Validity of visceral adiposity estimates from DXA against MRI in Kuwaiti men and women

OBJECTIVES

The prevalence of obesity and diabetes in the Middle East is among the highest in the world. Valid measures of abdominal adiposity are essential to understanding the metabolic consequences of obesity. Dual-energy X-ray absorptiometry (DXA) is increasingly being utilised to assess body composition in population studies, and has recently been used to estimate visceral adipose tissue (VAT). The aim of this study was to determine the accuracy of DXA-derived VAT in a Middle Eastern population using magnetic resonance imaging (MRI) as the criterion measure.

METHOD

VAT was estimated from abdominal DXA measures in 237 adult men (n=130) and women (n=107), aged 18-65 years, participating in the Kuwait Wellbeing Study. These estimates were compared with MRI measures of the corresponding anatomical region. The agreement between methods was assessed using Bland-Altman as well as correlation analysis.

RESULTS

Median MRI VAT was 1148.5 cm3 (95% confidence interval: 594.2-1734.6) in men and 711.3 cm3 (95% confidence interval: 395.5-1042.8) in women. DXA estimates of VAT showed high correlations with corresponding MRI measures (r=0.94 (P<0.0001) in men; r=0.93 (P<0.0001) in women). DXA overestimated VAT with a mean bias (95% limits of agreement) of 79.7 cm3 (-767 to 963) in men and 46.8 cm3 (-482 to 866) in women. The imprecision of DXA increased with increasing VAT level in both men and women.

CONCLUSION

DXA estimates of VAT are valid for use in Middle Eastern populations, although accuracy decreases with increasing level of visceral adiposity.

The impact of rapid weight loss on the leptin, adiponectin levels, and insulinresistance among adult free style wrestlers

AIM

Recent studies, shows the effective role of adipose tissue as an active endocrine organ. Leptin level increases in obese bodies while adiponectin as an antirisk factor reduction that contributes to decrease insulin resistance and anthropometric profiles. Hence, expected to the negative effects of weight loss on wrestlers' physiological function; leptin and adiponectin behaviors and insulin resistance in young wrestlers during their rapid weight loss program were examined.

METHODS

Fifteen young (23±1 yr) freestyle wrestlers with (weight 67.6±0.8 kg, BMI 22.5±0.2 kg/m²) in two (60 and 66 kg) weight categories were selected randomly. Caloric intake and anthropometric characteristics measured by standard methods. The leptin and adiponectin hormones and insulin resistance index were measured by sandwich and HOMA-IR methods respectively. Wrestlers performed a week rapid weight loss Protocol (average of 4% of body weight loss) under the supervision of their coach. Eventually, selected factors were measured after 12 and 24 hours of recovery, again.

RESULTS

The rapid weight loss (4%) program had a significantly reduced impact on anthropometric factors; leptin level, insulin resistance, and increased beta cell function, while the changes of adiponectin were not significant after weight loss.

CONCLUSION

Findings of this study shows that dramatic decrease in anthropometric factors follow the weight loss program that having a significant decrease on leptin, L/A ratio and HOMA-IR, without significant changes in adiponectin levels. These changes may have harmful physiological effects on wrestlers' bodies but they can be useful to regulate of fatty acid, glucose metabolism, and insulin resistance.

Experienced Airway Management in Laryngotracheal Injuries: Series of Cases, Survey and Review of Literature

Definitive airway control of penetrating laryngotracheal injury can be an extremely difficult challenge for the emergency physician. We report three serious cases of penetrating neck trauma with laryngeal injury that were managed successfully using different techniques of airway control in the Emergency Department (ED) of Hamad General Hospital during the three years from January 2006 through December 2008. Individualized assessment, identification of type of injury and familiarity with airway control techniques and the available options assure timely, safe and proper airway control in such injuries. Choice of technique in penetrating laryngotracheal injury is multifactorial and depends upon case presentation, physician preference, skill, and clinical constraints. The incidence of neck injury during this period was lower than in other reports; being 0.07 % of total trauma cases, while the incidence of penetrating neck injuries represented 17.6% of total neck injuries with no deaths. Implications Statement: Familiarity and availability of variant airway management techniques and variant surgical interventions in penetrating laryngotracheal injuries, improve outcome and reduce mortality.

IL-12 prevents the inhibitory effects of cis-urocanic acid on tumor antigen presentation by Langerhans cells: implications for photocarcinogenesis

UV radiation induces skin cancer primarily by its DNA-damaging properties, but also by its capacity to suppress the immune system. The photoisomer of urocanic acid (UCA), cis-UCA, is an important mediator of UV-induced immunosuppression and is involved in the inhibition of tumor immunity. The immunomodulatory cytokine IL-12 is known to counteract many of the immunosuppressive effects of UV radiation, including UV-induced immune tolerance. In this study, we addressed whether IL-12 also reverts the immunosuppressive activities of cis-UCA. Cis-UCA inhibits the ability of Langerhans cells to present tumor Ags for primary and secondary tumor immune responses. IL-12 treatment completely prevented the suppression by cis-UCA. IL-12 also protected mice from cis-UCA-induced suppression of contact hypersensitivity responses. To study the effects of cis-UCA on Ag-processing and Ag-presenting function in vitro, Langerhans cells were treated with UCA isomers and incubated with OVA or OVA peptide(323-339) before exposure to OVA-specific transgenic T cells. Cis-, but not trans-UCA suppressed Ag presentation, which was completely reversed upon addition of IL-12. Since these findings suggest that cis-UCA may play an important role in photocarcinogenesis by inhibiting a tumor immune response, mice were chronically UVB irradiated to induce skin cancer. Whereas all mice in the control groups developed tumors, mice treated with a mAb with specificity for cis-UCA showed a significantly reduced tumor incidence. These data strongly indicate the importance of cis-UCA during photocarcinogenesis and support the concept of counteracting cis-UCA as an alternative strategy to prevent UV-induced skin cancer, possibly via the application of IL-12.

Simultaneous photoconjugation of methylene blue and cis-Rh(phen)2Cl2+ to DNA via a synergistic effect

Irradiation of the red-light absorbing dye, methylene blue (MB), in the presence of the metal complex, cis-Rh(phen)2Cl2+ (BISPHEN), leads to irreversible photobinding of both reagents to DNA. Evidence from absorption and emission spectroscopy indicates that the dye is strongly complexed to the DNA at the concentrations used in the experiments and that this complex is unaffected by the presence of BISPHEN. The level of covalent binding is proportional to the absorbed light dose, with the quantum efficiency for covalent binding of BISPHEN to the DNA with 633 nm light equal to 3.5 x 10(-4). Electrospray ionization mass spectrum of a mixture of DNA fragments created by enzymatic degradation of DNA isolated following irradiation indicates that purine adducts are formed with both BISPHEN and the dye. In addition, UV-Vis and high-performance liquid chromatography analyses of the irradiated MB/BISPHEN/DNA mixture and isolated adducts show extensive conversion of the dye and metal complex to the corresponding N-demethylated and aquated derivatives, respectively. Triplet quenchers for MB, for example oxygen and benzoquinone, inhibit both the photoconjugation and the photochemistry of BISPHEN. A mechanism for the synergistic interaction is proposed that involves photoconjugation of both partners to the DNA following oxidation and reduction via electron transfer between 1MB*/DNA and 3MB*/BISPHEN.

Photonuclease activity of Taylor's blue

Taylor's blue (1,9-dimethylmethylene blue, DMMB+) associates with DNA, at least in part, through intercalation as is evidenced from the red shift in the absorption maximum, diminution of the fluorescence, and induced circular dichroism in the presence of nucleic acid. Irradiation of DMMB+/covalently closed circular supercoiled phiX174 phage DNA complex at lambda > 520 nm leads to DNA nicking in a dose-dependent manner.

Photoinduced cross-linking of RNA by cis-Rh(phen)2Cl2+ and cis-Rh(phen)(phi)Cl2+: a new family of light activatable nucleic acid cross-linking agents

The metal complexes, cis-Rh(phen)2Cl2+ and its more hydrophobic analog cis-Rh(phen)(phi)Cl2+, have been shown to photocross-link the 120-base phi29-encoded pRNA. Primer extension on the cis-Rh(phen)(phi)Cl2(+)-photocross-linked RNA revealed that guanines are responsible for the interstrand cross-links.

Simultaneous determination of methylene violet, halogenated methylene violet and their photoproducts in the presence of DNA by high-performance liquid chromatography using an internal surface reversed-phase column

A simple and rapid isocratic high-performance liquid chromatographic method for the analysis of methylene violet, a neutral phenothiazine dye, in the presence of DNA has been developed. These chromatographic conditions are also applicable to its N-demethylated, bromo and iodo analogs. The method utilizes an internal surface reversed-phase column and a mobile phase consisting of 20% acetonitrile in 50 mM phosphate buffer (pH 7.0) and detection at 280 nm. Under these conditions all five dyes are well resolved from one another and from the faster migrating DNA. The effects of organic modifiers, ionic strength and pH of the buffer on the capacity factors of the dyes have been investigated. The method has successfully been applied to detect the photoproducts of methylene violet and its bromo analog in the presence of DNA without removing the biopolymer from the reaction mixture.

Photobiological properties of methylene violet

The interaction of methylene violet (MV) and 4-bromomethylene violet (BrMV) with calf thymus and supercoiled phi X174 phage RF I DNA is reported. Measurements employing UV-visible absorption spectroscopy and equilibrium dialysis give evidence for the formation of complexes by each dye with DNA in the dark. They covalently bind to DNA, and MV nicks DNA, when the nucleic acid/dye mixtures are irradiated with visible light in a deoxygenated environment. Quantum efficiencies for singlet oxygen formation are 0.27 and 0.25 for MV and BrMV, respectively. A higher value (0.49) is observed for 4-iodomethylene violet (IMV).

Regulation of tumor antigen presentation by urocanic acid

Urocanic acid (UCA) accumulates in the epidermis after deamination of histidine. UCA isomerizes from the trans to the cis form upon exposure to environmental UV radiation. Cis-UCA is immunosuppressive in several models. Topically applied cis-UCA was reported to enhance the cutaneous tumor yield in chronically UV-irradiated mice, suggesting involvement of cis-UCA in photocarcinogenesis. Since Langerhans cells (LC) are capable of presenting tumor-associated Ags (TAA) for primary and secondary tumor-immune responses, we examined the effects of trans- and cis-UCA on LC tumor Ag presentation in a model of immunity to the S1509a spindle cell tumor (H-2a). In this system, induction of immunity requires exposure of LC to granulocyte-macrophage CSF. Naive CAF1 (H-2(a/d)) mice were immunized against S1509a by injection with granulocyte-macrophage CSF-exposed and TAA-pulsed epidermal cells (EC), as assessed by growth inhibition of inoculated tumor cells. Incubation of EC in cis-, but not trans-UCA completely inhibited Ag presentation in this system. Neither histamine antagonists nor indomethacin reversed these effects of cis-UCA. The ability of trans- and cis-UCA to modulate EC presentation of TAA for secondary immune responses was also examined. EC were pulsed with TAA in vitro and then injected into hind footpads of tumor-immune mice. After 24 h, footpad swelling was assessed as a measure of delayed-type hypersensitivity. Incubation with cis-, but again not trans-UCA before TAA exposure significantly inhibited elicitation of delayed-type hypersensitivity. These data indicate that cis-UCA may be an important regulator of LC Ag-presenting function in tumor-immune responses, and thus may play a role in photocarcinogenesis.

Regulation of tumor antigen presentation by urocanic acid

Urocanic acid (UCA) accumulates in the epidermis after deamination of histidine. UCA isomerizes from the trans to the cis form upon exposure to environmental UV radiation. Cis-UCA is immunosuppressive in several models. Topically applied cis-UCA was reported to enhance the cutaneous tumor yield in chronically UV-irradiated mice, suggesting involvement of cis-UCA in photocarcinogenesis. Since Langerhans cells (LC) are capable of presenting tumor-associated Ags (TAA) for primary and secondary tumor-immune responses, we examined the effects of trans- and cis-UCA on LC tumor Ag presentation in a model of immunity to the S1509a spindle cell tumor (H-2a). In this system, induction of immunity requires exposure of LC to granulocyte-macrophage CSF. Naive CAF1 (H-2(a/d)) mice were immunized against S1509a by injection with granulocyte-macrophage CSF-exposed and TAA-pulsed epidermal cells (EC), as assessed by growth inhibition of inoculated tumor cells. Incubation of EC in cis-, but not trans-UCA completely inhibited Ag presentation in this system. Neither histamine antagonists nor indomethacin reversed these effects of cis-UCA. The ability of trans- and cis-UCA to modulate EC presentation of TAA for secondary immune responses was also examined. EC were pulsed with TAA in vitro and then injected into hind footpads of tumor-immune mice. After 24 h, footpad swelling was assessed as a measure of delayed-type hypersensitivity. Incubation with cis-, but again not trans-UCA before TAA exposure significantly inhibited elicitation of delayed-type hypersensitivity. These data indicate that cis-UCA may be an important regulator of LC Ag-presenting function in tumor-immune responses, and thus may play a role in photocarcinogenesis.

Photosensitized inactivation of infectious DNA by urocanic acid, indoleacrylic acid and rhodium complexes

Naked, infectious single-stranded (ss) and double-stranded (ds) DNA from phages S13 and G4 were irradiated with 308 nm UV radiation in the absence and presence of several photobiologically active compounds: E- and Z-urocanic acid (E- and Z-UA), their methyl esters (E- and Z-MU), E- and Z-indoleacrylic acid (E- and Z-IA), cis-dichloro-bis(1,10-phenanthroline)rhodium(III) chloride (cDCBPR) and tris(1,10-phenanthroline)rhodium (III) perchlorate (TPR). E-urocanic acid protects against cyclobutane pyrimidine dimer formation in ssDNA but concomitantly photosensitizes the formation of other lesions that inactivate ssDNA. Z-urocanic acid also protects ssDNA against such dimerization but without the associated sensitized damage. The methyl ester isomers behave similarly. There is no such differential activity observed for the IA isomers, both of which sensitize the inactivation of ssDNA. Photostationary state mixtures of both UA and IA efficiently sensitize the inactivation of dsDNA, and cDCBPR strongly protects ssDNA from UV damage, while TPR is a significant sensitizer. Both of these metal complexes sensitize the inactivation of dsDNA slightly. For all compounds, cyclobutane pyrimidine dimers were the predominant lethal lesions produced by sensitization of the dsDNA, but they were not the major lethal lesions created by sensitization of the ssDNA. In the case of dsDNA, both UA and IA created pyrimidine dimers with a high degree of potential for mutagenesis, as determined by an assay that monitors the frequency of mutations following the spontaneous deamination of cytosine in photodimers.

Photolytic covalent binding of indoleacrylic acid to DNA

E-beta-Indol-3-ylacrylic acid (IA), radiolabelled at the 2 position with 14C, and calf thymus DNA have been irradiated with UV light (lambda greater than 280 nm) in phosphate buffer (pH 7.0). Re-isolation of the DNA indicates covalent binding of IA at levels of up to 295 nmol IA/mg native DNA (0.097 IA/base). Binding is observed for both native and heat denatured DNA, but is more efficient with the latter. Quantum efficiencies of 2.60 X 10(-5) and 2.30 X 10(-4) mol IA bound to native DNA/mol photon absorbed have been measured at 308 and 266 nm, respectively. Studies with the four polyribonucleotides indicate a strong preference for binding to poly[U]. Photolysis of either untreated or enzymatically degraded labeled native DNA with 254 nm light leads to the reformation of IA, and a 2 + 2 photocycloadduct of IA and thymidine has been isolated and characterized and matched by HPLC to a DNA derived adduct. Equilibrium dialysis studies provide no evidence for preassociation of IA to DNA.

Photochemical covalent binding of urocanic acid to polynucleic acids

Photolysis of E-[ring-2-14C]urocanic acid (UA) with native or denatured calf thymus DNA leads to covalent binding of the radiolabel to the nucleic acid. A similar observation is made upon photolysis of the labeled UA with the polyribonucleotides, in which case a strong preference is observed for binding to poly[U]. DNA or poly[U], which had been reacted with UA and purified by dialysis and multiple precipitations, releases UA upon further irradiation with 254 nm light (as expected for cyclobutane adducts). Quantum efficiencies for binding of the UA to native DNA have been measured at 308 and 266 nm and are 0.30 x 10(-5) and 1.3 x 10(-4), respectively, at comparable reactant concentrations. The large increase at the shorter wavelength (where DNA absorption is more competitive) is taken as evidence for the primary role of a DNA excited state in initiating the binding reaction(s).