Associations of overweight and of weight dissatisfaction among Palestinian adolescents: findings from the national study of Palestinian schoolchildren (HBSC-WBG2004).

BACKGROUND: Overweight and obesity as well as weight dissatisfaction have been increasing in prevalence worldwide. Body weight dissatisfaction and fear of fatness are potential contributors to disordered eating. The present study aimed to investigate the prevalence of self-reported overweight and weight dissatisfaction along with associations with socio-demographic characteristics, body image, health complaints, risk behaviours, physical activity and television viewing in adolescents in Palestine. METHODS: The 2003/04 Palestinian Health Behaviour in School-aged Children (HBSC) is a cross-sectional survey of 17,817 adolescents from 405 randomly selected schools. Students from a representative sample of grades 6, 8, 10 and 12 (aged 12-18 years) self-completed a modified version of the international World Health Organization collaborative Health Behaviour in School-aged Children (HBSC-2002) questionnaire. RESULTS: Although 16.5% of the adolescents were overweight, almost twice that number (32.1%) were dissatisfied with their weight (i.e. dieting or perceiving a need to diet). Of those adolescents, two-thirds were not actually overweight (56.4% boys; 73.5% girls). One-fifth of the total number of adolescents (16.0% boys; 24.0% girls) were not overweight but were dissatisfied with their weight. Boys reporting overweight or weight dissatisfaction were more likely to have mothers with higher education or to be from more affluent families. Among both genders, but especially among girls, weight dissatisfaction was positively associated with most of the outcome variables (body image, health complaints, risk behaviours, and television viewing) regardless of weight status, whereas weight status was associated with only a few of the outcome variables. CONCLUSIONS: Weight dissatisfaction, independent of weight status, is associated with body image, health complaints, risk behaviours and television viewing, and represents a potential health risk factor for adolescents. Preventive interventions should focus not only on weight status, but also on body weight dissatisfaction.

Design, synthesis, and correlation analysis of 7-substituted 4-hydroxyquinoline-3-carboxylic acids as inhibitors of cellular respiration.

Fifteen 7-substituted 4-hydroxyquinoline-3-carboxylic acids have been designed to minimize covariance between the physicochemical substituent parameters: pi, MR, and sigmap. The molecules have been synthesized and evaluated for their ability to inhibit the respiration of Ehrlich ascites cells as a whole cell model and for their ability to inhibit malate dehydrogenase as an intracellular target enzyme model. Correlation analysis indicates that ascites cell inhibition is linearly related to pi and that malate dehydrogenase inhibition is linearly related to MR.

7-substituted-4-hydroxyquinoline-3-carboxylic acids as inhibitors of dehydrogenase enzymes and of the respiration of Ehrlich ascites tumor cells: multivariate analysis and quantitative structure-activity relationship for polar substituents.

The inhibitory activities of a set of nine 7-substituted-4-hydroxyquinoline-3-carboxylic acids against three dehydrogenase enzymes and one whole cell system (Ehrlich ascites tumor cells) have been subjected to principal component analysis. The results clearly indicate that activity against the whole cell test system cannot directly be attributed to inhibition of the enzymes evaluated. The enzyme systems are reflected by the first component that can be identified with polar and steric parameters while hydrophobic effects are absent. The second component is entirely due to the inhibition of ascites cell respiration that depends primarily on hydrophobicity.

Quantitative structure-activity relationship of antifolate inhibition of bacteria cell cultures resistant and sensitive to methotrexate.

Sets of 5-(substituted benzyl)-2,4-diaminopyrimidines and 4,6-diamino-1,2-dihydro-2,2-dimethyl-1-(3-substituted phenyl)-s-triazines as well as several other antifolates were tested as inhibitors of Escherichia coli dihydrofolate reductase and E. coli cell cultures both sensitive and resistant to methotrexate. From the results quantitative structure-activity relationships (QSAR) were formulated. The triazines were found to inhibit sensitive and resistant cell cultures to the same degree, but the benzylpyrimidines showed marked differences against the two types of cells. Increased hydrophobicity produced benzylpyrimidines more active against the resistant E. coli cell. Metroprine did not discriminate between the two types of cells cultures, but pyrimethamine and 2,4-diamino-6-(2,5-dimethoxybenzyl)-5-methylpyrido[2,3-d]pyrimidin e (BW 301U) did. The results are compared with triazines and benzylpyrimidines acting on Lactobacillus casei and murine tumor cells sensitive and resistant to methotrexate. QSAR is shown to be an effective means for detecting receptor differences.

Comparative analysis of the cytotoxicity of substituted (phenylglyoxal bis(4-methyl-3-thiosemicarbazone)) copper (II) chelates.

Seven para-substituted [phenylglyoxal bis(4-methyl-3-thiosemicarbazone)]copper (II) chelates (12-18) have been designed, synthesized, and tested for their ability to inhibit the respiration of rat liver slices as a normal cell model and Ehrlich ascites cells as a tumor cell model. Relationships between chemical structure and respiratory inhibition are described on a quantitative basis using substituent contants (pi, Es, and sigmap) by computerized multiparameter regression analyses. The correlations indicate that changes in Es have the largest effect on liver slice toxicity of chelates while pi and sigmap account for most of the variation in toxicity to ascites cells. A comparative analysis strongly suggests that electron-donating substituents with greater water solubility should increase cytotoxicity to ascites cells at the expense of cytotoxicity to the rat liver cells. The predictions of the equations were checked by synthesizing and testing an additional derivative. The results strengthen the initial predictions.

Comparative analysis of the cytotoxicity of substituted [phenylglyoxal bis(4-methyl-3-thiosemicarbazone)] copper(II) chelates. 2. Parabolic correlations and their implications for selective toxicity.

The synthesis of an extended series of para-substituted [phenylglyoxal bis(4-methyl-3-thiosemicarbazone)] copper(II) chelates is reported. Subsequent biological evaluation and regression analysis have been performed, correlating pI50 with extrathermodynamic substituent parameters. Parabolic correlations with pi have resulted which predict optimum lipophilic character of the para substituent with respect to Ehrlich ascites cytotoxicity (pi0 = -2.13) and with respect to ascites vs. liver slice cytotoxicity (pi0 = -1.31). Results indicated clearly that the chelate most toxic to the tumor cell model may not be the most selective.

Comparison of the inhibition of methotrexate-sensitive and -resistant Lactobacillus casei cell cultures with purified Lactobacillus casei dihydrofolate reductase by 4,6-diamino-1,2-dihydro-2,2-dimethyl-1-(3-substituted-phenyl)-s-triazines. Use of quantitative structure-activity relationships in making inferences about the mechanism of resistance and the structure of the enzyme is situ compared with the enzyme in vitro.

The inhibitory action of a set of 4,5-diamino-1,2-dihydro-2,2-dimethyl-1-(3-substituted-phenyl)-s-triazines on Lactobacillus casei dihydrofolate reductase is compared with their action on methotrexate-resistant and methotrexate-sensitive cell cultures by means of quantitative structure-selectivity analysis. The analysis uncovers major differences in the steric and hydrophobic interactions of the substituents X with the three different systems. Correlation analysis is used to define the hydrophobic binding site for 3-X in the isolated enzyme. This is shown to be similar to that of the sensitive cells but different from that in the resistant cells, which have a larger hydrophobic binding site. When X has the general structure 3-CH2ZC6H4-Y (Z = O or NH), it is shown that Y does not interact with the isolated enzyme, but in the living cells, Y interacts with a molecular barrier in a way that can be quantitatively related to the molar refractivity of X. The methotrexate-resistant cells are resistant to highly hydrophilic inhibitors such as methotrexate but are not able to resist hydrophobic inhibitors. The results with the inhibition of L. casei dihydrofolate reductase are compared with the inhibition of enzyme from bovine liver.

Synthesis and quantitative structure-activity relationships of anticonvulsant 2,3,6-triaminopyridines.

The synthesis of 2,3,6-triaminopyridine derivatives, representing a unique chemical structure for anticonvulsants, is described. The synthetic program was performed (a) to identify more potent analogs, (b) to determine structural properties controlling potency as well as neurotoxicity, and (c) to reduce the requirements for animal testing. As a result, besides other structural properties, the overall molecular lipophilicity (log k', octanol-coated column) explained changes in anticonvulsant potency and neurotoxicity. Mimicking the interaction of the amphiphilic triaminopyridines with biological membranes, NMR experiments in the presence of lecithin vesicles were conducted in order to measure the phospholipid-binding parameter log delta (1/T2). Replacement of log k' with log delta (1/T2) in the correlation analysis afforded a more significant equation describing the anticonvulsant activity of 21 derivatives.

4-hydroxyquinoline-3-carboxylic acids as inhibitors of cell respiration. 2. Quantitative structure-activity relationship of dehydrogenase enzyme and Ehrlich ascites tumor cell inhibitions.

Studies on dehydrogenase enzyme inhibition have been extended with the design, synthesis, and correlation analysis of 7-[(substituted-benzyl)oxy]-, 7-[(substituted-phenethyl)oxy]-, and 7([substituted-phenoxy)ethoxy]-4-hydroxyquinoline-3-carboxylic acids. Sixteen new congeners and the fifteen molecules previously synthesized have been tested against cytoplasmic malate dehydrogenase and lactate dehydrogenase, as well as against mitochondrial malate dehydrogenase. The lipophilic congeners show a clear specificity for inhibition of the mitochondrial enzyme. Correlation analysis of the data on the three enzymes allows a comparison of the binding sites in quantitative terms, while examination of the data on inhibition of ascites tumor cell respiration affords an indication of membrane transport. A newly developed high-pressure liquid chromatography based retention index is compared to the octanol-water pi constant as a model for hydrophobic interactions.

The maximally attainable VO2 during exercise in humans: the peak vs. maximum issue.

The quantification of maximum oxygen uptake (V(O2 max)), a parameter characterizing the effective integration of the neural, cardiopulmonary, and metabolic systems, requires oxygen uptake (VO2) to attain a plateau. We were interested in whether a VO2 plateau was consistently manifest during maximal incremental ramp cycle ergometry and also in ascertaining the relationship between this peak VO2 (V(O2 peak)) and that determined from one, or several, maximal constant-load tests. Ventilatory and pulmonary gas-exchange variables were measured breath by breath with a turbine and mass spectrometer. On average, V(O2 peak) [3.51 +/- 0.8 (SD) l/min] for the ramp test did not differ from that extrapolated from the linear phase of the response in 71 subjects. In 12 of these subjects, the V(O2 peak) was less than the extrapolated value by 0.1-0.4 l/min (i.e., a "plateau"), and in 19 subjects, V(O2 peak) was higher by 0.05-0.4 l/min. In the remaining 40 subjects, we could not discriminate a difference. The V(O2 peak) from the incremental test also did not differ from that of a single maximum constant-load test in 38 subjects or from the V(O2 max) in 6 subjects who undertook a range of progressively greater discontinuous constant-load tests. A plateau in the actual VO2 response is therefore not an obligatory consequence of incremental exercise. Because the peak value attained was not different from the plateau in the plot of VO2 vs. work rate (for the constant-load tests), the V(O2 peak) attained on a maximum-effort incremental test is likely to be a valid index of V(O2 max), despite no evidence of a plateau in the data themselves. However, without additional tests, one cannot be certain.

Metagenomics-based analysis of viral communities in dairy lagoon wastewater.

Microbial populations, especially those of viruses, are poorly studied in dairy wastewater treatment operations. Here we report signature nucleic acid metagenomic sequences obtained by pyrosequencing viromes of virus-like particles that were extracted from two dairy waste treatment lagoons. The lagoons are operated in series, with Lagoon I being used as the primary stage and Lagoon II as the secondary stage of wastewater treatment. An average of 2000 sequences was obtained from each lagoon. More than 300 signatures from each lagoon matched sequences in the virus database of the National Center for Biotechnology Information (NCBI). We utilized a bioinformatics approach and transmission electron microscopy (TEM) to characterize the viral diversity and presence of potential viral pathogens within the lagoons. Our results showed differences in viral community compositions between Lagoon I and Lagoon II, suggesting that the viral community changes significantly in the transition of water between the two lagoons. Furthermore, the diverse viral community in the lagoon samples contained signature sequences of a variety of bacterial, plant, and animal viruses. Bacteriophage sequences dominated the viral community metagenomes in both lagoons. Ultimately these results can be used to identify viral bioindicators to rapidly assess wastewater treatment quality and the potential impacts of dairy operations on watersheds. Our viral metagenomic sequences have been submitted to GenBank (GPID 65805) and can provide insight into the composition and structure of viral communities within wastewaters of dairy lagoon systems.

A comparative analysis of the synergistic interaction between N1-phenylsulfanilamides and benzylpyrimidines using qsar techniques.

Growth inhibition of E. coli cell culture has been determined for a series of 4-substituted-N1-phenylsulfonilamides tested in the presence and absence of synergistic concentrations of trimethoprim. Quantitative structure-activity relationships, established by regression analysis, exhibit an identical dependence of bacterial growth inhibition on sulfonamide pKa irrespective of the presence or absence of trimethoprim. Examination of a small series of benzylpyrimidines in the presence or absence of 4-dimethylamino-N1-phenylsulfanilamide gave similar results. Since the presence of a synergistic agent affords no change in structure-activity relationships, it is concluded that no direct interaction between sulfonamides and benzylpyrimidines occurs and that the synergism observed is solely the result of the kinetic consequences of sequential blockade of the folate biosynthetic pathway.