Most proteins within living organisms contain glycans. Glycan structures can modulate the biological properties and function of glycoproteins. Developments in glycobiology have revealed a new type of glycosidic linkage to the peptide portion, the O-mannosyl linkage in mammals, although heretofore it had been thought to be specific to yeast. One of the best known O-mannosyl-modified glycoproteins is dystroglycan, which is a central component of dystrophin-glycoprotein complex isolated from skeletal muscle membranes. We identify and characterize a glycosyltransferase, UDP-N-acetylglucosamine: protein O-mannose β1,2-N-acetylglucosaminyltransferase (POMGnT1), involved in the biosynthesis of mammalian type O-mannosyl glycans. Finally, we find that the POMGnT1 gene is responsible for muscle-eye-brain disease (MEB). MEB is an autosomal recessive disorder characterized by congenital muscular dystrophy, ocular abnormalities and brain malformation (type II lissencephaly). Like MEB, recent data suggest that the aberrant protein glycosylation of a specific glycoprotein, α-dystroglycan, is the primary cause of some forms of congenital muscular dystrophy. Here I review the new insight into glycobiology of muscular dystrophy and neuronal migration disorder.
Four prostaglandin E (EP) receptor subtypes have been identified and cloned, designated as EP1, EP2, EP3 and EP4. These EP receptors are members of the G-protein coupled receptor family. EP3 receptor signals are primarily involved in inhibition of adenylyl cyclase via Gi activation, while EP2 and EP4 receptor signals cause a stimulation of adenylyl cyclase via Gs activation. Immune cells, such as mast cells, express multiple EP subtypes on their cell membranes, but few studies have been conducted to understand exactly what signals the main flow for the multiple subtypes expressing immune cells. We previously demonstrated that activation of Gi-coupled EP3 receptor exhibited a cooperative effect on cAMP synthesis induced by Gs-coupled EP2 receptor in COS-7 cells. Here we report that a selective EP4 agonist-induced adenylyl cyclase activity was augmented by simultaneous addition of a selective EP3 agonist in mastocytoma P-815 cells, which express mRNAs for both EP3 and EP4 subtypes. The augmentation in cAMP synthesis was found to be pertussis toxin-sensitive. P-815 cells are demonstrated to bind to Pronectin-F, a proteolytic fragment of fibronectin, in adhesion protein of the extracellular matrix, by addition of PGE2, which is mediated by PKA. The binding of P-815 cells to Pronectin-F mediated by EP4 receptor was augmented by the EP3 receptor. These findings indicate that two subtypes of PGE2 receptors, EP3 and EP4, cooperatively activate the cAMP-mediated adhesion event through induction of fibronectin ligand elicited by PGE2 in P-815 cells. Furthermore, the PGE2-induced adhesion response may contribute to the mast cell recruitment function on extracellular matrix during inflammation.
The formation of foam cells, a critical event in the early stages of atherosclerosis, is associated with the uptake of oxidized low-density lipoprotein (oxLDL) by macrophages and the subsequent accumulation of cholesterol ester formed by the catalytic action of acyl-CoA: cholesterol acyltransferase (ACAT). Although free cholesterol, a substrate for ACAT, is supplied from the intracellular cholesterol pool, little is known about the pathways involved in the supply of fatty acids, precursors for fatty acyl-CoA as another substrate for ACAT. Our recent studies were undertaken to examine the possible involvement of phospholipase A2 (PLA2) in the supply of fatty acids required for the cholesterol esterification. In mouse peritoneal macrophages and RAW264.7 macrophages, oxLDL induced the liberation of fatty acids from membrane phospholipids to increase cholesterol ester having the fatty acids as an acyl chain. The changes in these lipids were suppressed by the inhibition of cytosolic PLA2 (cPLA2). Although oxLDL did not affect the activity or amounts of cPLA2, preincubation with oxLDL enhanced the release of fatty acids induced by Ca2+ ionophore, which accelerates the hydrolytic action of cPLA2. We further observed that oxLDL induced the generation of ceramide through the de novo synthesis. Exogenous ceramide and 13-hydroxyoctadecadienoic acid, an oxidized lipid in oxLDL particles, also stimulated fatty acid release. Based on these findings, we propose that oxLDL activates cPLA2 to supply fatty acids required for the cholesterol esterification, through the acceleration of the hydrolytic action of cPLA2 by endogenous ceramide and by oxidized lipids in oxLDL particles in macrophages.
Anthracycline antibiotics, including adriamycin (ADM), are widely used to treat various human cancers, but their clinical use has been limited because of their cardiotoxicity. ADM is especially toxic to heart tissue. The mechanisms responsible for the cardiotoxic effect of ADM have been very/extremely controversial. This review focuses on the participation of free radicals generated by ADM in the cardiotoxic effect. ADM is reduced to a semiquinone radical species by microsomal NADPH-P450 reductase and mitochondrial NADH dehydrogenase. In the presence of oxygen, the reductive semiquinone radical species produces superoxide and hydroxyl radicals. Generally, lipid peroxidation proceeds by mediating the redox of iron. ADM extracts iron from ferritin to form ADM-Fe3+, which causes lipid peroxidation of membranes. These events may lead to disturbance of the membrane structure and dysfunction of mitochondria. However, superoxide dismutase and hydroxyl radical scavengers have little effect on lipid peroxidation induced by ADM-Fe3+. Alternatively, ADM is oxidatively activated by peroxidases to convert to an oxidative semiquinone radical, which participates in inactivation of mitochondrial enzymes or including succcinate dehydrogenase and creatine kinase. Here, we discuss the activation of ADM and the role of reductive and oxidative ADM semiquinone radicals in the cardiotoxic effect of this antibiotic.
To investigate the pharmacological and toxicological actions of purified snake enzymatic cream (PSE) isolated from Agkistrodon Halys Venom, erythematous dermatitis was induced by applying dinitrofluorobenezene (DNFB) on the back skin of guinea pigs. Consequent local alterations at different doses of PSE were observed and compared using negative control methods. In skin irritation and acute toxicological experiments, 500 times the effective doses were used in artificially lesioned skin. The marking criteria in the former were based on local manifestations, and in the latter, on changes of some indicators including body weight, breath, and heart rate before and after the experiments. PSE significantly alleviated erythematous dermatitis (p<0.01, t test) without systemic or local adverse drug reactions within 7 days. PSE as a new drug candidate poses a bright prospect in the prevention and treatment of dermatitis.
In the course of our characterization studies on anti-obese and antidiabetogenic principles in medicinal foodstuffs, we found that the methanolic extract from the stems of Salacia chinensis (Hippocerateaceae) showed potent anti-hyperglycemic effects in oral sucrose or maltose-loaded rats, inhibitory effects on intestinal α-glucosidase, rat lens aldose reductase, formation of Amadori compounds and advanced glycation end-products, nitric oxide production from lipopolysaccharide-activated mouse peritoneal macrophage, and radical scavenging activities. Those in vivo and in vitro biological activities were compared with those of S. oblonga and S. reticulata. In addition, we isolated the principal α-glucosidase inhibitor, salacinol, from the stems of S. chinensis and examined α-glucosidase inhibitory activities of eleven samples of S. chinensis collected in Thailand.
Objective: Drug-induced extrapyramidal symptoms (DIEPS) often substantially compromise quality of life (QOL) of patients receiving drugs with central antidopaminergic activities. A lack of comprehensive screening method based upon patients' subjective symptoms for detecting DIEPS appears to have prevented pharmacists from delivering satisfactory pharmaceutical care for these patients. Thus, we have attempted to develop a comprehensive questionnaire for screening patients having higher risks of developing DIEPS. Methods: One hundred fourteen outpatients taking gastroprokinetic drugs (itopride, cisapride, trimebutine, domperidone and metoclopramide) at least 2 weeks participated in the study. One patient with familial Parkinson disease served as a positive reference. They undertook a questionnaire consisting of 9 comprehensive questions written in non-technical words that were aimed to detect typical symptoms of Parkinsonism including akathisia and dyskinesia. Each symptom was scored in a semiquantitative scale [i.e., from 1 (not at all) to 5 (very much)] by the patients. Results: Of the 108 subjects who successfully completed the questionnaires, 43 gave scores 2 or greater indicating the presence of DIEPS. However, no statistically significant correlations were observed between the scores of any possible pairs of the questionnaire items. Five subjects had a mean questionnaire score of equal to or greater than 1.6, and the patient with familiar Parkinsonism had the highest mean score of 1.9. Conclusion: The questionnaire presented herein detected 4 patients with suspected DIEPS. Further studies should be warranted to assess whether it would be useful for pharmacists as a screening tool for DIEPS in patients having higher risks of DIEPS.
In the epidemic of influenza in fiscal 2002, there was a shortage in Japan of the anti-influenza virus medicine “oseltamivir”. For this reason, many medical institutions were forced to shorten the treatment period with this medication. In this study, we compared the shorter oseltamivir treatment and the indicated 5-day course of treatment with the index for the reconsultation rate and medication dispensing fee from the viewpoint of pharmacoeconomics and clinical effect. Oseltamivir was prescribed for 2, 3 or 5 days for the treatment of influenza, and the rate of reconsultation, type of virus and age were analyzed. The total fees paid to a pharmacy for influenza treatment were also calculated for pharmacoeconomic evaluation. Two-day treated patients had a higher rate of reconsultation compared with the 3- and 5-day treatment groups. Analysis of patients by influenza virus type and age showed no significant difference in reconsultation rate. The total medication dispensing fees for 2-, 3- and 5-day treatment with oseltamivir were 4713, 4755 and 6520 yen, respectively, that of 5-day treatment being significantly higher. These results suggest that 2-day treatment by oseltamivir was significantly high in reconsultation rate, and 5-day treatment was significantly high in medication dispensing fee, so 3-day treatment of influenza by this medicine is the most suitable from the viewpoint of pharmacoeconomics and clinical effect.
Early detection and early treatment of adverse drug reactions have recently become more important. It is natural that physicians should treat adverse drug reactions carefully, but it is also important to establish a system for their early systematic detection and treatment. Therefore, by comparing current data with that preserved in our clinical laboratory's data management registry and identifying values significantly different from earlier values, we established a screening system for any condition which may have a possible relationship with drugs and feeds back the results to the physician(s) in charge (drug safety management monitoring system). The effectiveness of the system was then evaluated. The subjects were outpatients who visited the Diabetes Endocrine Metabolism Center of our hospital during a six-month period. Cases where the possibility of a relationship between abnormal changes of laboratory data and drugs was not ruled out were reported to the attending physician using a drug safety monitoring report form. In 14 of 34 cases reported, a relationship with drugs could not be ruled out. Two of these 14 cases were reported to the Ministry of Health, Labour and Welfare because they were serious. Therefore, it was concluded that this system was useful for early detection of adverse reactions.