Placenta increta complicating a first-trimester abortion. A case report.

Placenta increta complicating pregnancy in the first trimester is rare. A patient with risk factors for placenta increta required a hysterectomy to control a hemorrhage after a first-trimester abortion. Pathologic study confirmed the preoperative diagnosis of placenta increta.

Social behavior and knowledge of social "scripts" among mentally retarded adults.

Mentally retarded individuals' script-based knowledge and performance of routine events was explored. Twenty mentally retarded adults and 20 nonretarded preschoolers were asked to sequence photographs of events depicted in familiar and novel contexts. Retarded individuals were better able to sequence events depicted in familiar contexts than in novel contexts, suggesting deficits in generalizing social knowledge. Preschoolers performed above chance levels in the familiar context only. Observations of retarded individuals during naturally occurring events indicated that actual social behavior was unrelated to event knowledge.

Mitochondria mediate amplification of luteinizing hormone action by adenosine in luteal cells.

Adenosine markedly amplifies the response of isolated rat and human luteal cells to LH via an intracellular site of action that is associated with an increase in cell ATP levels. This effect of adenosine is maximal in midstage cells and minimal at the onset of functional regression in late stage luteal cells. The objective of the present studies was to evaluate the role of mitochondria in mediating the action of adenosine in isolated rat luteal cells and to assess whether mitochondrial function may be compromised in regressing luteal cells. The present studies show that adenosine produced a significant increase in luteal cell levels of ADP and ATP, but had no effect on cell levels of GTP. Since ADP stimulates oxidative phosphorylation, we evaluated the role of mitochondria in mediating the amplification of LH action by adenosine in luteal cells with two mitochondrial inhibitors, oligomycin and dinitrophenol. Both inhibitors markedly reduced, in a dose-dependent manner, LH-stimulated cAMP accumulation in the presence or absence of adenosine. In parallel, both inhibitors decreased basal and adenosine-elevated ATP levels in a dose-related manner. Although late stage luteal cells showed a marked reduction in adenosine amplification of LH-stimulated cAMP accumulation, no change in adenosine-dependent elevation of cell levels of ATP was seen. We conclude that amplification of LH action and elevation of ATP levels in midstage cells by adenosine requires an increase in oxidative phosphorylation that is stimulated by an increase in cell levels of ADP. However, attenuation of adenosine amplification of LH action in late stage luteal cells is not due to impaired ATP production.

Selective amplification of luteinizing hormone by adenosine in rat luteal cells.

Adenosine amplification of LH-stimulated cAMP accumulation in rat luteal cells is rapid and dependent on mitochondrial ATP production. The objective of the present studies was to determine if this effect of adenosine is specific for LH and to gain information on the mechanism of the ATP-dependent amplification of LH action in rat luteal cells. Adenosine significantly amplified maximum cAMP accumulation in response to LH, isoproterenol, forskolin, and cholera toxin. However, amplification of this response by adenosine was significantly greater for LH than for the other agonists. The relative order of amplification by adenosine was LH greater than isoproterenol greater than forskolin greater than cholera toxin; the relative magnitudes of amplification by adenosine were 1, 0.6, 0.2, and 0.2, respectively. Neither LH, isoproterenol, forskolin, nor cholera toxin had any effect on cellular levels of ATP, and adenosine produced a similar rate of increase and maximal levels of ATP in the presence of all agonists. Ionomycin, a calcium ionophore, inhibited LH- and cholera toxin-stimulated cAMP accumulation and produced a dose-dependent depletion of ATP. Adenosine reversed the inhibitory effect of ionomycin on LH-stimulated cAMP accumulation and cellular levels of ATP. However, adenosine did not reverse the inhibitory effect of ionomycin on cholera toxin-stimulated cAMP accumulation, although its effects on cellular ATP levels were identical to those on LH. Thus, the selective amplification of LH by adenosine is not merely a substrate effect on adenylate cyclase activity. The nature of adenylate cyclase activation by cholera toxin and forskolin and the weak amplification by adenosine of these agonists compared to that of LH indicate that the site of the ATP-dependent action of adenosine appears to be before or on the G-protein of adenylate cyclase. We suggest that adenosine, by an ATP-dependent process, either increases the availability of functional LH receptors or increases coupling between the LH receptor and adenylate cyclase.

Luteolysis is linked to luteinizing hormone-induced depletion of adenosine triphosphate in vivo.

An elevation of ATP levels in luteal cells markedly enhances their response to gonadotropin. In contrast, depletion of ATP in all cells leads to a series of interrelated events that produces irreversible cell injury. Since the corpus luteum has a transient existence, functional regression and involution of this gland play a fundamental role in the regulation of reproduction. The objective of the present studies was to evaluate whether the luteal ATP content may be regulated in an endocrine fashion and whether luteolysis may be linked to depletion of ATP in the corpus luteum in vivo. The present studies show that removal of the pituitary, maintenance of luteal function in hypophysectomized rats with PRL, or acute treatment with prostaglandin F2 alpha had no effect on luteal ATP levels. However, LH produced a rapid and marked decrease in adenine nucleotide levels in both intact and hypophysectomized PRL-replaced rats, whereas GTP levels were unaffected. In pituitary-intact rats, this same effect of LH occurred within 5 min, was maximal (40% depletion) within 30 min, and was sustained for many hours. Depletion of ATP by LH was dose dependent and evident with low doses of LH. In addition, a decrease in luteal ATP levels was seen during functional luteolysis in the rat, which was directly related to a rise in the serum levels of LH, but not FSH. In contrast, LH had no effect on ATP depletion in isolated cells prepared from the total luteinized ovary, or in enriched preparations of luteal cells. Thus, the depletion of ATP by LH in vivo appears to be mediated by intraovarian agents of unknown nature. We suggest that the rise in LH levels that follows functional luteolysis, due to reduced negative feedback by progesterone, produces a rapid decrease in luteal ATP levels which induces irreversible cell damage and, ultimately, involution of the corpus luteum. This effect would, presumably, be exacerbated as LH levels rise to maximum at ovulation or until LH receptors become down-regulated.

Absence of detectable phosphocreatine in rat luteal cells.

Previous studies from this laboratory showed that adenosine amplifies the action of luteinizing hormone (LH) severalfold in rat and human luteal cells by an intracellular, adenosine 5'-triphosphate (ATP)-linked process. The objective of this study was to evaluate the contribution of phosphocreatine (PCr) and creatine kinase (CK) to the dynamics of luteal ATP metabolism. Levels of PCr in luteinized rat ovaries were similar to those seen in liver but were approximately 1 and 7% of levels found in skeletal and heart muscle, respectively. In isolated rat luteal cells, little detectable PCr was seen after incubation in the presence or absence of adenosine, although cell ATP levels were increased twofold by adenosine treatment. The presence or absence of LH had no effect on either PCr or ATP levels in incubations of isolated luteal cells. Analysis of CK activity in tissue and cell homogenates showed that the specific activity of CK in luteal cells was in the same range as that seen in liver but less than 1/30 of that seen in skeletal muscle. From these studies we conclude that rat luteal cells contain little, if any, PCr and low levels of CK. Thus the rapid changes in ATP levels that are seen in rat luteal tissue and cells may occur because these cells have little capacity to buffer ATP levels with a reservoir of high-energy phosphate groups in the form of PCr.

Purines, prostaglandins and peptides--nature and cellular mechanisms of action of local assist and assassin agents in the ovary.

The evidence for a paracrine, progonadotropic role of adenosine in ovarian cells is summarized along with a capsule review of the origin and mechanisms of release and action of adenosine in other tissues. Briefly, adenosine markedly amplified rat and human luteal cell cyclic AMP and progesterone accumulation in the presence, but not the absence, of LH. The site of action of adenosine was found to be intracellular, linked to its phosphorylation, which resulted in increased levels of ATP. In rat luteal cells, adenosine blocked the acute antigonadotropic (luteolytic) action of PGF2 alpha. In the follicle, adenosine release from granulosal cells appeared to be stimulated by FSH. Adenosine and a nonmetabolized adenosine analog, augmented FSH-dependent inhibition of oocyte maturation in the presence or absence of an adenosine transport inhibitor. Inhibition of oocyte maturation by adenosine thus appears to be mediated by extracellular purinergic receptors. Paracrine, antigonadotropic agents also appear to regulate ovarian function. For example, GnRH elicits antigonadotropic activity in rat granulosal and luteal cells. We describe a novel, GnRH-like, ovarian hormone (GLOH) which may be the physiological ligand whose action GnRH mimics in rat ovarian cells. This protein was shown to be distinctly different from GnRH and a variety of other cyclic and noncyclic peptides. PGF2 alpha is a well known leutolytic agent and a summary of the antigonadotropic mechanism of PGF2 alpha action in rat luteal cells is presented. In these cells, the action of GnRH (or possibly the GnRH-like protein) and PGF2 alpha are mediated by separate membrane receptors but they appeared to share the same intracellular second messenger. Evidence for a role of products of phosphoinositol as a mediator of these antigonadotropic agents is summarized. We suggest that the ultimate mediator of antigonadotropic agents is Ca2+ which is released in the luteal cell in response to the intracellular mediator of antigonadotropic agents. For example, pharmacological agents which increase intracellular levels of Ca2+, mimicked the antigonadotropic action of GnRH and PGF2 alpha in rat luteal cells. Also, Ca2+ directly inhibited LH-sensitive adenylate cyclase activity in isolated luteal membranes, a paradigm in which GnRH and PGF2 alpha were inactive. The mechanism of Ca2+ action appeared to be linked to interference with GTP activation of adenylate cyclase. However, removal of extracellular Ca2+ did not abrogate the action of either GnRH or PGF2 alpha.(ABSTRACT TRUNCATED AT 400 WORDS)

Luteolytic hormones are calcium-mediated, guanine nucleotide antagonists of gonadotropin-sensitive adenylate cyclase.

We suggest that regression of the corpus luteum is an active process induced by PGF2 alpha, GnRH, and a peptide of ovarian origin whose action GnRH mimics (20). The initial events involved in luteolysis occur within minutes, and they are intimately linked to inhibition of LH action. Membrane receptor binding of luteolytic hormones activates production of a second messenger (such as a product of PI turnover) that stimulates release of sequestered, intracellular Ca2+ by a mechanism linked to inhibition of microsomal Ca2+-ATPase activity. The increase in cytosolic Ca2+ inhibits adenylate cyclase activity by blocking GTP-dependent activation of adenylate cyclase. As a result, the cell response to LH is abolished and function is lost.

Novel use of synthetic oligonucleotide insertion mutants for the study of homologous recombination in mammalian cells.

Thymidine kinase-deficient mouse L cells have been transformed with plasmid DNAs carrying 8-base-pair Xho I linker insertion mutations in the coding region of the herpes simplex virus type 1 thymidine kinase gene. When the mutant plasmids are introduced individually into LTK- cells, transformation efficiencies are greatly reduced relative to the wild type. However, when two mutant plasmids are cotransferred into the same LTK- recipients, significantly higher frequencies of transformation are observed (30-300 times). Here we demonstrate the usefulness of linker insertions for the study of homologous recombination in detecting the existence of normal thymidine kinase gene sequences (i.e., sequences lacking the insertions after recombination are substantiated by DNA . DNA hybridization). In addition, the frequencies of recombination in the various "crosses" are consistent with the known positions of the mutations.