Corticotropin-releasing activity in the rat gastric antrum

Rat gastric antrum, duodenum, pancreas, and spleen were extracted in acetic acid, treated with acetone, and purified on a C-18 cartridge. These extracts, in a dose equivalent to one respective organ, were examined for CRF bioactivity in vitro using rat half pituitaries, with gastric antrum extract showing a significant CRF activity. The antrum extract showed a dose-related CRF activity in vitro using rat pituitary cell culture, and the dose-response curve appeared to be parallel with that of synthetic rat hypothalamic CRF. Subsequent ion-exchange chromatography on a SP-Sephadex column showed that antrum CRF coeluted with basic materials (SP-III fraction), while rat hypothalamic CRF coeluted with weakly basic materials (SP-II fraction). The SP-III fraction was further purified by gel filtration on Sephadex G-50. CRF activity was eluted in two areas: large mol wt fraction (10,000-15,000) and small mol wt fraction (1500-2000). Hypothalamic CRF was eluted between them. The CRF activities of the two fractions were completely abolished by trypsin digestion, suggesting a peptide nature. The large molecular weight fraction exhibited a steeper dose-response curve than the hypothalamic CRF in vitro using cell culture, and the response to a dose equivalent to two antra exceeded the maximum response exhibited by the hypothalamic CRF. However, the fraction failed to increase serum corticosterone when injected in pharmacologically blocked rats. On the other hand, the small molecular weight fraction showed a lesser CRF activity and a similar dose-response curve to that of the hypothalamic CRF as tested in vitro. This fraction significantly stimulated corticosterone secretion in vivo as well. The small molecular weight activity did not appear to be due to other peptides or amines which have been reported as causing ACTH release. Although the physiological roles of the small molecular weight antrum CRF are unknown, it is possible that this CRF plays a role during stress as a tissue CRF.     

Differential distribution of receptors for two fucose-binding lectins in embryos and adult tissues of the mouse

Ulex europaeus agglutinin-I (UEA-I) recognizes the Fuc alpha 1----2 Gal linkage. Receptors for UEA-I were not detected in mouse embryos until the 13th day of embryo-genesis, except for their temporary expression in early trophectoderm cells. In adult mice, UEA-I receptors were detected at various sites, including cells of the digestive tracts, the bronchial epithelium, Hassall's corpuscle of the thymus, and the skin. The fucose-binding protein of Lotus tetragonolobus (FBP) is another lectin that recognizes fucosyl residues. The distribution of FBP receptors was significantly different from that of UEA-I receptors. FBP receptors were first detected in late 8-cell embryos and were expressed in the embryonic ectoderm, visceral endoderm, and trophoblastic giant cells in egg-cylinders. At later stages, the distribution of FBP receptors became restricted to certain parts of the embryo. In the adult, the distribution of FBP receptors was more restricted than that of UEA-I receptors. Particularly in embryos before the 11th day of gestation, the distribution of FBP receptors resembled that of SSEA-1, which is defined by the Gal beta 1----4(Fuc alpha 1----3) GlcNAc linkage. From the specificity of FBP, we inferred that the disappearance of SSEA-1 and FBP receptors during embryogenesis is not the result of alpha 1----2 fucosylation of the terminal galactosyl residue in the determinant. The fact that the expression of two fucose-related cell-surface markers, i.e., UEA-I receptors and SSEA-1 (or FBP receptors), is developmentally regulated in an entirely different fashion is an excellent example illustrating the precise control of differentiation-dependent alterations in cell-surface carbohydrates.     

Protein phosphorylation of lysosomal arylsulfatase B in normal and leukemic leukocytes

An acidic variant form of arylsulfatase B from normal leukocytes and chronic myelogenous leukemia (CML) leukocytes was found to be phosphorylated at its serine and threonine residues through in vivo phosphorylation with 32Pi. However, the predominant phosphorylation site was serine in normal cells, in contrast to threonine in CML cells. A cyclic AMP-dependent protein kinase was responsible for phosphorylation of the sulfatase of CML cells.     

Effects of indomethacin, prostaglandin E2, prostaglandin F2α and 6-keto-prostaglandin F1α on hatching of mouse blastocysts

The present study has been performed to investigate how PGs would participate the hatching process. Effects of indomethacin, an antagonist to PGs biosynthesis, on the hatching of mouse blastocysts were examined in vitro. Furthermore, it was studied that prostaglandin E₂ (PGE₂), prostaglandin F_2α (PGF_2α) or 6-keto-prostaglandin F_1α (6-keto-PGF_1α) were added to the culture media with indomethacin. (1) The hatching was inhibited by indomethacin yet the inhibition was reversible. (2) In the groups with indomethacin and PGE₂, no improvement was seen in the inhibition of hatching and the inhibition was irreversible. (3) In the groups with indomethacin and PGF_2α, inhibition of hatching was improved in comparison with the group with indomethacin. (4) In the groups with indomethacin and 6-keto-PGF_1α, no improvement was seen. The above results indicated that PGF_2α possibly had an accelerating effect on hatching and a high concentration of PGE₂ would exert cytotoxic effect on blastocysts.     

Three cDNA clones encoding mouse transplantation antigens: Homology to immunoglobulin genes

We constructed cDNA libraries from poly(A)⁺ RNA isolated from cell lines of two different inbred strains of mice, and screened the libraries with a cDNA clone encoding a human transplantation antigen. Three cDNA clones were identified, sequenced and found to encode amino acid sequences highly homologous to portions of a known mouse transplantation antigen. Comparison of the cDNA sequences of mouse transplantation antigens with the constant region domains of the mouse immunoglobulin μ gene reveals a striking homology, which suggests that the two genes share a common ancestor. Antibody genes undergo DNA rearrangements during B cell differentiation that are correlated with their expression. In contrast, DNA blots with these cDNA probes suggest that the genes for the transplantation antigens are not rearranged in the genomes of liver or embryo cells, which express these antigens, as compared with sperm cells, which do not express these antigens. In Bam HI-digested liver DNAs from different inbred strains of mice, 10–15 bands of hybridization were found. Accordingly, the genes encoding the transplantation antigens appear to constitute a multigene family with similar gene numbers in different mice.     

Vascular eicosanoid production in experimental hypertensive rats with different mechanisms

This study investigated the release of prostacyclin (PGI2) and thromboxane A2 (TXA2) from the aortic walls of various experimental hypertensive rats, e.g. spontaneously hypertensive rats (SHR), Dahl salt-sensitive (Dahl S) rats, deoxycorticosterone (DOCA)-salt hypertensive rats and renovascular (2-kidney, 1-clip (2K1C) and 1-kidney, 1-clip (1K1C] hypertensive rats. The PGI2 generation was increased significantly in these hypertensive models, irrespective of the hypertensive mechanisms, when they developed established hypertension. Dahl S rats, having an impaired PGI2 production on a low salt diet, restored PGI2 generating capacity to the control level of Dahl salt-resistant rats when they were fed a high salt diet and developed salt-induced hypertension. On the other hand, the TXA2 generation in the vascular walls was enhanced particularly in rat models for genetic hypertension, and this system was unaltered in the models for secondary hypertension, e.g. DOCA-salt and renovascular hypertension. Thus, it is suggested that the elevation of blood pressure is associated with an increase in vascular PGI2 production, and that the increased vascular TXA2 production is a characteristic feature of genetic hypertension.     

Nutrient mobility in variable- and permanent-charge soils

Variable-charge (v-c) and permanent-charge (p-c) soils differ fundamentally with regard to many nutrient-cycling processes. Variable-charge soils are more common in the tropics than in temperature zones because their formation requires desilication, which proceeds fastest in warm, moist climates. The dynamics of nutrient mobility tend to be more complex in v-c than in p-c soils. For example, theory predicts that, as pH of v-c soils decreases, cation exchange capacity (CEC) also decreases and anion exchange capacity (AEC) increases. If AEC exceeds CEC, cations such as ammonium and potassium will be more mobile than anions such as nitrate; this is the reverse of the situation in p-c soils, on which most of our knowledge of nutrient cycling is based. Variable-charge surfaces sorb phosphorus, creating plant nutritional problems throughout large areas of the humid tropics. Desilication, the same process that creates v-c surfaces, results also in stable aggregation, creating soils that retain water, yet drain rapidly and resist erosion. The Soil Taxonomy system incorporates information on mineralogy, texture, and organic matter content, and therefore provides insights into patterns of charge chemistry and nutrient cycling across a wide range of soil types.     

Stimulation of ACTH release by human interleukin-1 beta, but not by interleukin-1 alpha, in conscious, freely-moving rats

Ever since two distinct molecules of human interleukin-1 (termed interleukin-1 alpha and interleukin-1 beta) were cloned, sequenced and expressed, it has been a matter of investigation whether these two forms of interleukin-1 possess an identical spectrum of biological activities. Our current studies of interleukin-1 and its involvement in the hypothalamic-pituitary-adrenal axis have indicated that there is a clear-cut differential response to interleukin-1 alpha and interleukin-1 beta. The intravenous injection of human recombinant interleukin-1 beta significantly increased the plasma levels of adrenocorticotropic hormone in a dose-related manner, whereas interleukin-1 alpha did not. This observation suggests for the first time that the two members of the interleukin-1 family may have a different spectrum of biological actions.