bluuebunny/crossref_metadata_2025_split huggingface dataset:
Airway hyperresponsiveness in a large group of subjects with α1‐antitrypsin deficiency: a cross‐sectional controlled study
Authors: Malerba M. , Radaeli A. , Ceriani L. , Tantucci C. , Grassi V. 
Published: March 2003

Abstract.  Malerba M, Radaeli A, Ceriani L, Tantucci C, Grassi V (University of Brescia, Brescia, Italy). Airway hyperresponsiveness in a large group of subjects with α1‐antitrypsin deficiency: a cross‐sectional controlled study. J Intern Med 2003; 253: 351–358.Background.  It has been suggested that subjects with α1‐antitrypsin (AAT) deficiency, lacking a major antiprotease defence against airway inflammation, might be more susceptible of development of airway hyperresponsiveness (AHR). Moreover, lower AAT blood levels might also be able to influence the severity of AHR.Objectives.  This study was aimed to investigate the prevalence of AHR in a large group of subjects with AAT deficiency included in the Italian Registry and to evaluate the relationship between AAT blood levels and the severity of AHR in this population.Design.  Cross‐sectional controlled study.Setting.  Regional Reference Centre for AAT deficiency in Brescia, Italy.Methods.  A total of 114 subjects with AAT deficiency underwent pulmonary function tests. Eighty‐six were eligible to perform a bronchial provocation test with methacholine (MCh) (baseline FEV1 > 60% predicted) to assess the provocative dose producing a 20% fall of FEV1 (PD20FEV1). Similar measurements were performed in a control group of 27 age‐matched normal subjects.Results.  The prevalence of AHR (PD20FEV1 < 2000 μg MCh) was not different between AAT deficiency subjects and controls (16.3% and 11.1%, respectively; P = 0.66), and also amongst two subgroups of AAT deficiency subjects divided according to different protease inhibitor (Pi) phenotypes (PiMZ‐MS, PiSZ‐ZZ). Hyperresponsive subjects with AAT deficiency, however, showed a positive correlation between AAT blood levels and PD20FEV1 values (r = 0.71, P < 0.01).Conclusions.  These findings indicate that AAT deficiency subjects did not exhibit a greater prevalence of airway hyperresponsiveness as compared with control subjects, but suggest that, in the subset of AAT deficiency subjects hyperresponsive to MCh, lower levels of AAT are associated with a higher severity of AHR.
Association between vitamin D receptor gene polymorphisms and tubular citrate handling in calcium nephrolithiasis
Authors: Mossetti G. , Vuotto P. , Rendina D. , Numis F. G. , Viceconti R. , Giordano F. , Cioffi M. , Scopacasa F. , Nunziata V. 
Published: March 2003

Abstract. Mossetti G, Vuotto P, Rendina D, Numis FG, Viceconti R, Giordano F, Cioffi M, Scopacasa F, Nunziata V (Federico II University Medical School, Naples, Italy). Association between vitamin D receptor gene polymorphisms and tubular citrate handling in calcium nephrolithiasis. J Intern Med 2003; 253: 194–200.Objectives.  Hypocitraturia is a risk factor for calcium nephrolithiasis. 1,25(OH)2D3 influences renal citrate handling and enhances citraturia. The aim of this study was to evaluate the relationship between vitamin D receptor (VDR) allelic variant and urinary citrate excretion in recurrent stone formers (SF) patients.Design.  Case–control study.Subjects.  A total of 220 recurrent calcium oxalate SF patients and 114 healthy control (C) subjects were enrolled for this study. Subjects with urinary tract infections, hyperparathyroidism, cystinuria >70 μmol/24 h, gouty diathesis, renal tubular acidosis, renal failure, chronic diarrhoeal states, intake of thiazide diuretics, angiotensin‐converting enzyme (ACE)‐inhibitors, glucocorticoids or oestrogens were excluded.A standard constant diet was given for 7 days. The 24‐h urinary citrate excretion and the active tubular reabsorption of filtered citrate (Rcit) were evaluated. Hypocitraturia was defined as a urinary citrate excretion lower than 1.7 mmol day−1. Stone formers patients and C were genotyped for BsmI and TaqI VDR alleles. Contingency table chi‐square tests were used to compare genotype frequencies in hypocitraturic SF patients, normocitraturic SF and C.Results.  The prevalence of hypocitraturia in SF patients was 32.7% (72 of 200). Hypocitraturia in these patients resulted from excessive Rcit of a normal load of citrate. We found a different distribution (P < 0.05) of BsmI and TaqI VDR genotypes in hypocitraturic SF patients compared with normocitraturic SF and C. In particular, the prevalence of bb and TT VDR genotypes in hypocitraturic SF was significantly higher than in normocitraturic SF and C.Conclusions.  These results point to a genetic association between BsmI and TaqI VDR polymorphisms and idiopathic hypocitraturia in calcium‐oxalate recurrent SF patients.
Changing sex ratio in acute coronary heart disease: data from Swedish national registers 1984–99
Authors: Rosengren A. , Thelle D. S. , Köster M. , Rosén M. 
Published: March 2003

Abstract.  Rosengren A, Thelle DS, Köster M, Rosén M (Sahlgrenska University Hospital/Östra, Göteborg; and National Board of Health and Welfare, Stockholm; Sweden). Changing sex ratio in acute coronary heart disease: data from Swedish national registers 1984–99. J Intern Med 2003; 253: 301–310.Objectives.  To examine trends in sex ratios for different manifestations of coronary disease.Design.  National Swedish registers on hospital discharges and cause‐specific deaths were used to calculate age‐ and sex‐specific trends and sex ratios for coronary admissions and deaths.Setting.  Nineteen Swedish counties, average population 4.8–5.1 million in the investigated age groups.Subjects.  All patients aged 25–84 years with first hospital admissions or deaths as a result of coronary heart disease in 1984–99, in total 432 871 cases.Main outcome measures.  Ratio men/women and rates (per 100 000) of acute myocardial infarction (AMI), acute admissions for angina and total of all acute admissions for any coronary disease.Results.  Below age of 65 years AMI incidence decreased more for men than for women and rates of acute admissions for angina increased more in women than in men. In men and women above 65 years trends were almost identical. In 1984–87 the ratio men/women with respect to myocardial infarction was 5.6 at age 25–44 years, but decreased to 3.7 in 1996–99. Corresponding sex ratios for angina decreased from 3.2 to 1.8 and for total coronary heart disease from 4.7 to 2.8. Amongst men and women aged 45–54 years, the sex ratio with respect to myocardial infarction decreased from 5.6 to 4.1, for angina from 2.4 to 1.7 and for total acute coronary disease from 4.2 to 2.7. Ratios men/women decreased less at higher ages and remained unchanged throughout the period in the oldest age group.Conclusions.  Overall, we found decreasing sex ratios at ages below 65, but above age 65 years trends in men and women were similar. These developments could be due to changing criteria for admission and diagnosis, but true differences in the clinical manifestation of coronary disease, possibly in response to secular trends in risk factor levels, cannot be excluded.
A silver impregnation utilizing only reagent‐grade chemicals for visualization of peripheral axons and fibroblasts
Authors: Novotny  , Mertens  
Published: March 2003

A silver impregnation procedure is described that enables the representation of numerous tissue components. It especially visualizes nerves and fibroblasts, which may be clearly distinguished from other tissue elements. Since it can be performed on thick sections, three‐dimensional analysis of nerve terminations and fibroblasts in the tissues can be performed. The results are illustrated with the innervation of the rat snout and human labial sweat glands for nerves, and with bovine and pathological human material for fibroblasts. Axons are visualized as thin, sinuous black structures, sometimes, as in the case of autonomic efferents, with varicosities. Fibroblasts are revealed in their total extent by the darker staining of their nuclei and cytoplasm compared with that of the surrounding collagen. Cell processes can thus be followed for long distances, and may be seen to approach other cells.Previously published methods for the visualization of nerves and fibroblasts depended upon the use of commercial formalin, which is subject to the manufacturers' modifications. The method presented here uses exclusively analytical‐grade reagents and distilled water. It is also less dependent than other methods on the fixation protocol.
Atomic force microscopy: influence of air drying and fixation on the morphology and viscoelasticity of cultured cells
Authors: Weyn  , Kalle  , Kumar‐Singh  , Van Marck  , Tanke  , Jacob  
Published: March 2003

The influence of fixation, air‐drying and liquid‐imaging on the morphology as well as on the viscoelasticity of malignant mesothelioma cells was studied by atomic force microscopy. In this study, dehydrated cells were more easily scanned and offered faster data recording than hydrated cells. However, the influence of fixation strength was more noticeable. Strong fixation induced flattening of the cytoplasm and loss of nuclear structure, resulting in a clearly visible cytoskeleton which could be easily seen as fibres orientated in the direction of the cell growth. By contrast, the morphology of hydrated cells was influenced to a lesser degree on fixation and showed an overall ‘rounding’ of the surface with vague, ill‐defined structures. Nuclear areas of these samples were difficult to image.Viscoelasticity measurements also exhibited large differences. Dehydrated cells were much harder and showed a uniform indentation profile over the whole cell that was independent of fixation. Indentation on hydrated cells was large and depended on the height of the measuring spot, the submembranous structure and, to a lesser extent, on fixation. To calculate an overall ‘cellular’ viscoelasticity, different methods were tested on these samples. Indentations of multiple, randomly chosen points, covering the whole cell, were measured and averaged to yield a mean indentation score. We avoided the thin and shadowed areas since it was shown that these regions were less suited for measuring. Using this design, large viscoelasticity differences were found, on which the influence of the external parameters could be shown. In another set‐up, layered imaging was tried. However, long data acquisition times caused cellular activation and rearrangement, making this scanning mode unsatisfactory.
Registration of serial sections of mouse liver cell nuclei
Authors: Baheerathan S. , Albregtsen F. , Danielsen H.E. 
Published: March 2003

Image registration of biological tissue is essential for 3D reconstruction, which is important for visualizing and quantifying the 3D relationships between internal structures of an object. The biological role of DNA organization, which is an extremely complex 3D architecture within the cell nucleus, has come into focus since it has become clear that the chromatin structure in itself functions as a regulator of DNA. Thus, 3D reconstruction of cell nuclei based on consecutive series of high‐resolution ultrathin slices may provide new information about the chromatin structure and its organizational changes during carcinogenesis.This work focuses mainly on the problem of registering successive serial transmission electron micrographs of ultrathin sections of mouse liver cell nuclei to analyse the 3D chromatin structure. A five‐step semiautomatic interactive registration method is proposed. The first two steps of the procedure correct the rotation and translation components by using the phase correlation. The third, fourth and fifth steps correct the global distortion, employing a point mapping method based on different ways of selecting the control points. In step three, the control points were automatically computed by phase correlating corresponding subimages of the reference and sensed image. A semiautomatic method is used in the fourth step to select the control points, i.e. an automated method for computing the centre of mass of manually identified anatomical structures in neighbouring slices. For the sections which could not be properly corrected by the four steps, a final step is introduced, where control points are manually selected in the reference and sensed images. An algorithm is proposed to examine the spatial distribution of selected control points.Four sets of serial sections of mouse liver cell nuclei, each with approximately 100 sections, are registered by the proposed method and also registered manually for the comparison of registration accuracy. Artificial X–Z and Z–Y sections of registered series were visually compared for the smoothness of the nuclear membrane. To quantify the registration accuracy and the extent of registration, the correlation coefficient (C) and the overlap index (C0) were computed over the registered structure of interest. In addition to the visual comparison and the comparison of C and C0, the registered serial sets were compared by 3D GLCM‐based texture features in the Z direction. The results demonstrate that the proposed semiautomatic registration technique achieved accurate results comparable to the manual registration. The proposed registration method relies only on the operator for rough pinpointing of cellular structures. Therefore, it should provide better reproducibility, and allow the user to operate the system faster and in a more relaxed manner than in a manual registration.
Radiation damage of water in environmental scanning electron microscopy
Authors: Royall C. P. , Thiel B. L. , Donald A. M. 
Published: March 2003

Specimen damage from the electron beam poses a considerable problem with electron microscopy. This damage is particularly acute in environmental scanning electron microscopy (ESEM) for two reasons. Firstly, owing to its ability to stabilise insulating and hydrated specimens, ESEM lends itself to polymeric and biological materials that are typically highly beam‐sensitive. Secondly, water acts as a source of small, highly mobile free radicals, which accelerate specimen degradation.By taking the results of single‐particle simulations of electron–water interactions, we determine the concentration of reactive species in a water specimen under ESEM conditions. We consider 12 species, which are produced in a Gaussian distribution, and annihilate according to a second‐order reaction scheme. Self‐diffusion along the concentration gradient is also modelled.We find that the dominant reactive species is the hydroxyl (.OH) radical. Annihilation of this species is suppressed due to the lower concentration of reactants. The relatively stable hydrogen peroxide is also found at large concentrations. By comparing two beam energies, 5 and 25 keV, we find a drastic increase in the quantities of reactive species produced with beam energy. The longer range of 25 keV primary electrons spreads reactive species over a wider region, which then decay far more slowly.
Characterization of nitride thin films by electron backscatter diffraction
Authors: Trager‐Cowan C. , Sweeney F. , Hastie J. , Manson‐Smith S. K. , Cowan D. A. , McColl D. , Mohammed A. , O’Donnell K. P. , Zubia D. , Hersee S. D. , Foxon C. T. , Harrison I. , Novikov S. V. 
Published: March 2003

SummaryThin films incorporating GaN, InGaN and AlGaN are presently arousing considerable excitement because of their suitability for UV and visible light‐emitting diodes and laser diodes. However, because of the lattice mismatch between presently used substrates and epitaxial nitride thin films, the films are of variable quality.In this paper we describe our preliminary studies of nitride thin films using electron backscattered diffraction (EBSD). We show that the EBSD technique may be used to reveal the relative orientation of an epitaxial thin film with respect to its substrate (a 90° rotation between a GaN epitaxial thin film and its sapphire substrate is observed) and to determine its tilt (a GaN thin film was found to be tilted by 13 ± 1° towards [1010]GaN), where the tilt is due to the inclination of the sapphire substrate (cut off‐axis by 10° from (0001)sapphire towards (1010)sapphire). We compare EBSD patterns obtained from As‐doped GaN films grown by plasma‐assisted molecular beam epitaxy (PA‐MBE) with low and high As4 flux, respectively. Higher As4 flux results in sharper, better defined patterns, this observation is consistent with the improved surface morphology observed in AFM studies. Finally, we show that more detail can be discerned in EBSD patterns from GaN thin films when samples are cooled.
Use of emission electron microscope for potential mapping in semiconductor microelectronics
Authors: Nepijko S. A. , Sedov N. N. , Schönhense G. , Escher M. 
Published: March 2003

SummaryAn emission electron microscope was used for visualization and measurement of the distribution of electric fields and potentials on the surface under study. The contrast of microfields is caused by the fact that slow‐moving electrons emitted from the object surface are deflected by these fields. The measurements were performed on a p‐n junction to which a voltage was applied. It is shown that the type of contrast from the p‐n junction can be reversed depending on the position of the contrast aperture restricting the electron beam. The same result was obtained by means of a computer simulation.
Video‐rate confocal endoscopy
Authors: Watson T. F. , Neil M. A. A. , Juškaitis R. , Cook R. J. , Wilson T. 
Published: March 2003

SummaryRigid endoscopes provide high quality optical images of reasonably accessible regions of the inner body, especially regions such as the aero‐digestive and genital tracts. In order to enhance the versatility of these instruments we describe a development that permits confocal endoscopic images to be obtained − along with traditional endoscopic images – in real‐time, from within the living patient. The system is based around a host lenslet‐array tandem scanning microscope, which is capable of producing images viewed directly by eye. These types of confocal microscope are configured for fluorescence imaging together with laser illumination. Hard and soft tissues in the mouth were imaged using this combined system.
Stereological estimation of tubular length
Authors: Gundersen H. J. G. 
Published: March 2003

SummaryVery efficient and unbiased principles exist for estimating the total three‐dimensional (3D), two‐dimensional and zero‐dimensional amounts of arbitrary structure in 3D space. The total one‐dimensional length of real structure, in the ordinary sense, is an abstraction from the point of view of integral geometry. All stereological estimators of ‘tubular length’ are thus approximations. In addition, they are riddled by biases due to several types of artificial edges and other practical problems. This paper discusses several of these and proposes practical solutions of minimal biases.
Precision of circular systematic sampling
Authors: Cruz‐Orive L. M. , Gual‐Arnau X. 
Published: March 2003

SummaryIn design stereology, many estimators require isotropic orientation of a test probe relative to the object in order to attain unbiasedness. In such cases, systematic sampling of orientations becomes imperative on grounds of efficiency and practical applicability. For instance, the planar nucleator and the vertical rotator imply systematic sampling on the circle, whereas the Buffon–Steinhaus method to estimate curve length in the plane, or the vertical designs to estimate surface area and curve length, imply systematic sampling on the semicircle. This leads to the need for predicting the precision of systematic sampling on the circle and the semicircle from a single sample. There are two main prediction approaches, namely the classical one of G. Matheron for non‐necessarily periodic measurement functions, and a recent approach based on a global symmetric model of the covariogram, more specific for periodic measurement functions. The latter approach seems at least as satisfactory as the former for small sample sizes, and it is developed here incorporating local errors. Detailed examples illustrating common stereological tools are included.
Software techniques for EELS to realize about 0.3 eV energy resolution using 300 kV FEG‐TEM
Authors: Kimoto K. , Matsui Y. 
Published: March 2003

SummaryIn this short communication we describe some software techniques for electron energy‐loss spectrum measurement. We prepared DigitalMicrograph (Gatan) scripts for multiple spectrum acquisitions, quasi‐simultaneous acquisition of low‐loss and core‐loss spectra, energy drift correction, and other operations. Narrow zero‐loss spread of 0.27 eV is demonstrated using a 300 kV field‐emission transmission electron microscope (TEM) (Hitachi, HF‐3000) and a post‐column energy filter (Gatan, GIF2002). The core‐loss spectrum is acquired with an energy resolution of 0.36 eV with high reproducibility. The present software techniques effectively achieve the intrinsic energy resolution of electron sources. Sample scripts are provided in the Appendix.
A method of normalizing cathodoluminescence images of electron transparent foils for thickness contrast applied to InGaN quantum wells
Authors: Boyall N. M. , Durose K. , Watson I. M. 
Published: March 2003

SummaryThe uniformity of panchromatic cathodoluminescence (CL) from In0.09Ga0.91N/GaN quantum wells at 100 K was investigated using a combined transmission electron microscope–cathodoluminescence instrument. A technique for correcting CL images of electron‐transparent wedge specimens for thickness contrast artefacts is presented. The foil thickness was estimated using the dynamical formulation of the relationship between the thickness and the (experimentally observed) transmitted electron intensity. For a given thickness the CL intensity was calculated using the Everhart–Hoff depth‐dose function and also taking into account surface recombination losses. Experimental CL images were normalized by dividing by the calculated CL value at each point. The procedure was successful in calculating the underlying materials contrast in CL images of thin specimens of InGaN single quantum wells. Non‐uniformities in the CL emission on the scale of ∼0.7 µm were observed.