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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Zeitschrift für Lebensmittel-Untersuchung und -Forschung 204 (1997), S. 425-428 
    ISSN: 1431-4630
    Keywords: Key words Selenium ; Milk ; Mineralization methods ; Fluorimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Methods for the mineralization of milk samples (whole milk, casein and the total protein fraction) were studied. The dry ashing method was eliminated because low recoveries (〈10%) of Se were obtained. Acid-induced digestion was assayed using several mixtures of acids: HNO3–HClO4, HNO3–HClO4– H2SO4, HNO3–HClO4–TCA (where TCA is trichoroacetic acid). The proportions and total amounts of the acids were also varied and the effect of this investigated. Mixtures HNO3–HClO4 and HNO3–HClO4–H2SO4 were not adequate to induce complete mineralization of the milk samples. The mixture HNO3–HClO4–TCA (3:1:2) was able to digest skimmed milk. Two successive digestions with this mixture (HNO3–HClO4–TCA (3:1:2)] were necessary to induce the complete digestion of casein and the total protein fractions and, in the latter case, a recovery of 94.5±5.2% (100 μg Se/l) was achieved.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Zeitschrift für Lebensmittel-Untersuchung und -Forschung 208 (1999), S. 162-168 
    ISSN: 1431-4630
    Keywords: Key words Cadmium ; Lead ; Milk ; Electrothermal atomic absorption spectrometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Concentrations of Pb and Cd were determined in samples of human, raw and pasteurized cow's and goat's milk and powdered infant formula. The following mean Cd concentrations (and ranges) were recorded: in human milk, 2.70 μg/l (0.6–11.3, n=55); in raw cow's milk, 4.88 μg/l (0.7–23.1, n=47); in pasteurized cow's milk, 4.30 μg/l (3.4–5.9, n=6); in goat's milk, 7.81 μg/l (1.0–18.4, n=38); and in powdered, infant formula, 3.81 μg/l (3.4–4.1, n=5). The concentrations (and ranges) of Pb were: in human milk, 8.34 μg/l (0.1–32.3, n=55); in raw cow's milk, 14.82 μg/l (1.3–39.1, n=28); in pasteurized cow's milk, 10.25 μg/l (6.9–19.6, n=6); in goat's milk, 11.86 μg/l (0.4–38.5, n=36); and in powdered, infant formula, 8.30 μg/l (5.1–10.6, n=5). Our data were within the normal ranges for each kind of milk. The Cd and Pb concentrations in goat's milk were significantly higher than the concentrations observed in the other milks, whereas human milk and powdered infant formula presented the lowest Cd and Pb concentrations. A considerable decrease in the concentration of Cd with the stage of lactation was observed. The concentrations of Cd and Pb in human, cow's and goat's milk also varied according to the time of year. The concentrations of Pb and Cd in the different milks did not present any risk to human health (infants or adults).
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Zeitschrift für Lebensmittel-Untersuchung und -Forschung 207 (1998), S. 174-179 
    ISSN: 1431-4630
    Keywords: Key words Selenium ; Human milk ; Powdered infant formula ; Intake ; Lactation stage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  Selenium (Se) concentrations in 58 samples of mature human milk from Canarian women were determined by spectrofluorimetry. According to the literature the Se concentrations found fall within the normal limits. The concentration of Se in human milk was compared with that in powdered infant formula and presented significantly lower concentrations in the latter. Babies fed with human milk had an adequate intake of Se. However, babies fed with powdered infant formula consumed only 56% of the requirements recommended by The National Research Council. No changes in Se concentration were observed between lactation stages. Human milk produced in springtime was found to be richer in Se than that produced in the autumn, which could be due to changes in the nutritional habits of the mothers. The mother's age, weight, height and number of previous children were not found to influence the Se levels in the milk.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Nach Durchtrennung des Hypophysenstiels wird eine Akkumulation von Neurosekretgranula sowohl im proximalen wie auch im distalen Stumpf des Stiels nachgewiesen. Elektronenmikroskopische und pharmakologische Untersuchungen machen wahrscheinlich, dass die Akkumulation im distalen Stumpf auf einen Reflux der Neurosekretgranula zurückzuführen ist.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1106
    Keywords: Subcommissural organ ; Plasma membrane proteins ; Organ culture ; Immunological destruction ; Bovine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The subcommissural organ (SCO) is a brain gland that secretes glycoproteins into the cerebrospinal fluid (CSF). It is an ancient and conserved secretory structure of the brain, developing very early in ontogeny. However, the function of the SCO is unknown. The secretory cells of the SCO are arranged into a single or double, irregularly shaped layer located at the interface of the CSF and nervous tissue. This has prevented its selective surgical destruction. The present investigation was designed to destroy the secretory cells of 30-day-old expiants of bovine SCO by use of an immunological approach. A membrane preparation enriched with plasma membrane of the secretory cells of the bovine SCO was obtained. This preparation was further processed to separate the structural proteins. A similar procedure was applied to obtain a fraction of integral proteins of the plasma membrane of a nonsecretory ciliated ependyma. Antisera were prepared against both preparations of integral proteins. The antiserum against the fraction obtained from the SCO cells immunostained the plasma membrane of the bovine SCO cells and in immunoblot it reacted with several proteins of the membrane preparation from SCO cells. When added to the culture medium this antibody bound to the apical plasma membrane of the secretory ependyma of the bovine SCO kept in culture; it caused the lysis of these cells when used together with complement. None of these properties were displayed by the antiserum raised against the integral proteins of the plasma membrane of the ciliated ependyma. This antiserum, however, immunostained the bovine ciliated ependyma neighboring the SCO. These results indicate that immunological surgery of the SCO in living animals may be possible to achieve.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-1106
    Keywords: Key words Subcommissural organ ; Reissner’s fiber ; Immunoneutralization ; Function ; Monoamine clearance ; Cerebrospinal fluid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The subcommissural organ (SCO) is a brain gland secreting glycoproteins into the cerebrospinal fluid (CSF), where they aggregate forming the Reissner’s fiber (RF). By the continuous addition of newly released glycoproteins, RF grows along the cerebral aqueduct, fourth ventricle, and central canal of the spinal cord. At the filum, RF-glycoproteins escape from the central canal and reach the local blood vessels. Despite a century of research, the function of the SCO remains elusive. The aim of the present investigation was to test the hypothesis that RF-glycoproteins, by binding and transporting monoamines out of the CSF, participate in the clearance of these compounds. A protocol was designed that led to the permanent immunoneutralization of the SCO through the maternal delivery of antibodies. This was achieved by transplacental transfer to the fetuses, and through the milk to the pups, of specific antibodies against SCO secretory proteins. The antibodies reached the CSF of the fetuses and pups and blocked the RF formation during the first months of life. Some of these animals died during the first postnatal weeks; those who survived displayed a rise in the CSF concentration of several monoamines, l-DOPA being the one with the highest rise. Adult rats transiently deprived of RF by a single injection of anti-RF antibodies into the CSF showed a transient rise in the CSF concentration of l-DOPA. All these results support the hypotheses that the SCO-RF complex participates in the clearance of monoamines from the CSF.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Evaluations of histopathological lesions in gill tissue were carried out in the freshwater fish Macropsobrycon uruguayanae following 30 and 60 days of exposure to 1.5 mg 1-1 of cadmium. The study was conducted on both fed and starved animals in order to determine the influence of feeding condition on cadmium toxicity. The main lesions observed and quantified were: (1) hyperplasia of primary lamellar epithelium; (2) hyperplasia of secondary lamellar epithelium; (3) separation of respiratory epithelium; (4) shortening of secondary lamellae; (5) epithelial necrosis; (6) fusion of adjacent secondary lamellae; (7) hypertrophy of respiratory epithelium; (8) lamellar telangiectasis; (9) hyperplasia of chloride cells; (10) mucinous metaplasia; and (11) inflammatory infiltration. Lesions 6, 8, 9 and 11 were only induced by exposure to cadmium, while lesion 4 could be produced only by starvation. Starved fish also showed a reduction in total body weight and length. Lesion 2 was shown to be non-specific, and produced by either cadmium, starvation or even exposure time. The possible mode of action of the experimental factors are discussed in relation to the observed pathologies.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-1106
    Keywords: Subcommissural organ ; Reissner's fibre ; Immunological blockade ; Cerebrospinal fluid circulation ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The subcommissural organ is an ependymal brain gland that secretes glycoproteins to the cerebrospinal fluid (CSF) of the thrid ventricle. They condense to form a fibre, Reissner's fibre (RF), that runs along the aqueduct and fourth ventricle and the central canal of the spinal cord. A single injection of an antibody against the secretory glycoproteins of RF into a lateral ventricle of adult rats results in animals permanently deprived of RF in the central canal and bearing a “short” RF extending only along the aqueduct and the fourth ventricle. These animals, together with untreated control animals were used to investigate the probable influence of RF in the circulation of CSF in the central canal of the spinal cord. For this purpose, two tracers (horseradish peroxidase and rabbit immunoglobulin) were injected into the ventricular CSF. The animals were killed 13, 20, 60, 120 and 240 min after the injection, and the amount of the tracers was estimated in tissue sections obtained at proximal, medial and distal levels of the spinal cord. In rats deprived of RF, a significant decrease in the amount of tracers present in the central canal was observed at all experimental intervals, being more evident at 20 min after the injection of the tracers. This suggests that lacking a RF in the central canal decreases the bulk flow of CSF along the central canal. Turbulences of the CSF at the entrance of the central canal of RF-deprived rats might explain the inability of the regenerating RF to progress along the central canal, as well as the reduced flow of CSF in the central canal of these animals.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The use of butyl-methyl-methacrylate embedding and the application of the silver methenamine (SM) method as a poststaining of the immunoperoxidase-DAB (IP) procedure led to the standardization of several useful methods for the visualization of tissue antigents at the light and electron microscope level. These procedures included: 1) Standardization of the actual methacrylate embedding; 2) The IP-SM method with an without periodic acid oxidation, which provided 100% intensification of the IP staining; 3) The IP-SM method made it possible to stain semithin sections (0.5 μm), and this in turn, permitted a) clear visualization under the light microscope of the intracellular distribution of antigens and, b) staining, in several adjacent sections, of roughly the same cytoplasmic region of the same cell with different primary antisera; 4) a double immunostaining whereby the first antigen in the sequence was revealed by the IP-SM method and the second by the IP procedure: 5) standardization of the IP and the IP-SM methods for post-embedding staining of ultrathin methacrylate sections. The combined application of methacrylate embedding and the IP-SM, and the use of an appropriate fixative, resulted in an ultrastructural immunocytochemical procedure characterized by a good immunoreactivity of the tissue sections, a strong and selective immunoreaction and a well preserved ultrastructure.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Histochemistry and cell biology 84 (1986), S. 31-40 
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ontogenetical development of the subcommissural organ (SCO) was investigated in chick embryos collected daily from the 1st to the 21st day of incubation. Some duck embryos, and adult chickens and ducks were also studied. Immunocytochemistry using an anti-Reissner's fiber (RF) serum as the primary antibody was the principal method used. In the chick embryos the events occurring at different days of incubation were: day 3 morphologically undifferentiated cells in the dorsal diencephalon displayed immunoreactive material (IRM); days 4 to 6 immunoreactive cells proliferated, formed a multilayered structure and developed processes which traversed the growing posterior commissure and ended at the brain surface; day 7 i) blood vessels penetrated the SCO, ii) scarce hypendymal cells appeared, iii) the first signs of ventricular release of IRM were noticed, iv) appearance of IRM bound to cells of the floor of the Sylvius aqueduct; day 7 to 10 the number of apical granules and amount of extracellular IRM increased progressively; day 11 RF was observed along the Sylvian aqueduct; day 12 RF was present in the lumbar spinal cord; day 13 IRM on the aqueductal floor disappeared; days 10 to 21 i) hypendymal cells proliferated, developed processes and migrated dorsally, ii) ependymal processes elongated and their endings covered the external limiting membrane. In adult specimens the ependymal cells lacked basal processes and the external membrane was contacted by hypendymal cells. The duck SCO appears to follow a similar pattern of development.
    Type of Medium: Electronic Resource
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