Trans-ACPD-induced phosphoinositide hydrolysis and modulation of hippocampal pyramidal cell excitability do not undergo parallel developmental regulation.

The selective metabotropic glutamate receptor agonist, trans-1-aminocyclopentane-1,3-dicarboxylic acid (trans-ACPD), stimulates phosphoinositide hydrolysis and elicits a number of electrophysiological responses in the hippocampus. If these effects are mediated by the same receptor subtype, they should undergo parallel developmental regulation. Therefore, we compared the phosphoinositide hydrolysis response and the electrophysiological responses to trans-ACPD at two different developmental stages. Trans-ACPD-stimulated phosphoinositide hydrolysis was significantly greater in hippocampal slices from immature (6-11-day-old) rats than from adults. In contrast, trans-ACPD elicited decreases in spike frequency adaptation and in the amplitude of the slow afterhyperpolarization in roughly equal percentages of immature and adult CA1 pyramidal cells. Similar results were obtained using the putative endogenous agonist, glutamate. These data support the hypothesis that certain electrophysiological effects of trans-ACPD are mediated by a metabotropic glutamate receptor that is distinct from the phosphoinositide hydrolysis-linked glutamate receptor.     

Early pregnancy complications: endovaginal sonographic findings correlated with human chorionic gonadotropin levels

Endovaginal sonography results were compared with quantitatively determined human chorionic gonadotropin (hCG) levels in 84 women referred for early pregnancy complications. Of the 27 with normal intrauterine pregnancies, an intrauterine gestational sac was prospectively identified in one of five cases (20%) in which hCG levels were below 500 IU/L (Second International Standard), four of five (80%) with hCG levels of 500-1,000 IU/L, and all 17 with hCG levels above 1,000 IU/L. In comparison, 17 of the 26 women with ectopic pregnancies (65%) had hCG levels greater than 1,000 IU/L, and none of the 26 had an intrauterine gestational sac. Endovaginal sonography demonstrated an adnexal mass and/or a gestational sac-like structure in 16 of the 17 cases (94%) in which hCG levels were above 1,000 IU/L, compared with only three of the nine (33%) with lower hCG levels (P less than .01). These findings indicate that an intrauterine gestational sac should be normally visualized with endovaginal sonography when the hCG level exceeds 1,000 IU/L, and that visualization of an extrauterine gestational sac and/or adnexal mass is significantly more likely in ectopic pregnancies when the hCG level exceeds 1,000 IU/L.     

Thymic cysts in mediastinal Hodgkin disease

Three cases of proved thymic cysts associated with mediastinal Hodgkin disease are presented. Two illustrate regression of lymphoma with chemotherapy but persistence of thymic cysts. The third case demonstrates a thymic cyst in untreated Hodgkin disease. These cases suggest that such cysts are probably neither coincidental with nor a consequence of therapy but are probably related to initial thymic involvement by Hodgkin disease.     

Transport of alpha-keto analogues of amino acids across blood-brain barrier in rats

The transport of 14C-labeled alpha-keto acids across the blood-brain barrier (BBB) was studied in rats anesthetized with sodium pentobarbital using a modification of a single-injection dual-isotope technique. alpha-Keto acids were found to cross the BBB via a saturable carrier-mediated transport system that may be specific based on lack of inhibition by glucose, isoleucine, and ketone bodies on the uptake of tracer levels of 14C-labeled alpha-keto acids. alpha-Ketobutyrate and alpha-keto-gamma-methiolbutyrate, both straight chain keto acids, and alpha-ketoisocaproate, a branched-chain keto acid, appeared to cross the barrier by a common carrier based on cross-inhibition studies. Aromatic keto acids had no effect on the uptake of tracer levels of these 14C-keto acids. The Km of transport of alpha-ketobutyrate, alpha-ketoisocaproate, and alpha-keto-gamma-methiolbutyrate, was 0.11, 0.60, and 0.33 mM, respectively. The corresponding Vmax was 15.7, 73.3, and 30.2 nmol . g-1 . min-1. Phenylpyruvate was found not to cross the BBB. Inhibition of brain uptake of alpha-keto acids by propionate and pyruvate, and not by DL-beta-hydroxybutyrate suggests that alpha-keto acids and monocarboxylic acids are transported either via a common system independent of ketone bodies or share an affinity with a monocarboxylic acid and an alpha-keto acid transport system.