Histamine receptor effects on dissipation of an intracellular proton gradient of isolated gastric mucosal surface cells

The effects of histamine and several H1 and H2 receptor agents on Na+/H+ and Cl-/HCO-3 exchange systems of isolated gastric mucosal surface cells were studied. The cells were acid-loaded by the NH4Cl prepulse technique and the spontaneous Na+- and HCO-3-induced dissipation of the intracellular proton gradient (pHi) was followed using the metachromatic dye acridine orange. Histamine (10(-2-5) M) stimulates HCO-3-induced dissipation of the pHi but has no effect on Na+-induced or spontaneous dissipation. The H1 agonist 2-(2-aminoethyl)pyridine and the H2 agonist dimaprit also have no effect on Na+-induced or spontaneous pHi dissipation. However, both of these agents mimic the effect of histamine on HCO-3-induced dissipation, but only at a higher concentration (10(-3) M). The combination of 2-(2-aminoethyl)pyridine and dimaprit produces a histamine-like effect at lower concentrations (10(-5) and 10(-4) M). The effects of histamine are blocked by either the H1 antagonists diphenhydramine and pyrilamine or the H2 antagonists cimetidine and SKF 93479. The results suggest that the effect of histamine on HCO-3-induced dissipation of a pHi in gastric mucosal surface cells is mediated through a coordinated mechanism involving both H1 and H2 receptor sites.     

Interleukin-1 derived from human monocytic leukemia cell line JOSK-I acts as an autocrine growth factor

Interleukin-1 (IL-1) enhances the growth of human monocytic leukemia cell line JOSK-I cells, which were recently established in our laboratory and which were demonstrated to produce a high level of IL-1 constitutively, in liquid as well as semisolid culture systems. Concomitantly, IL-1 stimulated the prostaglandin E2 synthesis and nitroblue tetrazolium dye-reducing capacity of JOSK-I cells. This indicates that IL-1 may act as autocrine growth factor for monocytes, and also suggests the possibility that this autocrine stimulation may play an important role in the pathophysiology of monocytic leukemia in vivo.     

Application of coomassie brilliant blue staining to cultured hepatocytes

Coomassie brilliant blue staining developed by Pena (1980) was applied to cultured hepatocytes of adult rats with some modifications. Many of organelles in the cytoplasms were clearly visible as blue granules by this method. Various cytoskeletal elements were also visualized clearly. Because of its simplicity, Coomassie blue staining proved to be a very powerful tool for study of morphological changes of cell organelles and cytoskeletal systems of cultured hepatocytes.     

The structure ofHLA-B35 suggests that it is derived fromHLA-Bw58 by two genetic mechanisms

The primary structure ofHLA-B51 andHLA-Bw52 suggested thatHLA-B51 was derived fromHLA-Bw52 by the combination of a genetic exchange withHLA-B8 and a point mutation. To investigate the evolution of theHLA-B5 cross reactive group, theHLA-B35 gene was cloned and the primary structure was determined.HLA-B35 is identical toHLA-Bw58 except in the α₁ domain. The α₁ domain ofHLA-B35 except Bw4/Bw6-associated amino acids is identical to that ofHLA-B51 ^*, which was suspected to be an intermediate gene betweenHLA-B51 andHLA-Bw52. These data suggest thatHLA-B35 has evolved fromHLA-Bw58 in two steps; an in vivo replacement of the α₁ domain withHLA-B51 and genetic exchange with one of theHLA-Bw6 genes. These three genes andHLA-Bw58 are postulated to share a common ancestor.     

Structural study of the sugar chains of human platelet thrombospondin

The asparagine-linked sugar chains of human platelet thrombospondin were released as oligosaccharides by hydrazinolysis. About 12 mol of sugar chains was released from one thrombospondin molecule. This was converted to radioactive oligosaccharides by sodium borotritide reduction after N-acetylation, and separated into one neutral and four acidic fractions by paper electrophoresis. More than 90% of the oligosaccharides were recovered in the acidic fraction. The acidic oligosaccharides were mostly converted to neutral oligosaccharides by sialidase treatment, indicating that they are sialyl derivatives. The neutral and sialidase-treated acidic oligosaccharides were further fractionated by Bio-Gel P-4 column chromatography. Structural study of each oligosaccharide by sequential exoglycosidase digestion and methylation analysis revealed that the thrombospondin contains mono-, bi-, tri-, and tetraantennary complex-type sugar chains in addition to a small amount of high-mannose type. Approximately 70% of the complex-type sugar chains was fucosylated at asparagine-linked N-acetylglucosamine residue and 19% of the biantennary complex-type sugar chains was bisected.     

Induction by mycoplasmas of tumor necrosis factor-alpha from macrophages

Several species of mycoplasmas including M. pneumoniae, the causative agent of human respiratory infection, were investigated for tumor necrosis factor-alpha (TNF-alpha) induction. The cytotoxic activity to Meth A cells of peritoneal macrophages purified from BALB/c mice was enhanced markedly when cultured with either viable or nonviable mycoplasmas. The supernatant of macrophage culture mixed with mycoplasmas, M. pneumoniae or A. laidlawii, showed a potent cytotoxic activity to TNF-alpha-sensitive but not to TNA-alpha-insensitive L cells. Addition of anti-TNA-alpha antiserum inhibited completely the cytotoxic activity of the supernatant, indicating that the cytotoxic activity is due mostly to TNF-alpha. These results strongly suggest that mycoplasmas possess an activity to induce TNF-alpha, which enhances the cytotoxic activity of macrophages and prevent infection with mycoplasmas in vivo.     

Stress fibers in the mesenteric mesothelial cells of the large intestine of the bullfrog,Rana catesbeiana

Summary Actin-containing cytoplasmic fibers were visualized in the mesenteric mesothelial cells of the large intestine of bullfrog tadpoles by rhodamine-phalloidin staining of en face preparations of mesothelial cells. These fibers were concurrently stained by immunofluorescence using antibodies to myosin or -actinin. Electron microscopy showed the presence of bundles of microfilaments in the basal cytoplasm of the cells. Such fibers in the mesothelial cells may be comparable to the stress fibers present in cultured cells. The mesothelial cells initially formed axially oriented stress fibers when they changed from a rhombic to a slender spindle-like shape. On the other hand, stress fibers disappeared as cells transformed from elongated to polygonal shapes during the period of metamorphic climax. Expression of stress fibers in these cells appears to be related to the degree of tension loaded on the mesentery, which may be generated by mesenteric winding. These stress fibers in the mesothelial cells may serve to regulate cellular transformation. They may also help to maintain cellular integrity by strengthening the cellular attachment to subepithelial tissue against tensile stress exerted on the mesentery.     

Induction of tumoricidal activated macrophages by a liposome-encapsulated glycolipid, trehalose 2,3,6'-trimycolate from Gordona aurantiaca

A mycolic acid-containing glycolipid, trehalose 2,3,6'-trimycolate, prepared from a non-pathogenic acid-fast bacterium Gordona aurantiaca, was shown to induce strong tumoricidal activity in peritoneal exudate cells by intravenous or intraperitoneal injection of liposome-encapsulated preparations. The mycolic acid derivative containing a high proportion of unsaturated fatty acids rendered macrophages cytotoxic against syngeneic mastocytoma cells in the absence of endotoxin, for over 14 days after the injection. The macrophages were ascertained to be at low intracellular levels of a lysosomal enzyme beta-galactosidase and an ectoenzyme alkaline phosphodiesterase, a specific pattern as previously described for "primed macrophages". However the culture supernatants of the peritoneal exudate cells were not cytotoxic.