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  • 1
    ISSN: 1432-0568
    Keywords: Placenta ; Umbilical cord ; Volumetric composition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We investigated whether variations in mode of attachment of umbilical cords and vessels coincided with differences in maternal haemoglobin genotype and neonatal factors or placental micro-volumetric composition. The incidence of placentae with marginally inserted cords, or those in which umbilical vessels separated prior to insertion, was not statistically different in samples from sickle cell patients having haemoglobin-SS and haemoglobin-SC genotypes, as compared with haemoglobin-AA controls. Results obtained from analysis of variance (ANOVA) suggest that the mode of insertion (status) of umbilical vessels may have clinical significance, because it produced differences in the main effects associated with neonatal gestational age, placental weight, and placental index. Point counting stereology was employed to estimate the microscopic compartment volumes of placentae prior to an assessment of statistical association between the data obtained and the status of umbilical vessels and maternal haemoglobin genotype. Furcate placentae (with separated umbilical vessels) had statistically greater than normal volumes of villi, villous trophoblast, and syncytial knots. We deduce that furcate placentae are prone to early delivery, because they are heavier, having more voluminous villi with more trophoblast and syncytial knots than controls.
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  • 2
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The secretion of plasma melatonin exhibits a diurnal variation in the common marmoset (Callithrix jacchus jacchus) (n = 12) with mean values of 125.8 fmol/ml during darkness and below assay sensitivity (mean 70.5 fmol/ml) during the light period. Both melatonin secretion and the rest activity cycle appeared to be phase advanced with relation to the light dark cycle which is consistent with an endogenous circadian period (tau) of 〈 24 h in this species.
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 14 (1993), S. 0 
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Well-established circadian physiology supports the view that photoperiodic time measurement utilizes the coincidence between the presence of light and a photosensitive phase of a 'biological clock' to alter reproductive status—the so-called external coincidence model of seasonal breeding. In this review, we examine the mechanism whereby photoperiod interacts with presumed suprachiasmatic nuclei activity to allow endogenous melatonin to normally synchronize reproductive activity to the optimal time of year. The Romney Marsh sheep is particularly explored as an experimental model. It is suggested that the on/off activity of seasonal reproduction may be a robust mechanism able to be predictably manipulated by the judicious use of the light/dark cycle and exogenous melatonin, but firmly based on circadian principles.
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  • 4
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 371 (1994), S. 563-564 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SIR - We wish to report the successful transfer to mice of two genes, cysE and cysK, from Escherichia coli which encode the enzymes necessary for the assimilation of inorganic sulphide for the biosynthesis of the amino-acid cysteine1'2. These mice are able to synthesize cysteine when ...
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  • 5
    ISSN: 1279-8517
    Keywords: Suprarenal glands ; Imaging ; Anatomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé A partir de coordonnées relevées sur trois séries de coupes anatomiques, les auteurs ont imaginé une incidence d'exploration tomographique, utilisable en IRM et en échographie, qui restitue l'image idéale de la glande surrénale dans son quadrilatère décrit par Testut. Cette incidence “anatomique” est verticale et oblique à 45°, intermédiaire entre les incidences sagittale et frontale auxquelles elle se substitue avantageusement. Un aspect nouveau du tomogramme surrénalien, rappelant l'image d'un triskèle, est décrit à propos de cette incidence.
    Notes: Summary Based on coordinates derived from three series of anatomic sections, the authors propose a view for tomographic investigation, applicable in MRI and ultrasound, which reconstructs the ideal image of the suprarenal gland in its quadrilateral as described by Testut. This “anatomic” view is 45° vertical and oblique, intermediate between the sagittal and frontal views, which it can advantageously replace. A new aspect of suprarenal tomography, recalling the image of a triskele, is described in the context of this view.
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  • 6
    ISSN: 1573-904X
    Keywords: Fourier transform-Raman ; polymorphism ; chlorpropamide ; factor analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract We analyzed binary mixtures of polymorphs A and B of chlorpropamide ((l-[4-chlorobenzenesulphonyl]-3-propyl urea)) by near-infrared Fourier transform Raman spectroscopy (FTRS). The individual polymorphs were prepared and characterized by differential scanning calorimetry (DSC), Fourier transform infrared (FT-IR) microscopy, and physical appearance. The FTR spectra of the two polymorphs showed distinct differences which result from "crystal splitting” effects. A series of 13 different mixtures of polymorph A and B was prepared by geometric mixing and their FTR spectra statistically analysed by factor analysis programming. Predictions of the A/B polymorphic composition of mixtures were made and compared with the theoretical values. The results demonstrate that FTRS combined with factor analysis programming may be successfully applied to the in situ monitoring of the A/B polymorphic nature of a chlorpropamide sample.
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  • 7
    ISSN: 1573-904X
    Keywords: Fourier transform (FT)-Raman spectroscopy ; Eudragit RS ; sulfasalazine ; microspheres
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract FT-Raman spectroscopy (FTRS) has been used to characterize microspheres produced from the pharmaceutical polymer Eudragit RS containing a range of concentrations of the drug sulfasalazine. While pure sulfasalazine produced an intense and complex Raman spectrum, the spectrum of drug-free Eudragit RS microspheres was considerably weaker in intensity and contained only a few prominent Raman scattering peaks. In spectra of the drug–polymer micro-spheres, peaks arising from the individual components could be identified. This enabled a quantitative analysis to be undertaken by calculating the ratio between the area of a sulfasalazine peak and the area of a Eudragit RS peak for each microsphere spectrum. A correlation was shown between the peak area ratio and the microsphere sulfasalazine content. FTRS was then applied to a series of microsphere samples which had been dissoluted into pH 7 buffer for 1, 3, 6, 9, 12, or 24 hr. For each spectrum, the drug-polymer peak area ratio was determined and this in turn enabled calculation of the residual drug content of the microsphere sample. FTRS-calculated data showed good agreement with microsphere drug content values determined spectrophotometrically.
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  • 8
    ISSN: 1573-904X
    Keywords: Eudragit ; poly(methacrylate) ; film coating ; controlled release ; quantitative analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A colorimetric ion-pair complexation method has been developed which provides a simple and rapid way of quantifying Eudragit RS100 and RL100 in pharmaceutical dosage forms. The quaternary ammonium groupings in these polymers appear to form an ion-pair complex with the dye tropaeolin OOO. When extracted into an organic phase, the optical density at 484 nm is linearly related to polymer concentration. Control of pH is important, and it should be maintained within the range 4.5 to 9.0. A wide range of pharmaceutical excipients commonly used in tablet, pellet, and film-coating formulations did not interfere with formation of the complex, but certain drugs were found to significantly enhance or decrease the assay response. Good reproducibility, precision, and accuracy were demonstrated when the method was applied to a film-coated pellet formulation containing an interfering drug (promethazine hydrochloride). However, removal of interfering substances must be optimized. The method was sufficiently sensitive for the determination of polymer on a single dose unit of encapsulated beads.
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  • 9
    ISSN: 1619-7089
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
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  • 10
    ISSN: 1432-136X
    Keywords: Trout ; Intestine ; Brush ; Border ; Cl−/HCO 3 − ; Carbonic anhydrase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary This paper presents a study of the mechanisms of Cl− transport through the brush border membranes of the posterior part of the intestine in the freshwater trout, Oncorhynchus mykiss. The mechanisms for Cl− transport in the posterior intestine are distinct from those in the middle intestine; an inwardly directed pH gradient stimulates Cl− uptake by bursh border membrane vesicles, indicating a Cl−/OH− exchange. A pH-regulated Cl− conductance is present, which is not activated at normal intracellular pH. Cl− uptake is stimulated by an outwardly directed HCO 3 − gradient revealing the presence of a Cl−/HCO 3 − exchange but, conversely, Cl− is not exchanged against SO 4 2- . In addition, carbonic anhydrase activities have been detected in both the intracellular and extracellular leaflets of the bursh border membranes which favour the establishment of a bicarbonate gradient. A model of Cl− transport mechanisms through the brush-border membranes of the posterior intestine of the freshwater trout is proposed.
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