Regional graft vs host reaction to H-Y antigen (immunological mechanisms)

Structural changes in the regional popliteal lymph nodes have been studied in C57Bl/6 male mice at the peak of the reaction "graft-versus-host" to H-Y antigen. Morphological and morphometrical investigations have been carried out in three groups of males (10 animals in each group). The first group includes intact animals (the first control group). To the males of the second group (the second control group) lymphoid cells are inoculated from intact C57Bl/6 females. To the males of the third group (experimental group) lymphoid cells are inoculated from H-Y antigen immunized C57Bl/6 females (anti-H-Y effector lymphocytes). The popliteal lymph nodes of the male mice from the third group twice increase in their size comparing to those in the control (the first and the second groups). Miotic activity increases in them 4.5 times, amount of cellular blast forms in medullary cords--4 times and 10 times--in the light zone of the cortical substance. Ratio of macrophages and eosinophils in structural components of the lymph nodes studied changes; this is, evidently, connected with massive destructive progresses, that take place in the lymph nodes of the animals from the third group. The results of the morphological investigations are in agreement with the hypothesis suggested, explaining the mechanism of development of the regional reaction "graft-versus-host" to H-Y antigen, basing on idiotype-antiidiotype interaction (the idiotypic network in the immune system).     

Characterization of catalase-negative mutants of methylotrophic yeastHansenula polymorpha

Three recently isolated catalase-negative mutants ofHansenula polymorpha lost the ability to grow on methanol but grew in media containing glucose, ethanol or glycerol. Their incubation in a medium with methanol resulted in an accumulation of hydrogen peroxide and cell death. During growth of a catalase-negative mutant in chemostat on a mixture of methanol and glucose, neither H₂O₂ accumulation nor cell death were observed up to the molar ratio of 10:1 of the two substrates. Cytochrome-c peroxidase and NADH-peroxidase activities were detected in the cells. In methylotrophic yeasts, catalase seems to be an enzyme characteristic of the metabolism of methanol but not needed for the metabolism of multicarbon substrates. The hydrogen peroxide produced during growth of the mutants on mixed substrates is detoxified by cytochrome-c peroxidase and other peroxidases. Translated by Č. Novotny     

Differential expression of interferon responsive genes in rodent models of transmissible spongiform encephalopathy disease

Background

Alzheimer's disease (AD) is characterized by a decline in cognitive function and accumulation of amyloid-β peptide (Aβ) in extracellular plaques. Mutations in amyloid precursor protein (APP) and presenilins alter APP metabolism resulting in accumulation of Aβ42, a peptide essential for the formation of amyloid deposits and proposed to initiate the cascade leading to AD. However, the role of Aβ40, the more prevalent Aβ peptide secreted by cells and a major component of cerebral Aβ deposits, is less clear. In this study, virally-mediated gene transfer was used to selectively increase hippocampal levels of human Aβ42 and Aβ40 in adult Wistar rats, allowing examination of the contribution of each to the cognitive deficits and pathology seen in AD.

Results

Adeno-associated viral (AAV) vectors encoding BRI-Aβ cDNAs were generated resulting in high-level hippocampal expression and secretion of the specific encoded Aβ peptide. As a comparison the effect of AAV-mediated overexpression of APPsw was also examined. Animals were tested for development of learning and memory deficits (open field, Morris water maze, passive avoidance, novel object recognition) three months after infusion of AAV. A range of impairments was found, with the most pronounced deficits observed in animals co-injected with both AAV-BRI-Aβ40 and AAV-BRI-Aβ42. Brain tissue was analyzed by ELISA and immunohistochemistry to quantify levels of detergent soluble and insoluble Aβ peptides. BRI-Aβ42 and the combination of BRI-Aβ40+42 overexpression resulted in elevated levels of detergent-insoluble Aβ. No significant increase in detergent-insoluble Aβ was seen in the rats expressing APPsw or BRI-Aβ40. No pathological features were noted in any rats, except the AAV-BRI-Aβ42 rats which showed focal, amorphous, Thioflavin-negative Aβ42 deposits.

Conclusion

The results show that AAV-mediated gene transfer is a valuable tool to model aspects of AD pathology in vivo, and demonstrate that whilst expression of Aβ42 alone is sufficient to initiate Aβ deposition, both Aβ40 and Aβ42 may contribute to cognitive deficits.     

Efficacy of hyaluronic acid binding assay in selecting motile spermatozoa with normal morphology at high magnification

Background  

The present study aimed to evaluate the efficacy of the hyaluronic acid (HA) binding assay in the selection of motile spermatozoa with normal morphology at high magnification (8400x).     

Routes to improving the reliability of low level DNA analysis using real-time PCR

Background  

Accurate quantification of DNA using quantitative real-time PCR at low levels is increasingly important for clinical, environmental and forensic applications. At low concentration levels (here referring to under 100 target copies) DNA quantification is sensitive to losses during preparation, and suffers from appreciable valid non-detection rates for sampling reasons. This paper reports studies on a real-time quantitative PCR assay targeting a region of the human SRY gene over a concentration range of 0.5 to 1000 target copies. The effects of different sample preparation and calibration methods on quantitative accuracy were investigated.