Decreased capacity for type-specific-antigen synthesis accounts for high prevalence of nontypeable strains of group B streptococci in Mexico

The low incidence of group B streptococcal (GBS) invasive neonatal disease in Mexico has been attributed to the low prevalence of serotype III strains, a major serotype in developed countries. In addition, nontypeable strains account for 12% of the isolates in Mexico and < 1% of the isolates in the United States. In this study, 57 GBS isolates (28 nontypeable by the Lancefield procedure) from carrier and infected neonates and women from Mexico were also examined for the presence of type-specific antigen by an enzymatic procedure using N-acetylmuramidase digestion of the cell wall to release soluble type-specific antigen. Of the 28 nontypeable strains from Mexico, 23 were typeable by the enzyme extraction procedure, with serotype III being the predominant serotype in invasive disease. These results suggest that nontypeable isolates of GBS should be further examined by the enzymatic extraction procedure to determine the presence of type-specific antigen. Furthermore, these limited results suggest that serotype III is likely a major serotype in invasive disease also in Mexico.     

Understanding the structure of the first atomic contact in gold

We have studied experimentally jump-to-contact (JC) and jump-out-of-contact (JOC) phenomena in gold electrodes. JC can be observed at first contact when two metals approach each other, while JOC occurs in the last contact before breaking. When the indentation depth between the electrodes is limited to a certain value of conductance, a highly reproducible behaviour in the evolution of the conductance can be obtained for hundreds of cycles of formation and rupture. Molecular dynamics simulations of this process show how the two metallic electrodes are shaped into tips of a well-defined crystallographic structure formed through a mechanical annealing mechanism. We report a detailed analysis of the atomic configurations obtained before contact and rupture of these stable structures and obtained their conductance using first-principles quantum transport calculations. These results help us understand the values of conductance obtained experimentally in the JC and JOC phenomena and improve our understanding of atomic-sized contacts and the evolution of their structural characteristics.     

Hypersensitivity as a cause of dermatologic and vaginal moniliasis resistant to topical therapy

The finding of multiple respiratory or skin allergies together with a high rate of improvement by desensitization leads the author to conclude that allergy is a predisposing factor for the chronicity or recurrence of vaginal or dermatologic moniliasis. Desensitization with Candida albicans antigen was the mainstay in the treatment of resistant dermatologic or vaginal moniliasis and the sole form of therapy in cases of nail involvement with deep seated lesions out of the reach of topical agents.     

Goat acetyl-coenzyme A carboxylase alpha: molecular characterization, polymorphism, and association with milk traits

Acetyl-coenzyme A carboxylase α (ACACA), the major regulatory enzyme of fatty acid biosynthesis, catalyzes the conversion of acetyl-CoA to malonyl-CoA. We have sequenced 5.5 kb of the goat ACACA cDNA in 18 individuals. The translated cDNA sequence encodes 1,832 AA and shares a high AA identity (99%) with the ovine and bovine ACACA orthologous sequences. One silent single nucleotide polymorphism was identified at exon 45 (C5493T). The genotyping of this polymorphism in 4 goat breeds, Murciano-Granadina, Teramana, Majorera, and Malagueña, showed that it was segregating in all 4 breeds at variable frequencies. In addition, a mixed animal model was used to evaluate the association of C5493T genotypes with milk traits. Results from this study show that the C5493T mutation was suggestively associated with fat yield, lactose content, and somatic cell count.