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  • Column liquid chromatography  (248)
  • Ultrastructure  (81)
  • Rat
  • Springer  (392)
  • American Chemical Society
  • Elsevier
  • 1990-1994  (215)
  • 1985-1989  (177)
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  • 1
    Electronic Resource
    Electronic Resource
    Ventricular and atrial myocytes of newborn rats synthesise and secrete atrial natriuretic peptide in culture: Light-and electron-microscopical localisation and chromatographic examination of stored and secreted molecular forms (1988)
    Springer
    Cell & tissue research 251 (1988), S. 161-169 
    Details
    ISSN: 1432-0878
    Keywords: Atrial natriuretic peptide ; Ventricular myocytes ; Atrial myocytes ; Cell culture ; Secretion ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary We have demonstrated that atrial natriuretic peptide-like immunoreactivity is stored and secreted by ventricular and atrial myocytes in dissociated cell culture preparations from the heart of newborn rat. Culture preparations were maintained in either foetal calf serum-supplemented medium 199 or in hormone-supplemented, serum-free medium 199. The presence of atrial natriuretic peptidelike immunoreactivity in the cultured myocytes was demonstrated at both light-and electron-microscopical levels. Release of atrial natriuretic peptide-like immunoreactivity into the culture medium was measured by radioimmunoassay; molecular forms of the stored and secreted peptide were determined by gel column chromatography. The atrial natriuretic peptide-like immunoreactivity of cultured atrial and ventricular myocytes was concentrated in the perinuclear cytoplasm and was localised to electron-dense secretory granules. The number of immunoreactive ventricular myocytes and the intensity of their immunofluorescence changed with time in culture and was higher in cultures in foetal calf serum-supplemented medium than in serum-free medium. Gamma-atrial natriuretic peptide was stored and released by cultured atrial and ventricular myocytes, but was broken down to alpha-atrial natriuretic peptide in the growth medium. This process was foetal calf serum-independent, since it occurred in both the media used, indicating that cardiac myocytes in culture may release a factor that cleaves gamma-atrial natriuretic peptide to form alphaatrial natriuretic peptide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00215461
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  • 2
    Electronic Resource
    Electronic Resource
    Sustained release of salmon calcitonin in vivo from lactide: Glycolide copolymer depots (1993)
    Springer
    Calcified tissue international 52 (1993), S. 361-364 
    Details
    ISSN: 1432-0827
    Keywords: Calcitonin ; Sustained release ; Copolymer depot ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Studies were carried out to determine whether monolithic depot formulations, prepared using lactide:glycolide copolymers, could be used to administer salmon calcitonin (sCT) to rats in vivo. Formulations containing 2, 5, or 10% (w/w) sCT were administered subcutaneously to female Wistar strain rats. Release of sCT was determined by measurement of peptide in plasma using a specific radioimmunoassay and by measurement of residual sCT in the depots after recovery at postmortem. Plasma calcium concentrations and cumulative weight gain of the animals were used to measure pharmacological effects of the released sCT. Release of sCT from the depots was controlled by the copolymer and was sustained for periods up to 10 days. However, the release of sCT from the depots did not significantly alter plasma calcium concentrations, and effects on cumulative weight gain were small and transient. Peptide loading of the formulations was shown to modify sCT release. Maximal release of sCT from depots containing 10% peptide occurred over a 7 to 14-day period postadministration, with 5% sCT release occurred between days 11 and 14, and with 2% sCT, the period of maximal release was between days 11 and 18. Release of peptide from the depots was essentially complete by 21 days postadministration irrespective of the peptide loading. These data suggest that lactide:glycolide copolymer depots may have application for the convenient clinical administration of sCT in metabolic bone diseases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00310200
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  • 3
    Electronic Resource
    Electronic Resource
    Quantitative changes in the lysosomal vacuolar system of rat hepatocytes during short-term starvation (1986)
    Springer
    Cell & tissue research 243 (1986), S. 641-648 
    Details
    ISSN: 1432-0878
    Keywords: Hepatocytes ; Lysosomes ; Macroautophagy ; Microautophagy ; Starvation ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ultrastructural morphometric analysis was used to study time-dependent variations in macro and microautophagy in rat hepatocytes. Except during periods of shortterm starvation for up to 24 h, animals were kept under standardized conditions of food intake. In hepatocytes of meal-fed rats the volume fraction of macroautophagic vacuoles is significantly higher at 23:00 h, i.e., immediately before food intake, compared to 11:00 h, i.e., 12 h following feeding. During fasting, macroautophagy drops to a low level. Microautophagic vacuoles in hepatocytes of meal-fed rats, sacrificed at 11:00 or 23:00 h respectively, do not show any significant quantitative differences. However, during 12 h of starvation, the volume fraction of microautophagic vacuoles rises significantly, whereas the numerical density remains constant. Subsequently, during the second 12-h period of fasting, the volume fraction of microautophagic vacuoles remains unchanged, but the numerical density increases. Over a period of 24 h of starvation the volume fraction of the total lysosomal system does not change significantly, whereas the numerical density rises. The time-dependent changes of the macroautophagic vacuolar system correlate with the circadian, food-related variations in the protein content of individual hepatocytes from meal-fed animals. The increase in volume fraction and thereafter in number of microautophagic vacuoles, as observed during starvation, coincides with a large decrease in protein content of individual hepatocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218073
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  • 4
    Electronic Resource
    Electronic Resource
    Determination of carbendazime in lettuce samples by SFE-HPLC (1994)
    Springer
    Chromatographia 38 (1994), S. 395-399 
    Details
    ISSN: 1612-1112
    Keywords: Supercritical fluid extraction ; Column liquid chromatography ; Carbendazime analysis ; Vegetable samples
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An SFE-HPLC method for the determination of carbendazime in lettuce leaves is described. The method involves a prior lyophilization of the sample and subsequent extraction with supercritical carbon dioxide containing methanol. The extraction conditions are as follows: amount of lyophilized sample, 1 g; CO2 density, 0.75 g/ml; temperature, 50 °C; flow-rate, 1.8 ml/min; dynamic extraction time, 25 min. Carbendazime is determined with an octadecylsilane column, an acetonitrile/water 30∶70 mobile phase and fluorescence detection at 285/317 nm. Carbendazime recoveries from spiked samples were all close to 100%. A comparison with the results from a conventional method for the determination of carbendazime reveals the new method to be more rapid, simple and reproducible for samples with low concentrations of analyte.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269786
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  • 5
    Electronic Resource
    Electronic Resource
    Determination of tacrolimus (FK 506) in whole blood using liquid chromatography and fluorescence detection (1994)
    Springer
    Chromatographia 39 (1994), S. 490-496 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Precolumn derivatization ; Dansylhydrazine ; Fluorescence detection ; Tacrolimus (FK 506) in blood
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A sensitive and selective liquid chromatographic method, using precolumn derivatization with dansylhydrazine followed by fluorescence detection, has been developed for the determination of tacrolimus (FK 506) in whole blood. After haemolysis, whole blood samples are extracted with diethyl ether and derivatized. After on-line removal of excess dansylhydrazine on a C18 precolumn, the derivative is loaded on to a C18 clean-up column, and a heart cut is subsequently transferred to a graphitized carbon column, where the final separation takes place. The method requires 1 ml of sample and has a limit of quantitation of 3 ng/ml. At the 15 ng/ml level the precision isca 10%, and the response is linear from the limit of quantitation toca 200 ng/ml of FK 506 in whole blood. The capacity of the method is 50 samples/day and about 1000 1-ml samples can be analyzed without changing either clean-up or separation column. Finally, the applicability of the method for therapeutic drug monitoring is shown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02278767
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  • 6
    Electronic Resource
    Electronic Resource
    Molecular shape recognition capability of liquid-crystal bonded phases in reversed-phase high performance liquid chromatography (1994)
    Springer
    Chromatographia 38 (1994), S. 295-303 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Liquid crystal phases ; Molecular shape recognition ; Polycyclic aromatic hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The chromatographic retention behaviour of two liquidcrystal bonded phases have been evaluated using polycyclic aromatic hydrocarbons (PAHs) as the probe samples in reversed-phase high performance liquid chromatography (RP-HPLC). The results clearly indicate that these phases have better planarity and shape recognition capabilities than commercially-avaialble polymeric octadecylsilica (ODS) phases whose strong planarity and shape selectivities were found earlier. It can also be concluded from the chromatographic observations that the shape recognition capability of these phases is dependent on both mobile phase composition and column temperature, but that the effect of mobile phase and temperature on the shape selectivity work independently. The retention behaviour can be explained by changes in the phase structure with changes of eluent composition and temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269771
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  • 7
    Electronic Resource
    Electronic Resource
    A microscopic investigation of enamel in wombat (Vombatus ursinus) (1985)
    Springer
    Cell & tissue research 242 (1985), S. 349-355 
    Details
    ISSN: 1432-0878
    Keywords: Teeth (Vombatus ursinus) ; Enamel (regions) ; Ultrastructure ; Enamel (mature and developing)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A study of the enamel of continuously growing Vombatus ursinus molars was carried out using the techniques of light microscopy, hardness testing, scanning electron microscopy and transmission electron microscopy. From the erupted end to within 8 mm of the growing end, mature enamel was observed and it was found that between comparable areas there were no significant ultrastructural differences in enamel; however, small (∼12nm diameter), loosely packed needle-like crystals characteristic of developing enamel were observed near the growing end. Mature enamel was found to consist of three optically-translucent regions interleaved with two opaque regions. Opaque enamel was softer than translucent enamel. The opacity and relative softness characteristic of two of the enamel regions was not related to prism pattern or orientation; it was, however, related to the presence of voids (∼28 nm diameter) in these regions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214547
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  • 8
    Electronic Resource
    Electronic Resource
    Neuropeptide Y: presence in sympathetic and parasympathetic innervation of the nasal mucosa (1990)
    Springer
    Cell & tissue research 259 (1990), S. 119-128 
    Details
    ISSN: 1432-0878
    Keywords: Nasal mucosa ; Neuropeptide Y (NPY) ; Vasoactive intestinal polypeptide (VIP) ; Peptide histidine isoleucine (PHI) ; Noradrenaline ; Sympathetic/parasympathetic innervation ; Pig ; Cat ; Guinea-pig ; Rat ; Man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The occurrence of neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP) and peptide histidine isoleucine (PHI) in the sympathetic and parasympathetic innervation of the nasal mucosa was studied in various species including man. A dense network of NPY-immunoreactive (IR) fibres was present around arteries and arterioles in the nasal mucosa of all species studied. NPY was also located in nerves around seromucous glands in pig and guinea-pig, but not in rat, cat and man. The NPY-IR glandular innervation corresponded to about 20% of the NPY content of the nasal mucosa as revealed by remaining NPY content determined by radioimmunoassay after sympathectomy. These periglandular NPY-positive fibres had a distribution similar to the VIP-IR and PHI-IR nerves but not to the noradrenergic markers tyrosine hydroxylase (TH) or dopamine-β-hydroxylase (DBH). The NPY nerves around glands and some perivascular fibres were not influenced by sympathectomy and probably originated in the sphenopalatine ganglion where NPY-IR and VIP-IR ganglion cells were present. The venous sinusoids were innervated by NPY-positive fibres in all species except the cat. Dense NPY and DBH-positive innervation was seen around thick-walled vessels in the pig nasal mucosa; the latter may represent arterio-venous shunts. Double-labelling experiments using TH and DBH, and surgical sympathectomy revealed that the majority of NPY-IR fibres around blood vessels were probably noradrenergic. The NPY-positive perivascular nerves that remained after sympathectomy in the pig nasal mucosa also contained VIP/PHI-IR. The major nasal blood vessels, i.e. sphenopalatine artery and vein, were also densely innervated by NPY-IR fibres of sympathetic origin. Perivascular VIP-IR fibres were present around small arteries, arterioles, venous sinusoids and arterio-venous shunt vessels of the nasal mucosa whereas major nasal vessels received only single VIP-positive nerves. The trigeminal ganglion of the species studied contained only single TH-IR or VIP-IR but no NPY-positive ganglion cells. It is concluded that NPY in the nasal mucosa is mainly present in perivascular nerves of sympathetic origin. In some species, such as pig, glandular and perivascular parasympathetic nerves, probably of VIP/PHI nature, also contain NPY.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00571436
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  • 9
    Electronic Resource
    Electronic Resource
    Histochemical and ultrastructural studies on the enterochromaffin-like cell in the gastric mucosa of the opossum Didelphis albiventris (Marsupialia) (1990)
    Springer
    Cell & tissue research 262 (1990), S. 425-430 
    Details
    ISSN: 1432-0878
    Keywords: Stomach ; Enteroendocrine cells ; Enterochromaffin-like (ECL) cell ; Enterochromaffin cell (EC) ; Histamine ; Ultrastructure ; Secretory granules ; Didelphis albiventris (Marsupialia)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An ultrastructural study of enterochromaffin-like (ECL) cells in the gastric mucosa of the white-belly opossum Didelphis albiventris (Marsupialia) was carried out. In parallel, histochemical methods were used at the light-microscopical level to demonstrate argentaffin cells, argyrophilic cells, and serotonin- and histamine-immunoreactive elements. Argentaffin and serotonin-immunoreactive cells were scattered, and argyrophilic cells were numerous, within the full thickness of the mucosa. Argyrophilic cell distribution was similar to that of histamine-immunoreactive elements. At the electron-microscopical level, the oxyntic mucosa of D. albiventris presented endocrine cells with secretory granules morphologically similar to those of the ECL cell of eutherian mammals. However, in this marsupial, the ECL cell exhibited a variable mixture of two distinct types of secretory granules: (1) granules with the morphological appearance of the eutherian ECL cell, and (2) granules morphologically similar to those of the eutherian enterochromaffin (EC) cells. Based on this morphological pattern of the ECL cell granules, it is proposed that in the oxyntic mucosa of the opossum D. albiventris, the EC and ECL cells represent distinct steps in the same line of cell differentiation; the ECL cell should also be a site of histamine storage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00305239
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  • 10
    Electronic Resource
    Electronic Resource
    Gonadotropin production and release in female goldfish (Carassius auratus) after administration of pimozide and an LHRH analogue as studied by electron microscopy and radioimmunoassay (1987)
    Springer
    Cell & tissue research 247 (1987), S. 477-482 
    Details
    ISSN: 1432-0878
    Keywords: Gonadotropic cells ; LHRH analogue ; Pimo-zide ; Ultrastructure ; Goldfish ; Carassius auratus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effect of pimozide and an LHRH-analogue (LHRH-A) on gonadotropic cells of the goldfish pituitary gland were described qualitatively and quantitatively. A scale of four categories was devised to reflect various ultrastructural appearances of the cells. Experimental animals were divided into a control group, a group injected with LHRH-A alone, pimozide alone, and groups receiving these two substances in combination. Fish injected with the single substance were killed 12 h after injection while the groups receiving the combined treatments were killed at 4, 12 and 48 h. Serum levels of gonadotropin measured by radioimmunoassay were used to indicate whether an increase in hormone release had occurred. An immunocytochemical technique, the protein A-gold procedure, assured that the cells studied were gonadotropes. The control group showed variation in the profiles of gonadotropic cells. The single treatment groups showed some increase in secretory inclusions. At 4 h after injection the combined treatment caused a significant increase in hormone granules; at 12 and 48 h there was a gradual decrease in content of secretory products, and an increase in vacuolization. The results indicate that the combined pimozide and LHRH-A treatment stimulated gonadotropin production as well as release.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00215739
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