Absent spermatogenesis despite early bilateral orchidopexy in 17-ketoreductase deficiency

We describe a 26-year-old patient with 17-ketoreductase deficiency who was raised as a male from 8 months and whose left testis was brought down at the age of 2.5 years and the right testis at the age of 4. Despite the early orchidopexy and not significantly decreased serum testosterone, he was sterile, and biopsy of the testes at the age of 26 revealed absence of spermatogenesis. This case indicates that the absence of spermatogonia in previously reported patients whose testes remained undescended until a later age could not be attributed solely to cryptorchidism. We suggest that decreased intratesticular testosterone due to steroidogenic defect in the developing testis mainly contributes to the arrest of spermatogenesis.     

NMR derived solution structure of an EF-hand calcium-binding protein from Entamoeba Histolytica.

We present the three-dimensional (3D) solution structure of a calcium-binding protein from Entamoeba histolytica (EhCaBP), an etiologic agent of amoebiasis affecting millions worldwide. EhCaBP is a 14.7 kDa (134 residues) monomeric protein thought to play a role in the pathogenesis of amoebiasis. The 3D structure of Ca(2+)-bound EhCaBP has been derived using multidimensional nuclear magnetic resonance (NMR) spectroscopic techniques. The study reveals the presence of two globular domains connected by a flexible linker region spanning 8 amino acid residues. Each domain consists of a pair of helix-loop-helix motifs similar to the canonical EF-hand motif of calcium-binding proteins. EhCaBP binds to four Ca(2+) with high affinity (two in each domain), and it is structurally related to calmodulin (CaM) and troponin C (TnC) despite its low sequence homology ( approximately 29%) with these proteins. NMR-derived structures of EhCaBP converge within each domain with low RMSDs and angular order-parameters for backbone torsion angles close to 1.0. However, the presence of a highly flexible central linker region results in an ill-defined orientation of the two domains relative to one other. These findings are supported by backbone (15)N relaxation rate measurements and deuterium exchange studies, which reveal low structural order parameters for residues in the central linker region. Earlier, biochemical studies showed that EhCaBP is involved in a novel signal transduction mechanism, distinct from CaM. A possible reason for such a functional diversity is revealed by a detailed comparison of the 3D structure of EhCaBP with that of CaM and TnC. The studies indicate a more open C-terminal domain for EhCaBP with larger water exposed total hydrophobic surface area as compared to CaM and TnC. Further dissimilarities between the structures include the presence of two Gly residues (G63 and G67) in the central linker region of EhCaBP, which seem to impart it a greater flexibility compared to CaM and TnC and also play crucial role in its biological function. Thus, unlike in CaM and TnC, wherein the length and/or composition of the central linker have been found to be crucial for their function, in EhCaBP, both flexibility as well as amino acid composition is required for the function of the protein.     

Phylogenetic Position of Amblyospora Hazard & Oldacre (Microspora: Amblyosporidae) Based on Small Subunit rRNA Data and Its Implication for the Evolution of the Microsporidia

ABSTRACT. Sequences of the small subunit rRNA genes of Amblyospora californica and an Amblyospora sp. from Culex salinarius were determined. These sequences were compared phylogenetically with 16 other microsporidia. The results suggest Amblyospora forms a sister taxon to the rest of the microsporidia examined. The basal position of Amblyospora is discussed with respect to the evolution of microsporidian life cycles. These sequences represent the longest microsporidian small subunit rRNA genes sequenced to date, 1,359 and 1,358 bp, respectively. Structural features and GC content (49% for both) are comparable to those of other microsporidia which have been sequenced.     

Obtaining antisera to Pseudomonas aeruginosa and Proteus antigens for performing immunoenzyme analyses in clinical practice

The data presented in this work indicate that specific antisera to P. aeruginosa and Proteus antigens can be produced by using extracts from these microorganisms, destroyed by ultrasonic treatment or by multiple freezing and thawing, for the immunization of rabbits. Blood serum samples from patients with purulent septic complications were studied for the presence of P. aeruginosa and Proteus antigens in ELISA with the use of peroxidase-labeled antibodies from antisera to P. aeruginosa and Proteus. This investigation revealed that during the first 3 days from the beginning of the clinical manifestations of the complications P. aeruginosa and Proteus antigens were detected in 86.4% and 83.4% of the patients, respectively. In the subsequent bacteriological study of wound discharge from these patients the corresponding microflora was detected.