Multifocal primary CNS T cell lymphoma of the spinal cord.

The majority of primary central nervous system lymphomas (PCNSL) are of B cell origin, and those of T cell origin are a distinct rarity. Furthermore, spinal cord involvement of T cell PCNSL is extremely rare and only a small number of cases have been reported. The authors report a case of multifocal T cell PCNSL mainly involving the intramedullary (IM) portion ofthe spinal cord in a 57-year-old woman. Neurological examination showed right leg weakness and hypesthesia below the T10 level. Magnetic resonance images revealed multiple well enhancing masses in the IM portion ofthe cervical and thoracic spinal cord and the cerebellum. Cytological examination of the cerebrospinal fluid revealed no malignant cells. As the mass at the C7 level was the largest among multiple masses, open biopsy was performed at that level. Histopathological examination confirmed malignant peripheral T cell lymphoma, unspecified (PTCL-U), small- and medium-sized cell type. Clinical and laboratory investigations failed to reveal any evidence of lymphomatous deposits elsewhere in the body. After biopsy, the patient received cranio-spinal irradiation, which included the whole brain and the spinal neuraxis. The clinical course, pathological findings and treatments are discussed and a review of the literature included.

Protein tyrosine kinase inhibitors modulate radiosensitivity and radiation-induced apoptosis in K562 cells.

We studied the modulating effect of protein tyrosine kinase inhibitors on the response of cells of the human chronic myelogenous leukemia cell line K562 to radiation. The radiosensitivity of the cells was increased by treatment with herbimycin A and decreased by treatment with genistein. This modulating effect of protein tyrosine kinase inhibitors on radiation sensitivity was associated with the alteration of the mode of radiation-induced cell death. After X irradiation, the cells arrested in the G(2) phase of the cell cycle, but these TP53(-/-) cells were unable to sustain cell cycle arrest. This G(2)-phase checkpoint deficit caused cell death. The morphological pattern of cell death was characterized by swelling of the cytoplasmic compartments, cytosolic vacuolation, disruption of the plasma membrane, less evident nuclear condensation, and faint DNA fragmentation, all of which were consistent with oncosis or cytoplasmic apoptosis. The nonreceptor protein tyrosine kinase inhibitor herbimycin A accelerated the induction of typical apoptosis by X irradiation, which was demonstrated by morphological assessments using nuclear staining and electron microscopy as well as oligonucleosomal fragmentation and caspase 3 activity. Herbimycin A is known to be a selective antagonist of the BCR/ABL kinase of Philadelphia chromosome-positive K562 cells; this kinase blocks the induction of apoptosis after X irradiation. Our results showed that the inhibition of protein tyrosine kinase by herbimycin A enhanced radiation-induced apoptosis in K562 cells. This effect was associated with the activation of caspase 3 and rapid abrogation of the G(2)-phase checkpoint with progression out of G(2) into G(1) phase. In contrast, the receptor-type protein tyrosine kinase inhibitor genistein protected K562 cells from all types of radiation-induced cell death through the inhibition of caspase 3 activity and prolonged maintenance of G(2)-phase arrest. Further investigations using this model may give valuable information about the mechanisms of radiation-induced apoptosis and about the radiosensitivity and radioresistance of chronic myelogenous leukemia cells having the Philadelphia chromosome.

Analysis of acoustic noise in MRI.

Acoustic or sound noise due to gradient pulsing has been one of the problems in magnetic resonance imaging (MRI), both in patient scanning as well as in many areas of psychiatric and neuroscience research such as functional MRI. Our recent observations in functional MRI for the visual and motor cortex show very different results with sound noise in comparison with the results obtained without sound noise. Although a number of ideas have been suggested in the literature about the possible elimination or reduction of sound noise, progress has been slow due to the basic role of gradient pulsing in MR imaging. Before we tackle the sound-noise-reduction problem, we believe that a systematic study of sound or acoustic noise behavior will provide important information for future endeavors in this area of research in MRI systems, in both commercial and research systems. Therefore, we report on some typical behavior of sound noise observed from MRI scanners and the analyses of their characteristics. Data are obtained both from a commercial MRI scanner (GE Signa 1.5-T EPI system) as well as a research-type MRI scanner (KAIS 2.0-T) developed at a university laboratory setting.