Creutzfeldt-Jakob disease and homocysteine levels in plasma and cerebrospinal fluid

Background: There is evidence that homocysteine contributes to various neurodegenerative disorders. Objective: To assess the values of homocysteine in patients with Creutzfeldt-Jakob disease (CJD) in both cerebrospinal fluid (CSF) and plasma. Methods: Study design: Case control study. Total homocysteine was quantified in CSF and plasma samples of CJD patients (n = 13) and healthy controls (n = 13). Results: Mean values in healthy controls: 0.15 mumol/l +/- 0.07 (CSF) and 9.10 mumol/l +/- 2.99 (plasma); mean values in CJD patients: 0.13 mumol/l +/- 0.03 (CSF) and 9.22 mumol/l +/- 1.81 (plasma). No significant differences between CJD patients and controls were observed (Mann-Whitney U, p > 0.05). Conclusions: The results indicate that the CSF and plasma of CJD patients showed no higher endogenous levels of homocysteine as compared to normal healthy controls. These findings provide no evidence for an additional role of homocysteine in the pathogenetic mechanisms underlying CJD neurodegeneration. Copyright (C) 2005 S. Karger AG, Basel

Effects of intra-operative fluoroscopic 3D-imaging on peri-operative imaging strategy in calcaneal fracture surgery

Introduction: Previous studies demonstrated that intra-operative fluoroscopic 3D-imaging (3D-imaging) in calcaneal fracture surgery is promising to prevent revision surgery and save costs. However, these studies limited their focus to corrections performed after 3D-imaging, thereby neglecting corrections after intra-operative fluoroscopic 2D-imaging (2D-imaging). The aim of this study was to assess the effects of additional 3D-imaging on intra-operative corrections, peri-operative imaging used, and patient-relevant outcomes compared to 2D-imaging alone. Patients and methods: In this before–after study, data of adult patients who underwent open reduction and internal fixation (ORIF) of a calcaneal fracture between 2000 and 2014 in our level-I Trauma center were collected. 3D-imaging (BV Pulsera with 3D-RX, Philips Healthcare, Best, The Netherlands) was available as of 2007 at the surgeons’ discretion. Patient and fracture characteristics, peri-operative imaging, intra-operative corrections and patient-relevant outcomes were collected from the hospital databases. Patients in whom additional 3D-imaging was applied were compared to those undergoing 2D-imaging alone. Results: A total of 231 patients were included of whom 107 (46%) were operated with the use of 3D-imaging. No significant differences were found in baseline characteristics. The median duration of surgery was significantly longer when using 3D-imaging (2:08 vs. 1:54 h; p = 0.002). Corrections after additional 3D-imaging were performed in 53% of the patients. However, significantly fewer corrections were made after 2D-imaging when 3D-imaging was available (Risk difference (RD) −15%; 95% Confidence interval (CI) −29 to −2). Peri-operative imaging, besides intra-operative 3D-imaging, and patient-relevant outcomes were similar between groups. Conclusion: Intra-operative 3D-imaging provides additional information resulting in additional corrections. Moreover, 3D-imaging probably changed the surgeons’ attitude to rely more on 3D-imaging, hence a 15%-decrease of corrections performed after 2D-imaging when 3D imaging was available. No substantiation for cost reduction was found through reduction in peri-operative imaging or in terms of improved patient-relevant outcomes

Numerical simulation of a collapsing bubble subject to gravity

© 2016 AIP Publishing LLC. The present paper focuses on the simulation of the expansion and aspherical collapse of a laser-generated bubble subjected to an acceleration field and comparison of the results with instances from high-speed videos. The interaction of the liquid and gas is handled with the volume of fluid method. Compressibility effects have been included for each phase to predict the propagation of pressure waves. Initial conditions were estimated through the Rayleigh Plesset equation, based on the maximum bubble size and collapse time. The simulation predictions indicate that during the expansion the bubble shape is very close to spherical. On the other hand, during the collapse the bubble point closest to the bottom of the container develops a slightly higher collapse velocity than the rest of the bubble surface. Over time, this causes momentum focusing and leads to a positive feedback mechanism that amplifies the collapse locally. At the latest collapse stages, a jet is formed at the axis of symmetry, with opposite direction to the acceleration vector, reaching velocities of even 300 m/s. The simulation results agree with the observed bubble evolution and pattern from the experiments, obtained using high speed imaging, showing the collapse mechanism in great detail and clarity

Simulation of bubble expansion and collapse in the vicinity of a free surface

The present paper focuses on the numerical simulation of the interaction of laser-generated bubbles with a free surface, including comparison of the results with instances from high-speed videos of the experiment. The Volume Of Fluid method was employed for tracking liquid and gas phases while compressibility effects were introduced with appropriate equations of state for each phase. Initial conditions of the bubble pressure were estimated through the traditional Rayleigh Plesset equation. The simulated bubble expands in a non-spherically symmetric way due to the interference of the free surface, obtaining an oval shape at the maximum size. During collapse, a jet with mushroom cap is formed at the axis of symmetry with the same direction as the gravity vector, which splits the initial bubble to an agglomeration of toroidal structures. Overall, the simulation results are in agreement with the experimental images, both quantitatively and qualitatively, while pressure waves are predicted both during the expansion and the collapse of the bubble. Minor discrepancies in the jet velocity and collapse rate are found and are attributed to the thermodynamic closure of the gas inside the bubble

Wetenschap, werkelijkheid en onrustige eiwitten

Oratie uitgesproken door prof.dr. Marcellus Ubbink bij de aanvaarding van het ambt van hoogleraar op het gebied van Protein Chemistry aan de Universiteit Leiden op vrijdag 13 mei 2011Macromolecular Biochemistr

Normohomocysteinaemia and vitamin-treated hyperhomocysteinaemia are associated with similiar risks of cardiovascular events in patients with premature peripheral arterial occlusive disease. A prospective cohort study

Objectives. Mild hyperhomocysteinaemia (HHC), fasting or after methionine loading, is associated with an increased risk and severity of atherosclerotic vascular disease. Post-methionine and fasting HHC are responsive to treatment with vitamin

The effect of lipid composition on the thermal stability of nanodiscs

Macromolecular Biochemistr

Design and development of a decision aid to enhance shared decision making by patients with an asymptomatic abdominal aortic aneurysm

Dirk T Ubbink1,2, Anouk M Knops1, Sjaak Molenaar1, Astrid Goossens11Department of Quality Assurance and Process Innovation and 2Department of Surgery, Academic Medical Center, Amsterdam, The NetherlandsObjective: To design, develop, and evaluate an evidence-based decision aid (DA) for patients with an asymptomatic abdominal aortic aneurysm (AAA) to inform them about the pros and cons of their treatment options (ie, surgery or watchful observation) and to help them make a shared decision.Methods: A multidisciplinary team defined criteria for the desired DA as to design, medical content and functionality, particularly for elderly users. Development was according to the international standard (IPDAS). Fifteen patients with an AAA, who were either treated or not yet treated, evaluated the tool.Results: A DA was developed to offer information about the disease, the risks and benefits of surgical treatment and watchful observation, and the individual possibilities and threats based on the patient’s aneurysm diameter and risk profile. The DA was improved and judged favorably by physicians and patients.Conclusion: This evidence-based DA for AAA patients, developed according to IPDAS criteria, is likely to be a simple, user-friendly tool to offer patients evidence-based information about the pros and cons of treatment options for AAA, to improve patients’ understanding of the disease and treatment options, and may support decision making based on individual values.Keywords: decision support techniques, research design, program development, abdominal aortic aneurysm, decision makin

Homocysteine, S-adenosylmethionine and S-adenosylhomocysteine are associated with retinal microvascular abnormalities: the Hoorn Study

The aim of the present study was to investigate the relationship between homocysteine and homocysteine metabolism components and retinal microvascular disorders in subjects with and without Type 2 diabetes. In this population-based study of 256 participants, aged 60-85 years, we determined total plasma homocysteine, SAM (S-adenosylmethionine) and SAH (S-adenosylhomocysteine) in plasma and erythrocytes, total folate in serum and erythrocytes, 5-MTHF (5-methyltetrahydrofolate), and vitamins B12 and B6. Participants were examined ophthalmologically by means of indirect funduscopy and two-field 45° fundus photography, and were graded for retinopathy and retinal sclerotic vessel abnormalities. A computer-assisted method was used to measure retinal vessel diameters. Total plasma homocysteine was inversely associated with retinal arteriolar diameters {standardized β, -0.20 [95% CI (confidence interval), -0.33 to - 0.07]} or a decrease of 3.78 μm CRAEs (central retinal arteriolar equivalents) per 1 S.D. increase in homocysteine level (= 4.6 μmol/l). In addition, the SAM/SAH ratio in plasma was inversely associated with retinal sclerotic vessel abnormalities and retinopathy [odds ratios, 0.61 (95% CI, 0.39-0.96) and 0.50 (95% CI, 0.30-0.83) per 1 S.D. respectively]. The associations were independent of age, sex, glucose tolerance status, other homocysteine metabolism components and cardiovascular risk factors. In conclusion, the results of the present study support the concept that total plasma homocysteine and a low SAM/SAH ratio in plasma, which may reflect reduced transmethylation reactions, may contribute to the pathogenesis of (retinal) microangiopathy. © The Authors

Lipid composition affects the thermal stability of cytochrome P450 3A4 in nanodiscs

Macromolecular Biochemistr