Role of CD4 molecule in intrathymic T-cell development.

We have investigated the role of CD4 molecules in intrathymic T-cell repertoire selection. The administration of monoclonal antibody (mAb) to CD4 in organ culture of murine foetal thymus (FTOC) completely inhibited the development of CD4+8- cells, and additional treatment with anti-class II MHC (Ia) mAb caused no further effects on this inhibition. On the other hand, when the potentially autoreactive cells in Mls-1a mice were monitored by expression of the Mls-1a-reactive V beta 6 gene product of T-cell receptor alpha beta (TcR alpha beta), the treatment with anti-CD4 resulted in the appearance of V beta 6-bearing cells to some extent, but this effect was considerably reinforced by the combinatory use of anti-Ia mAb with anti-CD4. In a model system where the bacterial superantigen staphylococcal enterotoxin B serves as self-antigen to deplete V beta 8-bearing cells in FTOC, the depletion of V beta 8+ cells was restored partially by anti-CD4 alone but completely by the combination with anti-Ia. These results suggest that CD4 is indispensable for positive selection of all CD4+8- thymocytes, whereas participation of CD4 in negative selection is only partial. It was also observed that the development of TcR alpha beta-bearing cells in the CD4-8- population was inhibited by the treatment with anti-CD4 mAb. In Mls-1a mice, V beta 6-bearing cells were developed in CD4-8+, CD4+8+, and also in CD4-8- populations after anti-CD4 mAb treatment. It is suggested that TcR alpha beta-bearing CD4-8- cells are possibly originated from CD4+ cells and undergo CD4-mediated thymic selection.     

Immunohistochemical localization of transforming growth factor alpha in chemically induced rat hepatocellular carcinomas with reference to differentiation and proliferation

Hepatocellular carcinomas (HCCs) were induced in male Fischer 344 rats with dietary 3'-methyl-4-(dimethylamino)-azobenzene treatment and were classified into solid, glandular (well- or poorly differentiated), and trabecular types. Investigation of cell proliferation kinetics and immunohistochemical localization of transforming growth factor alpha (TGF-alpha) demonstrated all solid (n = 24) and poorly differentiated glandular type (n = 6) HCCs to have TGF-alpha-positive nuclei. Nuclear staining of TGF-alpha was also observed in 13 of 28 (46%) trabecular-type HCCs, whereas 12 (43%) exhibited cytoplasmic staining, and 3 (11%) were negative. As for well-differentiated glandular HCCs, 7 of 20 (35%) were positively stained in their nucleus, another 7 (35%) demonstrated antibody binding in the cytoplasm, and 6 (30%) were negative. The order for growth rate evaluated by bromodeoxyuridine (BrdU) labeling was solid (38.22%), poorly differentiated glandular (26.82%), trabecular (7.98%), and well-differentiated glandular (2.57%) types. For trabecular HCCs with nuclear, cytoplasmic, or negative TGF reactions, values were 13.39% (n = 13), 3.61% (n = 12), and 2.01% (n = 3), respectively. Likewise, BrdU-labeling indices for the counterpart groups of well-differentiated glandular type HCCs were 4.53, 1.91, and 1.29%, respectively. The results indicate that TGF-alpha expression might be linked to histopathological differentiation and cell proliferation in rat HCCs.     

Roles of tyrosine kinase in insulin action on cell volume of fetal rat type II pneumocyte

The aim of the present study was to investigate the roles of tyrosine kinase (TK) in the insulin action on cell volume in fetal rat (20-day gestational age) type II pneumocyte. Insulin (100 nmol/l) increased cell volume, and this insulin (100 nmol/l) action was completely blocked by 50 μmol/l bumetanide (BMT) and 10 μmol/l amiloride (AML). This observation indicates that 100 nmol/l insulin activates BMT-sensitive Na⁺/K⁺/2Cl^? cotransporter and AML-sensitive pathways. The stimulatory action of 100 nmol/l insulin on BMT-sensitive Na⁺/K⁺/2Cl^? cotransporter was completely abolished by 10 μmol/l lavendustin A (LAV-A, an inhibitor of TK), however 100 nmol/l insulin could stimulate AML-sensitive pathways even in LAV-A (10 μmol/l)-treated cells. These observations indicate that the insulin (100 nmol/l) action on the BMT-sensitive Na⁺/K⁺/2Cl^? cotransporter is mediated through TK-dependent pathways, while 100 nmol/l insulin requires a TK-independent pathway to show the stimulatory action on the AML-sensitive pathways. From these observations we conclude that TK-dependent and -independent pathways are involved in the insulin (100 nmol/l) signaling in fetal rat type II pneumocyte.     

Topographical projections from the thalamus to the putamen in the cat

Thalamic projections to the putamen (Put) in the cat were studied by the retrograde horseradish peroxidase method. Major thalamic projections to the Put originate from the midline and intralaminar nuclear regions including the centre médian-parafascicular complex (CM-Pf). The other thalamic projections to the Put arise mainly from the suprageniculate nucleus (Sg), magnocellular division of the medial geniculate nucleus (MGm), caudomedial part of the lateroposterior nucleus (LP) and ventrolateral part of the ventromedial nucleus (VM). The VM projects to the rostral Put, while the posterior thalamic regions (Sg, MGm, LP) project to the caudal Put.     

An Autopsy Case of Peritoneal Malignant Mesothelioma in a Radiation Technologist

A case of peritoneal maligant mesothelioma in a radiation technologist, who had worked in this field for 34 years, is reported. Histopathologically, a biopsy specimen from the retroperitoneal tumor revealed a biphasic type of malignant mesothelioma. Electron microscopy disclosed that the tumor cells contained prominent microvilli, basal laminae adjacent to the stroma, junctional complexes, desmosomes, tonofilaments, clusters of glycogen granules, welt developed rough endoplasmic reticulum (RER), confronting cisternae showing direct continuity with the RER and membrane-bound granules suggestive of secretory activity. No increased amount of asbestos was detected in autopsied lung material or the peritoneal mesothelioma. The estimated cumulative dose of occupational irradiation was calculated to be about 40 to 50 rad at most. Irradiation was discussed in relation to the etiology of the peritoneal mosothelioma. Acta Pathol Jpn 40: 57–62, 1990.     

Simple method for the identification of oxidative fibers in skeletal muscle

Skeletal muscle is composed of several different types of myofiber: slow oxidative (SO), fast glycolytic oxidative and fast glycolytic. However, the classification is usually determined by myosin heavy chain typing rather than by metabolic index. In this study, the oxidative metabolic index was investigated as a possible method of myofiber typing. Myoglobin, which is involved in oxygen transport and storage in myofibers, and mitochondria, which are the central organelles for oxidative metabolism, were studied. High levels of myoglobin and mitochondria are believed to exist in SO fibers, but the current study showed that they are considerably richer in some fast type fibers. As myofiber typing using the oxidative metabolic index is important physiologically, an attempt was made to find a simple method for this purpose. Some mitochondrial proteins have been observed to auto-fluoresce but until now this effect was too faint to detect easily. Owing to the recent advances in cooling charge-coupled device technology, such auto-fluorescence can now be used for myofiber typing, and the simple and rapid method for doing so is reported here.     

Vp130, a chloroviral surface protein that interacts with the host Chlorella cell wall

A protein, Vp130, that interacts with the host cell wall was isolated from Chlorovirus CVK2. From its peptide sequence, the gene for Vp130 was identified on the PBCV-1 genomic sequence as an ORF combining A140R and A145R. In Vp130, the N-terminus was somehow modified and the C-terminus was occupied by 23-26 tandem repeats of a PAPK motif. In the internal region, Vp130 contained seven repeats of 70-73 amino acids, each copy of which was separated by PAPK sequences. This protein was well conserved among NC64A viruses. A recombinant rVp130N protein formed in Escherichia coli was shown not only to bind directly to the host cell wall in vitro but also to specifically bind to the host cells, as demonstrated by fluorescence microscopy. Because externally added rVp130N competed with CVK2 to bind to host cells, Vp130 is most likely to be a host-recognizing protein on the virion.     

The PPARgamma ligand, 15-Deoxy-Delta12,14-PGJ2, regulates apoptosis-related protein expression in cholangio cell carcinoma cells

PPARgamma is known to induce apoptosis in malignant tumor cells, but the mechanism of this induction is not well understood. We investigated induction of apoptosis with 15-Deoxy-Delta12,14-prostaglandin J2 (15d-PGJ2), a PPARgamma ligand, in cholangio cell carcinoma (CCC) cells (RBE, ETK-1 or HuCCT-1). Apoptosis was induced in RBE and ETK-1 cells with 15d-PGJ2, but not in HuCCT-1 cells, although PPARgamma was expressed in all CCC cells. Apoptosis-related proteins were also expressed, including FLIP, bclx, Apaf-1 and XIAP, but expression levels differed among the three cell lines. RBE cells treated with 15d-PGJ2 showed caspase activation, and it appeared that PPARgamma-induced apoptosis was dependent on caspase activation. However, neither ETK-1 nor HuCCT-1 cells showed significant activation of caspase-8 or -3 with 15d-PGJ2 treatment, raising the possibility of a caspase-independent apoptosis induction pathway. XIAP was down-regulated by 15d-PGJ2 in all three CCC cell lines. Therefore, 15d-PGJ2 induces apoptosis in CCC cells via caspase-dependent or independent pathways. 15d-PGJ2 may also induce down-regulation of XIAP and may promote caspase cascade activation through TNF-family receptor signaling pathways.     

Changes in hypothalamic temperature of rats after daily exposure to heat at a fixed time

Rats were subjected to an ambient temperature (T_a) of 33°C for ca. 5 h during the last half of the dark phase for 5, 14 or 28 consecutive days (heat-exposed rats, HE), while control rats were kept at a constant T_a of 24°C. After the heat exposure schedule, the levels of hypothalamic temperature (T_hy) as an index of body core temperature in the HE were significantly lower than those of the controls for 2–4 h in the last half of the dark phase. The low levels of T_hy persisted during the specific period for 1, 3 and 6 days after the end of the 5-, 14- and 28-day heat exposure schedules, respectively. These results confirm that, in rats subjected to daily heat exposure for ca. 5 h at a fixed time per day, their T_hy falls during the period when the rats were previously exposed to heat, and suggest that the duration of the specific T_hy change observed after completing the heat exposure schedule depends on the length of the heat exposure schedule.