bluuebunny/crossref_metadata_2025 huggingface dataset:
Microalbuminuria, cardiovascular disease and risk factors in a nondiabetic/nonhypertensive population. The Nord‐Trøndelag Health Study (HUNT, 1995–97), Norway
Authors: Romundstad S. , Holmen J. , Hallan H. , Kvenild K. , Krüger Ø. , Midthjell K.
Published: March 2003

Abstract. Romundstad S, Holmen J, Hallan H, Kvenild K, Krüger Ø, Midthjell K (HUNT Research Centre, Verdal, Norway; Levanger Hospital, Levanger, Norway; and Nærøy Health Centre, Nærøy, Norway). Microalbuminuria, cardiovascular disease and risk factors in a nondiabetic/nonhypertensive population. The Nord‐Trøndelag Health Study (HUNT, &1995–97), Norway. J Intern Med 2002; 252: 164–172.

Objective.  Microalbuminuria (MA) as an independent marker of cardiovascular morbidity and mortality in nondiabetic/nonhypertensive individuals is under international debate. The aim of this study was to investigate the associations between MA and known cardiovascular risk factors/markers and disease in a randomly selected nondiabetic/nonhypertensive sample.

Design.  Cross‐sectional study.

Setting.  Participants in the population‐based Nord‐Trøndelag Health Study (HUNT), Norway (n = 65 258).

Subjects.  A total of 2113 individuals (≥20 years), randomly selected without diabetes and treated hypertension, delivered three morning urine samples for MA analysis.

Main outcome measures.  MA expressed as albumin‐to‐creatinine ratio (ACR), cardiovascular risk factors and disease.

Results.  Increasing age, pulse pressure, systolic (SBP) and diastolic blood pressure (DBP) and coronary heart disease (CHD) significantly predicted MA in men and increasing pulse pressure, SBP and DBP were associated with MA in women, adjusted for other cardiovascular risk factors/markers. After excluding individuals with known CHD and untreated hypertension (SBP ≥ 140 mmHg, DBP ≥ 90 mmHg) and hence a high total risk of cardiovascular disease (CVD), only increasing age was associated with ACR in men and increasing SBP and pulse pressure in women. Smoking, elevated lipid and glucose levels were strongly associated with MA in individuals with a high total risk of CVD than in individuals with a low total risk.

Conclusion.  MA was associated with increasing blood pressure in both genders, age and CHD in men. Other cardiovascular risk factors/markers might be more influential in predicting ACR variation in nondiabetic/nonhypertensive individuals with a high total risk of CVD than in individuals with a low total risk.
Fever of unknown origin in the elderly
Authors: Tal S. , Guller V. , Gurevich A. , Levi S.
Published: March 2003

Fever of unknown origin (FUO) means fever that does not resolve itself in the period expected for self‐limited infection and whose cause cannot be ascertained despite considerable diagnostic efforts. The differential diagnosis is often different in older patients, and presentation of disease is frequently nonspecific and symptoms are difficult to interpret. Multisystem disease has emerged as the most frequent cause of FUO in the elderly, and temporal arteritis is the most frequent specific diagnosis. Infections, particular tuberculosis, remain an important group. FUO is often associated with treatable conditions in this age group. Early recognition and prompt initiation of appropriate empirical therapy are cornerstones of the strategy.
Trends in sudden cardiac death in the northern Sweden MONICA area 1985–99
Authors: Messner T. , Lundberg V.
Published: March 2003

Abstract. Messner T, Lundberg V (Kiruna District Hospital, Kiruna; Kalix District Hospital, Kalix; Umeå University Hospital, Umeå, Sweden). Trends in sudden cardiac death in the northern Sweden MONICA area 1985–99.J Intern Med2003;253:320–328.

Objectives. To describe time trends in sudden cardiac death (SCD) occurrences between 1985 and 1999.

Design. Cohort study with analysis of a database of all symptomatic and/or fatal acute myocardial infarctions (AMI) in the two northernmost counties in Sweden, partly north of the Arctic Circle.

Subjects. A total of 1139 cases of SCD amongst men and women aged 35–64 years.

Main outcome measure. Sudden cardiac death.

Results. Amongst men the proportion of SCD to all AMI deaths (within 28 days of an AMI) was 38% and for women 31%. The mean yearly incidence of SCD in this age group was 65 per 100 000 men and 12 per 100 000 women. Amongst men the mean yearly incidence decreased by 1.8% (95% confidence interval −3.2 to −0.3) and amongst women the decrease was 1.0% (95% confidence interval −4.4 to 2.4). Diabetes mellitus was more common in women compared with men (24% vs. 14%,P = 0.001). Men suffered an SCD more often around noon and on Saturdays, whereas women suffered their SCD on Mondays and Fridays. For season, men and women behaved similarly with a winter peak, although statistical significance was reached only for men.

Conclusions. The SCD decreased amongst men between 1985 and 1999. There was also a decrease amongst women during the same time period but not to a statistically significant degree, possibly caused by lack of statistical power due to small numbers.
Elevation of biochemical markers for myocardial damage prior to hospital admission in patients with acute chest pain or other symptoms raising suspicion of acute coronary syndrome
Authors: Svensson L. , Axelsson C. , Nordlander R. , Herlitz J.
Published: March 2003

Abstract.  Svensson L, Axelsson C, Nordlander R, Herlitz J (South Hospital, Stockholm; and Sahlgrenska University Hospital, Göteborg; Sweden). Elevation of biochemical markers for myocardial damage prior to hospital admission in patients with acute chest pain or other symptoms raising suspicion of acute coronary syndrome. J Intern Med 2003; 253: 311–319.

Objectives.  To evaluate the occurrence of elevation of serum biochemical markers for myocardial damage in the prehospital setting amongst patients who called for an ambulance due to a suspected acute coronary syndrome (ACS).

Design.  Prospective observational study.

Subjects.  All the patients who called for an ambulance due to suspected ACS.

Setting.  South Hospital's catchment area in Stockholm and in the Municipality of Göteborg, Sweden between January and November in the year 2000, were included.

Interventions.  On arrival of the ambulance crew, a blood sample was drawn for bedside analysis of serum myoglobin, creatine kinase MB and troponin I. A 12‐lead electrocardiogram (ECG) was simultaneously recorded.

Main outcome measures.  Elevation of biochemical markers prior to hospital admission.

Results.  In all, 511 patients participated on 538 occasions. Elevation of any biochemical marker was observed in 11% of all patients. The corresponding figure for patients developing myocardial infarction was 21%; for patients with myocardial ischaemia 8%; for patients with a possible myocardial ischaemia 4% and for patients with other diagnoses 5%. Amongst those who had a final diagnosis of acute myocardial infarction (AMI), 47% had ST‐elevation on initial ECG and 57% had either ST‐elevation or elevation of any biochemical marker.

Conclusion.  Bedside analysis of biochemical markers in serum is already feasible prior to hospital admission amongst patients with a suspected ACS. About 20% of patients with AMI have elevated biochemical markers at that stage. When found this data might increase the possibility of diagnosing an AMI very early in the course. However, false positives were found and whether this strategy will improve the triage of these patients in the prehospital setting remains to be proven.
Extrapolation of reciprocal creatinine plot is not reliable in predicting the onset of dialysis in patients with progressive renal insufficiency
Authors: Szeto C.‐C. , Leung C.‐B. , Wong T. Y.‐H. , Chow K.‐M. , Wang A. Y.‐M. , Lui S.‐F. , Li P. K.‐T.
Published: March 2003

Abstract.  Szeto C.‐C, Leung C.‐B, Wong T.Y.‐H, Chow K.‐M, Wang A.Y.‐M, Lui S.‐F, Li P.K.‐T (Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, Hong Kong, China). Extrapolation of reciprocal creatinine plot is not reliable in predicting the onset of dialysis in patients with progressive renal insufficiency. J Int Med 2003; 253: 335–342.

Background.  Reciprocal creatinine plot is often used to monitor patients with progressive renal insufficiency and to predict the onset of dialysis, although the latter practice has not been validated.

Objective.  We examined whether extrapolating the reciprocal creatinine plot can predict the onset of dialysis.

Setting.  Single centre study in the dialysis unit of a University teaching hospital.

Design.  We studied 170 consecutive patients with progressive renal insufficiency referred to a single nephrology unit and subsequently dialysed. Reciprocal creatinine plot was constructed by all available serum creatinine values before dialysis (the ‘definitive plot’). Four ‘interim plots’ were constructed for each patient by using serum creatinine below 400, 500, 600 and 700 μmol L−1. Interim plots with at least five points and Pearson's r > 0.9 were analysed. The date of dialysis was predicted from the least squares linear regression formula and a target serum creatinine level cor‐ responding to estimated creatinine clearance of 7 mL min−1, at which dialysis was recommended.

Results.  The median duration of observation was 25 months. After serum creatinine 500 μmol L−1, the slope of the interim plot remained stable and extrapolation was possible in 117 patients (68.8%). However, the limits of agreement for predicting the onset of dialysis were wide (from −11.7 to +9.5 months). At this creatinine level, the onset of dialysis fell within 1 month of the predicted onset in only 41 patients (24.1%). The limits of agreement for prediction narrowed when time points of higher serum creatinine were included into the plot. However, nine patients (5.3%) required dialysis within 1 month at creatinine 600 μmol L−1 and the dialysis was not predicted by the reciprocal creatinine plot. Target serum creatinine did not correlate with acute serum creatinine at which dialysis was started (r = 0.051, P = 0.51). A slower decline in renal function was associated with a higher prediction error (r = 0.212, P = 0.014).

Conclusions.  The onset of dialysis cannot be predicted by extrapolation of the reciprocal creatinine plot because of individual variation in the renal function that require dialysis. Dialysis would be almost imminent in some patients by the time serum creatinine reaches a level that allows accurate construction and extrapolation of a plot.
High‐pressure freezing causes structural alterations in phospholipid model membranes
Authors: Semmler  , Wunderlich  , Richter  , Meyer
Published: March 2003

The influence of high‐pressure freezing (HPF) on the lipid arrangement in phospholipid model membranes has been investigated. Liposomes consisting of pure dipalmitoylphosphatidylcholine (DPPC) and of DPPC mixed with a branched‐chain phosphocholine (1,2‐di(4‐dodecyl‐palmitoyl)‐sn‐glycero‐3‐phosphocholine) have been analysed by freeze‐fracture electron microscopy. The liposomes were frozen either by plunging into liquid propane or by HPF. The characteristic macroripple‐phase of the two‐component liposome system is drastically changed in its morphology when frozen under high‐pressure conditions. The influence of ethanol which acts as pressure transfer medium was ruled out by control experiments. In contrast, no high‐pressure alterations of the pure DPPC bilayer membrane have been observed. We assume that the modification of the binary system is due to a pressure‐induced relaxation of a stressed and unstable lipid molecule packing configuration. HPF was performed with a newly designed sample holder for using sandwiched copper platelets with the high‐pressure freezing machine Balzers HPM010. The sandwich construction turned out to be superior to the original holder system with regard to freeze‐fracturing of fluid samples. By inserting a spacer between the supports samples with a thickness of 20–100 μm can be high‐pressure frozen. The sandwich holder is provided with a thermocouple to monitor cooling rates and allows exact sample temperature control. Despite a two‐fold mass reduction compared to the original holder no HPF cooling rate improvement has been achieved (4000 °C s−1). We conclude that the cooling process in high‐pressure freezing is determined mainly by cryogen velocity.
Measurement‐based evaluation of optical pathlength distributions reconstructed from simulated differential interference contrast images
Authors: Van Munster  , Winter  , Aten
Published: March 2003

Recently a method was presented for reconstructing optical pathlength distributions (OPDs) from images of weak phase objects obtained by a conventional differential interference contrast (DIC) microscope. A potential application of this technique is the determination of the mass of biological objects: by integrating the optical pathlength over the projected surface of the image of an object, a measure of the dry mass, i.e. the total mass of all solid constituents present in the object, is obtained. To assess the possibilities of DIC microscopy for this application, simulations were performed on computer‐generated DIC images of objects of various sizes, shapes and orientation angles. After reconstructing the OPDs from these images, the integrated optical pathlength of each of the test objects was determined, and compared with the expected results. The parameter settings used in the reconstruction algorithm were found to be very important in obtaining a reliable measurement. Using optimal parameter settings, errors in the integrated OPD could be limited to a few per cent for circular objects within the investigated size range. For non‐circular objects, however, the orientation angle of the object relative to the lateral shift was found to influence the measured values. Ellipses with their long axes perpendicular to the shift direction had a significantly higher integrated OPD than ellipses orientated parallel to the shift. By adjusting the reconstruction parameters the effect could be limited, but complete elimination of the artefact was not possible within the parameter range investigated.
A simple method for the acquisition of high‐quality digital images from analog scanning electron microscopes
Authors: Gebert  , Preiss
Published: March 2003

A method is described for converting video signals of analog scanning electron microscopes (SEMs) into digital images of high quality. A plug‐in card commercially available for personal computers is used for the on‐line analog/digital conversion. A Windows application program written by the authors, together with low‐level software drivers supplied with the plug‐in card, allow digital images to be recorded, to be displayed simultaneously on the computer monitor and to be saved as a file in a standardized format. Compared to conventional photographic images obtained from the SEM camera system, the digital images possess superior sharpness of outline, excellent image definition, diminished noise and well‐defined grey‐scale tones. This method provides SEM images of high quality for less than $1000 from most older analog SEMs. In addition, the advantages of digital image processing can be applied to analog SEMs, including contrast enhancement, digital filtering and multichannel recording.
X‐ray microanalysis of native airway surface liquid collected by cryotechnique
Authors: Baconnais  , Zahm  , Kilian  , Bonhomme  , Gobillard  , Perchet  , Puchelle  , Balossier
Published: March 2003

The airway surface liquid (ASL) that lines the surface epithelium of the tracheobronchial tree is of vital importance to the airway defence against microbial invasion and damage due to environmental factors. Little is known about the ASL collected in situ in native conditions, owing to difficulties in collecting ASL without causing damage to the airway mucosa. We have developed a method to collect and analyse the elemental composition of tracheal ASL in pathogen‐free mice. A specially designed cryoprobe, adapted to the internal curvature of the mouse trachea, was used to collect the native ASL from the tracheal surface. The complete ASL elemental composition including [Na] = 5.5 ± 0.3, [Cl] = 1.3 ± 0.3, [K] = 1.1 ± 0.2, [Ca] = 1.2 ± 0.3, [P] = 1.5 ± 0.8, [S] = 1.7 ± 0.4 and [Mg] = 1.3 ± 0.4 mmol L−1 was determined by X‐ray micro‐analysis. We demonstrate here that the technique that we used for ASL collection maintained perfectly the airway epithelial integrity and functionality.
3D microscopy of transparent objects using third‐harmonic generation
Authors: Müller  , Squier  , Wilson  , Brakenhoff
Published: March 2003

It is demonstrated that third‐harmonic generation (THG) near interfaces in the refractive index or the third‐order nonlinear susceptibility (χ(3)) permits three‐dimensional imaging of transparent objects. The nonlinear dependence of THG on the excitation power provides inherent optical sectioning. At the same time, the nonresonant nature of THG, in combination with the near‐IR excitation wavelengths used (1–2 μm), render this technique potentially (biologically) nondamaging and nonbleaching. A specific property of THG imaging is its sensitivity to — and potential use for imaging of — the relative orientation of interfaces with respect to the axis of propagation of the excitation radiation.
An investigation of the electron irradiation of carbon blacks in various gas atmospheres using a modified electron microscope
Authors: Burden A.P. , Baigrie S. , Hutchison J.L.
Published: March 2003

The behaviour of carbon black particles immersed in a variety of gases and simultaneously irradiated with an electron beam has been investigated. Because this treatment was performed in a modified high‐resolution transmission electron microscope, the remarkable morphological and microstructural changes that occurred could be observed directly. In addition to the physical damage to the specimens, believed to be caused by a high flux of low energy ions generated by the electron beam, the use of reactive gases in this study exposed additional chemical sputtering effects that will be of importance for future controlled‐environment microscopy.
Electron beam‐induced changes in vitreous sections of biological samples
Authors: Sartori Blanc N. , Studer D. , Ruhl K. , Dubochet J.
Published: March 2003

Nonpretreated high pressure frozen samples of Zea mays, cartilage and human erythrocytes were cryosectioned and observed at 110 K in a cryoelectron microscope. Changes induced by medium doses of electron irradiation (< 10 ke nm−2) are described. After some ke nm−2, the most conspicuous cutting artefacts are erased to a large extent and the visibility of the cell organelles is improved. The sections, compressed in the cutting direction by the sectioning process, shrink once more, in the same direction, when irradiated. This shrinkage depends on the section support and on how the section is adsorbed to it. Shrinkage is not uniform; it is most pronounced in mitochondria, condensed chromatin and nucleolus. This differential shrinkage improves the visibility of major structures on the section and, as a result, ‘nicer’ images are recorded. However, this apparent improvement is a beam‐induced artefact that must be paired with a loss of high resolution information.
In‐situ observation of shape and atomic structure of Xe nanocrystals embedded in aluminium
Authors: FURUYA K. , ISHIKAWA N. , ALLEN C. W.
Published: March 2003

An imaging technique to determine in situ the shape and atomic structure of nanosized Xe crystals embedded in Al is described using high‐resolution transmission electron microscopy (HRTEM). The Xe nanocrystals, with sizes less than 5 nm were prepared by the implantation of 30 keV Xe+ into Al at room temperature. The fcc Xe nanocrystals are mesotactic with the Al lattice and have a lattice parameter ≈ 50% larger than that of Al. HRTEM images of the Xe were not clear in [110] zone axis illumination because of the small number of Xe atoms relative to Al atoms in any atom column. An off‐axial imaging technique that consists of tilting the specimen several degrees from a zone axis and defocusing to suppress the Al lattice fringes is employed for the 110 projection of the Xe/Al system and the structure of the Xe nanocrystals is successfully imaged. The Xe images clearly represent projections of cuboctahedra with faces parallel to eight Al {111} planes truncated by six {100} planes. The results of multislice image simulations using a three‐dimensional atomic model agreed well with the results obtained by the off‐axial imaging technique. The usefulness of the technique is demonstrated with observations of crystal defects introduced into the Xe under intense 1000 keV electron irradiation.
Retaining ionic concentrations during in vitro storage of tissue for microanalytical studies
Authors: HONGPAISAN J. , ROOMANS G. M.
Published: March 2003

When human or animal tissue is to be investigated by X‐ray microanalysis, it is sometimes necessary to store the tissue between removal from the organism and freezing. However, when excised tissue is stored in buffer, the elemental concentrations in the cell may change. In the present study, it was attempted to develop a storage buffer that would retain the cellular elemental concentrations close to their in situ values. To start, the NaCl component in Krebs–Ringer buffer was exchanged for K‐gluconate and KCl for NaCl. This buffer was called a ‘100% high K+ solution’. Starting from this solution, part of the K‐gluconate was replaced by an equivalent amount of NaCl. Incubation of excised rat liver (4 °C, 4 h) in 85% high K+ solution resulted in retention of cellular Na, K, Ca, S and Mg concentration most closely to the in situ state, whereas cellular Cl was retained best when the tissue was incubated in 75% high K+ solution. For rat submandibular gland, incubation in 80% high K+ solution resulted in optimal retention of cellular Na, K, Ca, P, S and Mg, while Cl was retained best in a 70% high K+ solution. Based on these results, an optimally modified Krebs–Ringer solution for the liver

would consist of 119 mM K+, 26 mM Na+ and 45 mM Cl−. An optimally modified Krebs–Ringer bicarbonate solution for the submandibular gland would be composed of 96 mM K+, 53 mM Na+ and 46 mM Cl−. After incubation in the modified solutions (at 4 °C), cellular Na, Mg, S, Cl, K and Ca in both tissues were maintained close to the in situ state throughout a 6‐h incubation. The cellular P concentration was reduced after incubation for 1 h; thereafter, in the liver cells it remained at this lower level for the rest of the incubation, whereas in the submandibular gland tissue it increased again after 4 h. The increase in cell volume (oedema) was less in tissue stored in the modified solutions, than in the 100% high K+ solutions. Incubation in high Na+ buffers (4 °C, 6 h) resulted in a progressive increase in the percentage of cells showing trypan blue uptake. A similar increase in trypan blue uptake was seen in the modified solution, but this increase levelled off after 4 h. After cholinergic stimulation in high Na+ solution (25 °C, 1 min), the expected decrease in cellular Cl concentration was seen in submandibular gland cells that had previously been preserved (4 °C, 4 h) in the modified solution, but not in those that had been preserved in the 100% high K+ solution.
Single‐fluorophore imaging with an unmodified epifluorescence microscope and conventional video camera
Authors: Adachi  , Kinosita JR  , Ando
Published: March 2003

Single fluorophores in aqueous solution were imaged in real time with a conventional silicon‐intensified target video camera connected to an unmodified commercial microscope (IX70, Olympus) with epifluorescence excitation with a high‐pressure mercury lamp. Neither a powerful laser nor an extremely sensitive video camera was required. Three experimental systems were used to demonstrate quantitatively that individual, moving or stationary Cy3 fluorophores could be imaged with the microscope: Cy3‐gelsolin attached to an actin filament sliding over heavy meromyosin, sliding actin filaments sparsely labelled with Cy3, and heavy meromyosin labelled with one or two Cy3 fluorophores. The results should encourage many laboratories to attempt ‘single‐molecule physiology’ in which the functions and mechanisms of molecular machines are studied at the single‐molecule level in an environment where the biological machines are fully active.
Photoluminescence imaging of phosphor particles using near‐field optical microscope with UV light excitation
Authors: Nishikawa S. , Isu T.
Published: March 2003

We have developed fibre probes suitable for 325 nm UV light excitation and a photoluminescence near‐field scanning optical microscope (NSOM) and demonstrated the photoluminescence imaging of phosphor BaMgAl10O17:Eu2+ (BAM) particles. The probe was fabricated by a two‐step‐etching method that we developed. The probe had a large taper angle at the top of the probe and a small taper angle at the root. The NSOM image was different from the topographical structure but roughly reflected the corresponding features of the particles. The inhomogeneity of the photoluminescence intensity between BAM particles was observed in the NSOM image. The photoluminescence intensity with various bandpass filters showed differences between the individual particles, which means that they have different spectra.
Optical microcantilever consisting of channel waveguide for scanning near‐field optical microscopy controlled by atomic force
Authors: Niwa T. , Mitsuoka Y. , Kato K. , Ichihara S. , Chiba N. , Shin‐Ogi M. , Nakajima K. , Muramatsu H. , Sakuhara T.
Published: March 2003

We develop a novel optical microcantilever for scanning near‐field optical microscopy controlled by atomic force mode (SNOM/AFM). The optical microcantilever has the bent channel waveguide, the corner of which acts as aperture with a large tip angle. The resonance frequency of the optical microcantilever is 9 kHz, and the spring constant is estimated to be 0.59 N/m. The optical microcantilever can be operated in contact mode of SNOM/AFM and we obtain the optical resolution of about 200 nm, which is as same size as the diameter of aperture. We confirm that the throughput of optical microcantilever with an aperture of 170 nm diameter would be improved to be more than 10−5.
Pronounced loss of cell nuclei and anisotropic deformation of thick sections
Authors: Andersen  , Gundersen
Published: March 2003

The local deformation and variations in section thickness are studied in 100‐μm thick vibratome sections of well‐fixed human brain tissue. During processing, including drying on glass slides, the section thickness is reduced to less than half, but close to the edges there is less shrinkage of the section thickness. Close to both surfaces there is a pronounced reduction in the number of neuronal nucleoli. At the scale of the original section, the upper 15 μm and the lower 10 μm are depleted. The loss is most pronounced at the upper surface, which is unprotected during processing. In the central 70% of the section height, where one would ordinarily use an optical disector for sampling, there is no indication of non‐uniform shrinkage. The simplest explanation for the observed loss of nucleoli is that all cells opened by the knife may lose their nuclei across an unprotected section surface. The observations do not generalize to other tissues and other preparation techniques, but illustrate the magnitude of some of the problems for uniform sampling and unbiased estimation in very thick sections. The uniform optical disector sampling of nucleoli in thick sections, as opposed to that of cell nuclei, raises a special problem, which is discussed briefly.
The shape of field emitters and the ion trajectories in three‐dimensional atom probes
Authors: Vurpillot  , Bostel  , Blavette
Published: March 2003

The lateral resolution of three‐dimensional atom probes is mainly controlled by the aberrations of the ion trajectories near the specimen surface. For the first time, a simulation program has been developed to reconstruct the ion trajectories near a sharp hemispherical electrode defined at the atomic scale. Surface atoms submitted to the highest field were removed one by one. The consecutive gradual change of the surface topology was taken into account in the calculation of ion trajectories. As the tip was ‘field evaporated’, the initial spherical shape of the emitter was observed to transform gradually into a polygonal shape. When the tip reached its equilibrium shape, the field distribution at the tip surface was found to be much more uniform compared to the initial distribution. The calculated distribution of ion impacts on the detector exhibits the presence of depleted zones both at the centre of low index poles and along <001> zone axes. These predictions are in excellent agreement with experiments.
Wide‐field optically sectioning fluorescence microscopy with laser illumination
Authors: Neil  , Squire  , Juškaitis  , Bastiaens  , Wilson
Published: March 2003

We describe an extremely simple method by which optically sectioned fluorescence images may be obtained with conventional microscopes using laser illumination. A one‐dimensional grid pattern is introduced into the illumination system, together with a rotating ground glass diffuser. This causes an image of the grid pattern to be projected into the specimen. Images taken at three spatial positions of the grid are processed in a simple manner to provide optically sectioned images of fluorescent specimens.
The spatial distribution and resolution of coaxial backscattered electrons in SEM, calculated by Monte Carlo simulations
Authors: Jiang  , Rosenberg  , Morin
Published: March 2003

We simulate, within a sample, the trajectories of the backscattered electrons detected in a scanning electron microscopy with a particular detection geometry. Thus we obtain the depth and lateral distributions, according to the adjustable parameter values, of the detected electrons. Finally, the scanline profile across a chemical edge is drawn. The conditions corresponding to the best lateral resolution are established; we obtain an ultimate resolution of the same order as the beam diameter.
Discrimination of polymorphic forms of a drug product by localized thermal analysis
Authors: Sanders G. H. W. , Roberts C. J. , Danesh A. , Murray A. J. , Price D. M. , Davies M. C. , Tendler S. J. B. , Wilkins M. J.
Published: March 2003

In chemical processing, it is important to distinguish between and identify polymorphic forms. We demonstrate the novel use of scanning thermal microscopy (SThM) and localized thermal analysis to distinguish and identify polymorphic forms of the drug cimetidine. These forms cannot be resolved by classical bulk thermal analysis. SThM reveals a sample consisting of a 50 : 50 mixture of the polymorphs contains regions of different thermal conductivity, corresponding to the different polymorphs. Localized thermal analysis of small volumes of pure polymorphic samples (approximately 50 µm3) shows that the origin of the thermal conductivity contrast lies, at least in part, with the presence of a surface water layer on the more hydrophilic polymorph.
Automatic image analysis methods for the determination of stereological parameters – application to the analysis of densification during solid state sintering of WC–Co compacts
Authors: Missiaen J.‐M. , Roure S.
Published: March 2003

Automatic image analysis methods which were used to determine microstructural parameters of sintered materials are presented. Estimation of stereological parameters at interfaces, when the system contains more than two phases, is particularly detailed. It is shown that the specific surface areas and mean curvatures of the various interfaces can be estimated in the numerical space of the images. The methods are applied to the analysis of densification during solid state sintering of WC–Co compacts. The microstructural evolution is commented on. Application of microstructural measurements to the analysis of densification kinetics is also discussed.
Probing confined fields with single molecules and vice versa
Authors: Sick B. , Hecht B. , Wild U. P. , Novotny L.
Published: March 2003

Single dye molecules are used as local probes to map the spatial distribution of the squared electric field components in the focus of a high numerical aperture lens. Simulated field distributions are quantitatively verified by experimentally obtained fluorescence excitation maps. We show that annular illumination can be used to engineer the field distribution in the focus at a dielectric/air interface such that electric field components in all directions acquire comparable magnitudes. The 3D orientation of molecular absorption dipoles can be determined by comparing measured to simulated image patterns. The presence of longitudinal electric field components in a focus is of particular interest in tip‐enhanced scanning near‐field optical microscopy.
Design and optimization of tapered structure of near‐field fibre probe based on finite‐difference time‐domain simulation
Authors: Nakamura H. , Sato T. , Kambe H. , Sawada K. , Saiki T.
Published: March 2003

The finite‐difference time‐domain method was employed to simulate light propagation in tapered near‐field fibre probes with small metal aperture. By conducting large‐volume simulations, including tapered metal‐cladding waveguide and connected optical fibre waveguide, we illustrated the coupling between these guiding modes as well as the electric field distribution in the vicinity of the aperture. The high collection efficiency of a double‐tapered probe was reproduced and was ascribed to the shortening of the cut‐off region and the efficient coupling to the guiding mode of the optical fibre. The dependence of the efficiency on the tapered structure parameters was also examined.
Sub‐wavelength region spectroscopy and local morphology of individual mesoscopic quantum systems
Authors: Vacha M. , Takei S. , Suzuki H. , Hashizume K.‐I. , Tani T.
Published: March 2003

Results of reflection microscopy and local reflection spectroscopy of J‐aggregates of two pseudoisocyanine dyes in a thin film polymer matrix are reported. The individual J‐aggregates assemble into fibre‐like shapes of large structural heterogeneity. Reflectance spectra obtained at different samples, different locations on one sample and even at different positions of the same aggregate fibre reveal a wide distribution of optical properties. The shapes and absolute reflectivities of the spectra are suggested to originate from varying strengths of exciton–photon interaction and from the effect of finite thickness of the aggregate fibres. Polarization dependence measurements of local reflectivities provide orientations of the exciton transition dipole moments at 572 nm and 540 nm with respect to the orientation of the aggregate fibres. Furthermore, modified synthesis of capped semiconductor nanocrystals of CdSe is presented. The method yields high quality quantum dots suitable for microscopic imaging and spectroscopy.
Direct interpretation of near‐field optical images
Authors: Dereux A. , Devaux E. , Weeber J. C. , Goudonnet J. P. , Girard C.
Published: March 2003

The interpretation of the detection process in near‐field optical microscopy is reviewed on the basis of a discussion about the possibility of establishing direct comparisons between experimental images and the solutions of Maxwell equations or the electromagnetic local density of states. On the basis of simple physical arguments, it is expected that the solutions of Maxwell equations should agree with images obtained by collecting mode near‐field microscopes, while the electromagnetic local density of states should be considered to provide a practical interpretation of illumination mode near‐field microscopes.

We review collecting mode near‐field microscope images where the conditions to obtain good agreement with the solutions of Maxwell equations have indeed been identified. In this context of collecting mode near‐field microscopes, a fundamentally different functionality between dielectric and gold‐coated tips has been clearly identified experimentally by checking against the solutions of Maxwell equations. It turns out that dielectric tips detect a signal proportional to the optical electric field intensity, whereas gold‐coated tips detect a signal proportional to the optical magnetic field intensity. The possible implications of this surprising phenomenon are discussed.
Super‐resolution microscopy using normal flow decoding and geometric constraints
Authors: Danuser G.
Published: March 2003

Prior knowledge about the observed scene provides the key to restoration of frequencies beyond the bandpass of an imaging system (super‐resolution). In conjunction with microscopy two super‐resolution mechanisms have been mainly reported: analytic continuation of the frequency spectrum, and constrained image deconvolution. This paper describes an alternative approach to super‐resolution. Prior knowledge is imposed through geometric and dynamic models of the scene. We illustrate our concept based on the stereo reconstruction of a micropipette moving in close proximity to a stationary target object. Information about the shape and the movement of the pipette is incorporated into the reconstruction algorithm. The algorithm was tested in a microrobot environment, where the pipette tip was tracked at sub‐Rayleigh distances to the target. Based on the tracking results, a machine vision module controlled the manipulation of microscopic objects, e.g. latex beads or diamond mono‐crystals. In the theoretical part of this paper we prove that knowledge of the form ‘the pipette has moved between two consecutive frames of the movie’ must result in a twofold increase in resolution. We used the normal flow of an image sequence to decode positional measures from motion evidence. In practice, super‐resolution factors between 3 and 5 were obtained. The additional gain originates from the geometric constraints that were imposed upon the stereo reconstruction of the pipette axis.
Iso‐butanol saturated water: a simple procedure for increasing staining intensity of resin sections for light and electron microscopy
Authors: Roberts I. M.
Published: March 2003

The addition of the alcohol iso‐butanol (2‐methylpropan‐1‐ol) to water was found to improve the post‐staining procedures for semi‐thin and ultrathin resin sections, for both light and electron microscopy. Stain penetration was enhanced with samples embedded in both acrylic and epoxy resins and provided structural information not previously seen. These improvements were found with general (non‐specific) stains and a fluorescence stain for light microscopy, as well as for a range of heavy metal stains for electron microscopy. The use of this water/solvent medium also gave improved results when used in a variety of immunogold labelling procedures, resulting in a greater specific label density without affecting background gold levels. The use of this solvent/water medium may have wider applications for other types of staining.
In situ high temperature microscopy study of the surface oxidation and phase transformations in titanium alloys
Authors: Malinov S. , Sha W. , Voon C. S.
Published: March 2003

Two popular commercial titanium alloys, Ti‐6Al‐4V and Ti‐6Al‐2Sn‐4Zr‐2Mo‐0.08Si, were used for in situ high temperature microscopy study. The experiments were performed on an optical microscope equipped with high temperature stage using both normal and florescence lights. Two kinds of experiments were performed, at continuous heating/cooling with different rates and in isothermal conditions at different temperatures. The changes taking place on the sample surface during the experiments were monitored. The morphology of the α⇒β⇒α phase transformation was recorded at different heat treatment conditions using the effect of thermal etching. An effect of sample surface oxidation and deoxidation was observed during continuous heating. The appearance and disappearance of ordered titanium oxides Ti3O and Ti2O are discussed based on the phase equilibrium diagram. The kinetics of the surface oxidation was monitored in both isothermal and continuous cooling conditions.
Determination of the water droplet size distribution of fat spreads using confocal scanning laser microscopy
Authors: Van Dalen G.
Published: March 2003

Knowledge of the water droplet size distribution of fat spreads is necessary for the development and production of high quality microbiological safe products. Fat spreads are water‐in‐oil emulsions. The water droplet size distribution can be determined by confocal scanning laser microscopy (CSLM) after staining the fat with Nile Red. The profiles of the non‐fluorescent water droplets in the 2D images are identified and measured using image analysis. The ‘true’ water droplet size distribution is calculated from the distribution of the measured profile diameters using a Wicksell transformation of log‐normal distributions. The influence of the fluorescent staining and CSLM parameters on the information were studied. The CSLM method was tested on fat spreads with a fat content ranging from 40% to 80%. The results were compared with those obtained by nuclear magnetic resonance spectroscopy (NMR). The distribution parameters [volume weighed geometric mean diameter (D̄3,3) and the standard deviation (σ) of the logarithm of the droplet diameter] calculated for 80% fat spreads are in good agreement with those obtained by NMR (within ± 7% relative). Small differences were found for 65% fat spreads and large differences were identified for 40% fat spreads. The precision for the determination of the D̄3,3 value by CSLM is worse than that of NMR, even when three images were used to calculate this parameter [3–11% and 1–6% relative standard deviation (RSD), respectively]. The precision for the determination of exp(σ) by CSLM is comparable or better than that of NMR (1–5% and 3–6% RSD, respectively). CSLM proved to be a reliable method for the determination of the water droplet size distribution of margarines (80% fat). The advantage of CSLM compared to NMR is that visual information is given about the water droplet size distribution in the sample.
Precise 3D image alignment in micro‐axial tomography
Authors: Matula P. , Kozubek M. , Staier F. , Hausmann M.
Published: March 2003

Micro (µ‐) axial tomography is a challenging technique in microscopy which improves quantitative imaging especially in cytogenetic applications by means of defined sample rotation under the microscope objective. The advantage of µ‐axial tomography is an effective improvement of the precision of distance measurements between point‐like objects. Under certain circumstances, the effective (3D) resolution can be improved by optimized acquisition depending on subsequent, multi‐perspective image recording of the same objects followed by reconstruction methods. This requires, however, a very precise alignment of the tilted views. We present a novel feature‐based image alignment method with a precision better than the full width at half maximum of the point spread function. The features are the positions (centres of gravity) of all fluorescent objects observed in the images (e.g. cell nuclei, fluorescent signals inside cell nuclei, fluorescent beads, etc.). Thus, real alignment precision depends on the localization precision of these objects. The method automatically determines the corresponding objects in subsequently tilted perspectives using a weighted bipartite graph. The optimum transformation function is computed in a least squares manner based on the coordinates of the centres of gravity of the matched objects. The theoretically feasible precision of the method was calculated using computer‐generated data and confirmed by tests on real image series obtained from data sets of 200 nm fluorescent nano‐particles. The advantages of the proposed algorithm are its speed and accuracy, which means that if enough objects are included, the real alignment precision is better than the axial localization precision of a single object. The alignment precision can be assessed directly from the algorithm's output. Thus, the method can be applied not only for image alignment and object matching in tilted view series in order to reconstruct (3D) images, but also to validate the experimental performance (e.g. mechanical precision of the tilting). In practice, the key application of the method is an improvement of the effective spatial (3D) resolution, because the well‐known spatial anisotropy in light microscopy can be overcome. This allows more precise distance measurements between point‐like objects.
Effects of the Two Somatostatin Variants Somatostatin‐14 and [Pro2, Met13]Somatostatin‐14 on Receptor Binding, Adenylyl Cyclase Activity and Growth Hormone Release from the Frog Pituitary
Authors: Jeandel  , Okuno  , Kobayashi  , Kikuyama  , Tostivint  , Lihrmann  , Chartrel  , Conlon  , Fournier  , Tonon  , Vaudry
Published: March 2003

Two isoforms of somatostatin from frog brain have been recently characterized, namely somatostatin‐14 (SS1) and [Pro2, Met13]somatostatin‐14 (SS2). The genes encoding for the precursors of these two somatostatin variants are expressed in hypothalamic nuclei involved in the control of the frog pituitary. The aim of the present study was to investigate the effect of SS1 and SS2 on adenohypophysial cells. Autoradiographic studies using [125I‐Tyr°,
d‐Trp8] SS1 as a radioligand revealed that somatostatin binding sites are evenly distributed in the frog pars distalis. The SS2 variant was significantly (P<0.01) more potent than SS1 in competing with the radioligand (IC50=1.2±0.2 and 5.6±0.6 nM, respectively). Both SS1 and SS2 induced a modest but significant reduction in cAMP formation in dispersed distal lobe cells but did not affect spontaneous growth hormone (GH) release. Synthetic human GRF (hGRF) induced a significant increase in cAMP accumulation and GH release in this system. Both SS1 and SS2 inhibited the stimulatory effects of hGRF on cAMP formation and GH secretion. These data show that the SS1 and SS2 variants can regulate adenohypophysial functions. The fact that GH cells are exclusively located in the dorsal area of the frog adenohypophysis, while somatostatin receptors are present throughout the pars distalis, indicates that the two somatostatin isoforms may control the secretion of pituitary hormones additional to GH in amphibians.
Effect of NMDA Receptor Antagonist MK‐801 on Light‐Induced Fos Expression in the Suprachiasmatic Nuclei and on Melatonin Production in the Syrian Hamster
Authors: Vuillez  , Jacob  , Teclemariam‐Mesbah  , Van Rossum  , Vivien‐Roels  , Pévet
Published: March 2003

In mammals, circadian rhythms generated by the suprachiasmatic nuclei (SCN) are daily synchronized by a light‐dark cycle. Photic information is transmitted to the SCN mainly through the direct retinohypothalamic tract, the neurotransmitters involved being excitatory amino acids. It is also commonly accepted that photoperiodic information coming from the retina via the SCN is transduced by the pineal into a nocturnal signal, i.e. melatonin production. Light exposure at night induces (1) an inhibition of melatonin synthesis and (2) an expression of c‐fos in numerous cells of SCN. To determine the role of the NMDA receptor in these effects, we treated Syrian hamsters with ip injections of MK‐801, a noncompetitive NMDA receptor antagonist. Several subpopulations of light‐sensitive cells in the SCN are affected by MK‐801. According to previous studies, MK‐801 inhibits light‐induced Fos immunoreactivity mainly in the most ventral part of the SCN. However, we observed that numerous other cells are still activated by light. When light is applied in the middle of the night, MK‐801 pretreatment does not reduce Fos‐ir in the dorsal SCN. At the beginning of the night, labeled cells in this part of the nucleus appear even more numerous after MK‐801. We also found that MK‐801 fails to reduce the light‐induced inhibition of melatonin synthesis. Moreover, in control animals, which received no light stimulation, ip injection of MK‐801 induces by itself a dose‐dependent inhibition of melatonin production.