Masanori Shozushima

Augmentation effects of lymphocyte activation by antigen-presenting macrophages on FDG uptake

Objective: Research on FDG-uptake by blood cells has revealed that FDG is incorporated by macrophages and granulocytes, as well as activated lymphocytes. These characteristics of FDG suggest the possibility of visualizing the distribution of immunocytes in target organs. The aim of this study was to investigate if mouse spleen-derived lymphocytes, activated by macrophages presenting sheep red blood cell (sRBC) antigens, could be traced by FDG.Methods: One percent of a sRBC suspension was injected into the peritoneal cavity of mice thereby creating immunity to the sRBC antigen. The splenocytes, consisting mostly of lymphocytes, were isolated, and serum containing the anti-sRBC antibody was mixed with sRBC to prepare sRBC-antibody complexes (sRBC-AbCs). Then five percent of a thioglycolate medium was injected into the peritoneal cavity of the same mice, and macrophages of ascitic cell origin were obtained. These macrophages were added to the sRBC-AbCs to induce sRBC antigen presenting macrophages. These were incubated with splenocytes obtained from sRBC immunized mouse (sRBC immunized splenocytes) or nonimmunized splenocytes to induce a T cell immune response. [3H]deoxyglucose ([3H]DG) and FDG were incorporated in splenocytes, and the quantity of their uptake was measured.Results: [3H]DG uptake by sRBC-immunized splenocytes was about eleven times as high as that of non-immunized splenocytes. In contrast, [3H]DG uptake by sRBC-immunized splenocytes, co-cultured with macrophages phagocytizing sRBC-AbCs, was about 40 times higher compared with non-immunized splenocytes. Splenocytes in non-immunized mice picked up very little [3H]DG, despite co-culture with macrophages phagocytizing sRBC-AbCs. Similar tendencies were observed with FDG.Conclusions: These results suggest that the SUV calculated in PET reflects not only the number of lymphocytes, but also the activation state of the lymphocytes themselves. In addition, the biodistribution of antigen specific lymphocytes, that have been taken up FDGin vitro and returned to the body, can be observed through PET.

Multiple myeloma with a distinct “sun-ray appearance” occurring in the jaw

SummaryThis manuscript presents an unusual radiographic manifestation of multiple myeloma occurring in the mandible. A 40-year-old man, referred to our hospital, presented with a swelling of the right mandible. Microscopic examination and laboratory tests confirmed the diagnosis of multiple myeloma. Radiographic examination revealed a well-developed sun-ray appearance suspected in osteogenic sarcoma. This observation suggested the possibility of the periosteal reaction in this case of multiple myeloma.

Tunable narrow-photon-energy x-ray source using a silicon single crystal

A preliminary experiment for producing narrow-photon-energy cone-beam x-rays using a silicon single crystal is described. In order to produce low-photon-energy x-rays, a 100-µm-focus x-ray generator in conjunction with a (111) plane silicon crystal is employed. The x-ray beams from the source are confined by an x-y diaphragm, and monochromatic cone beams are formed by the crystal and three lead plates. The x-ray generator consists of a main controller and a unit with a high-voltage circuit and a 100-µm-focus x-ray tube. In this experiment, the maximum tube voltage and current were 35 kV and 0.50 mA, respectively, and the x-ray intensity of the microfocus generator was 343 μGy/s at 1.0 m from the source with a tube voltage of 30 kV and a current of 0.50 mA. The effective photon energy is determined by Braggs angle, and the photon-energy width is regulated by the angle delta. Using this generator in conjunction with a computed radiography system, quasi-monochromatic radiography was performed using a cone beam with an effective energy of approximately 15.5 keV.

The relationship between histopathological findings in oral squamous cell carcinoma and FDG uptake on PET

ObjectivesIt is known that, in fluorine-18 fluorodeoxyglucose Positron Emission Tomography (FDG PET) for the diagnosis of oral cancer, FDG uptake may vary even among different cases of the same squamous cell carcinoma. However, the details of this phenomenon have not yet been elucidated. In this study, we analyzed the relationship between histopathological findings in oral squamous cell cancer and PET findings on FDG uptake.MethodsWe examined 45 patients with oral squamous cell carcinoma who had undergone FDG PET before treatment. FDG uptake was assessed by a standardized uptake value (SUV) calculated according to the PET-measured tissue concentration of FDG, the administered dose of radionuclide, and the body weight of the patient. The relationship between the mean SUV and each of the following parameters was examined: histological grade of malignancy, degree of cell differentiation, size and/or local extent of the primary lesion, and cell density of the tumor.ResultsThe mean SUV of FDG uptake did not depend on the histological grade of malignancy or on the degree of cell differentiation, but tended to be greater the larger the primary lesion. SUV also depended on cell density, increasing with the percentage of tumor parenchyma.ConclusionsIt is concluded that cancer cell density greatly influences the SUV of FDG, in that a tumor with fewer cellular elements in cancer tissue tends to become a false negative.

Two cases of mesodermal tumor in the simple bone cyst

A simple bone cyst is referred to as a solitary bone cyst of the mandible or a traumatic cyst. According to the literatures, it occurs most frequently in younger persons and in males probably because they are exposed to t raumatic injuries more often than females, however, the two Cases in our study are female. For their ages, one was 27 years old and the other was 36 years old at the time of the first detection. It is most generally believed that a cyst results from an injury but it is difficult to elicit a history of injury, particularly because the presence of the cyst does not come to light until several years later. The cyst-like images were more clearly demonstrated on the panoramic tomograms. There have been a few detailed studies but they concentrated mainly upon

Fluorescent x-ray tomography system for atomic imaging

A fluorescent x-ray tomography system is useful in performing fluorescent x-ray analysis for target atoms in biomedical objects utilizing a drug deliverly system. This tomography system is employed in order to measure iodine distribution in objects, and the system consists of a cerium x-ray generator, a 58-μm-thick stannum filter, a tungsten collimator, and a computed radiography system. Because K-series characteristic x-rays from the cerium target are absorbed effectively by iodine-based contrast media, iodine fluorescent x-rays from iodine atoms in the objects are produced. In the tomography system, when the objects are exposed by fan beams, the stannum filter easily transmits iodine Kα rays from a slice plane, and tomograms are obtained using the CR system and the collimator.

The transmitter-induced change in slope conductance of a receptor membrane as a function of the resting potential and equilibrium potential of the ion involved

Change in slope conductance has been widely used to evaluate the ion-channel activation by receptor agonists of various postsynaptic membranes. However, the agonist-induced change in slope conductance (delta G) depends not only on the change in membrane ionic permeabilities (delta P) but also on the changes in resting potential (E) and equilibrium potential (EA) of the ion involved (A). A constant field theory was applied to describe delta GA as a function of delta PA, E and EA, assuming that delta PA is not affected by the change in E or EA. This equation predicts that delta GNa will decrease if the membrane is depolarized or when ENa becomes more positive. Similarly, delta GK is expected to increase if the membrane is depolarized or when EK becomes more negative. Further, the equation describes that delta GCl will increase if the membrane is depolarized or when ECl becomes less negative. These changes in GNa, GK and GCl are well consistent with many data previously obtained from various types of receptor membranes. We conclude that the values of slope conductance measured at different E or EA must be carefully corrected in order to estimate the real voltage dependence of delta P or the ion-channel activation by receptor agonists.

Quantification of 11C-methionine Uptake During Proliferation of Cultured Human Cancer Cells

It has been reported that 11C-methionine (Met) is taken up in greater amounts when tumor cells are actively proliferating. This observation suggests that Met uptake depends on the cell cycle. This study was aimed at investigating the relationship between the cell cycle of cultured human cancer cells and Met uptake, and obtaining basic information for Met PET interpretation. HeLa S3 cells were synchronized by the double thymidine block method, and the relationship between cells synchronized at each phase and Met uptake was investigated during 14 hours after release. As a result, Met uptake was 73% of the peak level in the early S-phase immediately after release, gradually increased, and peaked in the early G2/M phase. Subsequently, Met uptake steeply declined over the late G2/M phase to 44% in the G1 phase. These results indicate that Met uptake depends on the cell cycle : Met accumulates highly from the S through G2/M phases and maximally in the G2 phase. Met PET seems to produce images reflecting the mitotic index of tumor cells, and predicts that more rapidly progressing malignant tumors will show a higher Met uptake.