Comparación del estado nutricional, cronotipo y conducta alimentaria en estudiantes universitarios chilenos que presentan el polimorfismo rs3749474T/C o rs4864548A/G del gen CLOCK / Comparison of nutritional status, chronotype and eating behavior in Chilean university students presenting the polymorphism rs3749474T / C or rs4864548A / G of the CLOCK gene

FUNDAMENTOS: El estado nutricional puede verse afectado por la conducta alimentaria y los ritmos circadianos. Estos se encuentran regulados por el gen CLOCK, cuyos alelos T del SNP rs3749474T/C y A del SNP rs4864548A/G, han sido asociados con la obesidad en adultos. MÉTODOS: Se evaluó a 65 sujetos usando la técnica PCR en tiempo real para determinar si era portadores del alelo T del SNP rs3749474T/C o del A del SNP rs4864548A/G. Se realizaron mediciones antropométricas, y se aplicó los cuestionarios TFEQ y el Horne-Östberg. RESULTADOS: De los 65 sujetos estudiados, 8 eran portadores del alelo T del SNP rs3749474T/C y 7 del A del SNP rs4864548A/G. Los portadores del alelo A presentaron mayores valores promedio de IMC (26,58), circunferencia de cintura (89,57cm) y porcentaje de grasa (31,56%) no existiendo diferencias estadísticamente significativas entre ellos. No se encontraron diferencias estadísticamente significativas en cuanto a la conducta alimentaria. El 66,67% del total de los sujetos presentó un cronotipo de tipo intermedio. CONCLUSIONES: Los portadores del alelo A del SNP rs4864548A/G presentarían un mayor potencial de sufrir problemas asociados a la obesidad, pero es necesario realizar estudios con poblaciones más grandes y con mejor paridad de género, que permita corroborar esta aseveración

BACKGROUND: Nutritional status may be affected by eating behavior and circadian rhythms. These are regulated by the CLOCK gene, whose T alleles of SNP rs3749474T / C and A of SNP rs4864548A / G, have been associated with obesity in adults. METHODS: 65 subjects were evaluated using the real-time PCR technique to determine whether they were carriers of the T allele of the SNP rs3749474T/C or the A of the SNP rs4864548A/G. Anthropometric measurements were made, and the TFEQ and Horne-Östberg questionnaires were applied. RESULTS: Of the 65 subjects studied, 8 were carriers of the T allele of the SNP rs3749474T / C and 7 of the A of the SNP rs4864548A/G. The carriers of the A allele had higher average BMI values (26.58), waist circumference (89.57cm) and fat percentage (31.56%), with no statistically significant differences between them. No statistically significant differences were found regarding eating behavior. 66.67% of the total subjects presented an intermediate type chronotype. CONCLUSIONS: The carriers of the A allele of SNP rs4864548A/G would have a greater potential to suffer problems associated with obesity, but studies with larger populations and with better gender parity are necessary, which allows to confirm this assertion

An Application of the Bayesian Periodicity Test to Identify Diurnal Rhythm Genes in the Brain.

Biological systems are extremely dynamic and many aspects of cellular processes show rhythmic circadian patterns. Extracting such information from large expression data is challenging. In this work, we present a modified application of the Empirical Bayes periodicity test to identify genes with diurnal rhythmic behavior in two brain regions. The hypothalamus and amygdala gene expression data were generated from 100 BXD recombinant inbred mice during the day hours. Brain samples were collected over the course of two days. We first filtered the transcripts based on rank correlation at matched time points between day-1 and day-2. We then applied the proposed test of periodicity to identify diurnal rhythm genes in the full cohort and gender-specific sub-cohorts. In hypothalamus, at a Benjamini-Hochberg false discovery rate (BH-FDR) of 0.01, we identified 15 transcripts with cyclic behavior in the full cohort, none, and 53 transcripts in the female and male cohort, respectively. Similarly, in amygdala, we identified 58 diurnal rhythm genes in the full cohort, and 1 and 28 in the female and male cohorts, respectively. In conclusion, we present a modified version of the empirical Bayes periodicity test to detect periodic expression patterns. Our results demonstrate that this approach can capture cyclic patterns from relatively noisy expression data sets.

Estandarización de aspectos preanalíticos para el estudio de biomarcadores de la enfermedad de Alzheimer en el líquido cefalorraquídeo / Standardization of preanalytical factors to study biomarkers of Alzheimer's disease in cerebrospinal fluid

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Mass spectrometry-based absolute quantification reveals rhythmic variation of mouse circadian clock proteins.

Absolute values of protein expression levels in cells are crucial information for understanding cellular biological systems. Precise quantification of proteins can be achieved by liquid chromatography (LC)-mass spectrometry (MS) analysis of enzymatic digests of proteins in the presence of isotope-labeled internal standards. Thus, development of a simple and easy way for the preparation of internal standards is advantageous for the analyses of multiple target proteins, which will allow systems-level studies. Here we describe a method, termed MS-based Quantification By isotope-labeled Cell-free products (MS-QBiC), which provides the simple and high-throughput preparation of internal standards by using a reconstituted cell-free protein synthesis system, and thereby facilitates both multiplexed and sensitive quantification of absolute amounts of target proteins. This method was applied to a systems-level dynamic analysis of mammalian circadian clock proteins, which consist of transcription factors and protein kinases that govern central and peripheral circadian clocks in mammals. Sixteen proteins from 20 selected circadian clock proteins were successfully quantified from mouse liver over a 24-h time series, and 14 proteins had circadian variations. Quantified values were applied to detect internal body time using a previously developed molecular timetable method. The analyses showed that single time-point data from wild-type mice can predict the endogenous state of the circadian clock, whereas data from clock mutant mice are not applicable because of the disappearance of circadian variation.

Disruption of rhythms of molecular clocks in primary synovial fibroblasts of patients with osteoarthritis and rheumatoid arthritis, role of IL-1ß/TNF.

INTRODUCTION: Circadian rhythms play an important role in the body and in single cells. Rhythms of molecular clocks have not been investigated in synovial fibroblasts (SF) of patients with osteoarthritis (OA) and rheumatoid arthritis (RA). The study was initiated to fill this gap and to study effects of interleukin (IL)-1ß/tumor necrosis factor (TNF) on rhythmicity in synovial fibroblasts of RA and OA patients. METHODS: The presence of BMAL-1, CLOCK, Period 1 and Period 2 proteins in synovial tissue was investigated by immunofluorescence. The presence of mRNA of molecular clocks was studied during 72 h by qPCR. Characteristics of rhythms were studied with time series analysis. RESULTS: BMAL-1, CLOCK, Period 1 and Period 2 proteins were abundantly present in synovial tissue of OA, RA and controls. Receiving synovial tissue at different operation time points during the day (8:00 am to 4:00 pm) did not reveal a rhythm of BMAL-1 or Period 1 protein. In OASF and RASF, no typical rhythm curve of molecular clock mRNA was observed. Time series analysis identified a first peak between 2 and 18 hours after synchronization but a period was not detectable due to loss of rhythm. TNF inhibited mRNA of CLOCK, Period 1 and Period 2 in OASF, while IL-1ß and TNF increased these factors in RASF. This was supported by dose-dependently increased levels in MH7A RA fibroblasts. In RASF, IL-1ß and TNF shifted the first peak of BMAL-1 mRNA to later time points (8 h to 14 h). CONCLUSION: Rhythmicity is not present in primary OASF and RASF, which is unexpected because fibroblasts usually demonstrate perfect rhythms during several days. This might lead to uncoupling of important cellular pathways.