Epidural Analgesia for Labour: Comparing the Effects of Continuous Epidural Infusion (CEI) and Programmed Intermittent Epidural Bolus (PIEB) on Obstetric Outcomes.

Objective: In the last few years there is a trend of transiting from the continuous epidural infusion (CEI) method for epidural analgesia to a new method - programmed intermittent epidural analgesia (PIEB). This change improves the quality of epidural analgesia, thanks to an increased spread of the anaesthetic in the epidural space and higher maternal satisfaction. Nevertheless, we must make sure that such change of method does not lead to worse obstetric and neonatal outcomes. Materials and Methods: This is a retrospective observational case control study. We compared several obstetrical outcomes between the CEI and PIEB groups, such as the rates of instrumental delivery, rates of caesarean section, duration of first and second stages of labour well as APGAR scores. We further segmented the subjects and examined them in groups of nulliparous and multiparous parturients. Results: 2696 parturients were included in this study: 1387 (51.4%) parturients in the CEI group and 1309 (48.6%) parturients in the PIEB group. No significant difference was found in instrumental or caesarean section delivery rates between groups. This result held even when the groups were differentiated between nulliparous and multiparous. No differences were revealed regarding first and second stage duration or APGAR scores. Conclusion: Our study demonstrates transition from the CEI to the PIEB method does not lead to any statistically significant effects on either obstetric or neonatal outcomes.

Production of bioactive, post-translationally modified, heterotrimeric, human recombinant type-I collagen in transgenic tobacco.

Collagen's biocompatibility, biodegradability and low immunogenicity render it advantageous for extensive application in pharmaceutical or biotechnological disciplines. However, typical collagen extraction from animal or cadaver sources harbors risks including allergenicity and potential sample contamination with pathogens. In this work, two human genes encoding recombinant heterotrimeric collagen type I (rhCOL1) were successfully coexpressed in tobacco plants with the human prolyl-4-hydroxylase (P4H) and lysyl hydroxylase 3 (LH3) enzymes, responsible for key posttranslational modifications of collagen. Plants coexpressing all five vacuole-targeted proteins generated intact procollagen yields of approximately 2% of the extracted total soluble proteins. Plant-extracted rhCOL1 formed thermally stable triple helical structures and demonstrated biofunctionality similar to human tissue-derived collagen supporting binding and proliferation of adult peripheral blood-derived endothelial progenitor-like cells. Through a simple, safe and scalable method of rhCOL1 production and purification from tobacco plants, this work broadens the potential applications of human recombinant collagen in regenerative medicine.

The expression level of threonine synthase and cystathionine-gamma-synthase is influenced by the level of both threonine and methionine in Arabidopsis plants.

The biosynthesis pathways of the essential amino acids methionine and threonine diverge from O-phosphohomoserine, an intermediate metabolite in the aspartate family of amino acids. Thus, the enzymes cystathionine-gamma-synthase (CGS) in the methionine pathway and threonine synthase (TS), the last enzyme in the threonine pathway, compete for this common substrate. To study this branching point, we overexpressed TS in sense and antisense orientation in Arabidopsis plants with the aim to study its effect on the level of threonine but more importantly on the methionine content. Positive correlation was found not only between TS expression level and threonine content, but also between TS/threonine and CGS expression level. Plants expressing the sense orientation of TS showed a higher level of threonine, increased expression level of CGS, and a significantly higher level of S-methylmethionine, the transport form of methionine. By contrast, plants expressing the antisense form of TS showed lower levels of threonine and of CGS expression level. In these antisense plants, the methionine level increased up to 47-fold compared to wild-type plants. To study further the effect of threonine on CGS expression level, wild-type plants were irrigated with threonine and control plants were irrigated with methionine or water. While threonine increased the expression level of CGS but reduced that of TS, methionine reduced the expression level of CGS but increased that of TS. This data demonstrate that both methionine and threonine affect the two enzymes at the branching point, thus controlling not only their own level, but also the level of each other. This mechanism probably aids in keeping the levels of these two essential amino acids sufficiently high to support plant growth.

Enhanced levels of methionine and cysteine in transgenic alfalfa (Medicago sativa L.) plants over-expressing the Arabidopsis cystathionine gamma-synthase gene.

With the aim of increasing the methionine level in alfalfa (Medicago sativa L.) and thus improving its nutritional quality, we produced transgenic alfalfa plants that expressed the Arabidopsis cystathionine gamma-synthase (AtCGS), the enzyme that controls the synthesis of the first intermediate metabolite in the methionine pathway. The AtCGS cDNA was driven by the Arabidopsis rubisco small subunit promoter to obtain expression in leaves. Thirty transgenic plants were examined for the transgene protein expression, and four lines with a high expression level were selected for further work. In these lines, the contents of methionine, S-methylmethionine (SMM), and methionine incorporated into the water-soluble protein fraction increased up to 32-fold, 19-fold, and 2.2-fold, respectively, compared with that in wild-type plants. Notably, in these four transgenic lines, the levels of free cysteine (the sulphur donor for methionine synthesis), glutathione (the cysteine storage and transport form), and protein-bound cysteine increased up to 2.6-fold, 5.5-fold, and 2.3-fold, respectively, relative to that in wild-type plants. As the transgenic alfalfa plants over-expressing AtCGS had significantly higher levels of both soluble and protein-bound methionine and cysteine, they may represent a model and target system for improving the nutritional quality of forage crops.

The N-terminal region of Arabidopsis cystathionine gamma-synthase plays an important regulatory role in methionine metabolism.

Cystathionine gamma-synthase (CGS) is a key enzyme of Met biosynthesis in bacteria and plants. Aligning the amino acid sequences revealed that the plant enzyme has an extended N-terminal region that is not found in the bacterial enzyme. However, this region is not essential for the catalytic activity of this enzyme, as deduced from the complementation test of an Escherichia coli CGS mutant. To determine the function of this N-terminal region, we overexpressed full-length Arabidopsis CGS and its truncated version that lacks the N-terminal region in transgenic tobacco (Nicotiana tabacum) plants. Transgenic plants expressing both types of CGS had a significant higher level of Met, S-methyl-Met, and Met content in their proteins. However, although plants expressing full-length CGS showed the same phenotype and developmental pattern as wild-type plants, those expressing the truncated CGS showed a severely abnormal phenotype. These abnormal plants also emitted high levels of Met catabolic products, dimethyl sulfide and carbon disulfide. The level of ethylene, the Met-derived hormone, was 40 times higher than in wild-type plants. Since the alien CGS was expressed at comparable levels in both types of transgenic plants, we further suggest that post-translational modification(s) occurs in this N-terminal region, which regulate CGS and/or Met metabolism. More specifically, since the absence of the N-terminal region leads to an impaired Met metabolism, the results further suggest that this region plays a role in protecting plants from a high level of Met catabolic products such as ethylene.