Comparative expression analysis of the renin-angiotensin system components between white and brown perivascular adipose tissue

Recent studies have demonstrated that the rat adipose tissue expresses some of the components necessary for the production of angiotensin II (Ang II) and the receptors mediating its actions. The aim of this work is to characterize the expression of the renin-angiotensin system (RAS) components in perivascular adipose tissue and to assess differences in the expression pattern depending on the vascular bed and type of adipose tissue. We analyzed Ang I and Ang II levels as well as mRNA levels of RAS components by a quantitative RT-PCR method in periaortic (PAT) and mesenteric adipose tissue (MAT) of 3-month-old male Wistar-Kyoto rats. PAT was identified as brown adipose tissue expressing uncoupling protein-1 (UCP-1). It had smaller adipocytes than those from MAT, which was identified as white adipose tissue. All RAS components, except renin, were detected in both PAT and MAT. Levels of expression of angiotensinogen, Ang-converting enzyme (ACE), and ACE2 were similar between PAT and MAT. Renin receptor expression was five times higher, whereas expression of chymase, AT(1a), and AT(2) receptors were significantly lower in PAT compared with MAT respectively. In addition, three isoforms of the AT(1a) receptor were found in perivascular adipose tissue. The AT(1b) receptor was found at very a low expression level. Ang II levels were higher in MAT with no differences between tissues in Ang I. The results show that the RAS is differentially expressed in white and brown perivascular adipose tissues implicating a different role for the system depending on the vascular bed and the type of adipose tissue.

Radiotherapy Treatment Verification

During a radiotherapy treatment, a dosimetric verification or a geometric localization can be done, in order to assess the quality of the treatment. The dosimetric verification is generally performed measuring the dose at some points inside (natural cavities) or outside the patient, and comparing it to the dose at the same points calculated and predicted by the treatment planning system. This can be done either with thermoluminescent or diodes dosimeters or with ionization chambers. The geometric localization can be done acquiring a portal image of the patient. Portal imaging can be performed either with films placed between metallic screens, or with an electronic portal imaging device such as fluoroscopic systems, solid state devices or matrix ionization chamber systems. In order to assess possible field placement errors, the portal images have to be compared with images obtained with the simulator in the same geometric conditions and/or with the digitally reconstructed radiograph (DRR) obtained with the treatment planning system. In particular, when using matrix ionization chamber systems, the portal images contain also information regarding the exit dose. This means that this kind of imaging device can be used both for geometric localization and for dosimetric verification. In this case, the exit dose measured by the portal image can be compared with the exit dose calculated and predicted by the treatment planning system. Some “in-vivo” applications of this methodology are presented.