Atropisomeric quinazolin-4-one derivatives are potent noncompetitive alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonists

Piriqualone (1) was found to be an antagonist of AMPA receptors. Structure activity optimization was conducted on each of the three rings in 1 to afford a series of potent and selective antagonists. The sterically crowded environment surrounding the N-3 aryl group provided sufficient thermal stability for atropisomers to be isolated. Separation of these atropisomers resulted in the identification of (+)-38 (CP-465,022), a compound that binds to the AMPA receptor with high affinity (IC50 = 36 nM) and displays potent anticonvulsant activity.     

Juvenile hormone diol kinase. I. Purification, characterization, and substrate specificity of juvenile hormone-selective diol kinase from Manduca sexta

Manduca sexta juvenile hormone diol kinase (JHDK) catalyzes the conversion of juvenile hormone (JH) diol to JH diol phosphate. JHDK may be the first example of a phosphotransferase directly involved in the catabolism and inactivation of a lipid-soluble hormone. JHDK is an enzyme crucial for secondary metabolism of JH and possesses high specificity and catalytic efficiency for JH diol. In this study, the purification and characterization of native JHDK are described; its enzymatic properties are examined; and its role in cellular JH metabolism is explored. Using a variety of potential substrates, we show that JHDK has a preference for ATP, but will catalyze the formation of JH diol phosphate with GTP as the phosphate donor. JHDK has a nanomolar K(m) for JH I diol and a low micromolar value for MgATP. JH II and III diols also serve as phosphate acceptors with low micromolar K(m), whereas other diol derivatives of terpenoid esters structurally similar to JH metabolites are not phosphorylated. The reaction proceeds via a sequential Bi Bi mechanism. JHDK is active as a homodimer with a subunit molecular mass of 20 kDa. JHDK binds 5'-p-fluorosulfonylbenzoyladenosine and is inhibited by micromolar levels of Ca2+.     

Antigen-driven oligoclonal expansion of tumor-infiltrating B cells in infiltrating ductal carcinoma of the breast

The objective of this study was to determine whether tumor-infiltrating B cells (TIL-B) of infiltrating ductal carcinoma (IDC) of the breast represent a tumor-specific humoral immune response. Immunohistochemical analysis of three Her-2/neu-negative IDC tumors from geriatric patients showed that TIL-B cluster in structures similar to germinal centers containing CD20(+) B lymphocyte and CD3(+) T lymphocyte zones with interdigitating CD21(+) follicular dendritic cells, suggesting an in situ immune response. A total of 29, 31, and 58 IgG1 H chain clones was sequenced from the three IDC tumors, respectively. Intratumoral oligoclonal expansion of TIL-B was demonstrated by a preponderance (45-68%) of clonal B cells. In contrast, only 7% of tumor-draining lymph node and 0% of healthy donor PBL IgG H chains were clonal, consistent with the larger repertoires of node and peripheral populations. Patterns and levels of TIL-B IgG H chain somatic hypermutation suggested affinity maturation in intratumoral germinal centers. To examine the specificity of TIL-B Ig, a phage-displayed Fab library was generated from the TIL-B of one IDC tumor. Panning with an allogeneic breast cancer cell line enriched Fab binding to breast cancer cells, but not nonmalignant cell lines tested. However, panning with autologous tumor tissue lysate increased binding of Fab to both tumor tissue lysate and healthy breast tissue lysate. These data suggest an in situ Ag-driven oligoclonal B cell response to a variety of tumor- and breast-associated Ags.     

Infrared imaging of 2-D temperature distribution during cryogen spray cooling

Cryogen spray cooling (CSC) is used in conjunction with pulsed laser irradiation for treatment of dermatologic indications. The main goal of this study was to determine the radial temperature distribution created by CSC and evaluate the importance of radial temperature gradients upon the subsequent analysis of tissue cooling throughout the skin. Since direct measurement of surface temperatures during CSC are hindered by the formation of a liquid cryogen layer, temperature distributions were estimated using a thin, black aluminum sheet. An infrared focal plane array camera was used to determine the 2-D backside temperature distribution during a cryogen spurt, which preliminary measurements have shown is a good indicator of the front-side temperature distribution. The measured temperature distribution was approximately gaussian in shape. Next, the transient temperature distributions in skin were calculated for two cases: 1) the standard 1-D solution which assumes a uniform cooling temperature distribution, and 2) a 2-D solution using a nonuniform surface cooling temperature distribution based upon the back-side infrared temperature measurements. At the end of a 100-ms cryogen spurt, calculations showed that, for the two cases, large discrepancies in temperatures at the surface and at a 60-micron depth were found at radii greater than 2.5 mm. These results suggest that it is necessary to consider radial temperature gradients during cryogen spray cooling of tissue.     

RAGE mediates amyloid-beta peptide transport across the blood-brain barrier and accumulation in brain

Amyloid-beta peptide (Abeta) interacts with the vasculature to influence Abeta levels in the brain and cerebral blood flow, providing a means of amplifying the Abeta-induced cellular stress underlying neuronal dysfunction and dementia. Systemic Abeta infusion and studies in genetically manipulated mice show that Abeta interaction with receptor for advanced glycation end products (RAGE)-bearing cells in the vessel wall results in transport of Abeta across the blood-brain barrier (BBB) and expression of proinflammatory cytokines and endothelin-1 (ET-1), the latter mediating Abeta-induced vasoconstriction. Inhibition of RAGE-ligand interaction suppresses accumulation of Abeta in brain parenchyma in a mouse transgenic model. These findings suggest that vascular RAGE is a target for inhibiting pathogenic consequences of Abeta-vascular interactions, including development of cerebral amyloidosis.     

Does nitric oxide contribute to the basal vasodilation of pregnancy in conscious rabbits?

Pregnancy produces marked systemic vasodilation, but the mechanism is unknown. Experiments were performed in conscious rabbits to test the hypotheses that increased nitric oxide (NO) production contributes to the increased vascular conductance, but that the contribution varies among vascular beds. Rabbits were instrumented with aortic and vena caval catheters and ultrasonic flow probes implanted around the ascending aorta, superior mesenteric artery, terminal aorta, and/or a femoral artery. Hemodynamic responses to intravenous injection of N(omega)-nitro-L-arginine (L-NA; 20 mg/kg or increasing doses of 2, 5, 10, 15, and 20 mg/kg) were determined in rabbits first before pregnancy (NP) and then at the end of gestation (P). L-NA produced similar increases in arterial pressure between groups, but the following responses were larger (P < 0.05) when the rabbits were pregnant: 1) decreases in total peripheral conductance [-3.7 +/- 0.3 (NP), -5.0 +/- 0.5 (P) ml x min(-1) x mmHg(-1)], 2) decreases in mesenteric conductance [-0.47 +/- 0.05 (NP), -0.63 +/- 0.07 (P) ml x min(-1) x mmHg(-1)], 3) decreases in terminal aortic conductance [-0.43 +/- 0.05 (NP), -0.95 +/- 0.19 ml x min(-1) x mmHg(-1) (P)], and 4) decreases in heart rate [-41 +/- 4 (NP), -62 +/- 5 beats/min (P)]. Nevertheless, total peripheral and terminal aortic conductances remained elevated in the pregnant rabbits (P < 0.05) after L-NA. Furthermore, decreases in cardiac output and femoral conductance were not different between the reproductive states. We conclude that the contribution of NO to vascular tone increases during pregnancy, but only in some vascular beds. Moreover, the data support a role for NO in the pregnancy-induced increase in basal heart rate. Finally, unknown factors in addition to NO must also underlie the basal vasodilation observed during pregnancy.