Quantitation of a mitochondrial DNA deletion in Parkinson's disease.

A 5 kilobase deletion in mitochondrial DNA (mtDNA) has been reported to be responsible for the specific complex I deficiency in the substantia nigra (SN) of the Parkinson's disease (PD) brain. We have studied mitochondrial respiratory chain function in the SN from control and PD subjects, and analysed mtDNA, extracted from the same tissues, by Southern blot and the polymerase chain reaction (PCR). Quantitation of the levels of the deletion indicate that it does not contribute to the pathogenesis of PD nor to a complex I deficiency but seems likely to be an age-related observation.     

The disulfide bridge pattern of snake venom disintegrins, flavoridin and echistatin.

Flavoridin and echistatin, isolated from the venom of Trimeresurus flavoviridis and Echis carinatus, respectively, belong to the disintegrin family of integrin beta 1 and beta 3 inhibitors of low molecular weight RGD-containing, cysteine-rich peptides. Since disulfide bonds are critical for expression of biological activity, we sought to determine their location in these two proteins. In flavoridin, direct evidence for the existence of linkage between Cys4-Cys19 and between Cys45 and Cys64 was obtained by analysis of proteolytic products, and indirect evidence suggests links between Cys6-Cys14 and Cys13-Cys36. In echistatin, links between Cys8-Cys37 and Cys20-Cys39 were identified by direct chemical analysis.     

Isolation of the alpha 3-chain of human type V collagen and characterization by partial sequencing.

The alpha 1 alpha 2 alpha 3-chain form of human type V collagen was solubilized from placenta by pepsin treatment and isolated by ion-exchange chromatography. The alpha 3-chain was further separated after denaturation of the triple helix also by ion-exchange chromatography, cleaved with lysyl endopeptidase and the fragments separated by size-exclusion chromatography and reversed phase HPLC. N-Terminal sequence analysis of the fragments and comparison to sequences contained in a database indicated a relatively high similarity of the alpha 3(V)-chain to alpha 1(V) and alpha 1(XI) with an identity of approximately 73%.     

Bradykinin and ATP stimulate L-arginine uptake and nitric oxide release in vascular endothelial cells.

The effects of bradykinin and ATP on L-arginine transport and nitric oxide (NO) production were studied in porcine aortic endothelial cells cultured and perfused on microcarriers and deprived of L-arginine for 24 h. Stimulation of cells with bradykinin (100 nM) or ATP (100 microM) resulted in a rapid increase in L-arginine uptake and NO release. In the presence of nitro-L-arginine (100 microM), an inhibitor of NO synthase, the stimulatory effect of bradykinin on L-arginine uptake was partially inhibited while NO release was completely abolished. Nitro-L-arginine alone was not an inhibitor of basal L-arginine transport, suggesting that its inhibitory action was not directly on the L-arginine transporter but a result of the inhibition of NO generation. These data indicate that during agonist-stimulated NO production there is a concomitant increase in the transport of L-arginine into endothelial cells providing a mechanism for the continual generation of NO.     

Fanconi anemia: evidence for linkage heterogeneity on chromosome 20q

Fanconi anemia is a rare autosomal recessive disorder in which affected individuals are predisposed to acute myelogenous leukemia and other malignancies. We report the results of a genetic linkage study involving 34 families enrolled in the International Fanconi Anemia Registry. A significant lod score was obtained between D20S20, an anonymous DNA segment from chromosome 20q, and Fanconi anemia (Zmax 3.04, theta max = 0.12). However, six other anonymous DNA segments from chromosome 20q, including D20S19, which is highly polymorphic and tightly linked to D20S20, showed no or only weak evidence for linkage to Fanconi anemia. An admixture test revealed significant evidence for linkage heterogeneity (chi 2 = 6.10, P = 0.01) at the D20S19 locus. Lod scores suggestive of linkage between Fanconi anemia and this locus were obtained with two of the largest kindreds studied (lods = 2.6 and 2.1, at theta = 0.001). Thus, our data support the provisional assignment of a Fanconi anemia gene to chromosome 20q.     

The IRRI blue-green algae collection and computerized information on the strains available for distribution

ORSTOM-IRRI collaborative program on nitrogen fixation     

Calcaneus secundarius: description and frequency in six skeletal samples

The calcaneus secundarius (CS) is a small accessory ossicle of the anterior calcaneal facet. A sample of 1,367 calcanei including early 20th century U.S. blacks and whites, XIIth Dynasty Egyptians, Islamic Period Bahrainis, and protohistoric American Indians from two states were examined to determine the frequency of this nonmetric trait. Statistical testing of the correlation of the trait with sex could only be performed on the blacks and whites, a documented cadaver collection. Tests of chi 2 indicated that, although sex differences were insignificant, significant group (not necessarily racial or geographical) differences existed at the .05 level. There was no correlation of side dominance in the overall sample, although significant population differences existed. The trait frequencies of the black and white samples were more similar to one another than to the nonindustrial groups who, in turn, were more similar to each other than to the Terry sample. The findings suggest that a CS is of genetic or congenital origin resulting in a secondary center of ossification in the anterior calcaneal facet.     

Sorbitol dehydrogenase genetics in the mouse: A ';null' mutant in a ';European' C57BL strain

A ';null' activity variant phenotype for sorbitol dehydrogenase (SDH) was observed in C57BL/LiA mice and used to examine the genetics of this enzyme. Linkage studies of the locus ( Sdh-1 ) with non-agouti (a) and a biochemical Iocus encoding liver L-α-hydroxyacid oxidase ( Hao-1 ) demonstrated that it is coincident with or closely linked to the structural locus, previously localized on chromosome 2. Alcohol dehydrogenase (ADH) isozymes were also examined, since the liver A₂ isozyme exhibited some activity as a sorbitol dehydrogenase on cellulose acetate zymograms. It is apparent that SDH activity is not ';essential' in this mouse strain.