Endotoxin stimulation of liver parenchymal cell phosphofructokinase activity requires nonparenchymal cells

The rate of carbohydrate flux through phosphofructokinase (measured as the rate of [3-3H]glucose detritiation) was increased fourfold in rat liver parenchymal cells incubated with conditioned medium from lipopolysaccharide-stimulated adherent liver non-parenchymal cells. The rate was not affected in parenchymal cells incubated either with lipopolysaccharide directly or with conditioned medium from non-stimulated non-parenchymal cells. The stimulation of carbohydrate flux through phosphofructokinase by conditioned medium was not duplicated by peptide cytokines known to be released by lipopolysaccharide-activated liver non-parenchymal cells (interleukin-1, interleukin-6, tumor necrosis factor-alpha, and transforming growth factor-beta) or platelet activating factor. Furthermore, formation of the active conditioned medium was not prevented by inclusion of cycloheximide or dexamethasone to inhibit cytokine synthesis, or indomethacin or BW755c to inhibit arachidonic acid metabolism, during lipopolysaccharide-stimulation of the non-parenchymal cells. The results indicate that intercellular communication between lipopolysaccharide-stimulated liver non-parenchymal cells and parenchymal cells by soluble mediators is responsible for the stimulation of liver phosphofructokinase activity during endotoxin-induced shock. Studies to isolate and identify the factor(s) in the conditioned medium are currently in progress.

Adolescent fertility-related behavior in the 1990s: risking the future continued

This article serves as an introduction to this special issue. It provides an overview for understanding adolescent fertility-related behavior in context, and briefly reviews each of the empirical articles that follow.

Pertussis toxin and H-7 distinguish mechanisms involved in eicosanoid release from lipopolysaccharide-primed macrophages. Eicosanoid release from lipopolysaccharide-primed macrophages

Release of eicosanoids is an important response of macrophages to inflammation and bacterial infection. At low concentrations, bacterial lipopolysaccharide (1-2 micrograms/ml) fails to stimulate eicosanoid release in resident peritoneal macrophages but primes the macrophages for a greatly enhanced release of eicosanoids on stimulation with the calcium ionophore A23187 (0.1 microM) or with phorbol 12-myristate 13-acetate (50 nM), an activator of protein kinase C. Incubation of macrophages with Bordetella pertussis toxin, prior to priming with lipopolysaccharide, inhibited the release of both cyclooxygenase and lipoxygenase products upon A23187 stimulation. Pertussis toxin treatment of macrophages had no effect on eicosanoid release when the stimulus was phorbol 12-myristate 13-acetate. The presence of 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7), an effective inhibitor of protein kinase C, during lipopolysaccharide priming and subsequent stimulation significantly inhibited eicosanoid release when phorbol 12-myristate 13-acetate was the stimulus, but did not affect eicosanoid release stimulated by A23187. Based on these results, at least two mechanisms, distinguished by apparent differences in sensitivity to pertussis-toxin-sensitive, guanine-nucleotide-binding proteins and protein kinase C, are involved in eicosanoid secretion by lipopolysaccharide-activated macrophages in response to A23187 and phorbol 12-myristate 13-acetate.

Correlates of age at first sexual intercourse in a national sample of young women

A subsample of 814 sexually experienced adolescent females from the 1979 U.S. National Survey of Young Women was analyzed to assess the correlates of age at 1st sexual intercourse. Multiple regression procedures were used to examine sets of variables sequentially. In the hierarchical regression model, the control variables (respondent's age, race, religion, and age at menarche), along with 3 independent variables (household income, ideal age at 1st marriage, and ideal age for 1st birth), predicted age at 1st intercourse. The control variables accounted for a major portion of the variance in the model. Of the controls, chronological age and age at menarche were highly significant across all models tested.

Endotoxin increases the liver fructose 2,6-bisphosphate concentration in fasted rats

Following endotoxin administration to fasted rats, the liver fructose 2,6-bisphosphate level is significantly increased within 1 hr, is elevated 2.3-fold by 3 hrs, and remains elevated 2 to 3-fold for at least 24 hrs. This increase in the potent allosteric activator of phosphofructokinase occurs when there is no change in the liver Glc 6-P, glycogen or cAMP concentrations, or in the activities of phosphoenolpyruvate carboxykinase or pyruvate kinase. The increase in fructose 2,6-bisphosphate concentration accounts for the increased phosphofructokinase activity previously observed in hepatocytes isolated 18 hours following endotoxin administration to rats (1). By stimulating the phosphofructokinase/Fru 1,6-bisphosphate cycle in the direction of glycolysis, fructose 2,6-bisphosphate is likely the factor responsible for decreased gluconeogenesis in endotoxemia.

Dehydroisoandrosterone prevention of autoimmune disease in NZB/W F1 mice: lack of an effect on associated immunological abnormalities

The effect of dietary dehydroisoandrosterone (DHA) on several immunological abnormalities associated with the development of systemic lupus erythematosus in New Zealand Black/New Zealand White F1 (NZB/W) female mice was examined. Despite the extraordinary benefits in prolonged survival and decreased synthesis of antibodies to double-stranded DNA obtained by adding DHA (0.4% w/v) to the diet fed to these mice (Lucas et al. (1985) J. Clin. Invest. 75, 2091-2093), remarkably small changes in the chemistry and function of the immune system were detected. DHA prevented the increases in spleen mass and in peritoneal cell number which occur with age in NZB/W female mice, but did not prevent the development of hypergammaglobulinemia. DHA did not affect peritoneal macrophage functions as measured by the phagocytosis of opsonized and non-opsonized sheep erythrocytes, or the zymosan-stimulated release of PGE2, 6-ketoPGF1 alpha, TXB2 and LTC4. In spleen, DHA delayed the loss of T-cell mitogenic responses until 5.5 months of age, but did not alter the spleen lymphocyte population.

Liver composition and lipid metabolism in NZB/W F1 female mice fed dehydroisoandrosterone

The beneficial effects obtained with dehydroisoandrosterone (DHA) feeding in the treatment of murine systemic lupus erythematosus are similar to those obtained with caloric restriction or with dietary manipulation of essential fatty acid availability. In this study, the fatty acid composition of selected tissues was examined in NZB/W F1 mice fed a diet containing 0.4% DHA. The effect of the DHA diet on liver composition and the activity of key hepatic enzymes involved in fatty acid synthesis and glucose metabolism was also investigated. The content of the essential fatty acid, arachidonate, was decreased in plasma cholesteryl esters and liver and kidney phospholipids in mice fed the DHA diet, yet no significant decrease in arachidonate content was observed in plasma phospholipid. The most striking change in both plasma and liver phospholipid was an increase in palmitic acid and a decrease in stearic acid, which could result from a decreased ability for fatty acid elongation. The liver mass was dramatically increased in the mice fed DHA, primarily from parenchymal cell hypertrophy, and contained little lipid. Significant changes in the activities of malic enzyme, glucose-6-phosphate dehydrogenase and pyruvate kinase, similar to those changes which occur with fasting, were observed during the initial adaptation to the DHA diet. The pyruvate kinase activity remained low, suggesting a decrease in liver glycolysis. These results are consistent with the concept that diets containing DHA result in an altered metabolism with a decreased dependence on carbohydrate metabolism and an increased metabolism of lipids.

Hormonal regulation of L-type pyruvate kinase in rat liver cells in culture

An immortalized rat liver cell line (RLC) expresses two isozymes of pyruvate kinase, the adult liver or L-type isozyme and an M-type isozyme presumed to be the M2-type. In RLC cells incubated in serum-free medium, the addition of 0.1 microM insulin maintained the initial level of L-type pyruvate kinase when it was high and induced the L-type isozyme when it was low. The addition of 1.0 mM dibutyryl cAMP and 0.5 mM theophylline decreased the L-type isozyme, even in the presence of insulin. The amount of M2-type isozyme was relatively constant under the conditions used. Regulation of the amount of L-type pyruvate kinase by both insulin and cAMP occurred primarily through changes in the rate of L-pyruvate kinase protein synthesis and translatable mRNA levels. These results are consistent with the in vivo observations that both insulin and glucagon regulate the rate of L-pyruvate kinase gene transcription and that cAMP is the dominant regulator of L-pyruvate kinase gene expression.

Altered factor VII activity in hemophilia

Factor VII levels have been studied in hemophilia A and B plasmas and normal controls in a controlled, prospective study. Three assay methods were used: a standard clotting assay (FVIIc-A); a modified clotting assay (FVIIc-B) (Seligsohn et al, Blood 52:978-988, 1978); and a coupled amidolytic assay. By the FVIIc-B assay, the hemophilic plasmas were significantly lower than in the normal group (68.2 +/- 3.3% [SE] and 83.5 +/- 3.8%, respectively; P less than .01). The amidolytic assay, however, which measures total factor VII regardless of its activity state (factor VII or VIIa), was higher in the patient group than in the control group (126.9 +/- 9.6% and 99.4 +/- 5.7%, respectively; P less than .01). Control experiments showed that the differences in FVIIc-B activity were not caused by artifactual activation of factor VII ex vivo in the control group. The mean FVIIc-A assay of hemophilic plasmas (126.3 +/- 6.5%) agreed closely with the amidolytic assay, suggesting that the FVIIc-A method is also insensitive to the factor VII activity state. These data support the hypothesis that the FVIIc-B assay is more sensitive to the presence of factor VIIa. The increased sensitivity of the FVIIc-B assay to factor VII activation was confirmed by comparison of the two clotting assays on plasma subjected to activation in glass at 4 degrees C. The results of this study indicate that factor VII in hemophilic plasma is less activated than in normal plasma. Whether this contributes to the bleeding diathesis of hemophilia is unknown. However, it does provide evidence for the idea that factor VII in vivo is normally subject to some degree of activation by an enzyme (or enzymes) generated by a turnover of the intrinsic pathway.

Paternal attachment behavior as related to presence at delivery and preparenthood classes: a pilot study

This pilot study explored father-infant attachment and its relationship to preparenthood classes, presence at delivery, and infant state. The sample consisted of 48 fathers and their infants who were observed in the mother's hospital room between 12 and 72 hours after delivery. The fathers were divided into three groups: those who took classes and were present at delivery, those who were present at delivery but did not take classes, and those who neither took classes nor were present at delivery. Fathers who were present at delivery demonstrated more social attachment behavior than fathers who were not present. Also, presence at delivery was significant in regard to total attachment scores. Sleeping infants elicited significantly less attachment behavior from fathers. Preparenthood classes were not significant in regard to fathers' attachment behavior. Results of this study support the theory of a sensitive period shortly after birth for the development of the parental-infant bond for fathers as well as mothers, and demonstrates, indirectly, that alert, awake infants may elicit certain attachment behaviors from fathers.