NMDA Receptor Heterogeneity During Postnatal Development of the Rat Brain: Differential Expression of the NR2A, NR2B, and NR2C Subunit Proteins

Abstract: Changes in the expression of the NMDA receptor subunits (NRs) NR2A, 2B, and 2C were investigated in histo blots of the developing rat brain with subunit-specific antisera. At birth, the NR2B subunit was detected almost ubiquitously, the NR2A subunit staining was faint and restricted to the hippocampus, cerebral cortex, and striatum, and no NR2C subunit immunoreactivity was detected. During the first 3 postnatal weeks, the NR2B subunit became confined to forebrain structures, whereas the NR2A immunoreactivity became abundantly expressed throughout the brain. The NR2C immunoreactivity emerged 5 days after birth in the olfactory bulb, thalamus, and vestibular nuclei and became very intense after 10 days in cerebellar granule cells, its primary site of expression in adulthood. After 3 weeks, NR2A and NR2B immunoreactivity decreased to adult levels, whereas NR2C immunoreactivity remained unchanged. The patterns of distribution of the subunit proteins were in agreement with those of their corresponding mRNAs, as monitored by in situ hybridization histochemistry, although the mRNA translation appeared to be delayed by several days in certain areas. Our results reveal a progressive increase in the heterogeneity of NMDA receptors due to the comparably late onset of NR2A and NR2C subunit expression and by the area-specific rearrangement of NR2B subunit expression following birth.     

Comparison of techniques for measuring pulse-wave velocity in the rat

Mitchell, Gary F., Marc A. Pfeffer, Peter V. Finn, andJanice M. Pfeffer. Comparison of techniques for measuringpulse-wave velocity in the rat. J. Appl.Physiol. 82(1): 203-210, 1997.We evaluatedmethods for measuring average and regional pulse-wave velocity alongthe full length of the aorta in 18-mo-old ether-anesthetized malespontaneously hypertensive rats. Catheter-tip manometers were placed inthe ascending and descending thoracic aorta via the right carotid andleft femoral arteries, respectively. As the distal catheter waswithdrawn at 1-cm intervals, the relationship between distal catheterinsertion distance and distance between transducers was determined fromthe intercept of the insertion distance vs. transmission delayregression line. Methods that assessed the foot-to-foot time delaybetween pressures accurately predicted the separation between catheters(measured distance of 14.3 cm; intercept of 14.0 ± 0.5 cm;P = not significant) were highlyreproducible (coefficient of variation of 2.3% for repeated measurements) and showed minimal variability (range 509 ± 30 to 600 ± 29 cm/s) along the full length of the aorta. Methods that madeuse of the pressure-pressure transfer function were spatially (range ofvalues along the aorta 367 ± 17 to 722 ± 39 cm/s) and temporally more variable, especially during vasoconstriction with methoxamine, due to the effects of reflected waves.

     

Modeling the population dynamics of annual plants with seed bank and density dependent effects

A model is proposed for the population dynamics of an annual plant (Sesbania vesicaria) with a seed bank (i.e. in which a proportion of seeds remain dormant for at least one year). A simple linear matrix model is deduced from the life cycle graph. The dominant eigenvalue of the projection matrix is estimated from demographic parameters derived from field studies. The estimated values for population growth rate () indicates that the study population should be experiencing a rapid exponential increase, but this was not the case in our population.The addition of density dependent effects on seedling survivorship and adult fecundity, effects for which field studies provide evidence, considerably improves our model. Depending on the demographic parameters, the model leads to stable equilibrium, oscillations, or chaos. Study of the behaviour of this model in the parameter space shows that the existence of a seed bank allows higher among-year variation of adult fecundity, without leaving the region of demographic stability. Field data obtained over 3 years confirm this prediction.     

Specific immunotherapy with vaccinia oncolysates

Summary A live vaccinia virus-augmented tumor cell vaccine (vaccinia oncolysate) has been used as a specific active immune mechanism stimulator against certain advanced human cancers. This preliminary trial, in which the same dose of vaccinia oncolysate was used in 29 patients, showed the vaccine to be safe, non-toxic, and potentially effective. This study was designed as a toxicity/feasibility trial at a single vaccine dose. There was no effort to look at other dose levels. The heterogeneity of this early tumor group only reflects the type of patient available to the study during the early phase of vaccine testing. Randomized prospective trials have begun to make future analysis easier.     

An estimate of spin diffusion in a spin subset: Application to iterative distance calculation from 3D 15N NOESY-HMQC

Summary A method for quantification of distances between amide hydrogens using only the 3D NOESY-HMQC experiment recorded on a ¹⁵N-labelled protein is presented. This method is based on an approximate expression of the NOE intensities between amide hydrogens obtained from continuum modelling of the non-amide spins; this expression is used in a distance calculation algorithm. The algorithm has been named CROWD, standing for Continuum approximation of Relaxati On path Ways between Dilute spins. This approximation as well as the CROWD algorithm are tested on a simulated case; the CROWD algorithm is then applied to experimental data, measured on a fragment of bacteriorhodopsin.     

Tripeptides as selective inhibitors of src-SH2 phosphoprotein interactions

Summary This paper describes the synthesis of phosphorylated peptides of the general structural Ac-Tyr(PO₃H₂)-Glu-Xaa_NH₂, where Xaa represents a hydrophobic -amino acid of d-configuration. These peptides displayed activities in the micromolar range in inhibiting src-SH2 domain/epidermal growth factor receptor interactions.     

Genetic and Cytogenetic Analysis of the ADH Region in DROSOPHILA MELANOGASTER

Eighteen Adh-negative mutations were selected with 1-pentyn-3-ol after feeding of formaldehyde. Twelve of the 18 were shown by cytological and genetic analysis to be deletions. Cytological examination of the deletions allowed us to localize the Adh gene to a region including bands 35B3-5 on the left arm of chromosome 2. The deletions were also used to order known visible loci located near Adh.--The vital loci near Adh were also investigated. A total of 109 lethal mutations were generated with EMS and 33 of these, localized within a region defined by the overlap of two of the deletions, were found to belong to 13 complementation groups. If one includes three other loci known to belong there (el, Adh and Sco) a total of 16 complemetation groups have been identified in the region close to Adh.     

Characterization of human blood platelet membrane proteins and glycoproteins by their isoelectric point (pI) and apparent molecular weight using two-dimensional electrophoresis and surface-labelling techniques

Intact human blood platelets were radioactively labelled at the surface by techniques specific for proteins or glycoproteins. Labelled platelet samples were analyzed by a high-resolution two-dimensional separation system involving isoelectric focusing in the first dimension and discontinuous sodium dodecyl sulphate-polyacrylamide gel electrophoresis in the second. The major platelet membrane glycoprotein (GP) bands (Ib, IIb, IIIa and IIIb) were found to be highly heterogeneous even after removal of terminal sialic acid residues. Lactoperoxidase-catalyzed iodination of platelets showed that the major labelled proteins (Ib, IIb, IIIa and IIIb) had altered isoelectric points ($\text{p}\text{I}$) and molecular weights after neuraminidase treatment. A number of membrane glycoproteins previously undetected by one-dimensional gel electrophoresis were demonstrated and good evidence provided that the major platelet surface proteins are glycosylated.