The association between umbilical cord abnormalities and the development of non-reassuring fetal heart rate leading to emergent cesarean deliveries.

OBJECTIVE: To study the contribution of umbilical cord (UC) abnormalities in emergent cesarean deliveries (ECDs) for non-reassuring fetal heart rate (NRFHR) and to explore their association with placental histopathology and neonatal outcome. STUDY DESIGN: Data from 530 ECDs for NRFHR were reviewed for the occurrence of UC abnormalities. Those included the presence of UC entanglements, the number and location of loops, true knots and short cord (<50 cm). Multiple UC entanglements were defined as ⩾ 2 UC loops. Results were compared with 530 vaginal deliveries (VD group) matched for maternal age, parity and gestational age. Additionally, we compared neonatal outcome and placental histopathology in cases of ECDs with a single vs multiple UC entanglements. Neonatal outcome consisted of low Apgar score (⩽ 7 at 5 min), cord blood pH ⩽ 7.1 and composite neonatal outcome that was defined as one or more of respiratory distress, necrotizing enterocolitis, sepsis, transfusion, ventilation, seizure, hypoxic-ischemic encephalopathy, phototherapy or death. Placental lesions were classified as: lesions related to maternal vascular supply, lesions related to fetal vascular supply (consistent with fetal thrombo-occlusive disease), and maternal and fetal inflammatory responses. RESULTS: UC entanglements, true knots and short cords were all more common in the ECD group compared with the VD group, P<0.001, P=0.002, P=0.004, respectively. The rate of one loop entanglement did not differ between the groups. The rate of multiple UC entanglements was higher in the ECD group compared with the VD group, 20.6% vs 6.4%, respectively, P<0.001. ECDs with multiple compared with single UC entanglement had higher rate of adverse neonatal outcome, P=0.031, and more placental fetal vascular lesions 19.3% vs 8.1%, P=0.027, respectively. CONCLUSION: Multiple UC entanglements, true knots and short cords were more common in ECDs for NRFHR, suggesting their role in the development of fetal placental vascular lesions and adverse neonatal outcome.

CYP77A19 and CYP77A20 characterized from Solanum tuberosum oxidize fatty acids in vitro and partially restore the wild phenotype in an Arabidopsis thaliana cutin mutant.

Cutin and suberin represent lipophilic polymers forming plant/environment interfaces in leaves and roots. Despite recent progress in Arabidopsis, there is still a lack on information concerning cutin and suberin synthesis, especially in crops. Based on sequence homology, we isolated two cDNA clones of new cytochrome P450s, CYP77A19 and CYP77A20 from potato tubers (Solanum tuberosum). Both enzymes hydroxylated lauric acid (C12:0) on position ω-1 to ω-5. They oxidized fatty acids with chain length ranging from C12 to C18 and catalysed hydroxylation of 16-hydroxypalmitic acid leading to dihydroxypalmitic (DHP) acids, the major C16 cutin and suberin monomers. CYP77A19 also produced epoxides from linoleic acid (C18:2). Exploration of expression pattern in potato by RT-qPCR revealed the presence of transcripts in all tissues tested with the highest expression in the seed compared with leaves. Water stress enhanced their expression level in roots but not in leaves. Application of methyl jasmonate specifically induced CYP77A19 expression. Expression of either gene in the Arabidopsis null mutant cyp77a6-1 defective in flower cutin restored petal cuticular impermeability. Nanoridges were also observed in CYP77A20-expressing lines. However, only very low levels of the major flower cutin monomer 10,16-dihydroxypalmitate and no C18 epoxy monomers were found in the cutin of the complemented lines.

CYP94A5, a new cytochrome P450 from Nicotiana tabacum is able to catalyze the oxidation of fatty acids to the omega-alcohol and to the corresponding diacid.

A full length cDNA encoding a new cytochrome P450-dependent fatty acid hydroxylase (CYP94A5) was isolated from a tobacco cDNA library. CYP94A5 was expressed in S. cerevisiae strain WAT11 containing a P450 reductase from Arabidopsis thaliana necessary for catalytic activity of cytochrome P450 enzymes. When incubated for 10 min in presence of NADPH with microsomes of recombinant yeast, 9,10-epoxystearic acid was converted into one major metabolite identified by GC/MS as 18-hydroxy-9,10-epoxystearic acid. The kinetic parameters of the reaction were Km,app = 0.9 +/- 0.2 microM and Vmax,app = 27 +/- 1 nmol x min(-1) x nmol(-1) P450. Increasing the incubation time to 1 h led to the formation of a compound identified by GC/MS as 9,10-epoxy-octadecan-1,18-dioic acid. The diacid was also produced in microsomal incubations of 18-hydroxy-9,10-epoxystearic acid. Metabolites were not produced in incubations with microsomes of yeast transformed with a control plasmid lacking CYP94A5 and their production was inhibited by antibodies raised against the P450 reductase, demonstrating the involvement of CYP94A5 in the reactions. The present study describes a cytochrome P450 able to catalyze the complete set of reactions oxidizing a terminal methyl group to the corresponding carboxyl. This new fatty acid hydroxylase is enantioselective: after incubation of a synthetic racemic mixture of 9,10-epoxystearic acid, the chirality of the residual epoxide was 40/60 in favor of 9R,10S enantiomer. CYP94A5 also catalyzed the omega-hydroxylation of saturated and unsaturated fatty acids with aliphatic chain ranging from C12 to C18.

Production in vitro by the cytochrome P450 CYP94A1 of major C18 cutin monomers and potential messengers in plant-pathogen interactions: enantioselectivity studies.

The major C(18) cutin monomers are 18-hydroxy-9,10-epoxystearic and 9,10,18-trihydroxystearic acids. These compounds are also known messengers in plant-pathogen interactions. We have previously shown that their common precursor 9,10-epoxystearic acid was formed by the epoxidation of oleic acid in Vicia sativa microsomes (Pinot, Salaün, Bosch, Lesot, Mioskowski and Durst (1992) Biochem. Biophys. Res. Commun. 184, 183-193). Here we determine the chirality of the epoxide produced as (9R,10S) and (9S,10R) in the ratio 90:10 respectively. We further show that microsomes from yeast expressing the cytochrome P450 CYP94A1 are capable of hydroxylating the methyl terminus of 9,10-epoxystearic and 9,10-dihydroxystearic acids in the presence of NADPH to form the corresponding 18-hydroxy derivatives. The reactions were not catalysed by microsomes from yeast transformed with a void plasmid or in absence of NADPH. After incubation of a synthetic racemic mixture of 9,10-epoxystearic acid with microsomes of yeast expressing CYP94A1, the chirality of the residual epoxide was shifted to 66:34 in favour of the (9S,10R) enantiomer. Both enantiomers were incubated separately and V(max)/K(m) values of 16 and 3.42 ml/min per nmol of P450 for (9R, 10S) and (9S,10R) respectively were determined, demonstrating that CYP94A1 is enantioselective for the (9R,10S) enantiomer, which is preferentially formed in V. sativa microsomes. Compared with the epoxide, the diol 9,10-dihydroxystearic acid was a much poorer substrate for the omega-hydroxylase, with a measured V(max)/K(m) of 0.33 ml/min per nmol of P450. Our results indicate that the activity of CYP94A1 is strongly influenced by the stereochemistry of the 9, 10-epoxide and the nature of substituents on carbons 9 and 10, with V(max)/K(m) values for epoxide>>oleic acid>diol.

Sex differences in elaborative strategies: a developmental analysis.

The present study examined sex differences in the use of elaboration in paired associate learning in adolescence and young adulthood. In Experiment 1, 48 eighth grade and 48 tenth grade students were asked to recall 24 word pairs, half of which were high frequency pairs, and half low frequency pairs. After recall, students reported the type of strategy used for each word pair (reading the pairs carefully, rehearsing the words, using imagery or constructing a verbal connection). Females used elaborative strategies more often, were more likely to recall elaborated pairs, and recalled more word pairs than males at both ages. These effects were observed in both high and low frequency word pairs. There was also a main effect of frequency, with elaboration more common with high frequency word pairs. In Experiment 2, college students performed the same paired-associates learning task, but with the added instruction to describe their elaborations in a sentence. At this age, there was a sex by materials interaction, with sex differences in strategy use only present with low frequency word pairs. These findings indicate that sex differences diminish under more favorable task conditions that encourage strategy use (high frequency word pairs) as males and females become more proficient strategy users, but remain under less favorable circumstances. An examination of the types of elaborations generated by college students indicated although males and females produced similar types of elaborations to the word pairs, sex differences in the recallability of low frequency words appeared with less interactive and more idiosyncratic elaborations.

Analysis of thymic stromal cell subpopulations grown in vitro on extracellular matrix in defined medium. III. Growth conditions of human thymic epithelial cells and immunomodulatory activities in their culture supernatant.

We report here on a new approach to the cultivation of human thymic epithelial (HTE) cells, which apparently allows more faithful preservation of cell function. This approach, previously developed by us for mouse thymic epithelial (MTE) cells, is based on the use of culture plates coated with extracellular matrix (ECM), and on the use of serum-free, growth factor-supplemented medium. The nutritional requirements of HTE and MTE are somewhat different. Although both are critically dependent on ECM and insulin, they differ in their dependency on other growth factors: selenium and transferrin are much more important for HTE cells, whereas epidermal growth factor and hydrocortisone play a more essential role in MTE cultures. The epithelial nature of the cultured cells is indicated by positive staining with anti-keratin antibodies and by the presence of desmosomes and tonofilaments. The ultrastructural appearance of the cells further suggests high metabolic and secretory activities, not usually found in corresponding cell lines. The culture supernatant (CS) of HTE cells exhibited a strong enhancing effect on thymocyte response to Con A stimulation, as measured by cell proliferation and lymphokine production. The effect was observed on both human and mouse thymocytes, but was much stronger in the homologous combination. Thymic factors tested in parallel did not have such a differential effect. The dose-effect relationships were in the form of a bell-shaped curve, with fivefold enhancement of response at the peak and a measurable effect even with 1:1000 dilution, when human thymocytes were used. The responding thymocytes were those which do not bind peanut agglutinin and are resistant to hydrocortisone. The culture system described here may have advantages for the in vitro study of thymic stromal cell function.