Spatial distribution of metals in sediments of the Ribeira Bay, Angra dos Reis, Rio de Janeiro, Brazil.

This study aims to analyze the spatial distributions of several metals in sediments from five sites in Ribeira Bay, Brazil. Ribeira Bay is a very important area to the local community, due to its artisan fishery, and it also has a biological relevance for many marine species that use mangroves as nursery and feeding sites. According to the results, the area was not considered a metal polluted area. Despite not having a significant source of metals inside the Bay nowadays, Ilha Grande Bay harbors a shipyard, an oil terminal, and a commercial port, as well as two thermonuclear power plants (Angra I e II), all of which indirectly influence the study area.

Macrosomia: a new formula for optimized fetal weight estimation.

OBJECTIVES: To develop and test a specific formula for estimating weight in the macrosomic fetus. METHODS: Ultrasound estimations of fetal weight were carried out within 1 week of delivery in 424 singleton fetuses with a birth weight of > or = 4000 g. Exclusion criteria were multiple pregnancy, intrauterine death and major structural or chromosomal anomalies. Stepwise regression modeling was used to derive a prediction formula with birth weight as the dependent variable and maternal booking weight and fetal biometric measurements as independent parameters. After a new formula for estimated fetal weight (EFW) had been developed in a formula-finding group (n = 284), it was compared with commonly used weight equations (evaluation group, n = 140). RESULTS: The new formula (log(e)EFW = 7.6377445039 + 0.0002951035 x maternal weight + 0.0003949464 x head circumference + 0.0005241529 x abdominal circumference + 0.0048698624 x femur length) proved to be superior to established equations, with the smallest mean error (mean +/- SD, -10 +/- 202 g), the smallest mean percentage error (mean +/- SD, -0.03 +/- 4.6%) and the lowest mean absolute percentage error (3.69 (range, 0.05-13.57)%) when studied in the evaluation group. With the new formula, 77.9% of estimates fell within +/- 5% of the actual weight at birth, 97.1% within +/- 10%, and 100% within +/- 15% and +/- 20%. CONCLUSIONS: The new formula allows better weight estimation in the macrosomic fetus.

A new sonographic weight formula for fetuses

PURPOSE: Birth weight is an important predictive parameter for neonatal morbidity and mortality in the small fetus. Accurate estimation of fetal weight is therefore a valuable tool for determining the further obstetric management. The majority of studies presenting new formulas have included relatively small samples with a narrow range of birth weights, mostly term fetuses. In a previous study, we evaluated several weight formulas over the whole range of birth weights and in defined subgroups. We were able to show that some regression formulas appeared to be favorable within these subgroups. Notably, the highest levels of inaccuracy were found in the group of infants with a birth weight of less than 2500 g. This led us to hypothesize that a formula based on the lower birth weight group might increase the accuracy of weight estimation. The aim of the present study was therefore to develop a new specific formula for estimating weight in fetuses less than or equal to 2500 g and to compare the new regression formula with commonly used weight equations. MATERIALS AND METHODS: This study included 260 pregnancies. The inclusion criteria were a singleton pregnancy; birth weight equal to or less than 2500 g; an ultrasound examination with complete biometric parameters within 7 days prior to delivery; and an absence of structural or chromosomal malformations. The data for the first 130 newborns were used to develop a new formula. The remaining 130 infants were used to evaluate the new regression formula and to compare it to commonly used weight equations. Stepwise regression analysis was carried out with the birth weight as the dependent variable and biometric parameters as independent parameters to obtain the best-fit formula. RESULTS: The mean absolute percentage error for the new formula was 7.71 %. Compared to the other formulas, it generated the highest intraclass correlation coefficient. By the limits of agreement, the new formula demonstrated only a slight tendency towards underestimating fetal weight, and it provided the smallest range of all weight equations. CONCLUSION: With proper application, our new formula can improve the accuracy of fetal weight estimation.

Weight estimation by three-dimensional ultrasound imaging in the small fetus.

OBJECTIVES: To improve birth weight estimation in fetuses weighing

How good is fetal weight estimation using volumetric methods?

PURPOSE: Birth weight is an important predictive parameter for neonatal morbidity and mortality, and accurate estimation of fetal weight is therefore a valuable tool for determining the further obstetric management. Many sonographic weight formulas have been introduced. Most of these widely accepted formulas were derived from non-linear regression analysis. Only few formulas have been constructed using other methods, such as the physically based volumetric method based on routine two-dimensional biometric parameters in the fetus. The rationale for calculating fetal weight from volumetric measurements was that weight should to be directly proportional to fetal volume. In a recent review by Dudley, this method was considered to have some advantages in comparison with conventional regression formulas. However, to the best of our knowledge, none of the published volumetric formulas has ever been evaluated in a large population of fetuses. The aim of this study was to compare the volumetry-based formulas with widely accepted weight equations derived from regression analysis. We evaluated weight equations over the whole weight range and in specific weight groups in order to find out whether some equations were preferable in the groups tested. MATERIALS AND METHODS: 3975 pregnancies were included in order to evaluate four conventional formulas and four formulas based on volumetric models. The inclusion criteria were a singleton pregnancy, ultrasound examination with complete biometric parameters within 7 days before delivery, and an absence of structural or chromosomal malformations. The equations were compared over the whole weight range and in specific weight groups. RESULTS: Over the whole weight range, no single formula was able to offer a substantial advantage. In the small fetus, the Hadlock formula was preferable due to its low level of systematic error. For mid-sized fetuses, the Schild formula should be considered. In macrosomic fetuses, all formulas tended to underestimate the actual birth weight. Here, the best accuracy was achieved using the Merz formula. CONCLUSION: Neither a volumetric formula nor a conventional formula proved to be superior over the whole weight range. Within specific weight groups, some formulas showed improved accuracy. However, new approaches such as three-dimensional ultrasonography need to be pursued further in order to achieve better results in fetal weight estimation.

Fetal adrenal haemorrhage--two-dimensional and three-dimensional imaging.

A case of prenatal adrenal haemorrhage first detected by 2-dimensional and 3-dimensional sonography at 27 weeks' gestation is reported. Ultrasound examination showed a large cystic mass (32 x 27 x 27 mm) in the right suprarenal region of the fetus. Two weeks later, the mass had slightly increased in size demonstrating hyperechoic areas within the cyst. Further serial ultrasound examinations revealed a progressive organisation of the cystic mass associated with a moderate reduction in size. The diagnosis of adrenal haemorrhage was confirmed by postnatal follow-up sonograms as the mass decreased in size from 28 x 21 x 21 mm on day 1 to 23 x 18 x 17 mm on day 42. Course and sonographic signs were typical for adrenal haemorrhage and the neonate was therefore managed without surgical exploration. The child is developing normally at 6 months of age.

Fetal weight estimation by ultrasound: comparison of 11 different formulae and examiners with differing skill levels.

PURPOSE: Fetal weight is an important predictive parameter of neonatal morbidity and mortality. Precise estimation of fetal weight is therefore a valuable item of information for further prenatal and obstetric management. Many regression formulae for sonographic fetal weight estimation have been published during the last 30 years, which, unfortunately, generally show poor rates of accuracy. The aim of this study was to compare commonly used formulae in different birth weight groups in order to assess whether any of the formulae are more or less favourable. The second purpose was to estimate the role of examiners on the accuracy of fetal weight estimation. MATERIALS AND METHODS: 11 different formulae were evaluated in a group of 1941 pregnancies. Each fetus underwent ultrasound examination with complete biometric parameters within seven days before delivery. The assessment was carried out by either experienced or inexperienced sonographers. RESULTS: Over the whole weight range and in the subgroup of newborns with a birth weight less than 2500 g (n = 160), two Hadlock regression formulae (including abdominal circumference, femur length, head circumference, biparietal diameter, and abdominal circumference, femur length, biparietal diameter, respectively) showed the best levels of accuracy. Infants with a birth weight between 2500 and 3999 g (n = 1570) were best estimated using the gender-specific Schild formula. Macrosomic newborns (n = 211) were best evaluated using Merz's regression formula. The more skilled sonographers were able to achieve much higher intraclass correlation coefficients for all formulae. CONCLUSION: Some regression formulae appear to be favourable within defined weight ranges. Accuracy of the formulae, however, is still unsatisfactory, and new formulae focusing on specific weight ranges (e. g., macrosomic fetuses) are needed. In addition, experience in obstetric ultrasound improves accuracy of fetal weight estimation.

[Eye disease and mode of delivery]. / Geburtsmodus bei präexistenten Augenerkrankungen.

Many ophthalmologists and obstetricians recommend either an assisted vaginal delivery with forceps or vacuum extraction or a Caesarean section in cases of pre-existing eye diseases such as severe myopia, retinal detachment, diabetic retinopathy, or glaucoma. These recommendations, however, are not evidence-based. None of the published trials have reported any retinal changes after vaginal delivery. In general, eye disease is not an indication for an instrumental or operative delivery provided that regular eye examinations (once each trimester) have been performed.

1H solid-state nuclear magnetic resonance study of the mobility of the tetrapropylammonium template in a purely siliceous MFI-type zeolite.

Dynamics of tetrapropylammonium (TPA) cation occluded during the synthesis in a siliceous MFI zeolite is investigated by 1H broad-line nuclear magnetic resonance (NMR) methods. Second moments M2, spin-lattice relaxation times T1 and T1 rho are measured in a large temperature domain. To al comparison, similar measurements are also reported in bulk tetrapropylammonium bromide (TPABr). Whereas methyl reorientation at low temperature and tumbling of the cation in the plastic phase are observed in crystalline TPABr in accordance with published studies, a new slower motion which could not be identified is observed below the phase transition. Such a motion is much more clearly shown by the existence of a minimum of T1 rho in a quenched sample. Our measurements in the zeolite demonstrate that the TPA template exhibits a larger and more complex mobility below 378 K. Beyond the fast methyl reorientation, the results disclose a motion which probably involves the entire propyl arms inside the channels. So the zeolite framework seems to make such a kind of motion easier. On the contrary, even at 450 K, the highest temperature investigated, the tumbling which would necessitate exchange of the propyl arms between the channels is not observed. A slow motion, responsible for a decrease of T1 rho above 350 K, could not be identified. While a simple correlation time is sufficient to describe the relaxation time dependences in TPABr, a distribution (such as Williams-Watts) is required to account for those in the zeolite.

MR detection of quantitative and structural changes in human aortic aneurysms.

Collagen is a major component of the extracellular matrix and a determinant of the elastic behavior of the human aorta. To investigate the changes found in aneurysmal degeneration, the authors studied the solid-state hydrogen-1 nuclear magnetic resonance line shape of collagen in aneurysms and normal human aortas. A three-component decomposition of the free induction decay was performed, with collagen characterized by a T2 of about 18 microseconds. The second moment of the collagen line shape was found to be increased in aneurysms (5.3 vs 4.8 G2), while, correspondingly, the T2 of collagen was lower in aneurysms (16.3 vs 17.7 microseconds). This corresponds to a modification of collagen structure and molecular motion. Collagen concentration was lower in nondiseased aortic walls (9.4% vs 7.3%). These results are discussed in reference to the contradictory conclusions in the current literature. The increase in collagen and the modification of its structure and molecular motion are explained by the need to resist an increasing tangential tension due to increased aortic diameter and diminished wall thickness in aneurysms and by intercalation or site binding in the helices or electric dipolar interactions in the less mobile side groups.

In vitro proton NMR study of collagen in human aortic wall.

The authors relate the findings in the 1H solid state line shape (at 60 MHz) of human aortic walls (n = 12) in native state and after histologically controlled selective lysis of collagen and elastin. An analysis of the line shape shows a composite free induction decay (FID) consisting of a low amplitude (3-7%) fast decaying component (T2 approximately 20 microseconds) and a slow decaying one (T2 > 1 ms). The fast component is identified as the protons of the collagen macromolecules. The second moment computed from the experimental fast component of the FID is in agreement with published studies examining the motional characteristics of collagen by multinuclear NMR employing spin labeling. A theoretical second moment is computed for the collagen macromolecular backbone from the atomic positions in the superhelix. Comparison with the observed experimental values allows determination of the step angle (29 degrees) of the fast rotational motion of the collagen strands along their long axis.

Characterization of human aortic collagen's elasticity by nuclear magnetic resonance.

The elasticity of the human aortic wall in longitudinal uniaxial elongation at high strain, known to be determined mostly from tissular collagen's behaviour, is studied and compared to the second moment of the 1H nuclear magnetic resonance (NMR) solid state line-shape, a proton nuclear magnetic resonance (at 60 MHz) characteristic for the molecular motion and the rigidity of the collagen macromolecular backbone. The 1H NMR signal of collagen is identified after selective histologically controlled chemical lysis. The computed second moment of the line-shape shows statistically significant correlation with the slope of the strain-stress curve of the aorta at high strain, thus proving the relationship between a macroscopic tissular elasticity parameter and a macromolecular rigidity characteristic of collagen, a major tissular component. In vivo extension of this technique (e.g., MRI) would allow us to gain information on the biomechanical state of the aorta, a naturally highly stressed and strained tissue.

Proton magnetic resonance relaxation times and biomechanical properties of human vascular wall. In vitro study at 4 MHz.

OBJECTIVES AND RATIONALE: Previous studies have suggested a relationship between tissue magnetic resonance (MR) relaxation times and its biomechanical behavior. To further investigate this relationship, the authors studied 41 human vascular wall samples from different anatomic localizations, including systemic and pulmonary arterial, as well as venous tissues. METHODS: The authors measured water content, proton MR T1 and T2 relaxation times, and two viscoelastic parameters of the samples at 4 MHz. RESULTS: T2, water content, and both viscoelastic variables significantly differed among the five anatomic localizations (P less than .05). Both T1 and T2 were significantly (P less than .05) and linearly related to viscoelastic parameters. Multiple linear regression showed that both viscoelastic parameters of a sample can be predicted from the measured values of T1 and T2. CONCLUSIONS: These results provide a basis for characterizing the mechanical stress of a tissue by knowing its MR relaxation times.