Lucette Bardet

Variations of Lactose and Oligosaccharides in Milk from Women of Blood Types Secretor A or H, Secretor Lewis, and Secretor H/Nonsecretor Lewis during the Course of Lactation

Variations of lactose and oligosaccharides in human milk were studied over a 3-month lactation period by dialysis, chromatography on Bio-gel P-2 column, paper chromatography, colorimetric analysis and gas chromatography. Milk samples were collected from donors of various blood and secretor types. An increase in the concentration of lactose was noted: 59.25 +/- 1.61 to 72.17 +/- 1.35 g/l for the group of secretor A secretor Lea Leb individuals, and from 62.25 +/- 1.35 to 73.15 +/- 3.45 g/l for the group of secretor H secretor Lea Leb individuals. A decrease in the concentration of oligosaccharides was also found: from 16.71 +/- 0.99 to 7.90 +/- 1.29 g/l and from 18.51 +/- 0.74 to 7.33 +/- 0.65 g/l, respectively, for these same groups. In secretor H nonsecretor Lewis individuals, the concentration of lactose increased from 67.97 +/- 3.09 to 77.42 +/- 1.88 g/l, and the concentration of oligosaccharides decreased from 13.27 +/- 0.40 to 3.47 +/- 0.33 g/l. Analysis of oligosaccharide composition by chromatography showed that variations are in relation to the secretor Lewis type. All oligosaccharides decreased equally throughout the lactation period, regardless of the blood group. The decrease was more rapid, however, in the nonsecretor Lewis individuals. In these individuals, the absence of certain oligosaccharides is not compensated by an overproduction of the other oligosaccharides present or by biosynthesis of structurally different oligosaccharides. The origin of these oligosaccharides is discussed.

Discriminant carbohydrate components of human milk according to donor secretor types.

Because of the variability of human milk carbohydrate composition, we determined the discriminant carbohydrate components of the milk of 18 mothers according to their ABH and Lewis secretor types during the first week of lactation. Comparative chromatograms revealed that the presence of neuraminyloligosaccharides is linked to the ABH secretor groups, and that the absence of oligosaccharides with Lea or Leb specificity is linked to the Lewis nonsecretor types. The study of carbohydrate composition according to donor secretor types consisted of measuring 16 variables from 69 samples. Analysis of variance showed significant differences between groups: high levels of N-acetylneuraminic acid and low levels of galactose distinguished ABH secretors from nonsecretors (p < 0.001). In the ABH secretor groups, A and H secretors had higher N-acetylglucosamine contents than B and AB secretors (p < 0.001) and lower galactose levels (p < 0.001). The Lewis secretor groups were distinguished by significantly higher fucose levels (p < 0.001). The ABH(+)Le(a - b -) group had higher lactose contents than the other groups (p < 0.01).

Effects of oral zinc gluconate on glucose effectiveness and insulin sensitivity in humans

Zinc improves both insulin secretion and insulin sensitivity, and exerts insulin-like effects. We investigated its acute effects on the parameters of glucose assimilation determined with the minimal model technique from frequent sampling intravenous glucose tolerance test (FSIVGTT) in seven healthy volunteers. FSIVGTTs (0.5 g/kg of glucose, followed by 2 U insulin iv injection at 19 min) were performed after the subjects had taken 20 mg zinc gluconate twice (the evening before and 30 min before the beginning of the test) or placebo pills (simple blind randomized protocol). Glucose assimilation was analyzed by calculating Kg (slope of the exponential decrease in glycemia), glucose effectiveness Sg (i.e., ability of glucose itself to increase its own disposal independent of insulin response), and SI (insulin sensitivity, i.e. the effect of increases in insulinemia on glucose disposal). The two latter parameters were calculated by fitting the experimental data with the two equations of Bergman’s “minimal model”. Zinc increased Kg (p<0.05) and Sg (p<0.05), whereas SI and insulin first-phase secretion did not significantly increase. This study suggests that zinc improves glucose assimilation, as evidenced by the increase in Kg, and that this improvement results mainly from an increase in glucose effectiveness (insulin-like effect), rather than an action on insulin response or insulin sensitivity.

Variations in oligosaccharides and lactose in human milk during the first week of lactation.

Variations in oligosaccharides and lactose in human milk were studied in 15 mothers during the first week of lactation. The neuraminyloligosaccharides and heavy neutral oligosaccharides increased slightly from days 2 to 5 postpartum and appeared to decrease until day 7. The lacto-N-difucohexaoses, lacto-N-fucopentaoses, and lacto-N-tetraose increased until day 5 and then decreased. Lactodifucotetraose and the fucosidolactoses decreased substantially until day 5 (p < 0.05) and appeared to stabilize in the following days. Lactose increased until day 5 (p < 0.05) and continued to increase thereafter. Lactose was negatively correlated with total oligosaccharides (p < 0.10). The fluctuations observed in total oligosaccharides from days 2 to 5 postpartum and their subsequent stabilization and regular decrease during lactation confirm the hypothesis of Kulski and Hartmann that mammary secretion occurs in three periods: colostrum for the first 36 h postpartum, transitional milk from days 2 to 5 postpartum, and mature milk after day 5. The oligosaccharide variations we found corresponded to those of other milk constituents observed by other authors. The significance of the oligosaccharide variations is discussed.

Serum zinc in highly trained adolescent gymnasts

Serum zinc was measured in 20 adolescent gymnasts (9 boys, 11 girls, age 12–15 yr) explored for detecting possible adverse effects of intense training on pubertal maturation and growth. They had low serum zinc (0.599±0.026 mg/L) when compared to matched control sedentary children (n=118 mean 0.81±0.014p<0.001). Girls had lower zinc than boys (0.557±0.023 vs 0.651±0.044p<0.001). Zinc was correlated to isometric adductor strength (r=0.468p<0.05). Children with serum zinc <0.6 mg/L had lower insulin-like growth factor binding protein 3 than others (2.326±0.264 vs 2.699±0.12p<0.01). Thus, zinc is lowered in trained adolescent gymnasts and even lower in females. This reduction could play some role in abnormalities of puberty, growth, or muscular performance.

Raman spectra of glycolic acid, L-lactic acid and D,L-lactic acid oligomers

Abstract Polymerization of glycolic acid, l - and d,l -lactic acid was followed by Raman spectroscopy in aqueous solution at different concentrations, in viscous and solid states. The Raman spectra of some oligomers obtained by progressive polycondensation of α-hydroxycarboxylic acid aqueous solutions were investigated in the 200–18 cm −1 region. Vibrational analysis revealed the characteristic peaks of ester groups that appeared in the repeat unit of the polymeric chain during the polymerization reaction, and those of the monomers which disappeared. In particular, the ν(CC) stretching vibrations occur in the 800–1000 cm −1 range, which is easily accessible because of the weak diffusion of water. Moreover, spectral monitoring of the semicrystalline sample of poly(glycolic acid) oligomers showed Raman peaks associated with the vibrations of the polymer in the amorphous and semicrystalline states.

Diurnal variations and within the feed in lactose and oligosaccharides of human milk

Variations of lactose and oligosaccharides in human milk were studied during the day and the feed, by dialysis, chromatography on Bio-gel P-2 column, paper chromatography, colorimetric analysis and gas chromatography. Progressive changes were found during the day, but not during the feed. A diurnal variation in milk lactose was seen, which was the inverse of the oligosaccharides. Significant negative correlations between lactose and oligosaccharides were seen in the afternoon and evening (p less than 0.05). The minimal mean value of lactose at 19.00 h is 58.64 +/- 5.28 g/l and the maximal mean values of oligosaccharides was 17.93 +/- 2.28 g/l. The data are discussed with regard to other milk constituents and to their possible physiological relevance.

Analyse vibrationnelle et structurale en série aliphatique insaturée: II. Spectres raman des acides fumarique et maléique en solution

Abstract The Raman spectra of fumaric and maleic acids in solution (H 2 O and D 2 O) have been studied from 250 to 4000 cm − . The analysis of the polarisation ratio of the observed lines has led us to establish that the fumaric acid molecule is planar (symmetry C 2h ) whereas the maleic acid is non-planar, this molecule belonging either to the C s group (the plane of symmetry being perpendicular to the C C double bond) or more probably to the C 2 group. An assignment of the observed lines as fundamentals is proposed.

Serum zinc and somatic growth in children with growth retardation

A possible role for zinc deficiency in some cases of growth retardation in southern France was investigated. Control values for zinc for 160 children (age=12.5±2.4 yr) are 0.85±0.22 mg/L (mean ±2 SD). Twenty-five children with low serum zinc values (<0.63 mg/L) and 25 matched short children with normal serum zinc values (>0.63 mg/L) were studied. Children in the two groups did not differ significantly in age, pubertal development, stature, and weight. For the 25 children whose serum values were low, we found significantly lower values for bone age delay, growth velocity in mm/month, as well as the ratio between calculated growth velocity and theoretical growth velocity for the bone age (so that zincemia was correlated to these parameters in the whole sample of 50 subjects). Nevertheless, no significant difference could be found between the two groups for serum somatomedin C, serum osteocalcin values, and GH responses to the GH stimulatory tests (exercise test, overnight sampling, insulin-induced hypoglycemia, arginine test). Therefore, low serum zinc is associated with a retardation in both somatic growth and pubertal maturation.

In vitro influence of zinc and magnesium on the deformability of red blood cells artificially hardened by heating

Trace elements have been shown to improve red blood cell (RBC) deformability: zinc in sickle cell disease and magnesium in an in vitro model of chemically rigidified erythrocytes. In this study, we investigated the effect and the influence of incubation time of zinc or magnesium on an in vitro model of rigidified RBCs by heating. Erythrocyte rigidity was determined by viscosimetry at high shear rate by a falling ball viscosimeter MT 90.In the first part of the study, six normal volunteers participated. Viscosimetry was performed on native blood before and after heating the sample for 10 min at 50°C. Therefore, increasing concentrations of zinc gluconate (final concentration: 0.5–4 g/L) or isotonic NaCl as control medium were added to the sample. Heating induced a twofold increase in all indices of RBC rigidity (p<0.05). At all these concentrations of zinc, a highly significant, dose-related fluidifying effect was observed (40–70%): this effect was immediately obtained and did not change over 60 min. Even at the highest concentration, recovery was not complete.In the second part of the study, we studied magnesium’s effects on blood. In a first protocol, whole blood was rigidified by heating at 56°C for 10 min, and the correcting effect of 5 min of incubation at 37°C of RBCs in 150 mmol/L NaCl, MgSO4, magnesium acetate, and magnesium gluconate was investigated. In a second protocol, the same incubation with NaCl and magnesium salts was made on blood that had not been previously heated. In a third protocol, the correcting effect of magnesium gluconate on heated red blood cells was tested at four concentrations (75, 150, 225, and 300 mmol/L) over 1 h, for evaluating the effects of both concentration and time. Erythrocyte rigidity by heating is corrected by the three salts employed in protocol 1 (compared to sodium). In protocol 2, the deformability of normal (nonheated) red cells is not modified by magnesium. In protocol 3, no marked modification over 1 h is observed. The correcting effect is not complete for 75 mmol/L Mg, but remains the same at the three other concentrations.This study shows that zinc and magnesium at supraphysiological concentration are able to reverse RBC’s rigidification induced by heating, but that magnesium does not modify the flexibility of normal RBCs. This article suggests that zinc and magnesium may be studied in vivo as potential pharmacologic tools for improving hemorheologic disturbances.