Abstract An Ion Chromatographic (IC) method for the determination of six organic acids and three inorganic anions in alkaline solutions was reported. Formic, acetic, propionic, oxalic, succinic, glutaric acid, F ‐ , Cl ‐ , and SO 4 2‐ were separated and determined in 33 min. The analytes were removed from Bayer liquor by using an ion‐exchange resin column. The chromatographic separation was achieved with only one IonPac AS11‐HC column thermostated at 30 °C. Organic acids and inorganic anions were detected with a suppressed conductance detector. The precision results' showed that the repeatability and reproducibility were <2.94 and <1.37 %, respectively. The accuracy of the method was assessed by the recoveries ranging from 86.3 to 105.6 %. Under optimum conditions the detection limits ranged from 0.008 to 0.053 mg/l.
To establish the stability of Ultranox 626 (an antioxidant added to plastics) in food simulants under migration conditions, migrations tests have been performed. A method has been developed for the determination of Ultranox 626 in the aqueous food simulants distilled water, 3% (w/v) acetic acid, and 15% (v/v) ethanol and in the fatty food simulants 95% (v/v) ethanol and isooctane. The method uses reversed-phase high-performance liquid chromatography with ultraviolet detection at 230 nm, is fast, and can be run automatically. To determine the stability of Ultranox 626, it was heated in each of the listed food simulants under the conditions stipulated in EU regulations for testing for compliance with migration limits. These experiments showed that this additive had acceptable stability in water, 15% and 95% (v/v) ethanol, and isooctane but that it decomposed completely in 3% (w/v) acetic acid. Migration testing with 3% acetic acid is of no use, since by the end of the testing regime the additive will have undergone substantial or total decomposition, and the level detected will not reflect the true level of migration. The EU Commission should replace 3% acetic acid with 15% ethanol as an appropriate test simulant for the determination of Ultranox 626 in all types of acid- and alcohol-containing foodstuffs. A number of experiments were carried out to develop a suitable method for the determination of Ultranox in fat simulants such as olive oil and HB 307. It appeared not possible, within the scope of this project, to obtain a method suitable to establish the stability of Ultranox 626 in fat simulants. Best results were obtained by freezing out the fat at -80 degrees C, but recovery was limited to 50%, which was insufficient for the intended purpose. Further experiments are required to establish the stability of Ultranox 626 in fat simulants such as olive oil and HB 307.
In chronic kidney disease (CKD), the prevalence of hypertension is very high, escalating with diminishing renal function. Typically, the diagnosis of hypertension and the clinical decisions regarding its treatment are based on daytime clinic blood pressure (BP) measurements. However, the correlation between BP level and target organ damage, cardiovascular risk and long-term prognosis is greater for ambulatory than clinic measurements. Moreover, evidence is consistent among numerous studies that the elevated risk and incidence of end-organ injury and fatal and non-fatal cardiovascular events are significantly associated with blunted night-time BP decline, and that the asleep BP better predicts cardiovascular events than either the awake or 24-h BP mean. The prevalence of abnormally high asleep BP is extensive in CKD, significantly increasing with its severity. In CKD, the diagnoses of hypertension and its therapeutic control are often inaccurate in the absence of complete and careful assessment of the entire 24 h, i.e. daytime and night-time, BP pattern. Accordingly, ambulatory BP monitoring should be the preferred method to comprehensively assess and decide the optimal clinical management of patients with CKD. Recent findings indicate therapeutic restoration of normal physiologic BP reduction during night-time sleep is the most significant independent predictor of decreased cardiovascular and cerebrovascular risk, both in patients with and without CKD, and is best achieved when antihypertensive medications, mainly those blocking the renin-angiotensin-aldosterone system, are routinely taken at bedtime.
Genetic risk is a primary contributing factor to the predisposition of a newborn child to elevated blood pressure later in life. To determine if there is a correlation between potential genetic risk as established by family history and measured physiological variables in the neonate, the systolic and diastolic blood pressures and heart rates of 150 newborn babies were automatically monitored at about 30-minute intervals for 48 hours with a Nippon Colin device, starting early after birth. Based on questionnaires given to the parents, the neonates were assigned to a group of either a negative or positive family history of high blood pressure. Circadian characteristics and descriptive statistics for the 3 circulatory variables were used for classification by a "monotest", an all-subsets variable selection technique for biomedical discriminant analysis. For a particular combination of variables, the monotest performs as many separate analyses as the number of subjects, each subject's data being compared with those of all others. When the circadian amplitudes of systolic blood pressure and heart rate and the circadian range of heart rate were used as a combined classifier, the monotest yielded a 70% classification equivalent to prior criteria, the latter being based on the family history of high blood pressure. The combined use of time-specified sampling hardware with signal processing and discriminant analysis software allows one to recognize parameters of blood pressure circadian variability as a source of information for neonatal classification according to cardiovascular risk.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
Between 1962 and 1965, before Kimura postulated the neutral theory of evolution (Kimura, 1968), Zuckerkandl and Pauling published two fundamental papers on the evolutionary rate of proteins (Zuckerkandl & Pauling, 1962; Zuckerkandl & Pauling, 1965). They noticed that the genetic distance of two sequences coding for the same protein, but isolated from different species, seems to increase linearly with the divergence time of the two species. Since several proteins showed a similar behavior, Zuckerkandl and Pauling hypothesized that the rate of evolution for any given protein is constant over time. This suggestion implies the existence of a sort of molecular clock ticking faster or slower for different genes but at a more or less constant rate for any given gene among different phylogenetic lineages (see Fig. 11.1). The clock hypothesis received an enormous popularity almost immediately for several reasons. If a molecular clock exists and the rate of evolution of a gene can be calculated, then this information can easily be used for dating the unknown divergence time between two species just by comparing their DNA or protein sequences. If, on the other hand, the information about the divergence time between two species (for example, estimated from fossil data) is known, then the rate of molecular evolution of a given gene can be inferred. An additional advantage of assuming a molecular clock is that it can render phylogenetic reconstruction much easier and more accurate (see Chapter 5).
The enzymatic activity of human carbonic anhydrase II (HCAII) was studied in the presence of nanoparticles of different nature and charge. Negatively charged nanoparticles inhibit HCAII whereas no effect is seen for positively charged particles. The kinetic effects were correlated with the strength of binding of the enzyme to the particle surface as measured by ITC and adsorption assays. Moreover, conformational changes upon adsorption were observed by circular dichroism. The main initial driving force for the adsorption of HCAII to nanoparticles is of electrostatic nature whereas the hydrophobic effect is not strong enough to drive the initial binding. This is corroborated by the fact that HCAII do not adsorb on positively charged hydrophobic polystyrene nanoparticles. Furthermore, the dehydration of the particle and protein surface seems to play an important role in the inactivation of HCAII by carboxyl-modified polystyrene nanoparticles. On the other hand, the inactivation by unmodified polystyrene nanoparticles is mainly driven by intramolecular interactions established between the protein and the nanoparticle surface upon conformational changes in the protein.
Quantitative genetics is the study of continuously varying traits which make up the majority of biological attributes of evolutionary and commercial interest. This book provides a much-needed up-to-date, in-depth yet accessible text for the field. In lucid language, the author guides readers through the main concepts of population and quantitative genetics and their applications. It is written to be approachable to even those without a strong mathematical background, including applied examples, a glossary of key terms, and problems and solutions to support students in grasping important theoretical developments and their relevance to real-world biology. An engaging, must-have textbook for advanced undergraduate and postgraduate students. Given its applied focus, it also equips researchers in genetics, genomics, evolutionary biology, animal and plant breeding, and conservation genetics with the understanding and tools for genetic improvement, comprehension of the genetic basis of human diseases, and conservation of biological resources.
In the present work, we study the effects that aggregation of humic acids in seawater, and its adsorption to surfaces, can have on the determination of Cu and Pb accumulation by phytoplankton within the context of metal bioavailability studies, using the diatom Thalassiosira weissflogii. Two methods commonly used for collection of algae to analyse metal content, filtration and centrifugation, were compared, and a procedure to differentiate the metal internalized by the alga from that adsorbed to cell walls-washing with 0.01 M ethylenediaminetetraacetic acid (EDTA)- was optimized for its use in seawater and in the presence of humic acids. The present results highlight the possibility of obtaining biased results if filtration is used to isolate the algae, and show that centrifugation is a more suitable procedure minimizing contribution of particulate and colloidal forms of metals to the measured cellular and intracellular metal contents. Thus a combination of centrifugation to isolate the algae from the medium with a 10 minutes washing with a washing agent composed of EDTA 0.01 M at pH 8 and NaCl and KCl to 0.5 M ionic strength is recommended to extract metals adsorbed to the surfaces of marine phytoplankton for a seawater containing humic substances. The importance of discriminating between internalized metal and total cellular metal in bioavailability studies is noted, given the different effects of humic substances on metal accumulation in the different cellular pools.
Dried leaves of Marchantia convoluta are largely used to protect livers, and to treat tumefaction of skins in China. Flavonoids from Marchantia convoluta (MCF) were the active components against hepatitis B virus. In this study, the pharmacological properties of MCF consisting of flavonoids determined by HPLC were examined in particular. High dosage of MCF (20 and 40 µg/mL) could significantly reduce the activity of ALT and AST in the serum of mice with acute hepatic injury caused by CCl4 and increase the contents of TP and ALP. MCF could inhibit the auricle tympanites of mice caused by dimethylbenzene. MCF inhibited obviously colibacillus, tyhoid bacillus, Staphylococcus aureus, bacillus enteritidis, hemolytic streptococci type B and Diplococcus pneumoniae. The results showed that MCF possess distinct effect of antibiosis, anti-inflammation and diuresis in mice. Key words: Marchantia convoluta, flavonoids, antibiosis, antiinflammation, diuresis Afr. J. Trad. Comp. Alt. Med. Vol.2(3) 2005: 244 - 252
