Toshiaki Yamaki

In vivo quantification of the metabolites in normal brain and brain tumors by proton MR spectroscopy using water as an internal standard

Metabolite concentrations in normal adult brains and in gliomas were quantitatively analyzed by in vivo proton magnetic resonance spectroscopy (MRS) using the fully relaxed water signal as an internal standard. Between January 1998 and October 2001, 28 healthy volunteers and 18 patients with gliomas were examined by in vivo proton MRS. Single voxel spectra were acquired using the point-resolved spectroscopic pulse sequence with a 1.5-T scanner (TR/TE/Ave = 3000 ms/30 ms/64). The calculated concentrations of N-acetyl-aspartate (NAA), creatine (Cre), choline (Cho), and water (H2O) in the normal hemispheric white matter were 23.59 +/- 2.62 mM (mean +/- SD), 13.06 +/- 1.8 mM, 4.28 +/- 0.8 mM, and 47280.96 +/- 5414.85 mM, respectively. The metabolite concentrations were not necessarily uniform in different parts of the brain. The concentrations of NAA and Cre decreased in all gliomas (p < 0.001). The NAA/Cho and NAA/H2O ratios can distinguish the normal brain from gliomas, and low-grade astrocytoma from high-grade group (p < 0.001). The concentration of taurine (Tau) in medulloblastomas was 29.64 +/- 5.76 mM. This is the first quantitative analysis of Tau in medulloblastoma in vivo and confirms earlier in vitro findings.

Cranial nerve assessment in posterior fossa tumors with fast imaging employing steady-state acquisition (FIESTA)

Steady-state free precession is widely used for ultra-fast cardiac or abdominal imaging. The purpose of this work was to assess fast imaging employing steady-state acquisition (FIESTA) and to evaluate its efficacy for depiction of the cranial nerve affected by the tumor. Twenty-three consecutive patients with posterior fossa tumors underwent FIESTA sequence after contrast agent administration, and then displacement of the cranial nerve was evaluated. The 23 patients with posterior fossa tumor consisted of 12 schwannomas, eight meningiomas, and three cases of epidermoid. Except in the cases of epidermoid, intensity of all tumors increased on FIESTA imaging of the contrast enhancement. In the schwannoma cases, visualization of the nerve became poorer as the tumor increased in size. In cases of encapsulated meningioma, all the cranial nerves of the posterior fossa were depicted regardless of location. The ability to depict the nerves was also significantly higher in meningioma patients than in schwannoma patients (P<0.05). In cases of epidermoid, extension of the tumors was depicted clearly. Although the FIESTA sequence offers similar contrast to other heavily T2-weighted sequences, it facilitated a superior assessment of the effect of tumors on cranial nerve anatomy. FIESTA sequence was useful for preoperative simulations of posterior fossa tumors.

Immunohistochemical analysis of the p53 family members in human craniopharyngiomas

Craniopharyngiomas are intracranial tumors that usually arise in the site around the sella turcica. They are composed of distinctive sheets of epithelial cells showing adamantinomatous or squamous-papillary histologic type. Because little is known about the tumorigenesis of cranio-pharyngiomas, we retrieved samples from 15 tumor cases to investigate the functional significance of the p53 family of transcription factors, which are known to be expressed in various human epithelia. Immunohistochemical analysis of these cases demonstrated similar expression profiles of p53 family members in the two histologic types of the tumor; i.e., strong nuclear expression of p63 was observed in all cell layers, and moderate to intense nuclear expression of p73 was observed in the basal cell layers. In contrast to p63 and p73, the reactivity of an archetypal tumor suppressor, p53, was occasional and weak in the two histologic types. Because p63 was widely expressed in the tumors, reverse transcription-polymerase chain reaction (RT-PCR) analysis was conducted to elucidate which spliced variant of p63 was expressed. The results showed that †Np63, lacking a terminal transactivation domain of p63, was the dominant isoform. Together with the reported evidence that the †Np63 isoform is highly expressed in human squamous-cell carcinomas, these data suggest that the cellular architecture characteristic of the expression of p53 family members may be required for the histogenesis of craniopharyngiomas, where †Np63 has a possible role in maintaining proliferative activity of the tumor cells, like squamous-cell carcinomas in other tissues.

Vascularized omentum graft for the reconstruction of the skull base after removal of a nasoethmoidal tumor with intracranial extension: case report.

A 16-year-old boy with rhabdomyosarcoma occupying the nasal cavities and the ethmoid sinus with intracranial extension underwent transcranial surgery. The intradural tumor was resected first with the affected dura of the anterior skull base, and the dural defect was repaired with fascia harvested from the sheath of the rectus abdominis muscle. The remaining tumor contiguous to the nasal cavities was completely extirpated. The cranial cavity was then exposed to the opened nasal cavities, where a revascularized omental graft was used to separate these compartments. Lyophilized dura was placed beforehand beneath the omental graft, as a roof to the nasal cavity, and was removed 3 weeks later through the nostril. A bony skull base repair was performed over the omentum using the inner table of the bone flap. Subcutaneous fat from the abdomen was placed on the bone graft for fixation and as an additional seal for the dural defect. Reconstruction of the anterior skull base with a vascularized omental transfer provides an efficient barrier to the nasal cavity. It also serves as an excellent supporting structure for regeneration of the mucosal epithelium of the nasal cavities.

Characterization of Rat T Cell Subset Antigen by Monoclonal Antibody

6B2‐B8 T cell hybridoma cells were used to immunize mice, and immune spleen cells were fused with NS/1 myeloma cells. One clone, designated RTH‐7, reacted with 89.5% of rat thymocytes, 30.2% of rat spleen cells, and 42.3% of rat lymph node cells. The RTH‐7 reacted with a subset of rat T cells but not with B cells. Double staining analysis demonstrated that RTH‐7 stained a rat T cell subset distinct from R1‐10B5‐positive cells that were known to be equivalent to mouse Lyt‐2. It was revealed that RTH‐7 and W3/25 recognize different antigenic epitopes on the same molecule. The RTH‐7 as well as W3/25 substantially inhibited the production of interleukin 2 by cells in mixed lymphocyte reaction and the lymphocyte proliferation induced by mixed lymphocyte reaction. The RTH‐7 inhibited the lymphocyte proliferation induced by Con A whereas W3/25 failed to do so. The RTH‐7 defined antigen has a molecular weight of 53,000 under reducing condition and 47,000 under nonreducing condition. The RTH‐7 defined antigen showed a wide range of heterogeneity in pI (6.2–8.8). The associated molecule of approximate molecular weight of 27,000 was occasionally detected with the RTH‐7 defined antigen in 6B2‐B8 T cell hybridoma cells as well as peripheral T cells but not in thymocytes. Thus, RTH‐7 detects a cell surface antigen of a functional T cell subset of rat origin.

Spinal cord infarct as the initial clinical presentation of intravascular malignant lymphomatosis

Intravascular malignant lymphomatosis (IML) is an extremely rare form of lymphoproliferative disorder that is characterized by proliferation of the lymphoma cells in the vascular lumens. We report on a 78-year-old man who initially presented with spinal cord infarct at the T11/12 level. Despite biopsies of the spinal cord and bone marrow from the sternum, the correct diagnosis was not made until autopsy. We identified 19 patients with IML showing spinal cord symptoms as the initial clinical manifestation, and considered the clinical and radiological characteristics as well as the limitations of biopsy. IML can be an important differential diagnosis of progressive paraparesis of unknown etiology.

The Heterogeneity of Target Recognition by Lymphokine‐activated Killer Precursor Cells

Lymphokine‐activated killer (LAK) cells were generated from peripheral blood lymphocytes (PBL) that were depleted of mature cytotoxic natural killer (NK) cells. PBL NK activity was abolished by pretreatment of effector cells with the toxic lysosomotropic agent l‐leucine methyl ester (LME) or by depletion of effector cells by K562 monolayer absorption (MA). Both treatments markedly reduced the proportion of cells expressing NK‐associated markers such as CD 16 (Leu 11b, B73.1), Leu 7, and NKH‐1 (Leu 19), whereas these treatments had minimal effects on cells expressing T cell markers (CD 3, CD 4, and CD 8). LME and MA also drastically decreased the proportion of K562 target‐binding lymphocytes. LAK activity against NK‐sensitive and NK‐resistant targets can be generated from the NK cell‐depleted PBL by incubation with interleukin‐2. Peak LAK activity generated from MA‐treated PBL was later than the peak of LAK activity generated from either untreated or LME‐treated PBL. Although MA of PBL on NK‐resistant S4 sarcoma targets had little effect on NK activity, LAK activity against both K562 and S4 targets was reduced. These results suggest that there are at least three LAK precursor subpopulations in PBL: mature NK cells that can bind and kill K562 targets (LME‐sensitive and MA‐sensitive); “pre‐NK”cells that can bind but cannot kill (LME‐resistant and MA‐sensitive); and non‐NK cells that cannot bind and cannot kill K562 targets (MA‐resistant).

Deletion of complex gangliosides of human glioma cells during mitotic cell division

Glycolipid compositions of the human glioma cell lineT98G were studied during each phase of thecell cycle to see if those cell surfacemolecules are concerned with cell proliferation. In vitrocultured non-synchronized T98G cells are composed of ceramidemonohexoside(CMH), ceramidedihexoside (CDH), ceramidetrihexoside (CTH) and neolactotetraosylceramide (nLc4Cer)as neutral glycolipids, and of sulfatide (CS), gangliosidesGM3, GM2, GD1a and several other gangliosides asacidic ones. While total glycolipid content per cellularweight was shown to be increased during theM phase, deletion of complex gangliosides particularly b-seriesgangliosides was recognized (p < 0.05). The glycolipidprofile in other phases was fairly consistent, andthere was no glycolipid molecule specific to acertain phase of the cell cycle. Relative enhancementof simple gangliosides with a decrease of complexones during mitotic division may imply the functionalinvolvement of complex gangliosides in cell-cell or cell-matrixattachment, which may have to be abandoned duringthe process of detachment from the matrix orcellular cleavage.

IMMUNOTHERAPY OF SOLID TOMOR BY INTRATUMORAL INFUSION OF LYMPHOKINE-ACTIVATED KILLER CELLS

Fifty million lymphokine‐activated killer (LAK) cells were infused into rat T9 gliosarcoma tumors for 1 hr at an infusion rate of 0.1 ml/hr. Cultured normal spleen cells were infused into similar tumors as a control. The LAK cell‐treated tumors began to regress at approximately 3 weeks after infusion and disappeared by 6 weeks, while the cultured normal spleen cell‐treated tumors grew progressively. Immunohistochemical analysis demonstrated prominent infiltration of cytotoxic/suppressor T cells in the LAK cell‐treated tumors, while few lymphocytes were recognized in the control tumors. These data suggested that LAK cells infused intratumorally might be capable of mediating tumor regression by inducing host immunity against the tumor.

Cancer and inflammation.

Inflammation is the succession of changes of a living tissue to injury and to the cause of injury, which can be regarded as hosts defensive reaction and repairing process of the injured tissue. On the other hand, cancer represents a pathologic disturbance of growth characterized by an excessive and unceasing proliferation of cells. It is assumed that when progressive growth of tumor injures the normal tissue active hosts defensive reaction against the tumor itself and subsequent injury may be expressed locally as inflammatory response.Our previous experiments with the autochthonous tumor system of the rat showed clearly that the intensity of the lymphocyte infiltration in the tumor tissue correlates with the tumor specific immune resistance. On the basis of the results, lymphocyte subpopulations and subsets infiltrating in various human cancer tissues were identified with antihuman lymphocyte monoclonal antibodies. It was demonstrated that the grade of lymphocyte infiltration, especially of T cells, in cancer tissue correlates with clinical prognosis. Furthermore, we performed functional analysis of tumor infiltrating cells in rat syngeneic tumor-host system. Various tumor infiltrating cells were shown to play an important role in eradicating the transplanted tumor. Killer/suppressor T cells were demonstrated to be the final effector cells recognizing specifically the target tumor cells. Thus the inflammatory response at the site of tumor can be regarded as the manifestation of host resistance against the tumor.