Micro-video study of moving bacterial flagellar filaments. I. Passive rotation by hydrodynamic force in vitro.
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Biomechanical Phenomena↗
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Rapid prescribing change, how do patients respond?
The cost of prescribed medication is an increasing burden on health care systems. British general practitioners have been encouraged to reduce their prescribing costs through financial incentives within the fundholding scheme. This study reports on one general practice which reduced prescribing expenditure as part of the move to fundholding. Interviews performed with practice staff and patients were analysed and combined with prescribing statistics and questionnaire data to give a picture of the balance between the experience of patients and practitioners. Fifty-three interviews with 17 patients revealed that most were willing to try cheaper treatments and that dissatisfaction was primarily with the communication they received rather than the change itself. Each patient had to decide how to respond to the change in their medication. The decision-making process and the main factors involved are described and discussed. The experience of having long-standing treatment changed can have an impact on the doctor-patient relationship. This was not found to be a large problem and, it is suggested, can be guarded against. Large-scale economies in prescribing are feasible for some practices, and patients will tolerate such changes if attention is paid to sensitive communication.
Communication↗
Molecular dynamics simulations of pressure effects on hydrophobic interactions.
We report results on the pressure effects on hydrophobic interactions obtained from molecular dynamics simulations of aqueous solutions of methanes in water. A wide range of pressures that is relevant to pressure denaturation of proteins is investigated. The characteristic features of water-mediated interactions between hydrophobic solutes are found to be pressure-dependent. In particular, with increasing pressure we find that (1) the solvent-separated configurations in the solute-solute potential of mean force (PMF) are stabilized with respect to the contact configurations; (2) the desolvation barrier increases monotonically with respect to both contact and solvent-separated configurations; (3) the locations of the minima and the barrier move toward shorter separations; and (4) pressure effects are considerably amplified for larger hydrophobic solutes. Together, these observations lend strong support to the picture of the pressure denaturation process proposed previously by Hummer et al. (Proc. Natl. Acad. Sci. U.S.A. 1998, 95, 1552): with increasing pressure, the transfer of water into protein interior becomes key to the pressure denaturation process, leading to the dissociation of close hydrophobic contacts and subsequent swelling of the hydrophobic protein interior through insertions of water molecules. The pressure dependence of the PMF between larger hydrophobic solutes shows that pressure effects on the interaction between hydrophobic amino acids may be considerably amplified compared to those on the methane-methane PMF.
Computer Simulation↗
Canard explosion and coherent biresonance in the rate oscillation of CO oxidation on platinum surface.
The relationship between canard explosion and coherent biresonance is analyzed by numerically investigating a temporal dynamical model of CO oxidation on Pt surface. Canard explosion, manifesting itself by a dramatic change in the amplitude and period of a periodic orbit within a very narrow interval of a control parameter, is the result of multiple time scales in a dynamical system and is common in excitable systems. Coherent biresonance, namely, two peaks on the signal-to-noise ratio (SNR) curve when varying noise intensity, is a novel phenomenon of coherent resonance which is well-known in excitable systems. When the control parameter is varied from a stable fixed point, crossing the supercritical Hopf bifurcation, one of the peaks that corresponds to relatively larger noise intensity, keeps a constant height and position, while the other becomes higher and moves to lower noise level. When we consider the case in which two control parameters are perturbed by independent noise simultaneously, an interesting picture of one valley between two ridges appears on the 3D surface of SNR.
Carbon Monoxide↗
Famine: a perspective for the nutrition community.
Famine is a nasty turn of events that intrudes on the world's consciousness from time to time. Pictures of starving people and acutely malnourished children, rampant disease, a rising death toll, and massive suffering in some far-off land move many among us to contribute to famine relief, shocked by the paradox of famine in a world "awash in grain". Those who think about it appreciate that famine is related to poverty, that it is often triggered by climatic instability, and that it is both an instrument and tragic by-product of political conflict. But few know very much about famine beyond such fleeting insights. Even fewer are aware that the collective response to famine is woefully deficient. Just as we in the nutrition community had to fight long and hard to get malnutrition onto the development agenda as an explicit concern of public policy, so we and others like us are going to have to labor hard again to do the same for famine. This paper is an attempt to crystallize the issues involved.
Africa↗
Analysis of functional scoliosis by means of an anisotropic beam model of the human spine.
An upright, muscle-relaxed human spine, suffering from a mild functional scoliosis, caused by a small difference in leg length, is modeled as an anisotropic, elastic beam. The lower end of the beam is built-in in a fixed body, i.e., the laterally tilted pelvis. The upper end is rigidly attached to a rigid body, i.e., the supported upper part of the trunk, which is supposed to move freely in the frontal plane. It is shown that the characteristic scoliotic curvature of the spine, observed on an X-ray picture, can be reproduced by means of buckling analysis of the beam model, using realistic values of geometric and loading parameters and a properly chosen bending stiffness, which is found to be in reasonable agreement with earlier experimental findings. The analysis also shows that the muscle-relaxed upright equilibrium position of the spine is mechanically unstable.
Biomechanical Phenomena↗
Effects of stimulant medication on the lateralisation of line bisection judgements of children with attention deficit hyperactivity disorder.
OBJECTIVES: Deficits in the maintenance of attention may underlie problems in attention deficit hyperactivity disorder (ADHD). Children with ADHD also show asymmetric attention deficits in traditional lateralisation and visuospatial orienting tasks, suggesting right hemispheric (and left hemispace) attentional disturbance. This study aimed to examine the lateralisation of selective attention in ADHD; specifically, the effect of a moving, random dot background, and stimulant medication in the line bisection task. METHODS: The performance of children with ADHD, on and off methylphenidate, was examined using a computerised horizontal line bisection task with moving and blank backgrounds. Twenty children with a DSM-IV diagnosis of ADHD participated with 20 controls, individually matched for age, sex, grade at school, and IQ. Twelve of the 20 children with ADHD were on stimulant medication at the time of testing. Horizontal lines of varying length were presented in the centre of a computer screen, with either a blank background, or a moving, random dot field. The random dots moved either leftward or rightward across the screen at either 40 mm/s or 80 mm/s. RESULTS: The children with ADHD off medication bisected lines significantly further to the right compared with controls, who showed a small leftward error. Methylphenidate normalised the performance of the children with ADHD for the task with the moving dots. CONCLUSIONS: These results support previous evidence for a right hemispheric hypoarousal theory of attentional dysfunction, and are consistent with the emerging picture of a lateralised dysfunction of frontostriatal circuitry in ADHD.
Analysis of Variance↗
[Pulsed Doppler transmitral flow in a case of myxoma of the left atrium].
This work deals with transmitral flow studied with Range Gate Pulsed Doppler Echocardiography in a 73 year old man affected by left atrial myxoma. The dominant clinical picture was pleural effusion and dyspnoea. Neither syncope nor systemic emboli were reported. Echocardiography (TM and 2D) and surgical inspection showed a large moving tumor connected to the interatrial septum with a short stalk. The histological examination gave evidence of myxoma. Range Gate Pulsed Doppler Echocardiography, using the apical four chamber view, was performed with the sample volume between the mitral leaflets and tumor. Peak velocities were normal, indicating no diastolic a-v gradient, probably the size of the tumor interfered with left atrial filling. The flow between the anterior leaflet and tumor was only protodiastolic: the myxoma leaning on the leaflet just after the opening stopped the blood stream. The flow between the posterior leaflet and tumor was variable, with single or multiple velocity peaks (early, middle and end diastole): this was probably caused by the intermittent obstruction of the a-v ostium. These data agree with the variability of the auscultation in the left atrial myxoma and show that the flow pattern is different from that of mitral stenosis.
Aged↗
A micelle model for the sedimentation behavior of bovine beta-casein.
The monomer-single polymer model of G.A. Gilbert (Disc. Faraday Soc. 20 (1955) 68) for moving boundary sedimentation has been used by Payens and colleagues to explain the observed results for bovine caseins, and by Harrington and colleagues to explain the observed results for myosin fibrils. Electron microscope pictures of Buchheim and Schmidt have subsequently revealed micellar beta-casein in the form of slightly elongated or spherical particles having a bimodal size distribution, but with a broad range of particle sizes, at concentrations not too far above the critical micelle concentration. The equilibrium properties of a broadly distributed micellar system can be fitted by the shell model developed by one of us, and in the present article, the shell model is extended to predict the moving boundary sedimentation behavior of such a system. The observed sedimentation patterns, as well as the critical concentration predictions of the monomer-single polymer Gilbert sedimentation model, are satisfactorily described with the present model, based on a continuous distribution of intermediates between monomers and the largest possible spherical micelles. For one example considered, the predicted frequency distribution of molecular weight is in qualitative agreement with the frequency distribution of particle volume found by Buchheim and Schmidt.
Animals↗
Techniques for the observation and measurement of red blood cell velocity in vessels of the guinea pig cochlea.
Fluorescence techniques combined with intravital microscopy provide a powerful approach to the study of cochlear blood microcirculation. In the current study, fluorescein isothiocyanate conjugated to high molecular weight dextrans was added to plasma to enhance the visual contrast of flowing blood in microscopic images from the guinea pig cochlea. Photometric signals, obtained from video pictures of the blood vessels, provided a means to continuously measure red cell velocity by using crosscorrelation algorithms to extract the time delay for moving features of the image. Alternatively, a small amount of fluorescently-labeled red blood cells (RBCs) were added to the vascular volume to serve as natural indicators of whole blood flow. The speed of these cells was measured by video photometric detection of the time required for the cells to pass between two predetermined positions in the television image. RBCs can be made fluorescent by chemical bonding of a fluorochrome to the cell membrane or by internal loading of the cell with an inert fluorochrome. Labeled RBCs provide a means to determine blood velocity in capillaries having extremely poor optical contrast, a situation which is generally the case for relatively thick tissues such as the lateral wall of the membranous labyrinth.
Animals↗
Optimizing segmental movement in the jumping header in soccer.
This study looks at segmental movements in the jumping header from an optimization viewpoint. Investigations on the header so far have focused on head restriction in the movement but have not clarified how and to what extent body segments influence the performance of the skill. In the present study a biomechanical model was used to analyze the jumping header in simulated competition to give a clear picture of an optimized header. Skilled soccer players headed balls at speeds of 13 m x s(-1) the results indicated that the head moves as a free non-restricted segment in the jumping header and should be allowed to do so, even though much soccer literature says otherwise to prevent injuries. The arm movement showed individual characteristics and gave no general advantages in optimizing ball speed after impact in the header The movement of the legs was, on the other hand, the single most important factor in the skill. Therefore, coaches and players shouldfocus on developing muscle strength in the stomach, back and pelvis and should put no restrictions on head and arm movement to optimize the jumping header.
Adult↗
Challenging cytokine redundancy: inflammatory cell movement and clinical course of experimental autoimmune encephalomyelitis are normal in lymphotoxin-deficient, but not tumor necrosis factor-deficient, mice.
Lymphotoxin (LT) is widely regarded as a proinflammatory cytokine with activities equivalent to tumor necrosis factor (TNF). The contribution of LT to experimental autoimmune encephalomyelitis (EAE) was examined using TNF/LTalpha-/- mice, TNF-/- mice, and a new LTalpha-/- line described here. All mice were generated directly in the C57BL/6 strain and used for the preparation of radiation bone marrow chimeras to reconstitute peripheral lymphoid organs and restore immunocompetence. This approach overcame the problems related to the lack of lymph nodes that results from LTalpha gene targeting. We show here that when LT is absent but TNF is present, EAE progresses normally. In contrast, when TNF is absent but LT is present, EAE is delayed in onset and inflammatory leukocytes fail to move normally into the central nervous system parenchyma, even at the peak of disease. In the absence of both cytokines, the clinical and histological picture is identical to that seen when TNF alone is deficient, including demyelination. Furthermore, the therapeutic inhibition of TNF and LTalpha with soluble TNF receptor in unmanipulated wild-type or TNF-/- mice exactly reproduces these outcomes. We conclude from these studies that TNF and LT are functionally distinct cytokines in vivo, and despite sharing common receptors, show no redundancy of function nor mutual compensation.
Animals↗
Who goes, who stays?
The merger announcement between DeWaal Pharmaceuticals and BioHealth Labs was front-page news. Pictures of CEO Steve Lindell and chairman Kaspar van de Velde had appeared in newspapers around the world. Two months later, the press had moved on to a new story, and the hard labor of integration loomed. Steve had worked tirelessly to clear regulatory hurdles, and all signs pointed toward approval in the near future. Now Steve was feeling pressure to attack the real challenge of the merger: bringing together two very different cultures as quickly and efficiently as possible. DeWaal was an established drug-maker based in the Netherlands, and BioHealth, headquartered just north of New York City, had in recent years become competitive at the highest tier of the market. The first step in integrating the two companies was to select the top layers of management for the new company. At the moment, there were some 120 people on two continents for about 65 senior-level jobs. Steve's urgency was not without cause: talented people from both sides were jumping ship, and BioHealth's stock price had dipped 20% after the initial euphoria over the deal had worn off. Complicating matters was confusion over who was really in charge: Steve wanted to take leadership and move ahead rapidly, but he was often disarmed by Kaspar's charming persuasiveness. As the two men attempt to work through the important personnel issues during a lunch meeting, they quickly hit a roadblock. How can they come to agreement about who goes and who stays? Four commentators offer advice in response to this fictional case.
Decision Making, Organizational↗
Intensity modulated radiation therapy--the shape of things to come?
Over the past century, the field of radiation oncology has seen tremendous technological advances. Some of these advances relate to biomedical accomplishments, while many are directly related to those achieved in computing and information technology. For example, developments in radiation treatment planning systems are intimately connected to progress in all of computing, and have culminated in the ability of radiation oncologists to accurately plan even the most complex therapy. Treatment machines, themselves tooled with embedded computer chips and processors, have evolved from rigid monstrosities to highly flexible, compact, machines capable of moving with robotic-like precision. The addition of multi-leaf collimators to these treatment machines has added yet another dimension to the picture. The ability to coordinate the fine motor movements of these collimators along with the coarser movements of the machine itself has required a level of control not possible manually. Computers again have provided a solution, and the result was not just a new means of directing the radiation beam, but a revolution in how radiation itself was delivered Intensity Modulated Radiation Therapy. Now, Intensity Modulated Radiation Therapy (IMRT) is practiced in hundreds of radiation oncology departments worldwide. The administration process, which challenges the most sophisticated computer planning and treatment control systems, requires not just proficient technical support, but also a dedicated administrative infrastructure. The payoff, however, promises to be big. Preliminary clinical outcome reports suggest that significant reductions in toxicity will be achievable, making increased control rates more likely. In addition, favorable CMS reimbursement changes make it probable that the technology will spread rapidly throughout the radiation oncology community. Studies are ongoing to help identify the most appropriate use of the therapy. Ultimately, IMRT is likely to become a readily available treatment for use in select cases.
Humans↗
[A technique of physical modification in mammography (author's transl)].
The authors propose a technique for use in association with mammography involving aspiration with traction which complements the standard procedure. Traction of the breast makes possible a dynamic study of the organ and its coverings. It may be used in association with radiography, xerography, thermography and transillumination. The changes in the pictures obtained should be compared to other techniques and may be of assistance to the radiologist in their interpretation. An image which does not move is suspicious. An area of translucence around a dense zone, appearing more clearly with traction, is suspicious. Images which do not converge towards the nipple are suspicious. In the light of the information obtained from these new techniques, further examinations may be requested. This simple technique poses no problems for the radiologist and is well accepted by the patient. It provides valuable information contributing to a better approach to diagnosis.
Adult↗
[Personal observations on participating in the production of a move: "Struggling with incurable disease - nursing of the patient at home"].
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Home Care Services↗
[Findings on proteinuria in selected diabetic patients. Relation to microangiopathy and its prognostic significance].
Urinary protein is usually above normal in diabetics, even when the disease is of recent onset. Values tend to move further away from physiological levels as the condition persists. Electrophoresis reveals a selective glomerular form, even in many subjects with a quantitatively normal picture and free of signs of micro- and macroangiopathy, as these are commonly defined, whereas non-selective glomerular proteinuria is observed in patients with micro- or macroangiopathic lesions, such as marked changes in renal clearance, intense proteinuria, hypertension, chronic renal failure. It is suggested that careful evaluation of urinary proteins can be usefully associated with examination of the fundus to obtain early warning of microangiopathic lesions in the two target organs, i.e. the kidneys and retinae.
Adolescent↗
Continuous arch wire technique using the bending art system.
The bending art system (BAS) enables computerized production of individual arch wires for the multiband technique. Treatment planning using the continuous arch technique as part of the bending art system has been described. Planning of the arch wires follows an initial camera picture taken in the patient's mouth, and is divided into the following steps: ideal arch, target arch and course of treatment. The ideal arch establishes the individual shape of the arch wires in the horizontal plane. Based on the input of various small adjustments, the ideal arch is transformed into the target arch which represents the final arch of the treatment. Finally, the sequence of the various arches is established. The geometry of the intermediate arches is calculated on the assumption that each tooth is moved the shortest possible distance during transformation from the initial arch to the target arch. This procedure, called the direct method, is compared with the newly developed indirect method. With the indirect method, the camera picture is taken of the initial cast and the target arch is produced in accordance with a setup model in ideal occlusion. In contrast to the straight-wire technique, treatment with the BAS is not finalized with a straight arch wire since the occlusion of the individual patient rarely complies with the straight-wire norm.
Computer-Aided Design↗