6-Keto-prostaglandin E1 and the decidual cell reaction in rats

Although there is considerable evidence that prostaglandins (PGs) are involved in the decidual cell reaction in rats, which PGs are involved is uncertain. In the present study, we investigated the possibility that 6-keto-PGE1 is involved. To determine its ability to induce decidualization, 6-keto-PGE1 was infused unilaterally from Alzet osmotic minipumps into the uterine lumen of ovariectomized rats treated with estrogen and progesterone to sensitize their uteri for the decidual cell reaction. To reduce endogenous PG production, indomethacin was injected 2-3 h prior to pump insertion and was included in the vehicle for PG infusion. As determined by uterine weights 5 days after pump insertion, 6-keto-PGE1 and PGE2 produced decidualization which was equivalent. As indicated by a dose-response study, 6-keto-PGE1 and PGE2 did not differ in their ability to bring about decidualization. To determine if a deciduogenic stimulus resulted in increased uterine production of 6-keto-PGE1, as assessed by uterine concentrations, 6-keto-PGE1 and PGE concentrations in the uterus were determined after the unilateral intrauterine injection of 100 microliters sesame oil. There were no significant differences between stimulated and non-stimulated horns in 6-keto-PGE1 concentrations, whereas the concentrations of PGE2 were elevated in the stimulated horns. These data indicate that while both exogenous 6-keto-PGE1 and PGE2 induce decidualization, only uterine PGE concentrations are elevated by deciduogenic stimuli. Thus it is unlikely that 6-keto-PGE1 plays a role in decidualization.     

Mechanisms of genetic control of immune responses

The mechanisms underlying Ir gene control of CMI were addressed by examining the DTH and Tprlf responses specific for the synthetic polymers GT, GAT, and GA. We show that BALB/c mice (GAT/GA responders, GT nonresponders) primed with GT fail to develop DTH and Tprlf responses specific for GT, GAT, or GA. GAT immunization resulted in DTH responses that could be elicited not only with GAT and GA but also with GT, demonstrating that GT-specific T_DH are present in nonresponder mice. GT-specific DTH was transferred with Thy-1⁺ Lyt-1⁺2^–, H-2 Irestricted, nylon wool nonadherent cells. GA-primed BALB/c mice developed GAT- and GA-, but not GT-apecific DTH responses, indicating that GA and GT do not cross-react at the T-cell level. The ability of GAT [but not a mixture of GA plus GT, or GT electrostatically complexed to the immunogenic carrier MBSA (GT-MBSA)] to induce GT-specific DTH suggested a requirement for covalent linkage of stimulatory GA and nonstimulatory GT determinants present on the GAT molecule. Similarly, GT-specific in vitro Tprlf responses could be demonstrated in GAT-primed mice exhibiting significant levels of GT-specific DTH but not in GT- or GT-MBSA-primed mice. Tolerization experiments also suggested that GT-specific Th were involved in the development of GT-specific DTH in GAT-primed mice. The GT nonresponsiveness of BALB/c mice for DTH and Tprlf responses could not be reversed by treatments designed to abrogate Ts activity (priming with GT-MBSA and CY injection), nor could GT-primed cells be shown to inhibit the development or elicitation of GT-specific CMI in GAT-primed mice during the afferent and/or efferent stages of DTH. Our results suggest that GT nonresponsiveness does not result from the absence of GT-specific T cells or preferential induction of Ts. The results are discussed in the context of hole-in-the-repertoire and antigen presentation (determinant selection) models of Ir gene control.Abbreviations used in this paper APC antigen-presenting cells - BSA bovine serum albumin - BSS Mishell-Dutton balanced salt solution - CFA complete Freund's adjuvant - CMI cell-mediated immunity - CY cyclophosphamide - DTH delayed-type hypersensitivity - GA poly(Glu⁶⁰Ala⁴⁰) - GAT poly (Glu⁶⁰Ala³⁰Tyr¹⁰) - GT poly(Glu⁵⁰Tyr⁵⁰) - GT-MBSA GT complexed to methylated bovine serum albumin - It immune response - LN lymph node - PPD purified protein derivative of tuberculin - TDH DTH T cells - Th helper T cells - Tprlf T-cell proliferation - Ts suppressor T cells - TsF T-cell suppressor factor(s)     

Effect of epidermal growth factor on lung liquid secretion in fetal sheep

Fetal lung liquid secretion depends on active transport of chloride ions. Chloride secretion in the stomach is inhibited by epidermal growth factor (EGF). For this reason, the effect of EGF on lung liquid secretion was measured using the impermeant-tracer technique in chronically-prepared fetal sheep. Infusion of EGF over 4 h resulted in decreased lung liquid secretion (from 4.2 +/- 0.6 to 1.7 +/- 0.8 ml/h, P = 0.02) and significant dose related tachycardia. During the infusion, plasma epinephrine levels increased from 27 +/- 5 to 67 +/- 13 pg/ml (P = 0.05) and norepinephrine levels increased from 257 +/- 31 to 544 +/- 69 pg/ml (P = 0.01). Since it is known that beta-adrenergic agonists inhibit lung liquid secretion, subsequent studies were performed with beta-adrenergic blockade using propranolol. Infusion of EGF and propranolol resulted in a significant decrease in lung liquid secretion (from 8.9 +/- 2.1 to 3.0 +/- 1.1 ml/h, P = 0.03). Infusion of propranolol alone had no demonstrable effect on lung liquid secretion. It is concluded that acute EGF infusion increases heart rate and stimulates catecholamine secretion in fetal sheep. EGF also inhibits lung liquid secretion, an effect which appears to be independent of a possible indirect catecholamine effect.     

Calcium regulation of ciliary activity in rabbit tracheal epithelial explants and outgrowth

Ciliated epithelial cells from rabbit trachea were employed to examine the role of Ca2+ in the regulation of ciliary motility. Tracheal explants and outgrowths were maintained in culture, and ciliary frequency was determined using a photomultiplier interfaced with a spectrum analyzer capable of Fast Fourier transform analysis. Relative cellular Ca2+ levels were determined by measuring 45Ca2+ uptake and efflux. Elevated cellular Ca2+, from exposure to 10(-5) M calcium ionophore A23187, led to an increase in ciliary frequency followed by inhibition of motility after prolonged treatment. A decrease in ciliary frequency was observed upon lowering intracellular Ca2+ by exposing the epithelium to 1 mM EGTA. Exposure of ciliated cells to 10(-4) M trifluoperazine resulted in inhibition of ciliary motility, a result suggesting a possible role for calmodulin- or phospholipid-sensitive Ca2+-dependent protein kinases in ciliary function. These results support the hypothesis that intracellular Ca2+ is actively involved in modulating the frequency of ciliary beat.     

Immobilization studies of whole microbial cells on transition metal activated inorganic supports

Summary Whole cells of Saccharomyces bayanus, Saccharomyces cerevisiae and Zymomonas mobilis were immobilized by chelation/metal-link processes onto porous inorganic carriers. The immobilized yeast cells displayed much higher sucrose hydrolyzing activities (90–517 U/g) than the bacterial, Z. mobilis, cells (0.76–1.65 U/g). The yeast cells chelated on hydrous metal oxide derivative of pumice stone presented higher initial -d-fructofuranosidase (invertase, EC 3.2.1.26) activity (161–517 U/g) than on other derivatives (90–201 U/g). The introduction of an organic bridge between the cells and the metal activator led to a decrease of the initial activity of the immobilized cells, however S. cerevisiae cells immobilized on the carbonyl derivative of titanium (IV) activated pumice stone, by covalent linkage, displayed a very stable behaviour, which in continuous operation at 30° C show only a slightly decrease on invertase activity for a two month period (half-life=470 days). The continuous hydrolysis of a 2% w/v sucrose solution at 30° C in an immobilized S. cerevisiae packed bed reactor was described by a simple kinetic model developed by the authors (Cabral et al., 1984a), which can also be used to predict the enzyme activity of the immobilized cells from conversion degree data.     

The structure of the neutral polysaccharide gum secreted by Rhizobium strain cb744

A previous investigation of the structure of the extracellular polysaccharide gum from the nitrogen-fixing Rhizobium strain cb744 (a member of the slow-growing Cowpea group) indicated that there were two β-(1→4)-linked d-glucopyranosyl residues for each α-(1→4)-linked d-mannopyranosyl residue, and that each mannose was substituted at O-6 by a β-d-galactopyranosyl residue having 71% of the galactose present as 4-O-methylgalactose. The present study shows that, although the gum appeared to have a simple tetrasaccharide repeating unit, it is composed of two closely associated components. One is a (1→4)-linked α-d-mannan substituted at each O-6 by a β-d-galactopyranosyl residue (71% 4-O-methylated). The second component is a (1→4)-linked β-d-glucan. The existence of the two polysaccharides was established by separation of the β-d-galactosidase-treated gum on a column of concanavalin A-Sepharose 4B. The d configurations were determined and the anomeric attribution of the linkages confirmed by the use of enzymes. The interaction between the two gum components is discussed.     

Some Properties of Thiosulfate-Oxidizing Enzyme from Marine Heterotroph 16B

Thiosulfate-oxidizing enzyme has been demonstrated in cell-free extracts of the marine, thiosulfate-oxidizing pseudomonad strain 16B. The enzyme, partially purified by ion-exchange chromatography and calcium phosphate gel treatment, catalyzed the oxidation of thiosulfate to tetrathionate with the concomitant reduction of ferricyanide. Native but not mammalian cytochrome c was also reduced by the enzyme in the presence of thiosulfate. The enzyme was located exclusively in the supernatant of ultracentrifuged cell extracts. The most purified enzyme preparation, like intact cells, exhibited a temperature optimum of 30 to 31°C. However, it exhibited no definite pH optimum. At pH 6.1 to 6.3 and 30°C, the K_m for thiosulfate was 1.57 mM. At lower temperatures, the apparent K_m for thiosulfate increased, but the apparent maximum velocity remained virtually unchanged. Thiosulfate oxidation in intact cells exhibited an increase in the pH optimum at lower temperatures. The thiosulfate-oxidizing enzyme of marine heterotroph 16B is compared with thiosulfate-oxidizing enzymes from other bacteria, and the effect of temperature on the relationship between pH and thiosulfate oxidation is discussed with reference to the natural habitat of the bacterium.