Mediterranean small mammals and insular syndrome: biometrical study of the long tailes field mouse (Apodemus sylavticus) (Rodentia Muridae) of Corsica

in Bonner Zoologische Beiträge (1993), 44(3-4), 147-163

The presence in Corsica of a field mouse is well known. Several authors have noted some of its morphological peculiarities but it was only recently (1980) that the presence of A. sylvaticus was ... [more ▼]

The presence in Corsica of a field mouse is well known. Several authors have noted some of its morphological peculiarities but it was only recently (1980) that the presence of A. sylvaticus was establblished with certainty. However, this evidence is based on a check of a limited number of individuals originating from a single locality. In order to generalize these observations, we performed o biochemical test on six Corsican mice caught in three distinct localites and a morpho biometrical study of 491 skulls. The results show that A. sylvaticus is spread all over the island and that A. flavicollis is probably absent. No sexual dimorphism was found but strong spatial variations in the cranial measurements were ividenced. There are far less important between the various Corsican sub samples than between the insular and the continenecal mice. The evolutionary and adaptive significance of the increase in size of insular mice is discussed in relation to the theory of island biogeography and to the present knowledge on the history of the mammalian settlement of the island. [less ▲]

Calcitonin for Prevention and Treatment of Osteoporosis

in American Journal of Medicine (1993), 95(5A), 44-47

There appears to be a consensus that 100 IU/day of nasally administered salmon calcitonin may prevent trabecular bone loss during the first year of the menopause. Strong evidence exists that half that ... [more ▼]

There appears to be a consensus that 100 IU/day of nasally administered salmon calcitonin may prevent trabecular bone loss during the first year of the menopause. Strong evidence exists that half that dose may also be sufficient to prevent trabecular bone loss and that higher doses (> or = 200 IU/day) induce a significant increase in spinal bone mineral content. Calcium supplements should be systemically administered when calcitonin is given, particularly at high doses. Rectal calcitonin seems also to be an efficient alternative in prevention of trabecular bone loss. Further studies are required to evaluate the effect of calcitonin in prevention of cortical bone loss. In established osteoporosis calcitonin may prevent further bone loss at trabecular and cortical sites. A similar benefit is obtained following parenteral or nasal administration of the drug. Long-term administration of nasal salmon calcitonin induces a significant dose-dependent gain of bone at the lumbar spine, whereas discontinuous therapy with a ratio of 1:2 or 2:3 between the treatment and nontreatment periods is the best regimen for cortical bone. Epidemiological, retrospective, and prospective studies provide a convergent network of evidence that calcitonin administration in osteoporosis contributes to reduce significantly the frequency of subsequent fractures, both in the spine and in the hip. Finally, in established osteoporosis, nasal calcitonin possesses a potent analgesic effect, reduces the duration of bed confinement, and decreases the number of concomitant analgesic medications. The well-demonstrated effects of nasal calcitonin permit it to be considered as a highly rational solution for the prevention and the treatment of postmenopausal osteoporosis. [less ▲]

Transplantations syngéniques de neurones et de cellules de Schwann dans la moelle épinière

Conference (1993, November 22)

ATMOS ATLAS-1 MEASUREMENTS OF SULFUR-HEXAFLUORIDE (SF6) IN THE LOWER STRATOSPHERE AND UPPER TROPOSPHERE

in Journal of Geophysical Research (1993), 98(D11), 20491-20494

Vertical profiles of sulfur hexafluoride (SF6) in the lower stratosphere and upper troposphere have been retrieved from 0.01-cm-1 resolution infrared solar occultation spectra recorded by the Atmospheric ... [more ▼]

Vertical profiles of sulfur hexafluoride (SF6) in the lower stratosphere and upper troposphere have been retrieved from 0.01-cm-1 resolution infrared solar occultation spectra recorded by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer during the ATLAS (Atmospheric Laboratory for Applications and Science) 1 shuttle mission of March 24 to April 2, 1992. Based on measurements of the unresolved absorption by the SF6 nu3 band Q branch at 947.9 cm-1, average SF6 volume mixing ratios and 1-sigma uncertainties of 3.20 +/- 0.54 parts per trillion by volume (pptv; 10(-12) ppv) at 200 mbar (approximately 11.8 km) declining to 2.86 +/- 0.29 pptv at 100 mbar (approximately 16.2 km) and 1.95 +/- 0.50 pptv at 30 mbar (approximately 23.9 km) have been retrieved. The profiles show no obvious dependence with latitude over the range of the measurements (eight occultations spanning 28-degrees-S to 54-degrees-S). Assuming an exponential growth model and applying a correction for the interhemispheric concentration difference, an average SF6 rate of increase of 8.7 +/- 2.2% per year, 2 sigma, between 12 and 18 km has been derived by fitting the present measurements, ATMOS measurements from the April-May 1985 Spacelab 3 mission, and balloon-borne IR measurements obtained in March 1981 and June 1988. [less ▲]

Vie et oeuvre de Guillaume Lekeu

Conference given outside the academic context (1993)

Surface concentration of chain ends in polystyrene determined by static secondary ion mass spectroscopy

in Macromolecules (1993), 26(23), 6251-6254

Site-directed mutagenesis of dicarboxylic acid residues of the penicillin-binding module of the Escherichia coli penicillin-binding protein 3

in FEMS Microbiology Letters (1993), 113(3), 247-251

The glutamic acid E396, aspartic acid D409 and glutamic acid E411 residues of the Escherichia coli penicillin-binding protein 3 were each converted into an alanine residue. As deduced from penicillin ... [more ▼]

The glutamic acid E396, aspartic acid D409 and glutamic acid E411 residues of the Escherichia coli penicillin-binding protein 3 were each converted into an alanine residue. As deduced from penicillin-binding and complementation experiments, none of these dicarboxylic acid residues is involved in the mechanism of acylation by penicillin and none of them is essential for the in vivo functioning of the PBP. The mutation E396, however, causes an increased thermolability of the protein. [less ▲]

Interactions between Active-Site-Serine Beta-Lactamases and Mechanism-Based Inactivators: A Kinetic Study and an Overview

in Biochemical Journal (1993), 295((Pt 3)), 705-711

The interactions between three class A beta-lactamases and three beta-lactamase inactivators (clavulanic acid, sulbactam and olivanic acid MM13902) were studied. Interestingly, the interaction between the ... [more ▼]

The interactions between three class A beta-lactamases and three beta-lactamase inactivators (clavulanic acid, sulbactam and olivanic acid MM13902) were studied. Interestingly, the interaction between the Streptomyces cacaoi beta-lactamase and clavulanate indicated little irreversible inactivation. With sulbactam, irreversible inactivation was found to occur with the three studied enzymes, but no evidence for transiently inactivated adducts was found. Irreversible inactivation of the S. albus G and S. cacaoi enzymes was particularly slow. With olivanate, irreversible inactivation was also observed with the three enzymes, but with the S. cacaoi enzyme, no hydrolysis could be detected. A tentative summary of the results found in the literature is also presented (including 6 beta-halogenopenicillanates), and the general conclusions underline the diversity of the mechanisms and the wide variations of the rate constants observed when class A beta-lactamases interact with beta-lactamase inactivators, in agreement with the behaviours of the same enzymes towards their good and poor substrates. [less ▲]

Mixmaster universe in fourth-order gravity theories

in Physical Review. D : Particles and Fields (1993), 48

We analyze the behavior of the Bianchi type-IX cosmological model in the full fourth-order theory of gravity in four space-time dimensions on approach to the singularity both analytically and numerically ... [more ▼]

We analyze the behavior of the Bianchi type-IX cosmological model in the full fourth-order theory of gravity in four space-time dimensions on approach to the singularity both analytically and numerically. By directly analyzing the full fourth-order field equations we prove explicitly that the Belinski-Khalatnikov-Lifshitz (BKL) analytic solution (and the accompanying bounce law) is also a solution to the more general case that we consider. But it appears to be nongeneric, because a perturbation analysis shows that power-law Kasner asymptotes are unstable on approach to the singularity. On the other hand, we find that the model possesses a stable isotropic monotonic power-law asymptotic solution and accordingly we show that there is a general solution which is nonchaotic near the space-time singularity. Numerical experiments confirm the existence of such a behavior. The inclusion of matter fields does not alter the evolution in the neighborhood of the singularity. The role of space-time dimensionality on the chaotic evolution of the mixmaster universe in these theories is also spelled out. In particular, we show that it is impossible to build a mixmaster universe in space-time dimensions higher than four in the full fourth-order gravity theory based on the BKL approximation scheme. [less ▲]

Towards a rational utilization of satellite imagery for Lisbon's metropolitan planning

in EARSeL International Journal "ADVANCES IN REMOTE SENSING" (1993), 2(3), 130-137

The knowledge of the actual structure and 'intensity of land cover is a fundamental information for the urban planning. Some aspects of the seeked information can be extracted from satellite imagery. This ... [more ▼]

The knowledge of the actual structure and 'intensity of land cover is a fundamental information for the urban planning. Some aspects of the seeked information can be extracted from satellite imagery. This presentation gives some exemples over the Metropolitan area of Lisbon. First, an image segmentation is accomplished over an XS3 band. This process leads to a rather valid subdivision of the region in morphological units. Secondly, the urban and vegetal categories, issued from a land cover classification, are modeled in the form of statistical surfaces. The statistical surfaces take advantage of the analytical power of a raster solving approach. Fi-nally, the urban and vegetal intensity surfaces are merged. The result can be considered as an attempt of ecozoning the considered region. The paper discuss also the possibilities of using remotly sensed data for urban planning. [less ▲]