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Biomedical subjects

B Bonnet

Publications and source records attributed to B Bonnet.

32 records · Page 2Linked to original sources
PubMed1990

Structural abnormality in LDL from diabetic patients as revealed by resonance Raman spectroscopy.

Resonance Raman spectra of low-density lipoprotein (LDL) isolated from the plasma of diabetic patients (age range 13-77 yr, mean age 37 yr) and age- and sex-matched control subjects were recorded in the 1000- to 1600-cm-1 region as a function of temperature (0-50 degrees C). Both nondiabetic and diabetic LDL yield spectra characterized by two major bands near 1160 and 1530 cm-1 due to the carotenoid component of lipoproteins. The relative intensity of 1530- and 1160-cm-1 bands, assigned to -C = C- and = C-C = stretchings, respectively, i.e., I1530-I1160 ratio, was plotted against temperature. For nondiabetic control subjects, the plots showed an inflection in the temperature range of 30-39 degrees C, which corresponded to the thermal transition of LDL. This transition was abolished in the LDL of diabetic patients (P less than 0.001), suggesting an altered lipid structure. The transition (30-39 degrees C) was also abolished in the in vitro glycosylated nondiabetic LDL. Lipid analysis did not show any appreciable change between nondiabetic control subjects and diabetic patients. The change in the thermal transition properties of diabetic LDL has been attributed to the organizational change in the LDL protein.

Adolescent↗
PubMed1985

Raman studies of structural rearrangements induced in human plasma lipoprotein carotenoids by malondialdehyde.

Raman and resonance Raman spectra of plasma lipoproteins +/- malondialdehyde were studied at concentrations which block the normal receptor-mediated uptake by cells. The strong resonance Raman bands at about 1010, 1162 and 1530 cm-1, due to the presence of carotenoids in the lipoproteins, are envisaged as structural probes. High resolution resonance Raman spectra of the 1500-1600 cm-1 region reveal multiple features suggesting the coexistence of several structural populations of beta-carotene whose precise assignment is complex. When plasma lipoproteins are reacted with malondialdehyde, a complex change occurs in the resonance Raman banding of beta-carotene in the 1500-1600 cm-1 region. Malonaldehyde (MDA) also modifies the acoustical region (70-200 cm-1 of low density lipoprotein (LDL) lipids. We suggest that malondialdehyde association with plasma lipoproteins alters the lipid structure via apoprotein or apoprotein/lipid associations.

Apolipoproteins↗
PubMed1984

Resonance Raman spectra of beta-carotene in native and modified low-density lipoprotein.

Low-density lipoproteins isolated between density 1.02 and 1.063 g/cm3 from normal fasting human plasma, show strong resonance Raman spectra due to the presence of beta-carotene. Three intense bands, at 1010, 1160 and 1530 cm-1, are assigned to the stretching vibrations of -C-CH3, = C-C = and -C = C- bonds, respectively, of beta-carotene. High-resolution spectra of the 1500-1600 cm-1 region reveal multiple features, suggesting the coexistence of several structural populations of beta-carotene. The modifications of lipoproteins with pH and temperature (30 degrees-42 degrees) change the resonance Raman spectra of beta-carotene. The specific binding of LDL at pH 7.0 by fibroblast cells is suppressed. Our experiments thus suggest that physical and chemical perturbations of plasma lipoproteins modify the lipid-protein interactions and thereby alter the configurational distribution of beta-carotene molecules within these particles.

Carotenoids↗
PubMed1984

Rhythmic circumnutation movement of the shoots in Phaseolus vulgaris L.

The apex of growing stems in twining plants describes a rhythmic movement in space called circumnutation. By the method of orthogonal projections, the position in space of the apex can be determined constantly. The mathematical analysis of data allowed us to determine that for Phaseolus vulgaris L. (cv. Mangetout Blanc de Juillet) grown under constant illumination and temperature (25 degrees C) the period is about 100 min. This movement has been related to rhythmic changes in the osmotic potential of the cells located in the bending zone of the stem for a constant period. These variations are longitudinally and laterally coordinated. Treatment with a solution of LiCl at 7 X 10(-3) M supplied to the root system induces a lengthening of the period. The effect of the treatment is reversed by K+ ions. From these results we deduce that rhythmic changes of the membranes are implicated in the circumnutation movements of twining plants.

Chlorides↗
PubMedDate not supplied

[Pyogenic osteomyelitis in Gaucher's disease].

Gaucher's disease is a sphingolipidosis which may be accompanied by severe pain in the bones. We report a case of Bacteroides fragilis osteomyelitis consecutive to surgical biopsy. The bone pain may be due to ischaemia of the bone or to a pyogenic osteomyelitis which is iatrogenic in most cases. The clinical and paraclinical features of these two entities are described after a review of the literature, and the main complementary examinations leading to their diagnosis are presented.

Adult↗
PubMedDate not supplied

A Raman spectroscopic investigation of dentin and enamel structures modified by lactic acid.

Confocal Raman microspectrometry allows a thorough molecular analysis of mineralised dental tissues. The output information is provided in the form of curves representing the intensity of the signal according to the frequency, and its mathematical exploitation permits all sorts of comparative and quantitative analyses. By this process, we investigated the in vitro action of lactic acid on enamel and dentin from human permanent teeth. Modifications due to the acidic attack essentially concern phosphate grouping PO(4)(3-), which represents the mineral phase in enamel and dentin (hydroxyapatite): on Raman spectra, changes in intensity of the PO(4)(3-) band are linked to the type of dentin, to its anatomical location, and to the age of the subject. The variability of the dentinal chemical structure was confirmed by a quantitative statistical analysis, revealing a significant spectral difference between coronal and root dentin.

Adult↗