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  • 1
    Electronic Resource
    Electronic Resource
    On the presence of a secondary cartilage in the mental symphyseal region of human embryos and fetuses (1994)
    Springer
    Surgical and radiologic anatomy 16 (1994), S. 379-384 
    Details
    ISSN: 1279-8517
    Keywords: Mental symphysis ; Secondary cartilage ; Ossification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé La présence d'un cartilage secondaire dans la région de la symphyse mentonnière a été étudiée dans ce travail. Une double coloration (avec le bleu alcian et le rouge alizarine S) a été réalisée sur 32 embryons et foetus humains (âgés de 8 à 17 semaines, longueur crâniocaudale- CRL - entre 37 et 124 mm) et sur leurs mandibules désarticulées. Les techniques histologiques et histochimiques ont été appliquées aux coupes sériées transversales de toutes les têtes foetales désarticulées. Le processus d'ossification observé au niveau de la symphyse mentonnière est tout à fait différent de celui du corps de la mandibule dont l'ossification membraneuse est induite par le cartilage de Meckel contigu. Nous n'avons détecté aucun signe de fusion du cartilage de Meckel avec le cartilage symphysaire qui se trouve dans l'espace symphysaire. Sur la base de nos constatations, nous suggérons que le cartilage secondaire mentonnier est capable de se transformer en os selon un processus d'ossification enchondrale. De plus le rôle des facteurs mécaniques dans le développement de la symphyse mentonnière est suggéré.
    Notes: Summary The presence of a secondary cartilage in the mental symphyseal region was examined in this study. A double-staining method -with alcian blue and alizarin red S -was performed on both whole human embryos and fetuses (developmental age between 8 and 17 weeks, crown-rump length, CRL, between 37 and 124 mm) and their disjointed mandibles. Histological and histochemical techniques were applied to transverse serial sections of whole disjointed fetal heads. The ossification process observed in the mental symphysis is quite different from that of the mandibular body, whose membranous ossification is induced by the contiguous Meckel's cartilage. No evidence of any fusion of Meckel's cartilage with the symphyseal cartilage, that lies within the symphyseal space, was detected. On the basis of these findings, we suggested that the mental secondary cartilage is able to change into bone according to an endochondral ossification process. Moreover, the role of mechanical causes in the development of the mental symphysis was hypothesized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01627657
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  • 2
    Electronic Resource
    Electronic Resource
    Dexamethasone treatment fails to increase arginine-induced insulin release in healthy subjects with low insulin response (1992)
    Springer
    Diabetologia 35 (1992), S. 367-371 
    Details
    ISSN: 1432-0428
    Keywords: Insulin secretion ; Type 2 (non-insulin-dependent) diabetes mellitus ; glucagon secretion ; C-peptide ; arginine ; dexamethasone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have compared insulin responses to L-arginine before and during dexamethasone treatment in healthy subjects, previously classified as subjects with either high or low insulin response according to a standardized glucose infusion test. Arginine stimulation was administered as a 150 mg/kg bolus followed by 10 mg·kg−1·min−1 to six subjects with high insulin response and to seven subjects with low insulin response. Before dexamethasone treatment the incremental insulin level during 0–10 min of arginine was higher in subjects with high (36.5±6.8 μU/ml) than in subjects with low response (14.5±2.3 μU/ml), p〈0.01 for difference. Dexamethasone treatment (6 mg/day for 60 h) markedly enhanced the insulin response to arginine in subjects with high response (+99% 0–30 min) but failed to affect the subjects with low response (+4% 0–30 min). The C-peptide response to arginine exhibited similar differences between groups. Decreased responsiveness to arginine in subjects with low insulin response, especially during dexamethasone treatment, suggests a Beta-cell capacity defect although a decreased potentiating-sensing effect of glucose cannot be completely ruled out.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00401204
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  • 3
    Electronic Resource
    Electronic Resource
    Irreversible loss of normal beta-cell regulation by glucose in neonatally streptozotocin diabetic rats (1994)
    Springer
    Diabetologia 37 (1994), S. 351-357 
    Details
    ISSN: 1432-0428
    Keywords: Key words Animal models NIDDM, insulin secretion, insulin mRNA, cytochrome b mRNA, islets of Langerhans.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Animals with NIDDM display abnormal glucose regulation of insulin secretion and biosynthesis. We tested reversibility of abnormal regulation by normoglycaemia using an islet transplantation technique. Inbred non-diabetic and neonatally STZ diabetic rats (n-STZ) were used. Transplantations insufficient to normalize the blood glucose levels (200 islets under kidney capsule) were performed from diabetic to normal (D-N) and from diabetic to diabetic (D-D), as well as from normal to normal (N-N) and from normal to diabetic (N-D) rats. Four weeks after transplantation, graft bearing kidneys were isolated and perfused with Krebs-Henseleit bicarbonate buffer to measure insulin secretion in response to 27.8 mmol/l glucose and 10 mmol/l arginine. Four weeks of normoglycaemia failed to restore glucose-induced insulin secretion from n-STZ islets (glucose induced increment: −1.7± 2.5 fmol/min in D-N, 1.2±7.1 fmol/min in D-D). In contrast to normal islets, normoglycaemia reduced insulin mRNA contents (60±24 in D-N, 496±119 in D-D; O. D.-arbitrary units). However, arginine-induced secretion was markedly enhanced by diabetic environment in both normal and n-STZ islet grafts. These results indicate that selected aspects of glucose recognition are irreversibly damaged by a long-term diabetic state or, alternatively, by a lasting effect of STZ administration. [Diabetologia (1994) 37: 351–357]
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00408470
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  • 4
    Electronic Resource
    Electronic Resource
    Influence of severe diabetes mellitus early in pregnancy in the rat: effects on insulin sensitivity and insulin secretion in the offspring (1991)
    Springer
    Diabetologia 34 (1991), S. 373-378 
    Details
    ISSN: 1432-0428
    Keywords: Diabetes in pregnancy ; insulin secretion ; insulin resistance ; hyperglycaemia ; glucose homeostasis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We studied the influence of severe diabetes early in pregnancy on insulin sensitivity and insulin secretion in the offspring. Diabetes (blood glucose 〉20 mmol/l) was induced in female Sprague-Dawley rats before mating. Diabetic dams were insulin treated during the second half of pregnancy (mean blood glucose 10.6 mmol/l). The offspring were reared by foster mothers. Offspring of both sexes were insulin resistant at four and seven months of age as evidenced by normal glucose tolerance after glucose (2 g/kg body weight intraperitoneally) concomitant with higher than normal rises in insulin levels. Regardless of fetal environment the male rats had higher glucose and insulin levels than the female rats. Insulin responses to glucose (27 mmol/l) in vitro in perfused pancreases were not increased by maternal diabetes, male gender or higher age. Conversely responses to 3-isobutyl-1-methylxanthine (1.0 mmol/l) were enhanced by all three conditions. The pancreatic content of insulin was only marginally affected by maternal diabetes. We conclude that severe diabetes during early pregnancy affects glucose homeostasis in the offspring primarily by diminishing insulin sensitivity and that susceptibility to this effect is not sex- or age-dependent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00403173
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  • 5
    Electronic Resource
    Electronic Resource
    Irreversible loss of normal beta-cell regulation by glucose in neonatally streptozotocin diabetic rats (1994)
    Springer
    Diabetologia 37 (1994), S. 351-357 
    Details
    ISSN: 1432-0428
    Keywords: Animal models NIDDM ; insulin secretion ; insulin mRNA ; cytochrome b mRNA ; islets of Langerhans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Animals with NIDDM display abnormal glucose regulation of insulin secretion and biosynthesis. We tested reversibility of abnormal regulation by normoglycaemia using an islet transplantation technique. Inbred non-diabetic and neonatally STZ diabetic rats (n-STZ) were used. Transplantations insufficient to normalize the blood glucose levels (200 islets under kidney capsule) were performed from diabetic to normal (D-N) and from diabetic to diabetic (D-D), as well as from normal to normal (N-N) and from normal to diabetic (N-D) rats. Four weeks after transplantation, graft bearing kidneys were isolated and perfused with Krebs-Henseleit bicarbonate buffer to measure insulin secretion in response to 27.8 mmol/l glucose and 10 mmol/l arginine. Four weeks of normoglycaemia failed to restore glucose-induced insulin secretion from n-STZ islets (glucose induced increment:-1.7±2.5 fmol/min in D-N, 1.2±7.1 fmol/min in D-D). In contrast to normal islets, normoglycaemia reduced insulin mRNA contents (60±24 in D-N, 496±119 in D-D; O.D.-arbitrary units). However, arginine-induced secretion was markedly enhanced by diabetic environment in both normal and n-STZ islet grafts. These results indicate that selected aspects of glucose recognition are irreversibly damaged by a long-term diabetic state or, alternatively, by a lasting effect of STZ administration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00408470
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  • 6
    Electronic Resource
    Electronic Resource
    Metastable fragmentation of (C4H10)nC4H+7 cluster ions induced by delayed isomerization reactions of C4H+7 (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 96 (1992), S. 5213-5219 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The metastable fragmentation of the cluster ions (C4H10)nC4H+q (q=7 to 10) produced by the electron impact ionization of a neutral n-butane cluster beam has been studied with a double focusing sector field mass spectrometer. For q〉7, the usual statistical single-monomer evaporation is the only observable metastable fragmentation channel. Surprisingly, the (C4H10)nC4H+7 cluster ions were found to exhibit a more complex metastable decay pattern, involving not only the single-monomer evaporation, but also two additional fragmentation channels leading to evaporation of 2 to 4 and 4 to 7 (C4H10) monomers, respectively. After studying the dependence of the parent and the fragment ion currents on the electron energy, we concluded that the C4H+7 ionic chromophore of the (C4H10)nC4H+7 cluster ion is produced after internal H− transfer between n-C4H10 and some primary fragment ion (e.g., C2H+5, C2H+3, C3H+3, CH+3, C3H+4 ) of n-butane within the cluster. A mechanism based on the energy storage in metastable isomers of the C4H+7 chromophore ion is suggested to explain the unusual metastable fragmentation pattern of (C4H10)nC4H+7 cluster ions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.462729
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  • 7
    Electronic Resource
    Electronic Resource
    Formation of the superhalogen ion SF−7 via electron attachment to SF6 clusters (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 96 (1992), S. 9241-9242 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Electron attachment to SF6 and SF6 clusters has been investigated in a molecular beam/electron impact ion source/mass spectrometer system. In accordance with recent theoretical predictions we were able to produce the superhalogen ion SF7− by electron attachment to SF6 clusters. SF7− has not been previously observed; its relative attachment cross section curve shows features more similar to that of F2− from SF6 than that of F− from SF6.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.462236
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  • 8
    Electronic Resource
    Electronic Resource
    Absolute partial and total electron impact ionization cross sections for C3H8 from threshold up to 950 eV (1993)
    Springer
    The European physical journal 25 (1993), S. 217-226 
    Details
    ISSN: 1434-6079
    Keywords: 34.80.Gs ; 35.20.Wg
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Electron impact ionization of propane (C3H8) was studied using the ion beam deflection technique and a double focussing mass spectrometer in conjunction with a recently developed correction procedure that accounts for discrimination due to the initial kinetic energy of fragment ions. The relative corrected partial ionization cross sections for the production of C3H 8 + , C3H 7 + , C3H 6 + , C3H 5 + , C3H 4 + , C3H 3 + , C3H 2 + , C3H+, C 3 + ; C2H 5 + , C2H 4 + , C2H 3 + , C2H 2 + , C2H+, C 2 + ; CH 3 + , CH 2 + , CH+, C+; C3H 5 2+ , C3H 4 2+ , C3H 3 2+ and C3H 2 2+ were determined from threshold up to 950 eV. Absolute partial ionization cross sections were obtained by charge weighted summing of all the observed partial ionization cross sections and by normalizing to a recent accurate determination of the total ionization cross section at 100 eV by Djuric et al. 1991. The absolute total ionization cross section curve obtained is in excellent agreement in shape and magnitude with the low energy data (〈200 eV) of Djuric et al. 1991 and the high energy data points of Schram et al. 1966.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01426883
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  • 9
    Electronic Resource
    Electronic Resource
    Production and stability of oxygen cluster cations and anions, revisited (1991)
    Springer
    The European physical journal 20 (1991), S. 201-203 
    Details
    ISSN: 1434-6079
    Keywords: 36.40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Stoichiometric and non-stoichiometric, positive and negative oxygen cluster ions (n up to 70) have been produced in a crossed neutral beam/electron beam ion source. The abundance and stability of the ions formed have been analyzed with a double focussing sector field mass spectrometer in a series of experiments. Positive and negative ion mass spectra observed exhibit distinct abundance anomalies, however, at different cluster sizes. Abundance maxima and minima correlate with correspondingly small and large metastable fractions of (O2) n + and (O2) n − ions, respectively. (O2) n + ions may also lose up top=(n−1) monomers by collision induced dissociation with monotonously decreasing probability with increasingp. Metastable fractions determined for (O2) n − ions produced with appr. zero eV electrons are in general larger than those for ions produced with appr. 7 eV electrons. (O2) n − ions are also observed to decay via autodetachment, with lifetimes increasing with increasing cluster size. Finally, here we were able to prove that an apparent loss of the monomer fragment O (and higher homologues) observed in the metastable time regime is due to ordinary metastable monomer evaporation in the acceleration region. Moreover, we will also present here some new data and interpretation concerning the electron attachment cross section function for O2 clusters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01543973
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  • 10
    Electronic Resource
    Electronic Resource
    Production and properties of CO2 cluster anions (1992)
    Springer
    The European physical journal 24 (1992), S. 289-296 
    Details
    ISSN: 1434-6079
    Keywords: 36.40.+d ; 35.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Stoichiometric and non-stoichiometric negatively charged CO2 cluster ions have been produced in a crossed neutral cluster/electron beam ion source. The abundance and stability of these ions have been studied with a double focussing sector field mass spectrometer. The observed abundance anomalies (“magic numbers”) in the mass spectra of (CO2) n − and (CO2) n O− ions correlate with corresponding small and large metastable fractions of these ions (for loss of one CO2 unit). Variation of the measured metastable fractions as a function ofn are related to corresponding changes in the monomer binding energies. In addition, we have observed for the first time (CO2) n O 2 − ions (i.e. at electron energies above 8 eV with an energy resonance at about 14 eV) and we discuss possible production mechanisms for these ions. Relative electron attachment cross sections have been determined in the energy regime O〈E≦20 eV for (CO2) n − , (CO2) n O− and (CO2) n O 2 − withn=1 to 20. The shape of the cross section function for (CO2) n O− is strongly dependent on the cluster sizen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01425751
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