Methylation and expression profiles of MGMT gene in thymic epithelial tumors

OBJECTIVES

A key challenge in diagnosis and treatment of thymic epithelial tumors (TET) is in improving our understanding of the genetic and epigenetic changes of these relatively rare tumors.

METHODS

Methylation specific PCR (MSP) and immunohistochemistry were applied to 66 TET to profile the methylation status of DNA repair gene O6-methylguanine DNA methyltransferase (MGMT) and its protein expression in TET to clarify the association between MGMT status and clinicopathological features, response to chemotherapy and overall survival.

RESULTS

MGMT methylation was significantly more frequent in thymic carcinoma than in thymoma (17/23, 74% versus 13/44, 29%; P<0.001). Loss of expression of MGMT protein was significantly more frequent in thymic carcinoma than in thymoma (20/23, 87% versus 10/44, 23%; P<0.0001). There is a significant correlation between of MGMT methylation and loss of its protein expression (P<0.0003). MGMT methylation and loss of expression were significantly more frequent in advanced thymic epithelial tumors (III/IV) than in early tumors (I/II).

CONCLUSION

MGMT methylation plays a soul role in development of TET, especially in thymic carcinoma. Therefore, translation of our results from basic molecular research to clinical practice may have important implication for considering MGMT methylation as a marker and a target of future therapies in TET.

Proper use of MR imaging for evaluation of low back pain (radiologist' view)

Magnetic resonance (MR) imaging has been recognized as a modality of choice in the evaluation of the spine. However, morphological abnormalities demonstrated by MR imaging do not always reflect low back pain (LBP). MR imaging should be interpreted with consideration of full clinical signs, symptoms, and other relevant background. At the same time, MR findings potentially relevant to LBP, such as morphological abnormalities of the disc, presence or absence of high intensity zone, abnormalities of the end plate and adjacent marrow signal, degree of nerve root compression, and degeneration of the facet joint, should be described without omission.

Redistribution in I-123 N-isopropyl-p iodoamphetamine single-photon emission computed tomography in cerebrovascular disease and the effects of rehabilitation

We performed N-isopropyl-p (I-123) iodoamphetamine (IMP) single-photon emission computed tomography (SPECT) on 28 patients with severe cerebrovascular disease before rehabilitation, and compared the degree of redistribution and the assessment of activities of daily living (ADL). We calculated a redistribution (RD) ratio in the central and peripheral parts of the lesions: RD ratio (c) and RD ratio (p). We classified the patients into four groups based on the degree of redistribution: complete: both RD ratio (c) and (p) > or = 75; peripheral: RD ratio (c) < 75, RD ratio (p) > or = 75; incomplete: both RD ratio (c) and (p) < 75 and at least one of RD ratio (c) or (p) > or = 25; no redistribution: both RD ratio (c) and (p) < 25. We assessed the ADL using the modified Barthel index (BI). deltaBI was defined as BI after rehabilitation-BI before rehabilitation (BIpost-BIpre). The deltaBI of the four groups were as follows: complete-redistribution group (40.8 +/- 22.8), peripheral-redistribution group (40.0 +/- 15.8), incomplete-redistribution group (27.2 +/- 22.6), no-redistribution group (8.8 +/- 12.3). The deltaBI of the complete and peripheral redistribution groups were significantly higher than that of the no-redistribution group. However, deltaBI was almost the same in the complete- and peripheral-redistribution groups. This suggests that the effect of rehabilitation might be closely related to the viability of the peripheral part of the lesion.