, many relatively poor binders each contribute to detailed readout in a truly egalitarian fashion.

Enjoying work or burdened by it? How anaesthetists experience and handle difficulties at work: a qualitative study †

BACKGROUND

The aim of this study was to explore difficulties at work from anaesthetists' own perspective and to examine how anaesthetists handle and cope with situations that are perceived as difficult and potentially stressful.

METHODS

Two sets of interviews were conducted with 19 specialist anaesthetists in Sweden. The first set of interviews aimed at finding how the anaesthetists experienced difficulties at work. It consisted of in-depth interviews based on one open-ended question. We analysed the interviews with a phenomenological method, looking for themes in anaesthetists' descriptions of difficulties at work. In the second set, the interviews were semi-structured with open-ended questions, based on themes found in the first interview set. These interviews aimed at exploring how the interviewees described their ways of handling difficulties and how they coped with potentially stressful situations.

RESULTS

Analysis of the first set of interviews resulted in five themes, describing how the anaesthetists experienced difficulties at work. All interviewees talked about difficulties related to more than one of the themes. The second set of interviews revealed two main categories of ways of handling difficulties. First, problem solving consisted of descriptions of methods for handling difficult situations which aimed at solving problems, and second, coping strategies described ways of appraising potentially stressful situations that minimized stress, despite the problem not being solved.

CONCLUSIONS

The anaesthetists interviewed in this study maintained that they enjoyed work and could see no external obstacles to doing a good job. They had arrived at a reconciliation of their work with its inherent difficulties and problems. Getting access to their coping strategies might help young anaesthetists to come to terms with their work.

Orthogonal protein purification--expanding the repertoire of GST fusion systems

We have previously developed a labeling scheme that can be used to site-specifically link human glutathione transferases (hGSTs) from the alpha class to chemical entities such as fluorophores and aldehydes. The reagents are in-house synthesized derivatives of glutathione (GS-derivatives). We have focused on a lysine mutant of hGST A1:A216K. In this study, we wanted to utilize these findings and improve on protein purification schemes that are using GSTs as fusion partners. We have used random mutagenesis to scramble the hydrophobic binding site of A216K through mutations at position M208 and isolated a library of 11 A216K/M208X mutants. All mutants were easily expressed and purified and retained all or parts of the catalytic properties of the parent GST. The mutants were stable over several days at room temperature. The A216K/M208X mutants could be site-specifically labeled using our designed fluorescent reagents. Furthermore, reaction with an aldehyde-containing reagent termed GS-Al results in site-specific introduction of an orthogonal handle for subsequent conjugation with aldehyde-reactive probes. Labeling with coumarin results in a fluorescent protein-conjugate that can bind glutathione (GSH) derivatives for subsequent affinity purification. The K(d) for S-hexyl-GSH of coumarin-labeled A216K was measured to be 2.5 microM. The candidate proteins A216K and A216K/M208F could be purified in high yield in a one-step procedure through affinity chromatography (Glutathione Sepharose 4B). The proteins can readily be perceived as improved GST fusion partners.

Large acoustic transients induced by nonthermal melting of InSb

We have observed large-amplitude strain waves following a rapid change in density of InSb due to nonthermal melting. The strain has been measured in real time via time-resolved x-ray diffraction, with a temporal resolution better than 2 ps. The change from the solid to liquid density of the surface layer launches a high-amplitude strain wave into the crystalline material below. This induces an effective plane rotation in the asymmetrically cut crystal leading to deflection of the diffracted beam. The uniform strain in the layer below the molten layer is 2.0(+/-0.2)%. A strain of this magnitude develops within 5 ps of the incident pulse showing that the liquid has reached the equilibrium density within this time frame. Both the strain amplitude and the depth of the strained material in the solid can be explained by assuming a reduction in the speed of sound in the nonequilibrium liquid compared to measured equilibrium values.

Carrier-density-dependent lattice stability in InSb

The ultrafast decay of the x-ray diffraction intensity following laser excitation of an InSb crystal has been utilized to observe carrier dependent changes in the potential energy surface. For the first time, an abrupt carrier dependent onset for potential energy surface softening and the appearance of accelerated atomic disordering for a very high average carrier density have been observed. Inertial dynamics dominate the early stages of crystal disordering for a wide range of carrier densities between the onset of crystal softening and the appearance of accelerated atomic disordering.

Being a young and inexperienced trainee anesthetist: a phenomenological study on tough working conditions

BACKGROUND

Physicians at the beginning of their specialist education have been reported to be especially exposed to stress and difficult working conditions. Considerable worry has also been caused by reports about anaesthetists dying at a younger age than other specialists as well as by reports about higher than average suicide rates among anaesthetists. Maybe as a consequence, many young doctors are reluctant to choose anaesthesiology as their future specialty. The aim of this study was to investigate what difficulties trainee anaesthetists experience at work.

METHODS

Nineteen trainee anaesthetists in six Swedish hospitals were interviewed. Phenomenological analysis of the interview text was performed.

RESULTS

All trainees had experienced considerable, sometimes extreme demands at work. Most of them often felt insufficient and inadequate and had problems with the professional role. Support from consultants was sometimes lacking. Some trainees expressed deep feelings of loneliness and helplessness in difficult clinical situations.

CONCLUSIONS

This study shows that trainee anaesthetists have to live up to high work demands, often with very little support. Because too much stress is an obstacle to professional learning, such working conditions are a hindrance to good specialist education. The first measure to be taken should be to ensure that all trainee anaesthetists always have easy access to senior cover.

Surface-Assisted Delivery of Fluorescent Groups to hGST A1-1 and a Lysine Mutant

Human glutathione transferase (hGST) A1-1 and a lysine mutant (A216K) can both be rapidly and site-specifically acylated on Y9 and K216, respectively, using a range of thiolesters of glutathione (GS-thiolesters) as modifying reagents. The present investigation was aimed at developing a method with which to deliver a fluorescent acyl group from a solid support under conditions compatible with standard protein purification schemes. A number of fluorescent GS-thiolesters with modified peptide backbones were therefore prepared and tested for reactivity toward hGST A1-1 and the A216K mutant. Substitutions at the alpha-NH2 part of the glutathione backbone were not tolerated by the proteins. However, two fluorescent reagents that carry a biotin moiety at the C-terminal part of glutathione were found through MALDI-MS experiments to react in solution with Y9 of the wild-type protein and one reagent with K216 of A216K. The reaction can take place in the presence of glutathione and even in a crude E. coli lysate of cells expressing A216K. Delivery of the fluorescent group to Y9 or K216 was possible using NeutrAvidin (NA) beads that had been preincubated with biotinylated reagent. Alternatively, excess reagent can be removed by a brief incubation with NA beads. We have thus now developed a system for protein labeling with easy removal of excess and used up low-molecular weight reagent. This strategy can conceivably be utilized in future protein purification and labeling experiments.

Observation of structural anisotropy and the onset of liquidlike motion during the nonthermal melting of InSb

The melting dynamics of laser excited InSb have been studied with femtosecond x-ray diffraction. These measurements observe the delayed onset of diffusive atomic motion, signaling the appearance of liquidlike dynamics. They also demonstrate that the root-mean-squared displacement in the [111] direction increases faster than in the [110] direction after the first 500 fs. This structural anisotropy indicates that the initially generated fluid differs significantly from the equilibrium liquid.

Atomic-Scale Visualization of Inertial Dynamics

The motion of atoms on interatomic potential energy surfaces is fundamental to the dynamics of liquids and solids. An accelerator-based source of femtosecond x-ray pulses allowed us to follow directly atomic displacements on an optically modified energy landscape, leading eventually to the transition from crystalline solid to disordered liquid. We show that, to first order in time, the dynamics are inertial, and we place constraints on the shape and curvature of the transition-state potential energy surface. Our measurements point toward analogies between this nonequilibrium phase transition and the short-time dynamics intrinsic to equilibrium liquids.

Picosecond x-ray studies of coherent folded acoustic phonons in a multiple quantum well

Coherent folded acoustic phonons in a multilayered GaSb/InAs epitaxial heterostructure were generated by femtosecond laser pulses and studied by means of ultrafast x-ray diffraction. Coherent phonons excited simultaneously in the fundamental acoustic branch and the first back-folded branch were detected. This represents the first clear evidence for phonon branch folding based directly on the atomic motion to which x-ray diffraction is sensitive. From a comparison of the measured phonon-modulated x-ray reflectivity with simulations, evidence was found for a reduction of the laser penetration depth. This reduction can be explained by the self-modulation of the refractive index due to photogenerated free carriers.

Clocking femtosecond X rays

Linear-accelerator-based sources will revolutionize ultrafast x-ray science due to their unprecedented brightness and short pulse duration. However, time-resolved studies at the resolution of the x-ray pulse duration are hampered by the inability to precisely synchronize an external laser to the accelerator. At the Sub-Picosecond Pulse Source at the Stanford Linear-Accelerator Center we solved this problem by measuring the arrival time of each high energy electron bunch with electro-optic sampling. This measurement indirectly determined the arrival time of each x-ray pulse relative to an external pump laser pulse with a time resolution of better than 60 fs rms.

Anti-inflammatory effects of a titanium-peroxy gel: role of oxygen metabolites and apoptosis

Polymorphonuclear neutrophils (PMN) are among the first inflammatory cells to arrive at an implant interface, where they encounter with the foreign material and may produce reactive oxygen species (ROS). During the interaction between titanium and ROS, titanium-peroxy (Ti-peroxy) compounds may be formed. We used a Ti-peroxy gel, made from titanium and hydrogen peroxide, to study the effects of Ti-peroxy compounds on PMN. In the absence of serum, the Ti-peroxy gel decreased the oxidative response of PMN to yeast and PMA and reduced PMN apoptosis without inducing necrosis. These effects could not be ascribed to the release of hydrogen peroxide from the Ti-peroxy gel, because a steady-state hydrogen peroxide producing system failed to mimic the effects of the gel. The effects were similarly unaffected when PMN were preincubated with beta(2)-integrin antibodies, questioning the involvement of adhesion molecules. Nevertheless, when a filter was used to separate the Ti-peroxy gel from the cells, the gel effect on PMN life span was abolished, pointing to a contact-dependent mechanism. In the presence of serum, the Ti-peroxy gel had no effect on the PMN oxidative response and life span, but appeared rather inert. In summary, this study demonstrates that the Ti-peroxy gel has potentially anti-inflammatory properties through a combined peroxide and physical contact effect, supporting the notion that interactions between titanium and inflammatory cells are responsible for the good performance of titanium in vivo.