[Current and new therapeutic options in inborn errors of metabolism]. / Actualités thérapeutiques dans les erreurs innées du métabolisme.

Inborn errors of metabolism (IEM) represent a vast group of orphan genetic disorders associated with enzyme deficiencies, substrates accumulation and products depletion. For several decades, the cornerstone of life-saving therapies in IEM was based on extreme manipulations of the nutritional intakes. Such outstanding dietary engineering is still relevant today, but new therapeutic avenues have emerged last years, based on better pathophysiological understanding and technological advances. In this paper, we summarize current and new therapeutic options in the field of IEM.

Les erreurs innées du métabolisme (EIM) représentent un groupe de conditions génétiques associées à une déficience enzymatique causant une accumulation du substrat en amont de la réaction et une déficience du produit en aval. Pendant des décennies, la pierre angulaire du traitement de ces affections a été basée sur des régimes drastiquement restrictifs. Ces manipulations diététiques extrêmes sont encore aujourd'hui d'actualité, mais l'arsenal thérapeutique s'est considérablement élargi ces dernières années, basé sur de meilleures connaissances physiopathologiques et sur des progrès technologiques et pharmacologiques. Dans cet article, nous résumons les différentes stratégies et nouveautés thérapeutiques dans le domaine des erreurs innées du métabolisme.

Discriminant value of blood and urinary corticoids for the diagnosis of scrapie in live sheep.

The mean (sd) concentration of plasma 20beta-dihydrocortisol in 126 scrapie-affected sheep was 5-5 (7.0) ng/ml compared with 1.1 (0.7) ng/ml in 52 healthy sheep. The mean (sd) concentration of creatinine in the urine of 93 scrapie-affected sheep was 2.43 (1.56) microg/ml compared with 0.94 (0.86) pg/ml in 49 healthy sheep and 1.10 (0-95) pg/ml in 25 sheep with other diseases. These discriminant analyses carried out on healthy and scrapie-affected sheep showed that plasma 20beta-dihydrocortisol and urinary creatinine were the best predictors of the disease, and classified correctly 98 per cent of healthy sheep and 82 per cent of scrapie-affected sheep.

Tartric acid-based linker for the solid-phase synthesis of C-terminal peptide alpha-oxo aldehydes.

A novel linker, based on the anchoring of (+)-dimethyl 2,3-O-isopropylidene-D-tartrate to PEGA or PEG-PS solid supports, was developed for the solid-phase synthesis of C-terminal peptide alpha-oxo aldehydes. Peptide elongation was performed using the 9-fluorenylmethoxycarbonyl/t-Bu chemistry. The peptide and the 1,2-diol were deprotected on the solid phase. Then, a periodic oxidation of the fully deprotected peptidyl-resin led to the simultaneous cleavage of the product from the solid support and to the generation of the alpha-oxo aldehyde moiety. The methodology allowed the distance between the alpha-oxo aldehyde and the peptide to be easily modulated. The C-terminal peptide alpha-oxo aldehydes synthesized in this study were found to be useful partners in hydrazone, thiazolidine, and oxime chemical ligations.

Synthesis of clustered glycoside-antigen conjugates by two one-pot, orthogonal, chemoselective ligation reactions: scope and limitations.

Major histocompatibility class II antigens have been bound to clustered glycosides for selective targeting of the dendritic cell mannose receptor. Di-, tetra-, and octavalent glycoside-antigen conjugates have been obtained after two, orthogonal, hydrazone/thioether ligations, performed by using thio derivatives of D-mannose, D-galactose, or D(-)-quinic acid, glyoxylyl (or hydrazino)-N-chloroacetylated lysinyl trees, and N-terminal hydrazino (or glyoxylyl) peptide antigens. Successful one-pot condensations have been developed to account for the nature of the antigens and the valency of the trees.

Novel hyperbranched glycomimetics recognized by the human mannose receptor: quinic or shikimic acid derivatives as mannose bioisosteres.

The mannose receptor mediates the internalization of a wide range of molecules or microorganisms in a pattern recognition manner. Therefore, it represents an attractive entry for specific drug, gene, or antigen delivery to macrophages and dendritic cells. In an attempt to design novel effective synthetic mannose receptor ligands, quinic and shikimic acid were selected as putative mannose mimics on the basis of X-ray crystallographic data from the related rat mannose-binding lectin. As the mannose receptor preferentially binds to molecules displaying several sugar residues, fluorescein-labeled cluster quinic and shikimic acid derivatives with valencies of two to eight were synthesized. Their mannose receptor mediated uptake was assayed on monocyte-derived human dendritic cells by cytofluorimetric analysis. Mannose-receptor specificity was further assessed by competitive inhibition assays with mannan, by confocal microscopy analysis, and by expression of the mannose receptor in transfected Cos-1 cells. Constructs derived from both quinic and shikimic acid were efficiently recognized by the mannose receptor with an optimum affinity for the molecules with a valency of four. As a result, commercially available quinic and shikimic acids appear as stable mannose bioisosteres, which should prove valuable tools for specific cell delivery.

Assessing ambulatory geriatric sleep complaints.

Sleep disturbances afflict more than 50% of adults age 65 and older. Sleep apnea and periodic limb movements of sleep are the primary sleep disorders in the elderly. Patient assessment tools, a thorough physical examination, and appropriate tests can simplify the diagnostic process; sleep center referral is not always warranted. Ultimately, accurate sleep disorder diagnoses can result in decreased geriatric morbidity and mortality, and increased patient quality of life.

Major hypercorticism is an endocrine feature of ewes with naturally occurring scrapie.

The aim of this study was to identify the origin of scrapie-induced hypercortisolism. Cortisol and ACTH kinetics and production rate were measured in 14 ewes (6 healthy and 8 scrapie-affected). It was shown that cortisol plasma clearance remained unmodified but that cortisol production rate and plasma concentrations of free cortisol were increased by a factor of 5, whereas the total cortisol plasma concentrations were only doubled. The apparent discrepancy between adrenal secretion rate and the corresponding total cortisol plasma levels was attributable to the scrapie-induced lower corticosteroid-binding globulin (CBG) binding capacity, which altered the ratio of free-to-bound cortisol. The secretion rate of ACTH from diseased ewes was increased by a factor of 1.5, in comparison with healthy ewes, and 4 of the 8 scrapie-affected ewes exhibited a decreased response to a low dexamethasone suppression test. The administration of tetracosactide induced a 2-fold increase in the cortisol production in diseased ewes, compared with that of healthy ewes, but the pituitary sensitivity to ovine CRF was not modified by the prion disease. In conclusion, natural scrapie displays a syndrome of hypercorticism associated with increased ACTH secretion, hyperresponsiveness of the adrenals, and lower CBG binding capacity, which leads to overexposure to CBG-free cortisol.

Melatonin and prolactin secretion profile in naturally occurring scrapie in ewe.

The 24 hr pattern of melatonin secretion was determined in scrapie-affected ewes during the clinical course of the disease. The melatonin response to a night interruption by a 1 hr period of illumination was also measured. Fourteen ewes (seven control and seven scrapie-affected ewes) were subjected to artificial short days (9L:15D). Four 24 hr blood sampling sessions separated by about 10 days were performed. Ewes were sacrificed when clinical signs had progressed to irreversible recumbency and the scrapie diagnosis was confirmed by histopathology. Plasma melatonin was assayed in all samples and prolactin was analysed in samples obtained during the second sampling session using RIA methods. The instantaneous amplitude of elevation of plasma melatonin concentrations was calculated for each ewe and each sampling session and the within-ewe repeatability of this parameter was evaluated. The within-ewe repeatability of instantaneous amplitude of melatonin secretion was apparently greater in control than in scrapie-affected ewes (72% vs. 39%). The light stimulus induced an abrupt decrease of night melatonin concentrations in all ewes. Prolactin secretion was not affected by the disease. It was concluded that the 24 hr pattern of melatonin secretion was maintained in scrapie-affected ewes. The retino-hypothalamic tract transducing light information remained functional in diseased ewes despite some evidence of histopathological changes of the pineal gland. The instability of melatonin secretion during the clinical course of scrapie could reflect a disturbance of pineal function. However, whether this effect exists or not, it could not be used to discriminate scrapie-affected ewes from control ones.

Synthesis of the two monomethyl esters of the disaccharide 4-O-alpha-D-galacturonosyl-D-galacturonic acid and of precursors for the preparation of higher oligomers methyl uronated in definite sequences.

Methyl (alpha-D-galactopyranosyluronic acid)-(1-->4)-D-galactopyranuronate and methyl alpha-D-galactopyranosyl-uronate-(1-->4)-D-galactopyranuronic acid have been synthesized by coupling methyl (benzyl 2,3-di-O-benzyl-beta-D-galactopyranosid)uronate (3) or benzyl (benzyl 2,3-di-O-benzyl-beta-D-galactopyranosid)uronate (4) with benzyl (phenyl 2,3,4-tri-O-benzyl-1-thio-beta-D-galactopyranosid)uronate and methyl (phenyl 2,3,4-tri-O-benzyl-1-thio-beta-D-galactopyranosid)uronate, respectively, using N-iodosuccinimide and trifluoromethanesulphonic acid as promoters, followed by removal of the benzyl groups. The 4'-OH unprotected dimers benzyl (methyl 2,3-di-O-benzyl-alpha-D-galactopyranosyluronate)-(1-->4)-(benzyl 2,3-di-O-benzyl-beta-D-galactopyranosid)uronate and methyl (benzyl 2,3-di-O-benzyl-alpha-D-galactopyranosyluronate)-(1-->4)-(benzyl 2,3-di-O-benzyl-beta-D-galactopyranosid)uronate were prepared from methyl (phenyl 2,3-di-O-benzyl-1-thio-4-O-trimethylsilyl-beta-D-galactopyranosid) uronate and benzyl (phenyl 2,3-di-O-benzyl-1-thio-4-O-trimethylsilyl-beta-D-galactopyranosid) uronate and acceptors 4 or 3, respectively. These compounds have been designed to serve as precursors for the preparation of higher-membered D-galacturonic acid oligomers methyl esterified in definite positions.

Preparation and in vitro antibacterial activity of 9-O-glycosyloxime derivatives of erythromycin A, a new class of macrolide antibiotics.

9-O-Glycosyloxime derivatives of erythromycin A have been synthesized and their in vitro antibacterial activity compared with that of erythromycin A (1). This new class of macrolide antibiotics showed reduced antibacterial spectrum. However, some derivatives were as or more active than erythromycin A (1) against strains, responsible for respiratory track infections, such as Haemophilus influenzae, Moraxella catarrhalis or Streptococcus pneumoniae.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD)-induced decrease in the fluidity of rat liver membranes.

1. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCCD)-induced lipid peroxidation has previously been demonstrated by assessing the hepatic content of thiobarbituric acid reactive substances (TBARS) as well as the NADPH-dependent microsomal formation of TBARS as well as the NADPH-dependent microsomal formation of TBARS using malondialdehyde as the standard. 2. Changes in membrane fluidity as a result of lipid peroxidation may occur. Therefore the dose- and time-dependent effects of TCDD on lipid peroxidation in mitochondrial, microsomal, and plasma membranes, and changes in membrane fluidity in these subcellular fractions, were examined. Animals were treated with either 50 or 100 micrograms TCDD/kg orally, and killed 3, 6, or 9 days post-treatment. 3. Time-dependent increases occurred in TBARS content and formation following TCDD administration for all three membranes. Similar results were observed after 50 and 100 micrograms TCDD/kg. 4. Following TCDD administration, fluorescence polarization measurements as determined by the fluorescence polarization (r) and anisotropy parameter (a.p.) values demonstrated significant decreases in membrane fluidity in all membrane fractions, indicative of membrane structural alterations. 5. Excellent inverse correlations between lipid peroxidation and membrane fluidity were observed. Thus, decreased membrane fluidity and increased membrane damage may contribute to the toxic manifestations of TCDD as a consequence of an oxidative stress.

Metabolic and ultrastructural changes in articular cartilage of rats fed dietary supplements of omega-3 fatty acids.

A "marginally deficient" essential fatty acid state was produced in male Sprague-Dawley rats by dietary supplementation with omega 3 fatty acids. Animals fed diets containing the highest amounts of these fatty acids (10% menhaden fish oil) demonstrated a 70% maximum decrease in the linoleic and arachidonic acid content of articular cartilage, a 30-40% decrease in cartilage hexosamine content, with little effect on hydroxyproline levels, and a 32% inhibition of proteoglycan synthesis. Histologic analysis revealed an occasional surface irregularity and localized depletion of Safranin O and toluidine blue staining of articular cartilage on the femoral heads from animals taking the higher doses. Electron microscopic analysis revealed a marked decrease in "dark-staining" chondrocytes relative to "light-staining" cells in all animals fed menhaden fish oil. The cartilaginous changes noted in this study reflect a causal relationship between chondrocyte metabolism and an altered unsaturated fatty acid content. The observed responses of chondrocytes to omega 3 fatty acids may be similar to those commonly associated with the development of early osteoarthrosis. It is not known whether similar changes are induced in other species, including humans, but these observations suggest that some caution must be taken in the long-term administration of menhaden fish oil or other omega 3 fatty acid-containing preparations in rheumatoid arthritis patients.

Suppression of diamine oxidase activity enhances postresection ileal proliferation in the rat.

To assess the influence of diamine oxidase activity on the adaptive process of the small bowel after resection, we administered aminoguanidine, a potent diamine oxidase inhibitor, to rats for 10 days after either small bowel transection (n = 5) or 80% jejunoileal resection (n = 7). Five or more additional animals from each group received saline as controls. Ileal mucosal homogenates from the resection group receiving aminoguanidine, when compared with those from resection controls, showed no diamine oxidase activity with increased putrescine content and ornithine decarboxylase activity. Mucosal proliferation, as measured by mucosal mass, protein content, and deoxyribonucleic acid content, was greater in the resected animals receiving aminoguanidine when compared with that of resection controls. Sucrase activity per gram of mucosa was almost identical in both resection groups. These results show that the suppression of diamine oxidase during the postresection adaptive period results in enhanced mucosal proliferation with no effect on mucosal functional differentiation. Diamine oxidase may play a regulatory role in adaptive intestinal proliferation.

Effects of dietary linoleic acid on mucosal adaptation after small bowel resection.

We have shown that dietary long-chain triglycerides and 16,16-dimethyl prostaglandin E2 enhance and aspirin impairs postresection mucosal adaptation in rats. The present studies examined the hypothesis that supplemental linoleic acid (LA) above the minimum requirement may enhance postresection mucosal adaptation through altered prostaglandin (PG) synthesis. Forty male Sprague-Dawley rats (105 +/- 5 g) were fed purified diet containing either 5% LA or 4% palmitic acid and 1% LA. After 2 weeks, 12 rats from each dietary group underwent 70% proximal jejunoileal resection and the remainder were sham-operated. Dietary regimens were continued for an additional 13 days. Mucosal fatty acid analysis of 1% LA group revealed a ratio of 20:3 n-9/20:4 n-6 lower than 0.2, indicating normal essential fatty acid status. Mucosal protein per centimeter bowel was higher in the 5% LA group compared to the 1% group, but mucosal DNA, maltase, and ex vivo PG synthesis were not affected. These results indicate that LA stimulates postresection mucosal hypertrophy, which does not appear to be related to PG synthesis.

Morphological and functional effects of 16,16-dimethyl-prostaglandin-E2 on mucosal adaptation after massive distal small bowel resection in the rat.

The ability of 16,16-dimethyl-prostaglandin-E2 (PGE) to augment mucosal adaptation 14 days after a 70% distal small bowel resection in the rat was evaluated. In resected (R) and sham operated (S) animals, subcutaneous PGE 75 mg/kg, 2 X/day, induced significant (p less than 0.05) increases in mucosal protein, DNA, and disaccharidase concentrations per centimetre of bowel. The respective per cent increases in the residual proximal small intestine compared with their respective untreated controls were: protein, R = 60%, S = 66%; DNA, R = 69%, S = 29%; maltase, R = 57%, S = 5%. The uptake of leucine by intestinal rings was significantly higher (50%) in the PGE treated group at a concentration of 2 mmol/l of substrate, while the uptake of glucose was similar in all groups. The drug appears to be an effective agent in stimulating morphological and functional adaptation after massive distal small bowel resection.

Reduced mucosal prostaglandin synthesis after massive small bowel resection.

Exogenous 16,16-di-methyl-prostaglandin (PG) E2 administration augments mucosal hyperplasia after massive small bowel resection in the rat. We, therefore, evaluated the ability of aspirin to inhibit mucosal PG synthesis in the small intestine and further evaluated the effects of reduced PG synthesis on mucosal adaptation after a 70% jejunoileal resection in male Sprague-Dawley rats. Sixteen of 27 resected and 8 of 16 sham-operated rats were given aspirin 20 mg/kg body wt subcutaneously every 8 h for 12 days; the remainder were given vehicle only. Although mucosal PGE2, PGF2 alpha, and thromboxane B2 synthesis were all reduced by aspirin administration to 20-40% of the control values, mucosal adaptation in resected animals as measured by mucosal weight, DNA, protein, and maltase levels was only inhibited in the distal ileum. Aspirin did not affect these values in the duodenum, the upper jejunum, and the midileum. This study provides evidence for some involvement of endogenous PGs in regulation of the mucosal adaptation process in the distal ileum after massive small bowel resection in the rat. However, lack of inhibition more proximally suggests that factors other than PGs are more important.