Spontaneous malignant lymphoma in an African green monkey naturally infected with simian T-lymphotropic virus (STLV)

An African green monkey naturally infected with simian T-lymphotropic virus (STLV) developed spontaneous malignant lymphoma of diffuse pleomorphic type. The clinical, hematological and histopathological characteristics were very similar to those of human adult T-cell leukemia.     

Simultaneous determination of tryptophan and its metabolites in mouse brain by high-performance liquid chromatography with fluorometric detection

A new method for the determination of tryptophan and its metabolites in a single mouse brain using high-performance liquid chromatography (HPLC) with fluorometric detection is described. Tryptophan, serotonin, 5-hydroxyindoleacetic acid, indoleacetic acid, and tryptophol were clearly separated by a C8 reverse-phase column. Tissue preparation is performed only to centrifuge homogenates of brain prior to the injection to HPLC. The sensitivity is in the range from 10 to 15 pg.     

Effect of Bordetella pertussis leukocytosis (lymphocytosis)-promoting factor (LPF) on the physical lymphoepithelial-cell association studied with the use of an in vitro model of mouse thymus

The effect of highly purified leukocytosis (lymphocytosis)-promoting factor (LPF) of Bordetella pertussis on physical lymphocyte and reticuloepithelial (RE) cell association was studied in an in vitro thymus model. First, a simplified in vitro system to assess the lympho-RE-cell association was developed. A completely confluent layer of thymic RE cells was formed by cultivating trypsinized thymus cell suspensions from 2- to 7-day-old mice. When thymic lymphoid cells were seeded on this cell layer and cultivated overnight, a significant proportion of them were found underneath the RE cell layer. This physical lympho-RE-cell association was quantitated by counting the lymphoid cells underneath the RE cell layers. Second, the effect of LPF on this physical lympho-RE-cell association phenomenon was investigated. Addition of LPF to the culture markedly inhibited the formation of the lympho-RE-cell complex; that is, it inhibited the infiltration of lymphoid cells under the RE cell layer. LPF rendered a nearly maximal level of inhibitory effect at a dose of 0.1 ng/ml. Furthermore, LPF enhanced the liberation of lymphoid cells from preformed lympho-RE-cell complexes. On the other hand, LPF had no direct cytotoxic effect on lymphoid cells at doses below 1 microgram/ml. In order to investigate whether LPF produced the effect by acting on lymphoid cells, RE cells, or both, the following experiments were performed. When lymphoid cells were pretreated with LPF and added to normal RE cell layers, the lympho-RE-cell association was maximally inhibited above the dose of 1 ng/ml. Treatment of these LPF-treated lymphoid cells with anti-LPF antibodies failed to abrogate the effect of LPF. When RE cell layers were similarly pretreated with LPF and were cultivated with normal lymphoid cells, however, much higher doses of LPF, above 100 ng/ml, were required for maximal inhibition. Furthermore, treatment of these LPF-treated RE cells with anti-LPF antibodies abrogated the effect of LPF. Therefore, the apparent effect of LPF on RE cells was considered to be due to the carry-over by RE cells of LPF, which should directly act on lymphoid cells at extremely low doses. On the basis of these results, it was concluded that LPF acted directly on lymphoid cells without mediation of RE cells. These in vitro results appear to parallel the effects of LPF in vivo, where it induces a depletion of cells in the thymus. The model may be useful to study this phenomenon and the concomitant accumulation of blood lymphocytes.     

Immunochemical evidence that myosin I heavy chain-like protein is identical to the 110-kilodalton brush-border protein

In a previous study, we identified a new mammalian myosin heavy chain, termed myosin I heavy chain-like protein (MIHC), by molecular cloning of a bovine intestinal cDNA clone. In this investigation, we examined the relationship between MIHC and the 110-kDa intestinal brush-border protein, which possesses a myosin-like ATPase activity. We raised antibodies against a chemically synthesized oligopeptide representing a part of the MIHC sequence. These antibodies reacted specifically in immunoblots with the 110-kDa protein in both purified 110-kDa protein-calmodulin complex and crude microvillar protein extracts. Staining of tissue sections with these antibodies was specifically localized to the brush-border microvilli of small intestines, indicating an identical cellular localization for both MIHC and the 110-kDa protein. Furthermore, analysis of the MIHC sequence revealed two putative calmodulin-binding sites, which is consistent with the fact that the 110-kDa protein forms a complex with calmodulin. These results strongly support the conclusion that MIHC is identical to the 110-kDa protein and suggest that not only the conventional myosin system but also the MIHC (110-kDa protein)-calmodulin complex may play an important role in ATP-dependent and Ca2+-induced brush-border contraction.     

Molecular cloning and characterization of the platelet-activating factor receptor gene expressed in the human heart.

PAF decreases cardiac contractility and blood pressure. To characterize the cardiac PAF receptor, we screened a human ventricular cDNA library in a low stringency condition, using a PCR product derived from guinea pig lung PAF receptor as a probe. Four clones were obtained and named HV1-4. In Xenopus oocytes injected with cRNA derived from HV3 or 4 but not from HV1 or 2, PAF elicited a Ca(2+)-activated Cl- current. HV3 and HV4 were duplicate clones, encoding a 342 amino-acid polypeptide which was identical to that of the human leukocyte PAF receptor. However, a portion of the 5' untranslated region of HV3 (or 4) was different from that of the leukocyte receptor cDNA. Northern blotting of human ventricles and atria using the HV3 insert showed a single band of approximately 4 kb. These results suggest a tissue-specific translational mechanism responsible for regulation of the expression of the PAF receptor mRNA in these tissues.     

Baculovirus p35 prevents developmentally programmed cell death and rescues a ced-9 mutant in the nematode Caenorhabditis elegans.

Programmed cell death, or apoptosis, occurs throughout the course of normal development in most animals and can also be elicited by a number of stimuli such as growth factor deprivation and viral infection. Certain morphological and biochemical characteristics of programmed cell death are similar among different tissues and species. During development of the nematode Caenorhabditis elegans, a single genetic pathway promotes the death of selected cells in a lineally fixed pattern. This pathway appears to be conserved among animal species. The baculovirus p35-encoding gene (p35) is an inhibitor of virus-induced apoptosis in insect cells. Here we demonstrate that expression of p35 in C. elegans prevents death of cells normally programmed to die. This suppression of developmentally programmed cell death results in appearance of extra surviving cells. Expression of p35 can rescue the embryonic lethality of a mutation in ced-9, an endogenous gene homologous to the mammalian apoptotic suppressor bcl-2, whose absence leads to ectopic cell deaths. These results support the hypothesis that viral infection can activate the same cell death pathway as is used during normal development and suggest that baculovirus p35 may act downstream or independently of ced-9 in this pathway.