Age-related Changes in Bovine α-crystallin and High-molecular-weight Protein

The high-molecular-weight (HMW) protein from the lens is composed mostly of α-crystallin in a highly aggregated state. Bovine HMW protein was carefully separated from α-crystallin by size-exclusion chromatography. α-Crystallin has chaperone-like ability whereby it stabilizes other proteins under conditions of stress (e.g. heat). Comparison of bovine HMW protein and α-crystallin shows that the HMW protein has a markedly reduced chaperone ability compared to α-crystallin. However, in contrast to the results of other workers, we observe no alteration with age in the ability of α-crystallin to act as a chaperone. Using electrospray ionisation mass spectrometry, changes in the phosphorylation of the α-crystallin subunits with age have been quantified. Phosphorylation of α-crystallin occurs early in life but does not alter in proportion after about three years of age. In addition, phosphorylation of the A subunit of α-crystallin has little effect on its chaperone ability. As is found in the artificially prepared HMW complex of α- and γ-crystallin, NMR spectroscopy shows that in the naturally occurring HMW protein, the short C-terminal extension of the α_Bsubunit has lost its flexibility whereas the α_Asubunit extension is still flexible. Post-translational modifications therefore seem to have little effect on the chaperone action of α-crystallin, but alterations in the quaternary structure of α-crystallin via incorporation into the HMW aggregate, lead to major changes in the chaperone ability of the protein. The results are consistent with the notion that one of the contributing factors to cataract formation in the lens is the depletion of α-crystallin with age as it is converted into the HMW protein.     

Monitoring Anti-HPA-1a Platelet Antibody Levels during Pregnancy Using the MAIPA Test

Anti-HPA-1a platelet antibody levels in pregnant women with a history of fetomaternal alloimmune thrombocytopenia (FMAIT) were monitored longitudinally using the monoclonal antibody immobilisation of platelet antigens (MAIPA) assay, in order to examine any variation in optical density (OD) readings obtained over the course of pregnancy and after delivery. Seven women were selected; 4 were studied retrospectively and 3 prospectively (the latter being treated with intravenous gammaglobulin; IVGG). Levels of anti-HPA-1a were measured at various intervals after delivery of the first affected infant, to post delivery of the following affected infant. A decrease in MAIPA OD was demonstrated in all patients during the course of these pregnancies. This assay is a useful tool for monitoring anti-HPA-1a in women with a history of infants affected with FMAIT. A maternal antibody 'resting' level prior to, or early in the first trimester, must be established for comparison.     

猕猴对不同极化方向微波辐射能量吸收的研究

为提供微波辐射安全标准必要的数据，研究了不同极化方向微波辐射能量对猕猴的影响。实验在医学微波无反射室中进行，分为电场，磁场和微波传输方向极化组，辐射频率１ＧＨｚ，用红外热图技术，对暴露在三种极化方向电磁场中猕猴面部各解剖特片部位及胸部在辐射前后进行温度变化的定量分析。     

Changes in the Subcellular Distribution of the Rat Uterus Oestrogen Receptor as Induced by Oestradiol,Tamoxifen and ZD 182,780

The aim of this work was to compare the subcellular distribution of the oestrogen receptor from the uteri of rats treated with vehicle alone (control group), oestradiol or one of the antio-estrogenic drugs tamoxifen and ZD 182,780. The nuclear, microsomal and cytosolic oestrogen receptor contents were evaluated by an immunoenzymatic method (“ER-EIA” kit from Abbott Laboratories) and the results in each fraction were expressed as a percentage of the total number of receptors. Parallel studies were performed to assess the uterotrophic effect of these drugs and to assess that they had reached the uterus. In the control group, we found that the oestrogen receptor was distributed mainly between the microsomal (29.1 ± 1.3%) and cytosolic (68.1 ±0.9%) fractions, with only a small amount located in the nucleus (2.8 ± 0.5%). When oestradiol was administered, the oestrogen receptor distribution was: nuclear 11.7 ± 2.0, microsomal 15.5 ± 1.3 and cytosolic 72.8 ± 3.3% and, in the tamoxifen group, the results were: nuclear 18.5 ± 1.5, microsomal 26.0 ± 31 and cytosolic 55.5 ± 3.4%, which shows a relative shift both to the control and the oestradiol-treated groups. In the uteri of rats treated with ZD 182,780 the results were very similar to those obtained in the control group. Our results indicate that the subcellular distribution of the oestrogen receptor varies according to the drug administered and that this receptor may not be located in a single subcellular compartment. Moreover, the nuclear uptake of the ZD 182,780-oestrogen receptor complex seems to be blocked, possibly due to impaired receptor dimerization. In the case of tamoxifen, the intracellular transport of the receptor also seems to be blocked, probably due to the nuclear retention of the receptor, thus suggesting that tamoxifen must impair the oestrogen receptor function on a step subsequent to the receptor dimerization.     

Differential distribution of N-acetylaspartylglutamate and N-acetylaspartate immunoreactivities in rat forebrain

Summary Contradictory immunohistochemical data have been reported on the localization of N-acetylaspartylglutamate in the rat forebrain, using different carbodiimide fixation protocols and antibody purification methods. In one case, N-acetylaspartylglutamate immunoreactivity was observed in apparent interneurons throughout all allocortical and isocortical regions, suggesting possible colocalization with GABA. In another case, strong immunoreactivity was observed in numerous pyramidal cells in neocortex and hippocampus, suggesting colocalization with glutamate or aspartate. Reconciling these disparate findings is crucial to understanding the role of N-acetylaspartylglutamate in nervous system function. Antibodies to N-acetylaspartylglutamate and a structurally related molecule, N-acetylaspartate, were purified in stages, and their cross-reactivities with protein conjugates of N-acetylaspartylglutamate and N-acetylaspartate were monitored at each stage by solidphase immunoassay. Reduction of the cross-reactivity of the anti-N-acetylaspartylglutamate antibodies to N-acetylaspartateprotein conjugates to about 1% eliminated significant staining of most pyramidal neurons in the rat forebrain. Utilizing highly purified antibodies, the distributions of N-acetylaspartylglutamate and N-acetylaspartate were examined in several major telencephalic and diencephalic regions of the rat, and were found to be distinct. N-acetylaspartylglutamate-immunoreactivity was observed in specific neuronal populations, including many groups thought to use GABA as a neurotransmitter. Among these were the globus pallidus, ventral pallidum, entopeducular nucleus, thalamic reticular nucleus, and scattered non-pyramidal neurons in all layers of isocortex and allocortex. N-acetylaspartate-immunoreactivity was more broadly distributed than N-acetylaspartylglutamate-immunoreactivity in the rat forebrain, appearing strongest in many pyramidal neurons. Although N-acetylaspartate-immunoreactivity was found in most neurons, it exhibited a great range of intensities between different neuronal types.