Enantioseparation of beta-methyl-substituted amino acids with cyclodextrins by capillary zone electrophoresis

Direct capillary zone electrophoretic methods were developed for the separation of the enantiomers of unnatural beta-methyl-amino acids such as erythro- and threo-beta-methylphenylalanine, beta-methyltyrosine, beta-methyltryptophan and beta-methyl-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid. Capillary zone electrophoresis was carried out using sulfopropylated-alpha-CD (SP2-alpha-CD), sulfopropylated-beta-CD (SP2-beta-CD) both with a degree of substitution of 2 moles/mole cyclodextrin, and sulfopropylated-beta-CD (SP4-beta-CD) with a degree of substitution of 4moles/mole beta-cyclodextrin. The effects of selector and buffer concentrations, electrolyte pH and applied voltage were studied on the separation efficiency. Varying the electrophoretic conditions with application of 20 kV, hydrodynamic injection, unmodified silica capillary, three different buffers (borate, phosphate and acetate) and modified cyclodextrins as chiral selectors all compounds investigated are nearly baseline resolved. The elution sequence was determined in most cases.     

The Burden of Provider-Initiated Preterm Birth and Associated Factors: Evidence from the Brazilian Multicenter Study on Preterm Birth (EMIP)

Background

About 15 million children are born under 37 weeks of gestation worldwide. Prematurity is the leading cause of neonatal deaths and short/long term morbidities, entailing consequences not only for the individual, but also their family, health agencies, facilities and all community. The provider-initiated preterm birth is currently one of the most important obstetric conditions related to preterm births, particularly in middle and high income countries, thus decreasing the need for therapeutic preterm birth is essential to reduce global prematurity. Therefore detailed knowledge on the factors associated with provider-initiated preterm birth is essential for the efforts to reduce preterm birth rates and its consequences. In this current analysis we aimed to assess the proportion of provider-initiated (pi-PTB) among preterm births in Brazil and identify associated factors.

Methods and Findings

This is an analysis of a multicenter cross-sectional study with a nested case-control component called Brazilian Multicenter Study on Preterm Birth (EMIP). EMIP was conducted in 20 referral obstetric hospitals located in the three most populated of the five Brazilian regions. We analysed data of women with pi-PTB, defined as childbirth occurring at less than 37 weeks, medically indicated for maternal/fetal compromise or both; and women with term birth, childbirth at or after 37 weeks. Maternal, sociodemographic, obstetric, prenatal care, delivery, and postnatal characteristics were assessed as possible factors associated with pi-PTB, compared to term births. The overall prevalence of preterm births was 12.3%. Of these, approximately one-third of cases were initiated by the provider. Hypertensive disorders, placental abruption, and diabetes were the main maternal conditions leading to pi-PTB. Caesarean section was the most common mode of delivery. Chronic hypertension (OR 7.47; 95%CI 4.02–13.88), preeclampsia/eclampsia/HELLP syndrome (OR 15.35; 6.57–35.88), multiple pregnancy (OR 12.49; 4.86–32.05), and chronic diabetes (OR 5.24; 2.68–10.25) were the most significant factors independently associated with pi-PTB.

Conclusions

pi-PTB is responsible for about one-third of all preterm births, requiring special attention. The decision-making process relative to the choice of provider-initiated birth is complex, and many factors should be elucidated to improve strategies for its prevention, including evidence-based guidelines on proper management of the corresponding clinical conditions.     

Effects of systemic and intracerebral administration of glucose oxidase on the blood sugar level in rats.

Intravenous administration of 10 to 40 U/g b.w. glucose oxidase produced hypoglycaemia in a dose-dependent manner. The enzyme-induced drop of the blood sugar level was associated with significant rise in serum potassium and the concentration of free fatty acids. Intracerebral application of glucose oxidase through chronically implanted cannula into the ventromedial, lateral hypothalamus, preoptic region and amygdaloid complex of nuclei failed to change the blood sugar level, although a moderate increase of the free fatty acids and corticosterone concentrations occurred. The local application of enzyme in the locus coeruleus region led to a significant rise of the blood sugar concentration. The observations suggest the sensitivity of brainstem catecholaminergic neuronal system to hypoglycaemia.     

Extra-pair paternity, testes size and testosterone level in relation to colour polymorphism in the barn owl Tyto alba

In many bird populations, individuals display one of several genetically inherited colour morphs. Colour polymorphism can be maintained by several mechanisms one of which being frequency-dependent selection with colour morphs signalling alternative mating strategies. One morph may be dominant and territorial, and another one adopt a sneaky behaviour to gain access to fertile females. We tested this hypothesis in the barn owl Tyto alba in which coloration varies from reddish-brown to white. This trait is heritable and neither sensitive to the environment in which individuals live nor to body condition. In Switzerland, reddish-brown males were observed to feed their brood at a higher rate and to produce more offspring than white males. This observation lead us to hypothesize that white males may equalise fitness by investing more effort in extra-pair copulations. This hypothesis predicts that lighter coloured males produce more extra-pair young, have larger testes and higher levels of circulating testosterone. However, our results are not consistent with these three predictions. First, paternity analyses of 54 broods with a total of 211 offspring revealed that only one young was not sired by the male that was feeding it. Second, testes size was not correlated with male plumage coloration suggesting that white males are not sexually more active. Finally, in nestlings at the time of feather growth testosterone level was not related to plumage coloration suggesting that this androgen is not required for the expression of this plumage trait. Our study therefore indicates that in the barn owl colour polymorphism plays no role in the probability of producing extra-pair young.     

Effects of Intracellular Calcium Chelation and Pifithrin-α on Deoxynucleotide Metabolism in Human Lymphocytes

Previously, we have found that activation of deoxycytidine kinase elicited by various DNA-damaging chemical agents could be prevented by BAPTA-AM, a cell-permeable calcium chelator or by pifithrin-α, a pharmacological inhibitor of p53. Here, we show that stimulation of deoxycytidine kinase by UV-light also is calcium-dependent and pifithrin-α-sensitive in tonsillar lymphocytes, while thymidine kinase 1 activity is stabilised in the presence of BAPTA-AM. Importantly, both UV-irradiation and calcium chelation decreased the incorporation of labelled deoxycytidine and thymidine into DNA. Pifithrin-alpha dramatically reduced the labelling of both the nucleotide and DNA fractions, possibly due to inhibition of transmembrane nucleoside transport.     

Purification and characterization of the catalytic subunit of cAMP dependent protein kinase from Drosophila melanogaster

Polyethylenimine selectivity precipitates a large fraction of the proteins present in a crude Drosophila embryonic extract. While the free catalytic subunit of the cAMP dependent protein kinase is quantitatively retained in the soluble fraction after polyethylenimine precipitation, the rest of the abundant and highly active protein kinases present in the embryo are quantitatively precipitated. The catalytic subunit of the cAMP dependent protein kinase was purified until apparent homogeneity from the soluble protein fraction after polyethylenimine precipitation. The pH optimum of the purified enzyme is 6.3. While magnesium is the preferred divalent cation for all the cAMP dependent protein kinases described previously, the Drosophila enzyme is three times more active if manganese is present as divalent cation compared with magnesium. The enzyme is tost active between 50–100 mM monovalent ion concentration. Heparin can selectively modulate the phosphorylation of different substrate proteins.     

Induction of in vitro androgenesis in anther and isolated microspore culture of different spelt wheat (<Emphasis Type="Italic">Triticum spelta</Emphasis> L.) genotypes

This is the first report on isolated microspore culture—derived spelt wheat. The efficiency of anther- and isolated microspore was compared using four genotypes (‘Franckenkorn’, ‘GK Fehér’, ‘Mv Martongold’, ‘Oberkulmer Rotkorn’). In anther culture, genotype dependency was observed, and cold pre-treatment enhanced the efficiency of the method. In isolated microspore culture, the ovary co-culture supported the development of embryo-like structures. The presence of growth regulators (0.5 mg/l 2,4-D and 0.5 mg/l kinetin) were not essential for the induction of androgenesis, but these increased the production of embryo-like structures, green and albino plantlets. The low plant regeneration rate and high number of albinos hinder the practical application of isolated microspore culture while anther culture was efficient for in vitro green plantlets production in spelt wheat. The mean of green plantlets production was 41.45/100 anthers (from 20.93 to 83.07 depending on genotype). The phenomenon of albinism was mitigated in anther culture (3.48 albinos/100 anthers). Altogether, 1720 anther culture—derived green plantlets were produced from the four genotypes.     

Evidence for a Rad18-independent frameshift mutagenesis pathway in human cell-free extracts

Bypass of replication blocks by specialized DNA polymerases is crucial for cell survival but may promote mutagenesis and genome instability. To gain insight into mutagenic sub-pathways that coexist in mammalian cells, we examined N-2-acetylaminofluorene (AAF)-induced frameshift mutagenesis by means of SV40-based shuttle vectors containing a single adduct. We found that in mammalian cells, as previously observed in E. coli, modification of the third guanine of two target sequences, 5'-GGG-3' (3G) and 5'-GGCGCC-3' (NarI site), induces -1 and -2 frameshift mutations, respectively. Using an in vitro assay for translesion synthesis, we investigated the biochemical control of these events. We showed that Pol eta, but neither Pol iota nor Pol zeta, plays a major role in the frameshift bypass of the AAF adduct located in the 3G sequence. By complementing PCNA-depleted extracts with either a wild-type or a non-ubiquitinatable form of PCNA, we found that this Pol eta-mediated pathway requires Rad18 and ubiquitination of PCNA. In contrast, when the AAF adduct is located within the NarI site, TLS is only partially dependent upon Pol eta and Rad18, unravelling the existence of alternative pathways that concurrently bypass this lesion.