A common allergenic epitope of Bermuda grass pollen shared by other grass pollens

The present study disclosed the cross-reactivity between Bermuda grass pollen (BGP) and other grass pollens using monoclonal antibodies (MAbs) and polyclonal antiserum. MAb 9–13, directed against a group of minor allergens of BGP (Cyn d Bd68K, 48K, 38K) was found to cross-react with extracts of ten other grass pollens. Immunoblotting assays illustrated that MAb 9–13 cross-reacted with multiple components of most of these pollens, and the major cross-reactive components had molecular weights of 29–36 kD. The cross-reactivity between BGP andLol pI, the group I allergen of rye grass pollen, was further evaluated;Lol pI was recognized by MAb 9–13, but not by our MAbs/polyclonal antiserum againstCyn dI, the major allergen of BGP. These results suggest that the epitope recognized by MAb 9–13 is a common (C) epitope shared byLol pI andCyn d Bd68K, 48K, 38K, andCyn dI does not share significant antigenicity withLol pI. In a modified radio-allergosorbent test, IgE antibodies in the serum of BGP-allergic patients reacted mildly with C-epitope-bearing components of both BGP and rye grass pollens, and this binding could be blocked specifically by MAb 9–13. This suggests that in addition to an antigenic cross-reaction, the C epitope can also lead to an allergenic cross-reaction.     

Age-Dependent Impairment of Mitochondrial Function in Primate Brain

Abstract: It has been hypothesized that some of the functional impairments associated with aging are the result of increasing oxidative damage to mitochondrial DNA that produces defects in oxidative phosphorylation. To test this hypothesis, we examined the enzymes that catalyze oxidative phosphorylation in crude mitochondrial preparations from frontoparietal cortex of 20 rhesus monkeys (5-34 years old). Samples were assayed for complex I, complex II-III, complex IV, complex V, and citrate synthase activities. When enzyme activities were corrected for citrate synthase activities (to account for variable degrees of mitochondrial enrichment), linear regression analysis demonstrated a significant negative correlation of the activities of complex I (p < 0.002) and complex IV (p < 0.03) with age but no significant change in complex II-III or complex V activities. Relative to animals 6.9 ± 0.9 years old (n = 7), the citrate synthase-corrected activity of complex I was reduced by 17% in animals 22.5 ± 0.9 years old (n = 6) (p < 0.05) and by 22% in animals 30.7 ± 0.9 years old (n = 7) (p < 0.01). Similar age-related reductions in the activities of complexes I and IV were obtained when enzyme activities were corrected for complex II-III activity. These findings show an age-associated progressive impairment of mitochondrial complex I and complex IV activities in cerebral cortices of primates.     

Aurintricarboxylic Acid Protects Hippocampal Neurons from NMDA-and Ischemia-Induced Toxicity In Vivo

Abstract: The polymeric dye aurintricarboxylic acid (ATA) has been shown to protect various cell types from apoptotic cell death, reportedly through inhibition of a calcium-dependent endonuclease activity. Recent studies have indicated that there may be some commonalities among apoptosis, programmed cell death, and certain other forms of neuronal death. To begin to explore the possibility of common biochemical mechanisms underlying ischemia-or excitotoxin-induced neuronal death and apoptosis in vivo, gerbils or rats subjected to transient global ischemia or NMDA microinjection, respectively, received a simultaneous intracerebral infusion of ATA or vehicle. As a biochemical marker of neuronal death, spectrin proteolysis, which is mediated by activation of calpain I, was measured in hippocampus after 24 h. ATA treatment resulted in a profound reduction of both NMDA-and ischemia-induced spectrin proteolysis, consistent with the possibility of some common mechanism in apoptosis and other forms of neuronal death in vivo.     

Relationship between cardiac output and oxygen uptake at the onset of exercise

The purpose of the present study was to assess the relationship between the rapidity of increased gas exchange (i.e. oxygen uptake ) and increased cardiac output ( ) during the transient phase following the onset of exercise. Five healthy male subjects performed multiple rest-exercise or light exercise (25 W)-exercise transitions on an electrically braked ergometer at exercise intensities of 50, 75, or 100 W for 6 min, respectively. Each transition was performed at least eight times for each load in random order. The was obtained by a breath-by-breath method, and was measured by an impedance method during normal breathing, using an ensemble average. On transitions from rest to exercise, rapidly increased during phase I with time constants of 6.8–7.3 s. The also showed a similar rapid increment with time constants of 6.0–6.8 s with an apparent increase in stroke volume (SV). In this phase I, increased to about 29.7%–34.1% of the steady-state value and increased to about 58.3%–87.0%. Thereafter, some 20 s after the onset of exercise a mono-exponential increase to steady-state occurred both in and with time constants of 26.7–32.3 and 23.7–34.4 s, respectively. The insignificant difference between and time constants in phase I and the abrupt increase in both and SV at the onset of exercise from rest provided further evidence for a cardiodynamic contribution to following the onset of exercise from rest.     

Specific bindings of [3H](+)PN200-110 and [125I]ω-conotoxin to crude membranes from differentiated NG108-15 cells

The characteristics of the specific bindings of [³H](+)PN200-110 (PN: L-type Ca channel antagonist) and [¹²⁵I]-conotoxin G VI A (-CgTX: neuronal L-or N-type Ca channel antagonist) to crude membranes from undifferentiated neuroblastoma x glioma hybrid NG108-15 (NG108-15) cells and differentiated cells induced with dibutyryl cAMP (Bt₂cAMP) were examined, because we have already observed that the magnitude and rate of KCL-stimulated⁴⁵Ca uptake by NG108-15 cells increased progressively during differentiation of the cells induced with Bt₂cAMP (unpublished results). The specific binding of [³H](+)PN to these crude membranes was saturable at various concentrations of 2.5–5.0 nM [³H](+)PN. Scatchard analysis showed that the specific binding of [³H](+)PN at equilibrium was significantly increased after differentiation of the NG108-15 cells with Bt₂cAMP, but that the apparent Kd value for the specific binding of [³H](+)PN was not influenced by treatment with Bt₂cAMP. The specific binding of [³H](+)PN to crude membranes from Bt₂cAMP-treated NG108-15 cells was inhibited by a calcium agonist and antagonists, the order of their inhibitory potencies being (+)PN>nitrendipine>(–)PNBay K 8644diltiazem = verapamil. Thus, PNs showed significant stereoselective inhibition of the specific binding of [³H(+)PN. On the other hand, [¹²⁵I]-CgTX at concentrations of 0.075–0.6 nM showed scarcely any specific binding to these crude membranes, although at 0.6 nM it showed specific binding to crude membranes from rat brain in the same experimental conditions. These results suggest that the increase in magnitude or rate of KCl-stimulated⁴⁵Ca uptake during differentiation of NG108-15 cells is partially due to quantitative alteration of voltage-sensitive Ca channels in the cells, and that there are scarcely any specific binding sites for [¹²⁵I]-CgTX on Bt₂cAMP-treated or untreated NG108-15 cells.     

Crystal structure analysis of amicyanin and apoamicyanin from Paracoccus denitrificans at 2.0 A and 1.8 A resolution.

The crystal structure of amicyanin, a cupredoxin isolated from Paracoccus denitrificans, has been determined by molecular replacement. The structure has been refined at 2.0 A resolution using energy-restrained least-squares procedures to a crystallographic residual of 15.7%. The copper-free protein, apoamicyanin, has also been refined to 1.8 A resolution with residual 15.5%. The protein is found to have a beta-sandwich topology with nine beta-strands forming two mixed beta-sheets. The secondary structure is very similar to that observed in the other classes of cupredoxins, such as plastocyanin and azurin. Amicyanin has approximately 20 residues at the N-terminus that have no equivalents in the other proteins; a portion of these residues forms the first beta-strand of the structure. The copper atom is located in a pocket between the beta-sheets and is found to have four coordinating ligands: two histidine nitrogens, one cysteine sulfur, and, at a longer distance, one methionine sulfur. The geometry of the copper coordination is very similar to that in the plant plastocyanins. Three of the four copper ligands are located in the loop between beta-strands eight and nine. This loop is shorter than that in the other cupredoxins, having only two residues each between the cysteine and histidine and the histidine and methionine ligands. The amicyanin and apoamicyanin structures are very similar; in particular, there is little difference in the positions of the coordinating ligands with or without copper. One of the copper ligands, a histidine, lies close to the protein surface and is surrounded on that surface by seven hydrophobic residues. This hydrophobic patch is thought to be important as an electron transfer site.