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In an attempt to assess the permeability of microvessels in the experimental brain tumor model, lanthanum ion (La3+) was used as a low-molecular weight electron microscopic probe. Rat glioma 9 L and adenocarcinoma ACL15 were transplanted to the brain and subflank of rats. The rats were then anesthetized sequentially perfused with saline, saline plus La3+ followed by a fixative in phosphate buffer. The brain and subcutaneous tumors were removed, further fixed, and processed for electron microscopy. La3 did not pass through the tight junctions of the normal cerebral endothelium. Similarly, La3+ did not penetrate the endothelial cell wall of the microvessels in the transplanted brain tumors. In contrast, extravasation of La3+ from the microvessels in the transplanted subcutaneous tumors was observed. The electron microscopy examination results indicate that the vesicular transport was a predominant mechanism in the penetration of La3+ through the endothelial cell wall. Since most chemotherapeutic agents similar as La3+ are of low molecular weight, we can suggest from the results of our present study that the blood tumor permeability of the anti-cancer agents in the rat model of brain glioma transplantation differs from that in the rat model of subcutaneous glioma transportation. In other words, our results indicate that when the subcutaneous glioma transplantation model is used in sensitivity tests of anti-cancer agents, it will possibly be very difficult to predict the anti-neoplastic effect in vivo.

Cultured rat astrocytes were incubated in the presence of cycloheximide (CHX; 20 microg/mL), a potent neuroprotective agent. Then cells were subjected to DNA gel electrophoresis. Electrophoresis showed DNA ladder formation, which is characteristic of apoptosis. Inhibitors of interleukin-1beta-converting enzyme (ICE) and caspase 32(CPP32), which play critical roles in certain apoptotic pathways, did not block the cycloheximide-induced apoptosis of cultured astrocytes. This observation indicates that the role of ICE and CPP32 is not significant in the CHX-induced astrocyte apoptosis process. When the blood-brain barrier was disrupted in the rat, the number of brain cells undergoing apoptosis was significantly higher after cycloheximide administration, in contrast to controls. Of the cells that produced glial fibrillary acidic protein, some were observed to undergo apoptosis. Although CHX has been shown to be useful as a neuroprotective agent against ischemic neuronal death, astroglial toxicity may be problematic, depending on CHX concentration. Therefore, a prudent use of this compound is recommended.

In an attempt to investigate the tumor type-specific ultrastructure of cultured brain tumors, collagen gel culture was utilized instead of the conventional monolayer culture. In order to avoid intermingling of the normal brain cells, tumors with a clear margin were chosen. The tumors were cultured first in the monolayer culture for a few passages, and then tumor cell pellets were prepared and embedded in the collagen gel. In the event that tumors failed to grow in the monolayer culture, small fragments of tumor tissue were embedded. Ultrastructurally, the tumor cell processes of central neurocytoma contained numerous dense-core vesicles. The formation of desmosomes was observed in the meningioma cell processes. The development of polypoid microvilli similar to those of the normal choroid plexus epithelium was observed in a case with ependymoma. A continuous basement membrane was seen surrounding the tumor cell processes facing the collagen gel in two ependymomas. These findings suggest the usefulness of the collagen gel culture in analyzing the tumor type-specific ultrastructure of cultured brain tumors and possibly in studying cellular differentiation.

The effect of the antitubulin agent colcemid on human glioma cells was investigated by sorting cells with different DNA content and subjecting them to confocal laser microscopy and transmission electron microscopy. The human glioma cell line U251MG was exposed to colcemid at a concentration of 0.05 microg for 16 h. Flow cytometric analysis revealed the accumulation of cells in S/G2M phase. Cells harvested from each of G0/G1 and S/G2M peaks were then analyzed by confocal laser microscopy and transmission electron microscopy. Confocal laser microscopy revealed that colcemid-treated cells harvested from the G0/G1 peak contained mitotic and apoptotic cells in addition to interphase cells. Electron microscopy confirmed that colcemid-treated cells in the G0/G1 peak had fragmented nuclei typical of apoptotic cells and mitotic cells with altered chromatin structure. Some mitotic cells obtained by mitotic shake-off after treatment with colcemid showed DNA strand breaks defined by in situ nick end labeling. The present study indicates that mitotic as well as interphase apoptosis occurs in U251MG cells following colcemid treatment.

臨床的に脳死に近い4症例(41～62歳)と脳死と判定された3症例(39～57歳)について,通常の脳波検査で採取された標準脳波と鼻咽頭後壁から得られたnasopharyngeal EEGとを脳波自動解析システムを用いて解析・検討した。そのうち脳死に近い2症例では,肉眼的にnasopharyngeal EEGに低電位で10～30μVのθ波がみられたが,他の5症例ではnaso-pharyngeal EEGもほとんど平坦化していた。さらに脳波自動解析システムを用いて脳波をデジタル化したところ,標準脳波の等価電位は健常人の等価電位よりも低値を示したのに対し,nasopharyngeal EEGの等価電位はいずれかの周波数領域において,低電位ながら健常人の等価電位分布の範囲内に留まっていた(7例中δ:2例,θ1:5例,θ2:2例,α1:2例,α3:5例,β1:5例)。このようなnasopharyngeal EEGの詳細な解析は「脳死」状態の把握に有用であると思われた。

We used flow cytometry to assess the cell cycle kinetics of cultured Maden Darby canine kidney cells after exposure to paraquat. Fluorescein diacetate fluorescence was used as a marker of cell viability, while bromodeoxyuridine incorporation was detected with a monoclonal antibody and propidium iodide staining to assess DNA synthesis. Flow cytometry was performed immediately, 48 h and 96 h after exposure to paraquat for 24 h. Lactate dehydrogenase release was also measured to determine the extent of cytolysis. Flow cytometry of paraquat-treated cells showed a marked increase of the S phase population immediately after exposure, at a time when there was no increase of lactate dehydrogenase release. In contrast, the cell cycle profile returned towards normal at 48 and 96 h after paraquat exposure, but lactate dehydrogenase release increased. These findings indicate that paraquat arrested cells in the S phase and that inhibition of DNA synthesis by this agent appeared to influence cell viability because S phase block occurred before cytolysis. In addition, this method proved useful for assessing the effects of paraquat on DNA synthesis by cultured cells.

Pharmacologic effects of cisplatin (CDDP) and peplomycin (PEP) on tumor cell kinetics were studied both in vitro and in vivo with the aid of flow cytometry (FCM). Double staining with propidium iodide (PI) and fluorescein isothiocyanate (FITC)-labeled bromodeoxyuridine (BrdU) was used to analyze the cell cycle, and the number of viable cells was determined with fluorescein diacetate (FDA). Effects of combining the 2 agents were also studied to establish the most effective method of combination therapy. Furthermore, these agents were tried clinically on the basis of experimental results. Results showed that CDDP exerted its action at the S and G2M phases in the cell cycle and PEP at the G2M phase. Among the combination regimens in the experiments with CDDP, PEP, and CDDP + PEP as analyzed by FCM, the strongest block on the G2M phase was shown in the one at a 2-day interval, resulting in the most effective killing of the tumor cells. Clinical trial of the combination therapy showed the same results as the in vitro experiment; the therapy proved useful for improving the patient's clinical condition and the results obtained with CT imaging and pathology.