All-trans retinoic acid modifies the expression of clock and disease marker genes

Restricted feeding (RF), a regimen that restricts the duration of food availability with no calorie restriction, entrains the circadian clock in peripheral tissues. Restricted feeding leads to high-amplitude circadian rhythms, which have been shown to promote wellness and reduce disease and inflammatory markers. Retinoids, such as all-trans retinoic acid (ATRA), act as anti-inflammatory agents. Thus far, the effect of ATRA combined with RF on the ability to delay the occurrence of age-associated changes, such as cancer and inflammation, is not known. We measured circadian expression of clock genes, disease marker genes and inflammatory markers in the serum, liver and jejunum in mice fed ad libitum (AL) or RF supplemented with 15 or 250 μg/kg body/day ATRA for 16 weeks. Our results show that ATRA supplementation led to phase shifts and reduced amplitudes in clock genes. Under AL, ATRA reduced the average daily messenger RNA (mRNA) levels of some disease markers, such as liver Afp and jejunum Afp, Alt and Gadd45β and aspartate transaminase (AST) protein in the serum, but increased the expression level of liver Crp mRNA. Under RF, ATRA reduced the average daily levels of jejunum Alt and Gadd45β and AST protein in the serum, but increased liver Afp, Alt, Gadd45β and Arginase mRNA. Altogether, our findings suggest that ATRA strongly affects circadian oscillation and disease marker levels. Moreover, its impact is different depending on the feeding regimen (AL or RF).     

Utility of a fluorescent vitamin E analogue as a probe for tocopherol transfer protein activity

The tocopherol transfer protein (TTP) is a member of the CRAL-TRIO family of lipid binding proteins that facilitates vitamin E transfer between membrane vesicles in vitro. In cultured hepatocytes, TTP enhances the secretion of tocopherol to the media; presumably, tocopherol transfer is at the basis of this biological activity. The mechanism underlying ligand transfer by TTP is presently unknown, and available tools for monitoring this activity suffer from complicated assay procedure and poor sensitivity. We report the characterization of a fluorescent vitamin E analogue, (R)-2,5,7,8-tetramethylchroman-2-[9-(7-nitrobenz[1,2,5]oxadiazol-4-ylamino)nonyl]chroman-6-ol (NBD-TOH), as a sensitive and convenient probe for the ligand binding and transfer activities of TTP. Upon binding to TTP, NBD-TOH fluorescence is blue shifted, and its intensity is greatly enhanced. We used these properties to accurately determine the affinity of NBD-TOH to TTP. The analogue binds to TTP reversibly and with high affinity (K(d) = 8.5 +/- 6 nM). We determined the affinity of NBD-TOH to a TTP protein in which lysine 59 is replaced with a tryptophan. When occurring in humans, this heritable mutation causes the ataxia with vitamin E deficiency (AVED) disorder. We find that the affinity of NBD-TOH to this mutant TTP is greatly diminished (K(d) = 71 +/- 19 nM). NBD-TOH functioned as a sensitive fluorophore in fluorescent resonance energy transfer (FRET) experiments. Using the fluorescent lipids TRITC-DHPE or Marina Blue-DHPE as a donor or an acceptor for NBD-TOH fluorescence, we obtained high-resolution kinetic data for tocopherol movement out of lipid bilayers, a key step in the TTP-facilitated ligand transfer reaction.     

Balance between noise and adaptation in competition models of perceptual bistability

Perceptual bistability occurs when a physical stimulus gives rise to two distinct interpretations that alternate irregularly. Noise and adaptation processes are two possible mechanisms for switching in neuronal competition models that describe the alternating behaviors. Either of these processes, if strong enough, could alone cause the alternations in dominance. We examined their relative role in producing alternations by studying models where by smoothly varying the parameters, one can change the rhythmogenesis mechanism from being adaptation-driven to noise-driven. In consideration of the experimental constraints on the statistics of the alternations (mean and shape of the dominance duration distribution and correlations between successive durations) we ask whether we can rule out one of the mechanisms. We conclude that in order to comply with the observed mean of the dominance durations and their coefficient of variation, the models must operate within a balance between the noise and adaptation strength—both mechanisms are involved in producing alternations, in such a way that the system operates near the boundary between being adaptation-driven and noise-driven.     

LDL-R AvaII and NcoI Polymorphisms: An Indirect Risk Factor for Coronary Heart Disease Among a Mendelian Population of Delhi, India

AvaII and NcoI polymorphisms in the low-density lipoprotein receptor (LDL-R) gene are reported to alter cholesterol levels. Although found to be highly polymorphic worldwide, these mutations have not been validated in any Indian population. This case–control association study was conducted in an endogamous business community of Delhi. Blood samples from 100 cases and 100 age- and sex-matched controls belonging to the same ethnic group were subjected to biochemical and molecular analyses. Medical history and anthropometric measurements were taken from all the enrolled subjects. Linkage disequilibrium between the two polymorphisms was found to be significant (P = 0.0016). Significant variability was observed for the AvaII polymorphism among cases concerning waist–hip ratio, serum triglyceride, and low-density lipoprotein, which in turn was found to be associated with coronary heart disease.     

Residues of thiamethoxam, aldicarb and its metabolites in coffee leaves and effect on the control of Leucoptera coffeella (Guérin-Mèneville) (Lepidoptera: Lyonetiidae)

The coffee leaf miner Leucoptera coffeella (Guérin-Mèneville), one of the major pests of coffee crops in Brazil, is mainly controlled with insecticides. The objective of this study was to evaluate the residues and the translocation of the insecticide thiamethoxam in coffee leaves, as well as to study its effect on the coffee leaf miner control, comparing it with aldicarb, used as standard. One experiment was set up in the county of Gar?a, SP from December/2001 to August/2002. The treatments used were: aldicarb 150 G at the rates of 2.25 and 4.50 g a.i./pit, thiamethoxam 10 GR, at the rates of 0.15 and 0.30 g a.i./pit and check. Twig samples were collected prior to and 30 , 60, 90, 120, 150, 180, 210 and 240 days after the application, at three coffee plant heights (lower, middle and upper third), and the percentage of mined leaves was evaluated. The determination of aldicarb residues, including their sulphoxide and sulfone metabolites and of thiamethoxam were performed by gas chromatography with a nitrogen-phosphorus and mass spectrometer detectors, respectively. The results indicated a uniform translocation of both insecticides in all three thirds of the coffee plants when applied to the soil. A higher persistence of thiamethoxam was verified with its residues being found for as far long as eight months following the application, while aldicarb residues, including the sulphoxide and sulfone metabolites, were found only until four to six months after the application. Control of the coffee leaf miner was observed with both insecticides.     

Sirt1 protects from K‐Ras‐driven lung carcinogenesis

The NAD⁺‐dependent deacetylase SIRT1 can be oncogenic or tumor suppressive depending on the tissue. Little is known about the role of SIRT1 in non‐small cell lung carcinoma (NSCLC), one of the deadliest cancers, that is frequently associated with mutated K‐RAS. Therefore, we investigated the effect of SIRT1 on K‐RAS‐driven lung carcinogenesis. We report that SIRT1 protein levels are downregulated by oncogenic K‐RAS in a MEK and PI3K‐dependent manner in mouse embryo fibroblasts (MEFs), and in human lung adenocarcinoma cell lines. Furthermore, Sirt1 overexpression in mice delays the appearance of K‐Ras^G12V‐driven lung adenocarcinomas, reducing the number and size of carcinomas at the time of death and extending survival. Consistently, lower levels of SIRT1 are associated with worse prognosis in human NSCLCs. Mechanistically, analysis of mouse Sirt1‐Tg pneumocytes, isolated shortly after K‐Ras^G12V activation, reveals that Sirt1 overexpression alters pathways involved in tumor development: proliferation, apoptosis, or extracellular matrix organization. Our work demonstrates a tumor suppressive role of SIRT1 in the development of K‐RAS‐driven lung adenocarcinomas in mice and humans, suggesting that the SIRT1–K‐RAS axis could be a therapeutic target for NSCLCs.     

An outcome analysis comparing the thoracodorsal and internal mammary vessels as recipient sites for microvascular breast reconstruction: a prospective study of 100 patients

The thoracodorsal vessels have been the standard recipient vessels for the majority of surgeons performing free transverse rectus abdominis musculocutaneous (TRAM) flap reconstructions. Recently, the internal mammary vessels have been recommended as the first-choice recipient vessels for microvascular breast reconstruction. This approach requires a shorter pedicle length, allows for central placement of flap tissue, and avoids axillary scarring. The use of the internal mammary vessels may provide for a shorter operative time and a higher-quality aesthetic reconstruction. The authors performed a prospective trial examining the differences in operative and aesthetic outcomes between each recipient site. A prospective trial of 108 consecutive free-tissue transfers was conducted in 100 patients. The first 60 TRAM flap patients were randomized so that 30 flaps were anastomosed to the internal mammary vessels and 30 were anastomosed to the thoracodorsal vessels, whereas the recipient vessels for the remaining 40 patients were left to the discretion of the surgeon. Of the 40 nonrandomized patients, 10 patients underwent reconstruction using the internal mammary vessels and 30 patients underwent reconstruction using the thoracodorsal vessels. The patients' medical history and hospital course were noted. To evaluate aesthetic outcome, a group of five blinded nonmedical observers and three blinded plastic surgeons graded the reconstructions in the 60 TRAM flap patients for symmetry and overall aesthetic result on a scale of 1 to 5. Blinded practitioners administered postoperative questionnaires to patients regarding recovery time and satisfaction with the aesthetic result. Forty-three flaps were transferred to the internal mammary vessels and 65 were transferred to the thoracodorsal vessels. No significant differences existed between groups with regard to age of preoperative risk factors. Average operative time was 6 hours in each group. Average hospital stay was 5.8 days in each group. Conversion from initial recipient vessel to a secondary recipient site occurred in 12.5 percent of internal mammary reconstructions and 7 percent of thoracodorsal reconstructions. All converted internal mammary cases occurred in left-sided reconstructions and were attributable to problems with the veins. Overall, 20 percent of left-sided internal mammary reconstructions were found to have an inadequate recipient vein. Unusable thoracodorsal vessels were found only in delayed reconstructions, at a rate of 15 percent in the delayed setting. All flaps from converted procedures survived without complications. Average follow-up was 20 months, during which time there was one flap loss in the thoracodorsal group. There were no significant differences in complication rates between groups. Average aesthetic grade was 3.6 in each group. Postoperative recovery time and overall patient satisfaction were not significantly different between groups. Either recipient site can provide for a safe and acceptable result; however, surgeons should be aware of conversion rates and plan appropriately if recipient vessels appear unusable for free-tissue transfer.