Is skin autofluorescence a marker of metabolic memory in pregnant women with diabetes?

AIM: To determine whether skin autofluorescence can help to detect those who have previously had abnormal glucose levels among women referred for diabetes during pregnancy. METHODS: Using an advanced glycation end product reader (AGE Reader(tm) (;) DiagnOptics BV, Groningen, the Netherlands), we measured forearm skin autofluorescence at 24-30 weeks of gestation in all women who were referred to our Nutrition Diabetology unit for diabetes during pregnancy. RESULTS: The study included 230 women (200 with gestational diabetes and 30 with pre-gestational diabetes, of whom 21 had Type 1 and nine had Type 2 diabetes) and a reference group of 22 normoglycaemic non-pregnant women. Skin autofluorescence was significantly higher in women with pre-gestational diabetes (1.97 ± 0.44 arbitary units) compared with gestational diabetes (1.77 ± 0.32 arbitary units; P = 0.003) and lower in the reference group (1.60 ± 0.32 arbitary units; P = 0.009 vs all pregnant women). Among women with gestational diabetes, 71 had a history of hyperglycaemia (i.e. gestational diabetes or macrosomia in a previous pregnancy or discovery of diabetes before 24th gestational week in the present pregnancy). These women had higher levels of skin autofluorescence (1.83 ± 0.35 arbitary units) than women with gestational diabetes without previous history of hyperglycaemia (1.73 ± 0.30 arbitary units; P = 0.04, non-significant, adjusted for age). Skin autofluorescence increased with the number of criteria present for previous hyperglycaemia (P for trend = 0.008) and was significantly associated with having two or three criteria for hyperglycaemia after adjusting for age (P = 0.02). CONCLUSIONS: Skin autofluorescence could reflect previous long-term hyperglycaemia in pregnant women, and could therefore be a marker of metabolic memory.

Control and prediction of the course of brewery fermentations by gravimetric analysis.

A simple, fast and cheap test suitable for predicting the course of brewery fermentations based on mass analysis is described and its efficiency is evaluated. Compared to commonly used yeast vitality tests, this analysis takes into account wort composition and other factors that influence fermentation performance. It can be used to predict the shape of the fermentation curve in brewery fermentations and in research and development projects concerning yeast vitality, fermentation conditions and wort composition. It can also be a useful tool for homebrewers to control their fermentations.

[A Nematode Nobel Prize: Caenorhabditis elegans]. / Un Nématode Prix Nobel: Caenorhabditis elegans.

The Nematode Caenorhabditis elegans (C. elegans) is an established model increasingly used for studying human disease pathogenesis. C. elegans models are based on the mutagenesis of human disease genes conserved in this Nematode or on the transgenesis with disease genes not conserved in C. elegans. Genetic examinations will give new insights on the cellular and molecular mechanisms that are altered in some neurodegenerative diseases like Duchenne's muscular dystrophy, Huntington's disease and Alzheimer's disease. C. elegans may be used for primary screening of new compounds that may be used as drugs in these diseases.

Biochemical and metabolic peculiarities of some parasites availing as targets for therapy.

Biochemical and metabolic peculiarities of some parasites involved in their interactions with their hosts are reviewed according to (1) carbohydrate metabolism comprising glycolysis, Pasteur effect, CO2 fixation and electron transport system; (2) amino acid and protein metabolism ; (3) purine and pyrimidine nucleotides metabolism. These peculiarities are becoming targets for treatment without affecting the host.

The mechanisms of action of antiprotozoal and anthelmintic drugs in man.

The mechanisms of action of antiprotozoal and anthelmintic drugs are reviewed according to: (1) drugs interfering with metabolic processes; (2) drugs interfering with reproduction and larval physiology; and (3) drugs interfering with neuromuscular physiology of parasites.

A high-yield outbred suckling mouse model of cryptosporidiosis.

Outbred suckling mice (NMRI strain) were used as hosts. They were initially inoculated with oocysts of human origin, and subsequently with parasites recovered from the mouse ileal mucosa. Cryptosporidia were counted in an aliquot of whole-ileum homogenate. Parasite load was expressed as cryptosporidia per centimeter of ileum. Serial passage of C. parvum in NMRI mouse litters led to a gradual amplification of parasite burden relative to animals initially inoculated with the human isolate.

Intestinal lipid metabolism in suckling rats infected with Giardia duodenalis.

We carried out a quantitative and qualitative analysis of intestinal digestion of neutral lipids in suckling rats infected with Giardia duodenalis. Total lipids were measured after extraction from the contents of the stomach, proximal and distal small bowel, caecum and colon. Amounts gradually fell from the stomach to the colon and were identical in infected animals and controls, although high values were occasionally found in the caecum of infected rats. Relative glyceride quantities were determined by means of high-performance thin-layer chromatography. Triglycerides were absent from the distal small bowel, and only free fatty acids and cholesterol were present in the caecum, reflecting normal digestion of neutral lipids in infected suckling rats. Our results suggest that G. duodenalis does not impair intestinal fat digestion in suckling rats.

Plasmodium falciparum: differential sensitivity in vitro to E-64 (cysteine protease inhibitor) and Pepstatin A (aspartyl protease inhibitor).

We investigated the effect of a cysteine proteinase inhibitor (E-64) and an aspartyl proteinase inhibitor (Pepstatin A) on asexual erythrocytic stages of Plasmodium falciparum in culture. These two protease inhibitors showed different patterns of activity. E-64 acted preferentially against trophozoite and schizont stages. After 48 h incubation at high concentrations of E-64 (28, 140, 280 microM), growth was totally abolished and the parasites presented characteristic enlarged food vacuoles. Morphological alterations were also seen after shorter incubation periods (6 h at 28 microM) or 12 h at the inhibitory concentration 50% (12 microM), but an additional culture period (24 h) in inhibitor-free medium allowed normal parasite development, demonstrating a parasitostatic effect. E-64 acts on parasite multiplication; the normal merozoite maturation was altered and the normal reinvasion process partially impaired. Pepstatin A used at the inhibitory concentration 50% (4 microM) killed the parasites before trophozoite development and had a major effect on schizonts maturation. No altered parasite development occurred during an additional culture period without Pepstatin A, demonstrating a parasiticidal effect. E-64 and Pepstatin A used in combination inhibit the parasite growth with a strong synergistic effect.

[Participation of cytokines and immune sera to the cytoadherence of erythrocytes infected by Plasmodium falciparum on the endothelial cells in culture]. / Participation des cytokines et des sérums immuns à la cytoadhérence des hématies parasitées par Plasmodium falciparum sur des cellules endothéliales en culture.

In vitro binding capacity of erythrocytes infected with P. falciparum and the modulation of cytoadherence on human endothelial cells by cytokines and sera from semi immune subjects in relation to cytoadherence were studied. Tumor necrosis factor and interleukin-3, alone or in combination with granulocyte macrophage-colony stimulating factor, enhanced in vitro cytoadherence. Contrary to pooled immune sera, patients' sera obtained during acute or convalescent phase did not reverse nor inhibit in vitro cytoadherence.

Lymphoproliferative responses to synthetic peptides from merozoite ring-infected erythrocyte surface antigen and circumsporozoite protein: a longitudinal study during a falciparum malaria episode.

Proliferative responses of peripheral blood lymphocytes to synthetic peptides representing major epitopes of two malaria antigens (the merozoite ring-infected erythrocyte surface antigen and the sporozoite circumsporozoite protein) were investigated in Madagascar during a clinical Plasmodium falciparum episode. Thirty-seven patients greater than 10 years of age were enrolled at the beginning of the malaria transmission season and followed for four weeks. At enrollment, when the subjects presented with an acute infection, lymphocytes recovered from approximately 30% of them proliferated after peptide stimulation. These proliferative responses decreased sharply one and two weeks after treatment, with less than 10% responding to each peptide. Four weeks after treatment, the responses were only partially restored. The amplitude of these variations was not related to the initial parasitemia. At the individual level, proliferative response to each peptide varied greatly during the followup period, and this variation was unrelated to the presence of parasites in the blood.

Human immune response in Plasmodium falciparum malaria. Synthetic peptides corresponding to known epitopes of the Pf155/RESA antigen induce production of parasite-specific antibodies in vitro.

Autologous cell mixtures containing T cells, B cells, and adherent accessory cells from individuals primed to the malaria parasite Plasmodium falciparum by repeated natural infections were investigated for induction of Ig and antibody secretion in vitro. In vitro activation of cell cultures with two synthetic peptides corresponding to immunodominant T cell epitopes of the merozoite Ag ring-infected erythrocyte surface Ag (Mr 155,000) (Pf155/RESA), one from its carboxyl-terminal repeat and one from its nonrepeated amino-terminal region, gave rise to significant IgG secretion. Supernatants from lymphocyte cultures activated with either one of these peptides contained antibodies reacting with P. falciparum Ag in immunofluorescence assays and with Pf155/RESA peptides in a slot blot assay. No anti-P. falciparum antibodies were induced in the medium controls by lymphocyte stimulation with either tetanus toxoid or PWM. Induction in vitro of anti-Pf155/RESA antibodies was correlated with the presence of such antibodies in the sera of the lymphocyte donors, suggesting that the induction of antibody secretion reflected a secondary response in vitro of in vivo primed cells. Inspection of antibody profiles in individual donors revealed that the peptide corresponding to a sequence in the 3' repeat region induced anti-Pf155/RESA peptide antibodies reacting with identical or related and cross-reacting sequences in the 3' or 5' repeat region of the molecule. In contrast, the peptide corresponding to a nonrepeated T cell epitope in the amino terminus of the molecule only induced antibodies to an immunodominant amino-terminal B cell epitope partly overlapping with the T cell reactive sequence. Similar findings were made in the lymphocyte donors' plasma, frequently displaying significant correlations between antibody reactivities to the repeat peptides but not between these reactivities and those to the amino-terminal peptide. The marked specificity of this antibody formation in vitro suggests an underlying process of cognate recognition involving Ag-specific T and B cells reacting with different segments of the inducer peptide. The present experimental system should be well suited for identification of Th epitopes capable of inducing the production of antibodies of defined specificity in the human system.

Antimalarial activity and cytotoxicity of Evodia fatraina stem bark extracts.

Stem bark extracts of Evodia fatraina (Rutaceae) were tested for antimalarial activity in vitro on Plasmodium falciparum using an isotopic semi-microtest and in vivo on Plasmodium berghei in mice. Ethyl acetate extract showed moderate antimalarial activity in vitro (IC50 = 8.5 micrograms ml-1). However, ethanolic extract exhibited significant potency in vivo (65% suppression of parasitaemia). Moreover, low toxicity against HeLa cells and L 929 fibroblasts was observed with ethanolic extract (IC50 = 95 micrograms ml-1 and 60 micrograms ml-1, respectively).

Persistence of cellular and humoral response to synthetic peptides from defined Plasmodium falciparum antigens.

The cellular and humoral immune responses to synthetic peptides reproducing the repeat sequences of two major vaccine candidates (circumsporozoite protein and Pfl55/RESA) were investigated in two groups of African subjects according to the length of their stay outside endemic areas. The relation between the lymphoproliferative response and the antibody levels to these antigens was studied. The results confirm the existence of T-cell epitopes within the repeat sequences of the CS protein and the Pfl55/RESA capable of inducing lymphocyte proliferation. Cellular response to all studied peptides was more frequently observed in individuals living in France for less than one year than in individuals living in France for a longer time. T-cell proliferation in the presence of the tetrapeptide and of the octapeptide from the C-terminus repeat of Pfl55/RESA was related, with an immunodominance of the tetrapeptide over the octapeptide. Cellular responses to the CS protein repeat and to the 11-amino-acid peptide from the Pfl55/RESA N-terminus were the longest lasting after termination of exposure. In a given individual, cellular and humoral responses were not related for any peptide studied.

Plasmodium falciparum: isolation and characterization of a 55-kDa protease with a cathepsin D-like activity from P. falciparum.

Native electrophoresis followed by imprint digest method using hemoglobin as substrate allowed the detection of parasite hemoglobinase activity at acidic pH (3.9 to 5). This protease was inhibited specifically by pepstatin A and insensitive to other protease inhibitors. The molecular weight determination using modified SDS-PAGE followed by imprint digest method, demonstrated a single area of activity at 55-58 kDa, similar to cathepsin D characterized in eucaryotic cells. The parasitic origin has been shown by radiolabeling experiments with [35S]-methionine. The 55-kDa protein was immunoprecipitated by a rabbit anti-cathepsin D serum.

[Intestinal humoral immunity and digestive opportunistic infections associated with AIDS]. / Immunité humorale intestinale et infections opportunistes digestives associées au SIDA.

The infectious diarrhea in AIDS is principaly due to Cryptosporidium. The study of the inflammatory and humoral immunity proteins reveal a high exudative enteropathy associated with an IgA, IgG and IgM intestinal immune response. However, this barrier of defence is not sufficient to eradicate the infectious agent.

[Giardia intestinalis: transmission electron microscopy study of in vitro excystation]. / Giardia intestinalis: étude en microscopie électronique à transmission du dékystement in vitro.

The in vitro excystation process in Giardia intestinalis was studied by transmission electron microscopy (TEM). Untreated cysts served as controls. The excystation process was monitored by examination of organisms after the in vitro induction and at several times during the incubation phase. The control cyts had a thick wall, made of microfibrils, that appeared not to contain any weak areas. The peritrophic space extended between the cyst wall and the organism peripherally, the space was delimited by a thin cytoplasmic layer, "the outer cytoplasmic envelope" that subtended the cyst wall. During the in vitro incubation, the trophozoite cytoplasm retracted from the wall; thus, the peritrophic space became progressively larger. The outer cytoplasmic envelope detached from the cyst wall, then broke up forming numerous small vesicles lodged between the wall and the organism. The tight arrangement of the wall microfibirils was lost. Electron-dense vacuoles appeared in the peripheral cytoplasm of the trophozoite. The organism emerged through the posterior end of the cyst, leaving behind the empty husk. Emergence was followed by cell division. The possible interrelationships of biochemical and mechanical factors affecting the process of excystation are discussed in light of the present TEM findings.