[Avoidable visual impairment among residents in care institutions: lessons from an intervention project in the Den Bosch region]. / Onnodige slechtziendheid onder ouderen in zorginstellingen: lessen uit een interventieproject in de regio Den Bosch.

INTRODUCTION: Many elderly in care institutions in The Netherlands are visually impaired (visual acuity < 0.3). They fall more frequently, are more depressed and require more care. In this project visually impaired residents were identified and referred for adequate eye care. The aim of this study is to evaluate the intervention, including validation of the screening, assessment of the prevalence and causes of visual impairment as well as the outcome of the treatment. The effectiveness of the care chain is also evaluated. MATERIALS AND METHODS: 640 residents were offered a basic eye examination and 210 of them were referred, via their general practitioner, to an optometrist (10), ophthalmologist (98), or centre for visually impaired persons (1). RESULTS: Compliance in this study was poor. The prevalence of visual impairment (24%) was lower than in comparable studies. Cataract was the main cause in 51%. Overall 17 (8.1%) residents were treated by ophthalmologists and nine (4.3%) were referred to optical shops. Constraints in the care chain are identified. DISCUSSION: Vision screening in care institutions for elderly is feasible and useful. The care chain should be shorter and simpler. That will increase the effectiveness of this intervention, and thereby the quality of life for many residents.

Mathematically aggregating experts' predictions of possible futures.

Structured protocols offer a transparent and systematic way to elicit and combine/aggregate, probabilistic predictions from multiple experts. These judgements can be aggregated behaviourally or mathematically to derive a final group prediction. Mathematical rules (e.g., weighted linear combinations of judgments) provide an objective approach to aggregation. The quality of this aggregation can be defined in terms of accuracy, calibration and informativeness. These measures can be used to compare different aggregation approaches and help decide on which aggregation produces the "best" final prediction. When experts' performance can be scored on similar questions ahead of time, these scores can be translated into performance-based weights, and a performance-based weighted aggregation can then be used. When this is not possible though, several other aggregation methods, informed by measurable proxies for good performance, can be formulated and compared. Here, we develop a suite of aggregation methods, informed by previous experience and the available literature. We differentially weight our experts' estimates by measures of reasoning, engagement, openness to changing their mind, informativeness, prior knowledge, and extremity, asymmetry or granularity of estimates. Next, we investigate the relative performance of these aggregation methods using three datasets. The main goal of this research is to explore how measures of knowledge and behaviour of individuals can be leveraged to produce a better performing combined group judgment. Although the accuracy, calibration, and informativeness of the majority of methods are very similar, a couple of the aggregation methods consistently distinguish themselves as among the best or worst. Moreover, the majority of methods outperform the usual benchmarks provided by the simple average or the median of estimates.

Identification of an unusual paramagnetic species and of three [2Fe-2S] clusters in the iron-only hydrogenase from the hyperthermophilic bacterium Thermotoga maritima.

Thermotoga maritima is a H2-producing, fermentative anaerobe and is one of the most thermophilic bacteria known. Its iron-only (Fe-)hydrogenase was previously shown to be a homotetramer and to contain two [4Fe-4S] and two [2Fe-2S] clusters per monomer, but the enzyme lacked the characteristic EPR signal of the oxidized H cluster, the proposed site of H2 catalysis in mesophilic Fe-hydrogenases (Juszczak, A., Aono, S. and Adams, M.W.W. (1991) J. Biol. Chem. 266, 13834-13841). The two types of cluster were shown by spectroelectrochemistry to have reduction potentials (Em) of -390 and -440 mV, respectively. We have now identified two additional redox centers in the enzyme, a [2Fe-2S] center with a higher reduction potential (Em = -365 mV) and an unusual paramagnetic species (Em > -200 mV). The higher potential [2Fe-2S] center can be reduced by sodium dithionite at pH 6.0 and exhibits an axial-type EPR signal with gz = 2.026 and gy = gx = 1.940. The two lower potential [2Fe-2S] centers are fully reduced by sodium dithionite only at pH 10.0. Both of these clusters in their reduced states exhibit rhombic-type EPR signals with gz = 2.005, gy = 1.955, and gx = 1.921. This hydrogenase is therefore thought to contain three [2Fe-2S] clusters, as well as two [4Fe-4S] clusters. In addition, a nearly isotropic EPR signal (g = 2.01) was observed when the enzyme was anaerobically oxidized by organic dyes such as thionine (E alpha = 64 mV) or 2,6-dichlorophenolindophenol (E alpha = 217 mV). This resonance was not observed at 20 K due to relaxation broadening and therefore did not arise from a conventional organic radical. The oxidized enzyme was fully active in an H2 production assay, and also reacted directly with H2. In contrast, the air-oxidized enzyme was inactive and did not exhibit the g = 2.01 EPR signal. This resonance was assigned to a novel paramagnetic species with an approximate Em value of -70 mV. It is thought to be associated with the H2 activating site of this atypical Fe-hydrogenase.

Physical characterization of a totally synthetic rubredoxin.

The entire polypeptide of hyperthermophilic Pyrococcus furiosus rubredoxin was synthesized in order to specifically probe structural determinants of protein thermostability. The uv-visible, circular dichroic, electron paramagnetic, and nuclear magnetic resonance spectra, and electrochemical properties, of the native and synthetic proteins were essentially identical. The synthetic protein had a half-life for denaturation of 24 hr at 80 degrees C. The synthetic protein is considerably more thermostable than nonhyperthermophilic rubredoxins, but not as stable as the native protein. Based on the spectroscopic evidence, it appears that the synthetic protein is incorporating iron properly to form holoprotein, but the peptide still may not be folded correctly.

A national survey of attitudes towards the use of MRI in patients known to have intracranial aneurysm clips.

The objective of this study was to determine the attitudes and practice of neuroradiology centres across the UK regarding the use of MRI in patients known to have intracranial aneurysm clips. A postal survey comprising three questions and a comments section was sent to 35 neuroradiology centres across the UK. There were 32 (91%) respondents to the single questionnaire. 16 (50%) respondents said that they would not consider performing MRI on a patient with an intracranial aneurysm clip. Of the remaining 50%, all said that identification of the clip type and assurance of its safety would be needed prior to scanning the patient. The magnetic strength of the system did not appear to affect the decision regarding whether or not to perform MRI on such patients. There was a variation in attitude towards the use of MRI in such patients between different regions. Neuroradiology centres are equally divided in their attitude and practice about whether it is safe to use MR to image a patient known to have an intracranial aneurysm clip. This is most probably due to the conflicting literature, as well as uncertainty about the identification and ferromagnetic properties of individual clips.

A new technique in nasal-tip reduction surgery.

This article presents a technique for the reduction of the overprojected nasal tip with a proportional reduction of the nostril-margin circumference. To achieve these reductions, a modified open rhinoplasty technique is used, which is unique in that it involves the total transection of the columella through the medial crura of the alar cartilage. The alar cartilage is raised with the flap. The technique was first developed and introduced by the senior author (R.A.S.) 25 years ago and has since been refined through the execution of several thousand rhinoplasties. The results continue to be consistent and pleasing from both the patients' and the surgeon's points of view.

A method for identification of vertebral level.

A method of spinal level marking applicable particularly for use in thoracolumbar posterior spinal operations is described. The use of patent blue V dye in this procedure is discussed in a consecutive series of over 100 cases. No serious adverse effects were observed. The technique ensures accurate identification of spinal marking and helps to minimize anaesthetic time.

Central trigeminal involvement in multiple sclerosis using high-resolution MRI at 3 T.

Trigeminal neuralgia and sensory disturbance is common in multiple sclerosis (MS). Recent literature suggests that signal abnormalities in the cisternal trigeminal nerve and pontine root entry zone are seen in approximately 3% of MS patients, using conventional diagnostic MRI. The objective of this study was to determine the prevalence of trigeminal lesions using high-resolution MRI at 3T. Forty-seven patients with clinically definite MS, chosen at random from the outpatient population of a neuroscience centre underwent MRI on a Siemens 3T Trio machine. Three 3D sequences of T2 TSE (turbo spin echo), T2 FLAIR (fluid attenuated inversion recovery) and T1 IR (inversion recovery) were acquired in the coronal plane. The sequences were of contiguous 1 mm slices with in-plane resolution of up to 0.5 mm by 0.5 mm. Images were read by both a neurologist and a neuroradiologist. Any clinical history of trigeminal symptoms was determined for all subjects. The results showed that 11 patients (23%) had high signal in the trigeminal root entry zone and either the trans-cisternal nerve or pontine nucleus; example images are given. MRI changes did not correspond to clinical symptoms (chi square probability 1.000). The study concludes that high-resolution MRI at 3T yielded a high prevalence of detectable trigeminal abnormality in the MS sample studied. MRI involvement did not correspond to trigeminal symptoms.

3D MRI in multiple sclerosis: a study of three sequences at 3 T.

The objective of this study was to assess the feasibility of using 3D acquisition at 3 T for imaging patients with multiple sclerosis (MS). Feasibility was assessed by three criteria based on acquisition time, specific absorption rate (SAR) and image quality. 47 patients with clinically definite MS underwent imaging in a Siemens 3T Trio MR scanner. Patient safety data were obtained following the scan sessions. The study had local ethics approval. The following three-dimensional (3D) sequences, all acquired coronally, were used: T2 fluid attenuated inversion recovery (FLAIR) (repetition time (TR) 6000 ms, echo time (TE) 353 ms, inversion time (TI) 2200 ms), 0.5x0.5x1 mm voxels, acquisition time 10 min 38 s; T2 turbo spin echo (TSE) (TR 3000 ms, TE 354 ms), 1x1x1 mm voxels, acquisition time 8 min 29 s; T1 inversion recovery (IR) (TR 2040 ms, TE 5.56 ms, TI 1100 ms), matrix 512x448 (0.5x0.5 mm pixels), 0.5x0.5x1 mm voxels, acquisition time 7 min 38 s. Total acquisition time was 26 min 45 s. Example images are presented. 3D scanning at 3 T provides highly detailed, high quality images with acquisition times tolerated by MS patients, even by those with severe disability. The volumetric data are suitable for a wide variety of post-processing techniques; the authors suggest that 3D studies at 3 T should be considered as the possible brain imaging protocol for either cross-sectional or longitudinal studies in MS and that the 3D T2 FLAIR sequence should be considered for the purposes of radiological diagnosis.

Magnetic resonance image findings in the early post-operative period after anterior cervical discectomy.

If early neurological deterioration occurs following anterior cervical discectomy, the patient should be evaluated by urgent MRI scanning. In order to interpret such a scan it is essential to know what the normal post-operative MRI appearance is following an uncomplicated procedure. In the lumbar spine it is well recognized that early post-operative imaging following discectomy is difficult to interpret with a high rate of false positive scans. The normal appearance of MRI in the early post-operative period was evaluated prospectively in 15 patients undergoing anterior cervical discectomy without fusion for either cervical radiculopathy or myelopathy. MRI was performed on the first post-operative day, at 6 weeks and 6 months. The successful outcome of the procedure was validated by uniform improvement of Visual Analogue Scale measurement for neck and arm pain, the Neck Disability Index and European Myelopathy Score as appropriate. In contrast to the established findings following lumbar discectomy, only two cases showed a persistent epidural mass in the first post-operative scan and this had completely resolved at 6 months. All patients had foraminal narrowing and root or cord compression pre-operatively. Sixty six percent of cases showed persistent foraminal narrowing on sequential imaging up to 6 months despite showing good symptomatic improvement. All cases demonstrated high signal in the operated disc space on T2 weighted imaging on the first post-operative day and this finding persisted in 13 of 15 scans performed at 6 weeks. Post contrast imaging demonstrated no enhancement of operated disc space and adjacent vertebral body on the first post-operative day, whereas all scans at 6 weeks showed enhancement and such enhancement persisted at 6 months in 50%. Persistent epidural filling defects are uncommon following successful anterior cervical discectomy but persistence of foraminal narrowing is common despite successful outcome. Enhancement of the disc space is also common and does not in itself imply infection.

Imaging abnormalities in sporadic hemiplegic migraine on conventional MRI, diffusion and perfusion MRI and MRS.

Prolonged hemiparetic migraine aura can cause diagnostic confusion and be mistaken for ischaemic stroke occurring during the course of a migraine--'migrainous infarction'. We report a case of prolonged hemiparesis occurring during the course of a migraine attack. Though initially confused with migrainous infarction, we suggest with sequential magnetic resonance imaging, magnetic resonance angiography, diffusion, perfusion images and magnetic resonance spectroscopy that the hemiplegia was not of vascular origin and that the patient had sporadic hemiplegic migraine. We hypothesize that the mechanisms of sporadic hemiplegic migraine probably lie at a cellular level, similiar to familial hemiplegic migraine.

A pressure- and temperature-controlled electrochemical cell for investigating biological electron transfer reactions.

The construction and operation of a cell for pressure- and temperature-controlled direct electrochemical studies of oxygen-sensitive biological materials is described. The stainless steel electrochemical cell, which contains a pyrolytic graphite working electrode, and Ag/AgCl counter and reference electrodes in an isolated compartment, easily maintains pressures between 1 and 2000 atm, and temperatures between 4 degrees C and at least 100 degrees C. The utility of the cell was demonstrated by determining the reduction potential of a redox dye, phenol red, by square wave voltammetry as a function of pressure and temperature. Thermodynamic parameters associated with electron transfer (delta V degree, delta beta, delta S degree, and delta H degree) were determined from the pressure and temperature/reduction potential profiles. Both pressure- and temperature-dependent reduction potentials of phenol red were attributed to differences in solvent interactions between its oxidation states. A discussion regarding the analysis of electrostatic interaction energies of biomolecules through pressure- and temperature-controlled electrochemical studies is presented.

Medium-chain acylcoenzyme-A dehydrogenase deficiency. Not just another Reye syndrome.

The medium-chain acylcoenzyme-A dehydrogenase enzyme (MCAD) is involved in the initial stages of breakdown of medium-chain-length fatty acids in mitochondria. A deficiency of this enzyme can become symptomatic during a catabolic state and may resemble Reye syndrome. We report the case of a 17-month-old white girl whose 1-day history of vomiting and agitation followed by generalized unresponsiveness caused her to be brought to a local emergency department. She died after resuscitative efforts failed, and an autopsy revealed severe cerebral edema, marked hepatic steatosis, and steatosis of the renal tubule epithelia. Electron microscopy of the liver showed cytoplasmic lipid spherules and mitochondria with dense matrices, changes similar to Reye syndrome; however, postmortem examination of the decedent's blood revealed elevated medium-chain-length acylcarnitines diagnostic of an MCAD deficiency. Although uncommon, a deficiency of this enzyme should be considered in apparent Reye syndrome victims.

Redox properties of several bacterial ferredoxins using square wave voltammetry.

The equilibrium reduction potential of the 2[4Fe-4S] ferredoxin (Fd) isolated from four different bacterial strains was determined at a methyl viologen-modified gold electrode using square wave voltammetry. The observed reduction potential at pH 8 for Clostridium thermoaceticum Fd was -385 mV; Clostridium pasteurianum, -393 mV; Clostridium thermosaccharolyticum, -408 mV; and Chromatium vinosum, -460 mV versus normal hydrogen electrode at 25 degrees C. The reduction potential of the C. pasteurianum Fd was found to be pH independent from pH 6.4 to 8.7, indicating that the electron transfer mechanism does not involve proton exchange. In contrast, the reduction potential of the C. thermosaccharolyticum Fd was found to be pH dependent from pH 6.4 to 8.7, with pKox approximately 7 and pKred approximately 7.5. The +30 mV change in reduction potential from pH 8.7 to 6.4 was attributed to an electrostatic interaction between the iron-sulfur cluster II and the protonated histidine 2 residue located about 6 A away. The Ch. vinosum Fd interacted reversibly at the methyl viologen-modified gold electrode, and its reduction potential was verified using visible spectroelectrochemistry. The reduction potential of Ch. vinosum Fd was found to be 30 mV more positive than previously reported. The similarities of the bacterial Fd reduction potentials are discussed in terms of the homology of their primary structure as reflected by the similarities in the visible and circular dichroic spectra.

A temperature-controlled, anaerobic cell for direct electrochemical studies.

The construction and operation of a cell for temperature-controlled, direct electrochemical studies of oxygen-sensitive materials are described. The borosilicate cell contains a pyrolytic graphite working electrode, a Ag/AgCl reference electrode, and a platinum counter electrode, all of which can be readily interchanged with other types of electrodes. It is surrounded by a water jacket constructed of steel and Lexan, which can easily maintain temperatures between 4 degrees C and at least 90 degrees C. The entire cell was designed to minimize the number, complexity, and expense of components, as well as minimize required sample volume (250 microliters) and sources of oxygen leakage. As examples of the cell's utility, the redox properties of two common organic redox dyes, methyl viologen and thionin, were determined by differential pulse voltammetry at temperatures from 30 to 90 degrees C.

Sudden cardiac death associated with hypoplasia of the coronary arteries and conduction system alteration.

We present a case of sudden cardiac death in a 24-year-old woman with evidence of hypoplasia of the left anterior descending (LAD) and posterior descending (PDA) coronary arteries. These vessels averaged 0.7 mm in internal diameter combined, in contrast to an average of 2.4 mm in control coronary arteries (p < 0.001). The myocardium exhibited areas of acute and chronic ischemic change. Also, the cardiac conduction system (CCS) had diffuse cellular enlargement, believed to be secondary to ischemia. The cells of the sinoatrial node (SAN) and the Purkinje cells of the proximal right bundle branch (RBB) averaged 28.5 and 25.6 microns, respectively. These were significantly larger than the SAN cells (21.6 microns, p = 0.002) and larger than the Purkinje cells (15.9 microns, p = 0.012) of control cases. We report that hypoplastic coronary artery disease is a cause of sudden death, is associated with varying degrees of ischemic change in the heart, and can be associated with condition system alteration.

The lethal hit stage of mouse T and non-T cell-mediated cytolysis: differences in cation requirements and characterization of an analytical "cation pulse" method.

We investigated in detail the cation requirements of two different systems of mouse cell-mediated cytolysis in vitro, at their recognition, post-recognition hit and target cell disintegration stages. In T cell-mediated cytolysis, respectively Mg++ or Ca++, Ca++, and no cations, were required. In non-T cell-mediated hemolysis, respectively no cations, Mg++, and no cations, were required. Two main conclusions can be drawn. First, the cation requirements are different from one system to the other especially at the post-recognition hit stage, which strongly suggests the existence of differences between both systems as to the actual mechanism of lysis. Second, the cation requirements are different within each system from one step to another. This formed the basis of a step-by-step analysis of the lytic process, leading to the characterization of a cation pulse method for the experimental isolation and further study of the post-recognition hit stage of cell-mediated cytolysis.

Purification and characterization of an iron-nickel hydrogenase from Thermococcus celer.

Thermococcus celer cells contain a single hydrogenase located in the cytoplasm, which has been purified to apparent homogeneity using three chromatographic steps: Q-Sepharose, DEAE-Fast Flow, and Sephacryl S-200. In vitro assays demonstrated that this enzyme was able to catalyze the oxidation as well as the evolution of H2. T. celer hydrogenase had an apparent MW of 155,000+/-30,000 by gel filtration. When analyzed by SDS polyacrylamide gel electrophoresis a single band of 41,000+/-2,000 was detected. Hydrogenase activity was also detected in situ in a SDS polyacrylamide gel followed by an activity staining procedure revealing a single band corresponding to a protein of apparent Mr 84,000+/-3,000. Measurements of iron and acid-labile sulfide in different preparations of T. celer hydrogenase gave values ranging from 24 to 30 g-atoms Fe/mole of protein and 24 to 36 g-atoms of acid-labile sulfide per mole of protein. Nickel is present in 1.9-2.3 atoms per mole of protein. Copper, tungsten, and molybdenum were detected in amounts lower than 0.5 g-atoms per mole of protein. T. celer hydrogenase was inactive at ambient temperature, exhibited a dramatic increase in activity above 70 degrees C, and had an optimal activity above 90 degrees C. This enzyme showed no loss of activity after incubation at 80 degrees C for 28 h, but lost 50% of its initial activity after incubation at 96 degrees C for 20 h. Hydrogenase exhibited a half-life of approximately 25 min in air. However, after treating the air-exposed sample with sodium dithionite, more than 95% of the original activity was recovered. Copper sulfate, magnesium chloride and nitrite were also inactivators of this enzyme.

Pyruvate ferredoxin oxidoreductases of the hyperthermophilic archaeon, Pyrococcus furiosus, and the hyperthermophilic bacterium, Thermotoga maritima, have different catalytic mechanisms.

Pyruvate ferredoxin oxidoreductase (POR) has been previously purified from two hyperthermophiles, the archaeon Pyrococcus furiosus (Pf, Topt = 100 degrees C) and the bacterium Thermotoga maritima (Tm, Topt = 80 degrees C). Each catalyzes the oxidative decarboxylation of pyruvate to acetyl-CoA and CO2 near the optimal growth temperature of the organism and are virtually inactive at 25 degrees C. Both PORs contain a thiamine pyrophosphate (TPP) cofactor and at least two [4Fe-4S] ferredoxin-type clusters. We have now shown, using EPR spectroscopy and metal analyses, that PfPOR also contains an unusual copper center that is not present in Tm POR. In addition, distinct catalytic intermediates were generated in both enzymes by the addition, separately and in combination, of the substrates pyruvate and CoASH, and these were examined by EPR spectroscopy. The addition of pyruvate to oxidized Pf POR produced an isotropic signal centered at g = 2.01, which was measurably broader in the presence of pyruvate-2(13)C. This signal, which was assigned to a (hydroxyethyl)thiamine pyrophosphate radical intermediate, was not observed in Tm POR under the same experimental conditions. Incubation of the oxidized enzymes with CoASH resulted in the partial reduction of the copper site in Pf POR and the partial reduction of a novel iron-sulfur center in Tm POR, which was not seen in the dithionite-reduced enzyme. The addition of both pyruvate and CoASH to the PORs in their oxidized states resulted in the reduction of the same iron-sulfur centers that are reduced by sodium dithionite.(ABSTRACT TRUNCATED AT 250 WORDS)