Clastogen-induced chromosomal breakage as a marker for first trimester prenatal diagnosis of Fanconi anemia

Summary Using cultured trophoblast cells obtained by chorionic villus biopsy, we diagnosed Fanconi anemia (FA) in two pregnancies and excluded it in eight pregnancies at risk for the syndrome. Baseline chromosomal breakage and breakage induced by diepoxybutane (DEB) were analyzed. Increased breakage was used as a marker for the syndrome. Our results were unambiguous and provide a reliable method for prenatal detection of FA in the first trimester of pregnancy.     

A study of diabetes in relation to blood groups and cholesterol levels

Summary Four hundred and sixteen patients suffering from diabetes were studied for AB0 Rhesus blood groups, to find out whether there is any association between blood group and diabetes. Though the relative incidence was found to be higher in blood group 0 and B, the difference was not statistically significant. This study confirms the earlier findings of high cholesterol levels in diabetes, particularly in patients with blood groups A and AB, and the overall mean cholesterol level as 253 mg/100 ml. This study also shows that diabetes with a cholesterol level of more than 300 mg/100 ml is a coronary risk factor.

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Zusammenfassung 416 Patienten mit Diabetes wurden nach AB0 und Rh untersucht, um Assoziationen zwischen Blutgruppe und Diabetes zu finden. Es fand sich ein leichtes, nicht signifikantes Überwiegen von 0 und B. Ein besonders hoher Serum-Cholesteral-Spiegel fand sich beim Diabetes insbesondere bei Patienten der Gruppen A und AB. Die Studie zeigt auch, daß ein Cholesteral-Spiegel von mehr als 300 mg% ein Risikofaktor für Coronarerkrankungen ist.

     

Duplication of an Xp segment that includes the ZFX locus causes sex inversion in man

Summary Two 46,XY females with tandem duplications of an X short arm segment were studied by cytogenetic and Southern blot analysis. The results show that the duplicated segment in each case included the Xp21.2–Xp22.2 interval, resulting in a double dose of ZFX on the single active X chromosome. The results from our two cases, in conjunction with those reported by other workers, lead us to conclude that the duplication is the reason for the sex inversion. If ZFY and ZFX are indeed sex-determining gene loci, these findings favour a model of sex determination characterized by antagonistic interaction between these genes.     

Cytogenetic findings in 4952 prenatal diagnoses. An Italian collaborative study

Summary The development of prenatal diagnosis in Italy was made difficult by the restrictions of the old abortion law and only in recent years has a consistent number of cases been investigated. We report the experience on prenatal chromosome diagnosis of ten Italian centers participating in a collaborative study on 4952 diagnoses performed from 1972 to 1980. The main indication groups were: advanced maternal age (2882 cases), previous child with chromosome anomaly from parents with normal karyotype (847 cases), and chromosome anomaly in one parent (97 cases). The other indications for amniocentesis, including cases without a cytogenetic risk, have been assembled into a miscellaneous group (1126 cases). We found 125 abnormal fetal karyotypes (2.5%) of which 89 were unbalanced (1.8%). The frequencies and types of chromosome anomalies are reported in detail for each indication group and are compared with the corresponding ones from the European Munich Conference. The great majority of these Italian data were not included in the Munich report.     

Systematic Dissection of the Metabolic-Apoptotic Interface in AML Reveals Heme Biosynthesis to Be a Regulator of Drug Sensitivity

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Three-dimensional structure of a complex of galanthamine (Nivalin) with acetylcholinesterase from Torpedo californica: implications for the design of new anti-Alzheimer drugs

The 3D structure of a complex of the anti-Alzheimer drug galanthamine with Torpedo californica acetylcholinesterase is reported. Galanthamine, a tertiary alkaloid extracted from several species of Amarylidacae, is so far the only drug that shows a dual activity, being both an acetylcholinesterase inhibitor and an allosteric potentiator of the nicotinic response induced by acetylcholine and competitive agonists. The X-ray structure, at 2.5A resolution, shows an unexpected orientation of the ligand within the active site, as well as unusual protein-ligand interactions. The inhibitor binds at the base of the active site gorge, interacting with both the acyl-binding pocket and the principal quaternary ammonium-binding site. However, the tertiary amine group of galanthamine does not directly interact with Trp84. A docking study using the program AUTODOCK correctly predicts the orientation of galanthamine in the active site. The docked lowest-energy structure has a root mean square deviation of 0.5A with respect to the corresponding crystal structure of the complex. The observed binding mode explains the affinities of a series of structural analogs of galanthamine and provides a rational basis for structure-based drug design of synthetic derivatives with improved pharmacological properties. Proteins 2001;42:182-191.     

Efficient folding of the FcepsilonRI alpha-chain membrane-proximal domain D2 depends on the presence of the N-terminal domain D1

Human high affinity receptor for IgE is a membrane glycoprotein multichain complex presenting two extracellular Ig modules in its alpha-chain (D1D2). The receptor IgE binding region is located within the membrane-proximal module D2, while the N-terminal module D1 appears to promote an optimal receptor conformation for IgE binding. To understand the structural relationship between the two modules, we dissected FcepsilonRI alpha-chain into its discrete Ig units and expressed them in mammalian cells. Unexpectedly, D2 was secreted as a disulphide-linked dimer, while D1 was monomeric. Active secretion and full glycosylation of dimeric D2 suggest a native-like conformation of the protein, justifying the escape from the endoplasmic reticulum/Golgi quality control systems. We then propose a domain-swapping model for D2, in which two interdigitated polypeptide chains assume the overall conformation of two Ig modules, as observed for rat CD2 N-terminal domain. Fusion of an unrelated Ig fold moiety at the N terminus of D2 did not interfere with its dimerisation. While D1D2 assumes a correct fold, co-expression of both isolated domains in the same cell did not restore monomeric folding of D2. Thus, D1 appears to assist the appropriate folding of FcepsilonRI alpha-chain, acting as an uncleavable intramolecular chaperone-like block towards D2.     

The Structure of the T190M Mutant of Murine α-Dystroglycan at High Resolution: Insight into the Molecular Basis of a Primary Dystroglycanopathy

The severe dystroglycanopathy known as a form of limb-girdle muscular dystrophy (LGMD2P) is an autosomal recessive disease caused by the point mutation T192M in α-dystroglycan. Functional expression analysis in vitro and in vivo indicated that the mutation was responsible for a decrease in posttranslational glycosylation of dystroglycan, eventually interfering with its extracellular-matrix receptor function and laminin binding in skeletal muscle and brain. The X-ray crystal structure of the missense variant T190M of the murine N-terminal domain of α-dystroglycan (50-313) has been determined, and showed an overall topology (Ig-like domain followed by a basket-shaped domain reminiscent of the small subunit ribosomal protein S6) very similar to that of the wild-type structure. The crystallographic analysis revealed a change of the conformation assumed by the highly flexible loop encompassing residues 159–180. Moreover, a solvent shell reorganization around Met190 affects the interaction between the B1–B5 anti-parallel strands forming part of the floor of the basket-shaped domain, with likely repercussions on the folding stability of the protein domain(s) and on the overall molecular flexibility. Chemical denaturation and limited proteolysis experiments point to a decreased stability of the T190M variant with respect to its wild-type counterpart. This mutation may render the entire L-shaped protein architecture less flexible. The overall reduced flexibility and stability may affect the functional properties of α-dystroglycan via negatively influencing its binding behavior to factors needed for dystroglycan maturation, and may lay the molecular basis of the T190M-driven primary dystroglycanopathy.