Anthropometry Versus Imaging for Prediction of Inflammation Among Hispanic Girls

Objective: This study aimed to compare total and regional estimates of body composition, by direct and indirect techniques, for the optimal prediction of C‐reactive protein (CRP) among young (aged 9‐12 years) Hispanic girls (N = 232). Methods: Standard anthropometric techniques were used to measure height, weight, and waist circumference. Dual‐energy X‐ray absorptiometry (DXA) and peripheral quantitative computed tomography (pQCT) assessed body composition. Fasting serum CRP was measured by the AU5812 Clinical Chemistry Analyzer (Beckman Coulter, Brea, California). Associations between each total and regional body composition parameter and CRP were tested using linear regression (log‐transformed, continuous CRP) and ordinal logistic regression (CRP < 1.0, ≥ 1.0‐2.9, and ≥ 3.0 mg/L), controlling for maturation, dietary energy, physical activity, and medications. Results: All measures of total and regional body fat were positively associated with CRP (P < 0.0001) except for intermuscular fat by pQCT. There were no clinically relevant differences in their association with CRP between anthropometric (BMI; waist circumference) and DXA‐derived (total fat and regional fat: trunk, gynoid, android fat, leg) measures of fat. Conclusions: Measurement of body habitus in Hispanic girls, by multiple commonly available means, predicts CRP equally well.     

Age-related induction and disappearance of carcinogen-DNA-adducts in livers of rats exposed to low levels of 2-acetylaminofluorene

It was investigated whether in vivo aging of rat liver is associated with changes in the induction and rate of disappearance of DNA damage. For this purpose 6- and 36-month-old rats were intraperitoneally injected with a single, low dose (5 mg/kg body wt.) of the model liver carcinogen 2-acetylaminofluorene (AAF). Using the 32P-postlabeling assay we found that N-(deoxyguanosin-8-yl)-2-aminofluorene (dG-C8-AF) was the major DNA-adduct formed. The minor adduct N-(deoxyguanosin-8-yl)-2-acetylaminofluorene (dG-C8-AAF) could only be detected after doses of 20 mg/kg or more. Quantitation of adduct levels at various time points after treatment indicated a rapid induction of AF-adducts, which were already present at 6 h after treatment. The subsequent loss of AF-adducts was relatively slow, as was indicated by the presence of a substantial amount of AF-adducts as late as 21 days after treatment. Slight age-related differences in the pattern of induction and disappearance of AF-adducts and a somewhat higher level of persisting lesions in old than in young rats were observed.     

Determination of spontaneous loss of heterozygosity mutations in Aprt heterozygous mice.

A mouse model was generated to investigate loss of heterozygosity (LOH) events in somatic cells. The adenine phosphoribosyltransferase ( Aprt ) gene was disrupted in embryonic stem cells using a conventional gene targeting approach and subsequently Aprt hetero-zygous and homozygous mice were derived. Aprt homozygous deficient animals were viable though the mendelian inheritance pattern was skewed. On average these mice died at 6 months of age from severe renal failure. In T-lymphocytes of Aprt heterozygous mice the mean spontaneous mutant frequency at the Aprt locus was 8.7 x 10(-6) while the frequency was 0.8 x 10(-6) at the hypoxanthine phosphoribosyltransferase locus. In order to determine whether LOH events contribute to the high spontaneous mutant frequency at the Aprt locus, 140 Aprt mutant T-lymphocyte clones were expanded and analysed by allele-specific PCR. In 97 (69%) of these clones the wild-type allele had been lost. Nine of the mutant clones were characterized in more detail using dual-coloured fluorescence in situ hybridization analysis. Five out of six of the mutant clones which arose from an LOH event, based on the PCR assay, contained a duplication of the targeted allele. Therefore, mitotic recombination or chromosome loss followed by duplication of the remaining homologue appears to be the predominant mechanism for the in vivo generation of Aprt mutant T-lymphocytes.     

Isolation of LUMINIDEPENDENS: a gene involved in the control of flowering time in Arabidopsis.

Plants have evolved the ability to regulate flowering in response to environmental signals such as temperature and photoperiod. The physiology and genetics of floral induction have been studied extensively, but the molecular mechanisms that underlie this process are poorly understood. To study this process, we isolated a gene, LUMINIDEPENDENS (LD), that is involved in the timing of flowering in Arabidopsis. Mutations in this gene render Arabidopsis late flowering and appear to affect light perception. The late-flowering phenotype of the ld mutation was partially suppressed by vernalization. Genomic and cDNA clones of the LD gene were characterized. The predicted amino acid sequence of the LD protein contains 953 residues and includes two putative bipartite nuclear localization signals and a glutamine-rich region.     

A high-throughput assay for the comprehensive profiling of DNA ligase fidelity

DNA ligases have broad application in molecular biology, from traditional cloning methods to modern synthetic biology and molecular diagnostics protocols. Ligation-based detection of polynucleotide sequences can be achieved by the ligation of probe oligonucleotides when annealed to a complementary target sequence. In order to achieve a high sensitivity and low background, the ligase must efficiently join correctly base-paired substrates, while discriminating against the ligation of substrates containing even one mismatched base pair. In the current study, we report the use of capillary electrophoresis to rapidly generate mismatch fidelity profiles that interrogate all 256 possible base-pair combinations at a ligation junction in a single experiment. Rapid screening of ligase fidelity in a 96-well plate format has allowed the study of ligase fidelity in unprecedented depth. As an example of this new method, herein we report the ligation fidelity of Thermus thermophilus DNA ligase at a range of temperatures, buffer pH and monovalent cation strength. This screen allows the selection of reaction conditions that maximize fidelity without sacrificing activity, while generating a profile of specific mismatches that ligate detectably under each set of conditions.     

Regulation of UvrD Helicase Activity by MutL

Escherichia coli UvrD is a superfamily 1 helicase/translocase involved in multiple DNA metabolic processes including methyl-directed mismatch DNA repair. Although a UvrD monomer can translocate along single-stranded DNA, a UvrD dimer is needed for processive helicase activity in vitro. E. coli MutL, a regulatory protein involved in methyl-directed mismatch repair, stimulates UvrD helicase activity; however, the mechanism is not well understood. Using single-molecule fluorescence and ensemble approaches, we find that a single MutL dimer can activate latent UvrD monomer helicase activity. However, we also find that MutL stimulates UvrD dimer helicase activity. We further find that MutL enhances the DNA-unwinding processivity of UvrD. Hence, MutL acts as a processivity factor by binding to and presumably moving along with UvrD to facilitate DNA unwinding.     

Validity of bioelectric impedance for body composition assessment in children

Whole-body bioelectrical impedance analysis (BIA) was evaluated for its reliability and accuracy in estimating body composition in children. The hypothesis that the index, body height2 divided by resistance (RI), can accurately predict fat-free body mass (FFB) and percent fat (%FAT) in children was tested on 94 caucasian children 10-14 yr old. Criterion variables were FFB and %FAT estimated using multicomponent equations developed for children. BIA measurements (resistance and reactance) were found to be reliable. Prediction accuracy (standard error of the estimate, SEE) for FFB from RI alone was 2.6 kg and for %FAT from RI and body weight was 4.2%. For RI, anthropometric variables and reactance, the SEE improved to 1.9 kg FFB. For RI and anthropometric variables, the SEE was 3.3% FAT. For anthropometric variables alone, the SEE's were 2.1 kg FFB and 3.2% FAT. Adult FFB and %FAT prediction equations cross-validated with this sample resulted in SEE's similar to those for adult samples. We conclude that RI together with anthropometry is a reliable and an acceptably accurate method of estimating FFB mass and %FAT in children.     

Simulation of Sound Waves Using the Lattice Boltzmann Method for Fluid Flow: Benchmark Cases for Outdoor Sound Propagation

Propagation of sound waves in air can be considered as a special case of fluid dynamics. Consequently, the lattice Boltzmann method (LBM) for fluid flow can be used for simulating sound propagation. In this article application of the LBM to sound propagation is illustrated for various cases: free-field propagation, propagation over porous and non-porous ground, propagation over a noise barrier, and propagation in an atmosphere with wind. LBM results are compared with solutions of the equations of acoustics. It is found that the LBM works well for sound waves, but dissipation of sound waves with the LBM is generally much larger than real dissipation of sound waves in air. To circumvent this problem it is proposed here to use the LBM for assessing the excess sound level, i.e. the difference between the sound level and the free-field sound level. The effect of dissipation on the excess sound level is much smaller than the effect on the sound level, so the LBM can be used to estimate the excess sound level for a non-dissipative atmosphere, which is a useful quantity in atmospheric acoustics. To reduce dissipation in an LBM simulation two approaches are considered: i) reduction of the kinematic viscosity and ii) reduction of the lattice spacing.