Tissue-specific expression of senescence biomarkers in spontaneously hypertensive rats: evidence of premature aging in hypertension.

Background: Cellular senescence is an age-related physiological process that contributes to tissue dysfunction and accelerated onset of chronic metabolic diseases including hypertension. Indeed, elevation of blood pressure in hypertension coincides with premature vascular aging and dysfunction. In addition, onsets of metabolic disturbance and osteopenia in patients with hypertension have also been reported. It is possible that hypertension enhances premature aging and causes progressive loss of function in multiple organs. However, the landscape of cellular senescence in critical tissues affected by hypertension remains elusive. Materials and Methods: Heart, liver, bone, hypothalamus, and kidney were collected from spontaneously hypertensive rats (SHR) and age- and sex-matched normotensive Wistar rats (WT) at 6, 12, 24 and 36 weeks of age (n = 10 animals/group). Changes in mRNA levels of senescence biomarkers namely cyclin-dependent kinase (CDK) inhibitors (CDKIs), i.e., Cdkn2a (encoding p16Ink4a) and Cdkn1a (encoding p21cip1) as well as senescence-associated secretory phenotypes (SASPs), i.e., Timp1, Mmp12, Il6 and Cxcl1, were determined. Additionally, bone collagen alignment and hydroxy apatite crystal dimensions were determined by synchrotron radiation small- and wide-angle X-ray scattering (SAXS/WAXS) techniques. Results: Real-time PCR revealed that transcript levels of genes encoding CDKIs and SASPs in the heart and liver were upregulated in SHR from 6 to 36 weeks of age. Expression of Timp1 and Cxcl1 was increased in bone tissues isolated from 36-week-old SHR. In contrast, we found that expression levels of Timp1 and Il6 mRNA were decreased in hypothalamus and kidney of SHR in all age groups. Simultaneous SAXS/WAXS analysis also revealed misalignment of bone collagen fibers in SHR as compared to WT. Conclusion: Premature aging was identified in an organ directly affected by high blood pressure (i.e., heart) and those with known functional defects in SHR (i.e., liver and bone). Cellular senescence was not evident in organs with autoregulation of blood pressure (i.e., brain and kidney). Our study suggested that cellular senescence is induced by persistently elevated blood pressure and in part, leading to organ dysfunction. Therefore, interventions that can both lower blood pressure and prevent cellular senescence should provide therapeutic benefits for treatment of cardiovascular and metabolic consequences.

Performance Evaluation of Focal Plane Array (FPA)-FTIR and Synchrotron Radiation (SR)-FTIR Microspectroscopy to Classify Rice Components.

The development of biochemical analysis techniques to study heterogeneous biological samples is increasing. These techniques include synchrotron radiation Fourier transform infrared (SR-FTIR) microspectroscopy. This method has been applied to analyze biological tissue with multivariate statistical analysis to classify the components revealed by the spectral data. This study aims to compare the efficiencies of SR-FTIR microspectroscopy and focal plane array (FPA)-FTIR microspectroscopy when classifying rice tissue components. Spectral data were acquired for mapping the same sample areas from both techniques. Principal component analysis and cluster imaging were used to investigate the biochemical variations of the tissue types. The classification was based on the functional groups of pectin, protein, and polysaccharide. Four layers from SR-FTIR microspectroscopy including pericarp, aleurone layer, sub-aleurone layer, and endosperm were classified using cluster imaging, while FPA-FTIR microspectroscopy could classify only three layers of pericarp, aleurone layer, and endosperm. Moreover, SR-FTIR microspectroscopy increased the image contrast of the biochemical distribution in rice tissue more efficiently than FPA-FTIR microspectroscopy. We have demonstrated the capability of the high-resolution synchrotron technique and its ability to clarify small structures in rice tissue. The use of this technique might increase in future studies of tissue characterization.