Sterol composition and biosynthesis in the sponge Spheciospongia vesparia

The sterol composition of Spheciospongia vesparia from the Caribbean Sea is reported. Three groups of sterols, Δ⁵, Δ⁰, Δ^5,7, were found. The isolated 5α,8α-epidioxy sterols appeared to be predominantly, if not exclusively, artifacts. The auto-oxidation of native Δ^5,7-sterols to 5α,8α-epidioxy sterols has been investigated. A transformation of dietary Δ⁵-sterols to Δ^5,7-sterols has been demonstrated in Spheciospongia vesparia. © 1998 SCI     

Antimicrobial Properties of TiO2 Microparticles Coated with Ca- and Cu-Based Composite Layers

The ability of TiO₂ to generate reactive oxygen species under UV radiation makes it an efficient candidate in antimicrobial studies. In this context, the preparation of TiO₂ microparticles coated with Ca- and Cu-based composite layers over which Cu(II), Cu(I), and Cu(0) species were identified is presented here. The obtained materials were characterized by a wide range of analytical methods, such as X-ray diffraction, electron microscopy (TEM, SEM), X-ray photoelectron (XPS), and UV-VIS spectroscopy. The antimicrobial efficiency was evaluated using qualitative and quantitative standard methods and standard clinical microbial strains. A significant aspect of this composite is that the antimicrobial properties were evidenced both in the presence and absence of the light, as result of competition between photo and electrical effects. However, the antibacterial effect was similar in darkness and light for all samples. Because no photocatalytic properties were found in the absence of copper, the results sustain the antibacterial effect of the electric field (generated by the electrostatic potential of the composite layer) both under the dark and in light conditions. In this way, the composite layers supported on the TiO₂ microparticles’ surface can offer continuous antibacterial protection and do not require the presence of a permanent light source for activation. However, the antimicrobial effect in the dark is more significant and is considered to be the result of the electric field effect generated on the composite layer.     

The K+-Dependent and -Independent Pyruvate Kinases Acquire the Active Conformation by Different Mechanisms

Eukarya pyruvate kinases possess glutamate at position 117 (numbering of rabbit muscle enzyme), whereas bacteria have either glutamate or lysine. Those with E117 are K⁺-dependent, whereas those with K117 are K⁺-independent. In a phylogenetic tree, 80% of the sequences with E117 are occupied by T113/K114/T120 and 77% of those with K117 possess L113/Q114/(L,I,V)120. This work aims to understand these residues’ contribution to the K⁺-independent pyruvate kinases using the K⁺-dependent rabbit muscle enzyme. Residues 117 and 120 are crucial in the differences between the K⁺-dependent and -independent mutants. K⁺-independent activity increased with L113 and Q114 to K117, but L120 induced structural differences that inactivated the enzyme. T120 appears to be key in folding the protein and closure of the lid of the active site to acquire its active conformation in the K⁺-dependent enzymes. E117K mutant was K⁺-independent and the enzyme acquired the active conformation by a different mechanism. In the K⁺-independent apoenzyme of Mycobacterium tuberculosis, K72 (K117) flips out of the active site; in the holoenzyme, K72 faces toward the active site bridging the substrates through water molecules. The results provide evidence that two different mechanisms have evolved for the catalysis of this reaction.     

Reduced Photosynthetic Activity is Directly Correlated with 2-(3<Emphasis Type="Italic">H</Emphasis>)-benzoxazolinone Accumulation in Lettuce Leaves

2-(3H)-Benzoxazolinone (BOA) is a secondary plant metabolite previously found to inhibit plant growth and development. The phytotoxic activity of BOA has been extensively demonstrated over the last years. However, the relation of BOA phytotoxicity with BOA accumulation in plant leaves has not been thoroughly investigated. In this work, BOA phytotoxicity on photosynthesis (ΦPSII and Pn) of lettuce (Lactuca sativa L. cv. Great Lakes) was studied, and these results were correlated with BOA quantities in the leaves. BOA-treated plants showed reduced photosynthesis rate 6 h after the beginning of the treatment, and the efficiency of photosystem II started to be affected 10 h after treatment. These results were correlated with an increasing concentration of BOA in leaves that starts 6 h after treatment and shows a maximum at 96 h.     

Body mass index in a group of Venezuelan pregnant women and its relationship with the newborns' anthropometry

To assess the relationship between maternal body mass index (BMI) at early gestation and the newborns' anthropometry, 105 mother-infant dyads from a public Maternity Hospital in Valencia Venezuela, were studied during 1998-2000. Weight and height of adult women between 10 and 15 weeks of gestation were used to calculate BMI according to Atalah's reference (Low weight, Normal, Over weight). Term newborns were assessed using gestational age calculated according to the Capurro method. Their weight, height, and head circumference were recorded, and were characterized using a Venezuelan reference. Newborns whose birth weight (BW) was pound 10th percentile were considered "small for gestational age" (SGA), and those with BW (3) 90th percentile as "large for gestational age" (LGA). One-way ANOVA and Tukey's Post Hoc test were used for group comparisons. There were 41.9% of "low weight" mothers, and 13.4% of SGA newborns. There were differences in the newborns' weight and height according to "Low weight" maternal BMI with "Normal" and "Over weight" maternal BMI (p < 0.05). A high prevalence of nutritional deficit was observed from the beginning of the gestational period, as well as a relationship between maternal BMI and the newborn's anthropometry.     

Analysis of composite nanofibrous layers by confocal Raman microscopy

A method for the determination of nanofibrous mats chemical composition based on Raman spectroscopy and singular value decomposition is presented. Two different composite samples – a simultaneously spun and a layer-by-layer sample – consisting of polycaprolactone and poly(ethylene) oxide were prepared by electrospinning. Using Raman mapping, we were able to determine the chemical composition in various local areas within each sample, and to distinguish and image substantial changes in the distribution of the polymers caused by various preparation parameters. The ratio between both polymers was expressed as the relative fraction of the particular chemical compound. The results were validated by the Fourier transform infrared spectroscopy. The presence of two different substances in the nanofibrous mats was also proved by scanning electron microscopy. Confocal micro-Raman spectroscopy with its chemical sensitivity and spatial resolution may be used to identify inhomogeneities in the nanofibrous materials and could be of great help in the optimization of the electrospinning process.     

Study of the effect of different iron salts used to fortify infant formulas on the bioavailability of trace elements using ICP-OES

Five different iron salts—sulphate, lactate, diphosphate, encapsulated sulphate, and EDTA-Fe(III)—were used to fortify an infant formula to study possible differences in iron bioavailability. The effect of iron fortification at two levels (0.5 mg Fe 100 kcal⁻¹ and 1.5 mg Fe 100 kcal⁻¹) on the bioavailability of other important trace elements such as copper and zinc were also evaluated. An in vitro method based on element dialysability (i.e., the fraction available by absorption) to simulate newborn digestion was applied to study iron, copper and zinc bioavailability. Enzyme treatment was carried out in two stages involving pepsin at pH 5.0 followed by pancreatin at pH 7.0. The incubation times were short to mimic the transit of meal in an infant's gastrointestinal tract. Iron, copper and zinc were determined using inductively coupled plasma atomic emission spectrometry using an axially configured device. The percentages of Fe, Cu and Zn dialysable at both iron fortification levels are discussed. From these results, EDTA-Fe (III) appears to be the most adequate salt for iron fortification of infant formulas.     

Saturated fat and heart disease: The latest evidence

In recent years, many nutrition news headlines exclaimed that saturated fat was not linked to heart disease, leaving the public confused about whether to limit intake, as has been the dietary recommendation for several decades. However, a more nuanced look at the evidence indicates that high saturated fat diets are in fact not benign with respect to heart disease risk. Dietary recommendations should emphasize replacing saturated fats typical in red and processed meats, and certain tropical oils and dairy forms, with healthier polyunsaturated and monounsaturated fat‐rich foods, such as nuts, olive oil, and fatty fish, as well as healthy sources of carbohydrates, such as fiber‐rich whole‐grain foods, rather than refined‐grain and sugar‐laden foods.