bluuebunny/crossref_metadata_2025_split huggingface dataset:
A single gold particle as a probe for apertureless scanning near‐field optical microscopy
Authors: Kalkbrenner T. , Ramstein M. , Mlynek J. , Sandoghdar V. 
Published: March 2003

We report on the fabrication, characterization and application of a probe consisting of a single gold nanoparticle for apertureless scanning near‐field optical microscopy. Particles with diameters of 100 nm have been successfully and reproducibly mounted at the end of sharp glass fibre tips. We present the first optical images taken with such a probe. We have also recorded plasmon resonances of gold particles and discuss schemes for exploiting the wavelength dependence of their scattering cross‐section for a novel form of apertureless scanning near‐field optical microscopy.
Characterizing the deformed state in Al‐0.1 Mg alloy using high‐resolution electron backscattered diffraction
Authors: Hurley P. J. , Humphreys F. J. 
Published: March 2003

SummaryThe application of high resolution electron backscatter diffraction (EBSD) in a field emission gun scanning electron microscope to the characterization of a deformed aluminium alloy is discussed and the results are compared with those obtained by transmission electron microscopy. It is shown that the adequate spatial resolution, accompanied by the improvement in angular resolution to ~0.5° that can be achieved by data processing, together with the extensive quantitative data obtainable, make EBSD a suitable method for characterizing the cell or subgrain structures in deformed aluminium. The various methods of analysing EBSD data to obtain subgrain sizes are discussed and it is concluded that absolute subgrain reconstruction is the most accurate.
Light microscopy evaluation of polyurethane vascular grafts porosity by Sudan Black B staining
Authors: Soldani G. , Losi P. , Milioni C. , Raffi A. 
Published: March 2003

SummaryIn small‐diameter vascular grafts, the porosity of the internal surface plays an important role because it affects initial thrombus deposition and therefore the graft’s patency. As well as many other studies reported in the literature we have carried out a study of the relationship between porosity and the manufacturing parameters of polyurethane (PU) grafts by standard scanning electron microscopy (SEM) analysis. However, SEM was not completely satisfactory for evaluating the ‘sponge‐like’ uptake of water by the graft due to the unavoidable water loss and metal coating during preparation. In fact this preparation produces artefacts of the three‐dimensional porous structure. To avoid this problem we investigated the possibility of observing the graft’s internal surface through a stereomicroscope after it had absorbed water. We looked into a simple staining procedure which preferentially colours the PU graft fibres with respect to the void areas. After testing different kinds of stains, we eventually found that Sudan Black B, which usually stains for all kinds of lipid, turned out to be an excellent stain for the water‐loaded PU grafts when diluted with ethanol. This staining procedure, coupled with a computerized image analysis system, allowed us to evaluate the degree of void and average void size of the graft internal surface and to correlate these data with graft density and manufacturing parameters.
Fibre‐optic two‐photon scanning fluorescence microscopy
Authors: Bird D. , Gu M. 
Published: March 2003

SummaryTwo geometries of a novel two‐photon fluorescence microscope incorporating single‐mode fibre optics for the delivery of ultrashort‐pulsed illumination to a remote sample are characterized. First, a 785 nm single‐mode optical fibre is implemented in a scanning microscope, which demonstrates that an improvement in axial resolution is achieved due to the non‐linear response of the fibre to intense ultrashort‐pulsed light. Second, a 785 nm single‐mode optical fibre coupler is adapted, in which case spectral broadening and blue shifting of the ultrashort‐pulsed laser beam caused by the non‐linear response of the fibre to ultrashort‐pulsed illumination are experimentally characterized. An investigation into the impact of temporal broadening of the ultrashort‐pulsed beam on the systems is also considered. The coupling efficiency of both geometries for various illumination wavelengths is also presented. The introduction of the fibre coupler to the system has significant advantages, including an improved optical sectioning effect and a reduction in the number of bulk optical components resulting in a low‐cost, compact instrument. Sets of three‐dimensional images of fluorescent polymer microspheres and biological material confirm these features.
Automatic quantification of viability in epithelial cell cultures by texture analysis
Authors: Malpica N. , Santos A. , Tejedor A. , Torres A. , Castilla M. , García‐Barreno P. , Desco M. 
Published: March 2003

SummaryQuantification of live cells in phase contrast microscopy images allows in vivo assessment of the viability of cultured cells. An automatic screening procedure seems advisable because of the large number of cells that must be counted to achieve reasonable accuracy. This paper presents a method that quantifies necrosis in cell cultures by texture analysis of microscope images.The image is divided into regions of equal size that are classified by means of a segmentation algorithm based on texture analysis into three categories: live cells, necrotic cells and background. The classification uses three discriminant functions, built from parameters derived from the histogram and the co‐occurrence matrix and calculated by performing an initial stepwise discriminant analysis on 21 sample images from a training set.The areas occupied by live and necrotic cells and number of live cells have been obtained for primary cellular cultures in intervals of 48 h during 2 weeks. The results have been compared with those obtained by an experienced observer, showing a very good correlation (Pearson's coefficient 0.95, kappa 0.87, N= 1600).A method has been developed that provides an accuracy similar to that provided by an expert, while allowing a much higher number of fields to be counted.
Vasopressin (V1a) Receptor Binding, mRNA Expression and Transcriptional Regulation by Androgen in the Syrian Hamster Brain
Authors: Young L. J. , Wang Z. , Cooper T. T. , Albers H. Elliott 
Published: March 2003

AbstractArginine vasopressin plays an important role in the regulation of social behaviours in rodents. In the Syrian hamster, vasopressin injected directly into the brain stimulates scent marking and aggressive behaviour in a steroid dependent manner and is therefore a useful model for investigating steroid‐peptide–behaviour interactions. In this study, we used in situ hybridization and radioligand binding assays on adjacent sections of hamster brains to compare the relative distribution of vasopressin (V1a) receptor mRNA and V1a receptor binding. V1a receptor mRNA and binding are abundant in the lateral septum, bed nucleus of the stria terminalis, medial preoptic nucleus, anterodorsal thalamus and suprachiasmatic nucleus. Moderate receptor binding and low levels of receptor mRNA are present in the central nucleus of the amygdala and a lateral zone from the medial preoptic area through the anterior hypothalamus. V1a receptor mRNA is anatomically more restricted in several areas compared to the ligand binding pattern, which is consistent with significant spread of receptor protein along neuronal processes. Comparison of V1a receptor ligand binding and mRNA in intact, castrated, and castrated‐testosterone treated animals reveals that V1a receptors in the medial preoptic nucleus are regulated by androgen, most likely by an upregulation of V1a receptor gene expression in a cluster of neurones concentrated in the ventromedial part of this nucleus. This study confirms the presence of the V1a subtype of vasopressin receptors in behaviourally important regions of the hamster brain and suggests that transcriptional regulation by gonadal steroids may play a role in modulating behavioural sensitivity to vasopressin.
Effect of Superior Cervical Ganglionectomy on 24‐h Variations in Hormone Secretion from the Anterior Hypophysis and in Hypothalamic Monoamine Turnover During the Preclinical Phase of Freund's Adjuvant Arthritis in Rats
Authors: Castrillón P. O. , Cardinali D. P. , Pazo D. , Cutrera R. A. , Esquifino A. I. 
Published: March 2003

AbstractThe effect of superior cervical ganglionectomy (SCGx) on 24‐h rhythms of circulating adrenocorticotropic hormone (ACTH), growth hormone (GH), prolactin and luteinizing hormone (LH) and of hypothalamic noradrenaline content and dopamine and serotonin turnover, was assessed in rats 3 days after administering Freund's complete adjuvant. In sham‐operated rats, Freund's adjuvant injection increased serum ACTH without affecting its diurnal rhythmicity. SCGx, performed 10 days earlier, suppressed 24‐h rhythmicity and augmented mean values of circulating ACTH. A depressive effect of immunization on GH release was found in both sham‐operated and SCGx rats. GH concentrations did not exhibit diurnal rhythmicity and decreased after immunization. Time‐of‐day‐related changes in serum prolactin were significant for all examined groups, except for SCGx‐immunized rats. Freund's adjuvant administration augmented prolactin secretion. Daily changes in serum LH concentration and a decrease after immunization were found in both sham‐operated and SCGx rats. SCGx: (i) counteracted inhibition of daily variations of noradrenaline content in medial hypothalamus of Freund's adjuvant‐injected rats; (ii) decreased anterior hypothalamic dopamine turnover and augmented it in the medial hypothalamus; (iii) lowered amplitude of serotonin turnover rhythm in medial hypothalamus. The data indicate that several early changes in levels and 24‐h rhythms of circulating ACTH and prolactin, and in hypothalamic noradrenaline content and dopamine and serotonin turnover, were modified by a previous SCGx in Freund's adjuvant‐injected rats.
Agonist‐Mediated Endocytosis of Rat Somatostatin Receptor Subtype 3 Involves β‐Arrestin and Clathrin Coated Vesicles
Authors: Kreuzer O. J. , Krisch B. , Déry O. , Bunnett N. W. , Meyerhof W. 
Published: March 2003

AbstractAgonist‐induced endocytosis of somatostatin receptors determines subsequent cellular responsiveness to peptide agonist and influences somatostatin receptor scintigraphy, a technique to image various tumours. We examined the internalization of sst3HSV, an epitope‐tagged type 3 somatostatin receptor, in transfected rat neuroendocrine insulinoma cells. Stimulation of these cells with somatostatin induced trafficking of coexpressed enhanced green fluorescence protein/β‐arrestin1 fusion protein and sst3HSV to colocalize in the same endocytic vesicles. Coexpression of a dominant negative mutant of the arrestin fusion protein with the receptor blocked the internalization of sst3HSV. Stimulation with somatostatin also induced the transient translocation of α‐adaptin, a component of the adaptor protein complex 2, to the plasma membrane. α‐adaptin and clathrin colocalized with the receptor. By electron microscopy, we observed internalized sst3 in clathrin coated pits, endosomes and at the limiting membrane of multivesicular bodies, a location typical for receptors being recycled. Concordantly, we observed sst3HSV colocalized with Rab11 in a perinuclear compartment which is likely to correspond to the pericentriolar recycling endosome. Thus, agonist‐induced endocytosis of sst3 depends on its interaction with β‐arrestin, involves the adaptor protein complex 2 and proceeds via clathrin coated vesicles to the recycling compartment.
Analysis of Steroid‐Induced Genes in the Rat Preoptic Area‐Anterior Hypothalamus Using a Differential‐Display Reverse Transcriptase‐Polymerase Chain Reaction
Authors: Park S. , Seong J. Y. , Son G. H. , Kang S. S. , Lee S. , Kim S. R. , Kim K. 
Published: March 2003

AbstractSteroid hormones modulate a variety of physiological functions in the hypothalamus. We attempted to identify steroid‐regulated genes in the rat preoptic area‐anterior hypothalamus by comparing differentially expressed mRNAs. Adult female rats were ovariectomized and, 1 week later, a silastic capsule containing 17β‐oestradiol (180 µg/ml) was subcutaneously implanted. After 2 days, a single injection of progesterone (1 mg) was administered at 10.00 h and rats were killed at 17.00 h on the same day. Differential‐display polymerase chain reaction followed by Northern blot analysis showed that 10 clones were differentially regulated. Using homology search in Genbank, three genes were identified as sodium, potassium‐ATPase β1, protein kinase C‐binding Nell‐homologue protein and evectin‐1. Further characterization of 10 clones showed that the expression patterns were tissue‐specific and differentially regulated during puberty. Among these, mRNAs for protein kinase C‐binding Nell‐homologue protein, evectin‐1 and human CGI‐118 protein‐like gene were induced after vagina opening, and differentially expressed during the oestrous cycle. Taken together, several steroid‐regulated genes identified in the present study may play an important role in regulating hypothalamic functions, including puberty and the oestrous cycle.
Role of Extra‐Ovarian Oestrogens in the Regulation of Gonadotropin Releasing Hormone mRNA Expression in the Rat Brain
Authors: Pelletier G. , Labrie C. , Martel C. , Li S. , Labrie F. 
Published: March 2003

AbstractTo further understand the role of oestrogens in the regulation of gonadotropin releasing hormone (GnRH) mRNA expression in the female rat brain, the effect of EM‐652.HCl, a pure anti‐oestrogen, was studied in intact and ovariectomized rats as well as in rats chronically treated with a GnRH agonist d‐trp6, des‐Gly‐NH210 GnRH ethylamide (GnRH‐A), a treatment which blocks ovarian steroidogenesis. Quantitative in situ hybridization was used to measure GnRH mRNA at the cellular level in the preoptic‐anterior hypothalamic area. It was found that, 49 weeks after ovariectomy (OVX), the number of silver grains per cell corresponding to GnRH mRNA was increased by 34%. Long‐term administration (49 weeks) of EM‐652.HCl to OVX rats resulted in a further increase (11% over the levels measured in OVX rats) in the hybridization signal. By contrast, in intact female rats, treated during 52 weeks with EM‐652.HCl, a 49% increase in the GnRH hybridization signal was detected. In rats treated with GnRH‐A during the same period, a 20% decrease in GnRH mRNA was observed. When EM‐652.HCl was administered concomitantly with GnRH‐A, a further 63% increase over the mRNA levels recorded in GnRH‐A treated rats was found. Thus, long‐term treatment with the anti‐oestrogen EM‐652.HCl can upregulate GnRH mRNA expression in intact female rats, OVX rats and female rats chronically treated with a GnRH‐A. It is suggested that the pure anti‐oestrogen EM‐652.HCl can exert an influence on the oestrogen feedback mechanism involved in the regulation of GnRH neuronal activity by neutralizing the action of locally produced or low circulating levels of oestrogens remaining after OVX or GnRH‐A treatment.
Facilitation of Ca2+ Store‐Dependent Noradrenaline Release After an N‐Methyl‐d‐Aspartate Receptor Antagonist in the Rat Supraoptic Nucleus
Authors: Liu X. , Onaka T. , Yagi K. 
Published: March 2003

AbstractWe examined the role of N‐methyl‐d‐aspartate (NMDA) receptors in the control of noradrenaline release in the supraoptic nucleus (SON) using a microdialysis method in urethane‐anaesthetized rats. Local application of 0.5 mm NMDA into the SON by retrodialysis decreased noradrenaline content in the dialysate from the SON. On the other hand, MK‐801, a channel blocker of NMDA receptors, or D(–)2‐amino‐5‐phosphonopentanoic acid (AP‐5), a competitive NMDA receptor antagonist, increased the basal noradrenaline content. Tetrodotoxin did not completely block the noradrenaline increase after NMDA antagonists. Infusion of Ca2+‐free solution containing Ni2+ and Cd2+, or a mixture of ω‐agatoxin IVA and ω‐conotoxin GVIA, voltage‐sensitive Ca2+ channels blockers, did not block noradrenaline increase after AP‐5, but blocked noradrenaline increase after high K+. Infusion of intracellular Ca2+ blockers, thapsigargin or TMB‐8, impaired noradrenaline increase after AP‐5 but not that after high K+. These data are consistent with the hypothesis that activation of an NMDA receptor inhibits an intracellular Ca2+ store‐dependent noradrenaline release from nerve terminals in the SON.
Differential Expression of Vasopressin, Oxytocin and Corticotrophin‐Releasing Hormone Messenger RNA in the Paraventricular Nucleus of the Prairie Vole Brain Following Stress
Authors: Liu Y. , Curtis J. T. , Fowler C. D. , Spencer C. , Houpt T. , Wang Z. X. 
Published: March 2003

AbstractForced swimming, as an effective stressor, has been found to facilitate the development of pair bonds in male but to interfere with this behaviour in female prairie voles (Microtus ochrogaster). In the present study, we found that forced swimming differentially influenced the expression of messenger RNA for vasopressin, oxytocin and corticotrophin‐releasing hormone (CRH) in the paraventricular nucleus of the hypothalamus (PVN) in the prairie vole brain. Forced swimming did not alter vasopressin mRNA labelling, but did induce a sustained decrease in oxytocin mRNA labelling and a progressive increase in CRH mRNA labelling in the PVN. The elevated CRH mRNA labelling appeared to be due to an increased number of cells synthesizing CRH mRNA and an enhanced ability of individual cells to produce CRH mRNA. Male and female prairie voles did not differ in the vasopressin, oxytocin or CRH mRNA expression either at the basal levels or in response to swimming stress. Together, these data indicate that the hypothalamic response of vasopressin, oxytocin and CRH messenger RNAs to swimming stress is regulated by distinct transcriptional factors. In addition, it seems unlikely that these changes are involved directly in the sex differences in pair bond formation.
Ventral Tegmental Area Infusions of Inhibitors of the Biosynthesis and Metabolism of 3α,5α‐THP Attenuate Lordosis of Hormone‐Primed and Behavioural Oestrous Rats and Hamsters
Authors: Frye C. A. , Vongher J. M. 
Published: March 2003

AbstractThe importance of progesterone biosynthesis and metabolism to 5α‐pregnan‐3α‐ol‐20‐one (3α,5α‐THP), which exerts its effects via GABAA/benzodiazepine receptor complexes (GBRs) rather than intracellular progestin receptors (PRs), was investigated for its effects on sexual receptivity. Epostane, a 3β‐hydroxysteroid dehydrogenase inhibitor, blocks progesterone and 3α,5α‐THP biosynthesis. Finasteride, a 5α‐reductase inhibitor, blocks the metabolism of progesterone to dihydroprogesterone (DHP), which is subsequently metabolized to 3α,5α‐THP. Indomethacin, a 3α‐hydroxysteroid oxidoreductase inhibitor, blocks DHP's metabolism to 3α,5α‐THP, and its oxidation to DHP. Epostane, finasteride, indomethacin or vehicle were infused intracranially in the ventral tegmental area (VTA) of hormone‐primed or naturally receptive rats and hamsters and sexual behaviour was recorded. Epostane, finasteride and indomethacin to the VTA significantly reduced lordosis, compared to vehicle infusions, in hormone‐primed and behavioural oestrous rats and hamsters. Radioimmunoassay revealed that concentrations of midbrain 3α,5α‐THP were reduced following epostane, finasteride or indomethacin infusions that significantly decreased lordosis. Immunocytochemistry for 3α,5α‐THP revealed the number of immunoreactive cells were significantly reduced in the VTA following epostane, finasteride or indomethacin infusion to the VTA, but not other midbrain sites. These data suggest that biosynthesis of progestins, and the metabolism of progesterone to 3α,5α‐THP in the VTA, are important for progestin‐facilitated sexual receptivity of rats and hamsters.
Coregulator Proteins and Corticosteroid Action in the Brain
Authors: Meijer O. C. 
Published: March 2003

AbstractThe corticosteroid hormones cortisol and corticosterone are secreted by the adrenal gland in response to stress. They have profound effects on brain function, which are mediated by the related mineralocorticoid (MR) and glucocorticoid (GR) receptors. The MR and GR are ligand‐activated transcription factors and exert different, sometimes opposing effects on the brain. The balance between these two receptor activities is considered essential for appropriate corticosteroid signalling and health. An exciting recent insight in steroid biology is that the nature and magnitude of steroid receptor‐mediated responses depend not only on ligand and receptor availability, but also in a critical manner on the presence of downstream mediator proteins (coregulators), such as the steroid receptor coactivators and nuclear receptor corepressors. Members of the coregulator families differ in their specific interactions with steroid receptors, as well as in their distribution throughout the brain and pituitary. The activity of these proteins can be regulated both at the expression level, and by post‐translational modifications. These characteristics make coregulator proteins of outstanding interest as determinants of receptor, cell and state‐dependent effects of MR and GR signalling (and steroid receptor signalling in general) in the brain.
Genetic Selection For Coping Style Predicts Stressor Susceptibility
Authors: Veenema A. H. , Meijer O. C. , De Kloet E. R. , Koolhaas J. M. 
Published: March 2003

AbstractGenetically selected aggressive (SAL) and nonaggressive (LAL) male wild house‐mice which show distinctly different coping styles, also display a differential regulation of the hypothalamic‐pituitary‐adrenal axis after exposure to an acute stressor. To test the hypothesis that coping style predicts stressor susceptibility, the present study examined line differences in response to a chronic stressor. Chronic psychosocial stress was evoked using two paradigms. In the first paradigm, a SAL or LAL male was living in sensory contact (except tactile contact) with a dominant SAL male for 25 days (sensory contact stress). In the second paradigm, a SAL or LAL male was, in addition to the first paradigm, defeated by a SAL male for 21 consecutive days (defeat stress). The sensory contact stressor induced in LAL mice chronic body weight loss and increased plasma adrenocorticotropic hormone levels compared to SAL mice and increased corticosterone levels, thymus involution and lower hippocampal mineralocorticoid receptor (MR) : glucocorticoid receptor (GR) ratio compared to LAL controls. The defeat stressor increased corticosterone secretion and caused adrenal hypertrophy and thymus involution in both mouse lines. Defeated LAL mice showed long‐lasting body weight loss and higher corticosterone concentrations than SAL mice and lower hippocampal MR : GR ratio and decreased immobility behaviour in the forced swimming test than LAL controls. Hypothalamic corticotropin‐releasing hormone mRNA expression was higher in defeated SAL than in controls. The present data show that both stress paradigms induced line‐dependent physiological and neuroendocrine changes, but that the sensory contact stressor produced chronic stress symptoms in LAL mice only. This latter stress paradigm therefore seems promising to analyse the role of genetic factors in the individual differences in stress‐related psychopathology.