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991.
P L Black H Phillips H R Tribble R Pennington M Schneider J E Talmadge 《Journal of cellular biochemistry》1988,36(4):377-392
The mechanism of therapeutic activity of recombinant murine interferon-gamma (rMu IFN-gamma) and the IFN inducer polyinosinic-polycytidylic acid solubilized with poly-L-lysine in carboxy methyl cellulose (pICLC) in treating metastatic disease was investigated by comparing effector cell augmentation with therapeutic activity in mice bearing experimental lung metastases (B16-BL6 melanoma). Effector cell functions in spleen, peripheral blood, and lung (the organ with tumor) were tested after 1 and 3 weeks of rMu IFN-gamma or pICLC administration (intravenous, three times a week). In these studies, natural killer (NK), lymphokine-activated killer (LAK), cytolytic T lymphocytes (CTL) (against specific and nonspecific targets), and macrophage tumoricidal and tumoristatic activities were measured. rM IFN-gamma and pICLC had therapeutic activity and immunomodulatory activity in most assays of immune function examined. Specific CTL activity of pulmonary parenchymal mononuclear cells (PPMC), but not in splenocytes or peripheral blood lymphocytes (PBL), during week 3 and not during week 1, correlated with the therapeutic activity of rMu IFN-gamma and of pICLC. Macrophage tumoricidal activity in PPMC, but not in alveolar macrophages, also correlated with the therapeutic activity of rMu IFN-gamma, but the opposite was true for the therapeutic activity of pICLC. NK activity of PPMC, but not of splenocytes or PBL, during week 1 correlated with the therapeutic activity of pICLC; in contrast, NK activity at any site did not correlate with the therapeutic activity of rMu IFN-gamma. LAK activity at any site did not correlate with the therapeutic activity of either agent. 相似文献
992.
Richard C. Woodman John T. Curnutte Bernard M. Babior 《Free radical biology & medicine》1988,5(5-6):355-361
We examined the effects of the recombinant human colony stimulating factors GM-CSF and G-CSF, cycloheximide (a protein synthesis inhibitor) and dihydrocytochalasin B (a microfilament disrupting agent) upon FMLP (N-formyl-methionyl-leucylphenylalanine)-stimulated O2 − production by neutrophils. We confirmed a time dependent augmentation of O2 − production following preincubation of neutrophils either alone or with colony stimulating factors. Furthermore, we found that GM-CSF, but not G-CSF, increased O2 − production at some concentrations of the stimulus. Preincubation of neutrophils with cycloheximide in the absence of CSF caused a marked fall in O2−-production that was first evident at 2 hours. The fall in O2−-forming capacity caused by cycloheximide was much less pronounced if dihydrocytochalasin B was also included in the preincubation buffer. These findings suggest a previously unrecognized role for de novo protein synthesis in maintaining the ability of neutrophils to manufacture O2−, and support earlier studies indicating that the cycling of FMLP receptors between the cell membrane and an intracellular compartment is important in determining the magnitude of the respiratory burst in FMLP-stimulated neutrophils. 相似文献
993.
A. M. Tomson R. Demets W. L. Homan D. Stegwee H. van den Ende 《Sexual plant reproduction》1988,1(1):46-50
Summary We describe a circadian rhythm in the surface density of receptors that play a dominant role in the mating process of the unicellular green alga Chlamydomonas eugametos.These receptors — called agglutinins — are large glycoproteins extrinsically bound to the membrane of gamete flagella. We found circadian fluctuations in their density. Since inhibition of protein synthesis affected the agglutinin density without a lag period at any time,we conclude that the density was dependent on de novo synthesis and that the fluctuations in density are caused by circadian oscillations in the rate of agglutinin synthesis. This phenomenon evidently underlies the pronounced endogenous rhythm in mating competence that we described previously (Demets et al. 1987). Finally, we speculate on the nature of the time keeping mechanism that is generating these rhythmic events. 相似文献
994.
Masamitsu Wada 《Journal of plant research》1988,101(4):519-528
Chloroplast proliferation was investigated inAdiantum protonemata growing under continuous red light. Cell division is absent when cells are grown under red light. The chloroplast
number increases as the cell length increases, therefore the chloroplasts divide in the absence of cell division. Chloroplasts
in the basal part of the filamentous protonemal cell migrate gradually toward the cell apex, but there is no large net migration
from the tip to the base or vice versa, indicating that chloroplast division takes place in the apical part of the protonemata.
Chloroplast number in the apical 100 μm was maintained at about 200 during cell growth at least over eight days. The chloroplasts
were either dumbbell- or ellipsoid-shaped. Dumbbell-shaped chloroplasts are abundant everywhere in a protonema, ranging from
30 to 50% of the total chloroplasts. The dumbbell-shaped chloroplasts attached to or very close to the plasma membrane seem
to be the ones that are dividing but the dumbbell-shaped ones in the other regions do not divide. These data support the hypothesis
that a signal from the plasma membrane induces the dumbbell-shaped chloroplasts to divide. 相似文献
995.
Robert W. Ridge 《Journal of plant research》1988,101(4):427-441
The freeze-substitution method was applied toVicia hirsuta root hairs to test its effectiveness in improving preservation of the cell ultrastruture. Freeze-substitution almost certainly
represents more faithfully the structure of the hair cell. A previously unreported ‘pyriformis’ vesicle is described. Also
unique to freeze-substituted material are coated secretory vesicles; a smooth plasma membrane profile; mitochondrial ribosomes;
long microfilament bundles which are associated with vesicles, mitochondria, coated pits and coated vesicles; microtubule-associated
filaments; well-preserved coated vesicles and coated pits with enclosing rings; a pliciform nucleus. The results are discussed
in context of previous reports using conventional fixation techniques. 相似文献
996.
Observation was made on early ontogeny of vascular cambium in the developing root ofGinkgo biloba L. After completion of root elongation, the vascular meristem gradually acquires cambial characteristics. Strips of the periclinal
division of cells in transverse section are observed on the inner side of phloem when the primary xylem and phloem in the
stele have been established. The strips are united into a continuous layer between phloem and xylem. In tangenital section,
the procambium shows a homogeneous structure, which is initially composed of short cells with transverse end walls and subsequently,
of long cells with tapering ends. Then, the procambium is organized into two systems of cells; axial strands of short cells
with transverse end walls resulting from the sporadic transverse divisions of long cells, and long cells with tapering ends.
Still later, the short cells are divided frequently in a trasverse plane exhibiting one or a few cells in width and several
decades of cells in height, while the long cells are elongated. The frequency of transverse divisions of the short cells decreases
in subsequent stages. Eventually, the short cells in axial strands are vertically separated from one another by the elongation
of neighboring long cells and by the decrease in the frequency of transverse divisions of short cells themselves. Cambial
initials occur in two forms; ray initials a few cells in height and one cell in width derived from the short cells, and fusiform
initials with tapering ends derived from the long cells. 相似文献
997.
Human-human hybridoma SH-76 cells were found to produce a factor that supported the growth of lymphocytic cells at low densities. The factor was purified from serum-free conditioned medium of the hybridoma cells by a successive application of ammonium sulfate precipitation, DEAE-Toyopearl, TSK G3000 SW and DEAE-5PW column chromatograph. The purified factor was a 72K single protein. The factor showed marked growth stimulating effect on lymphocytic cell lines, but had no effect on the growth of human adhesive cancer cell lines. Thus, the factor is a lymphocytic clonal growth factor (LCGF), as found previously in human plasma (Miyata, 1988). The LCGF of SH-76 cells could be produced in growth factor-free RPMI medium and purified easily from the conditioned medium. The factor is inactivated by heating at over 80°C, but is much more stable than the LCGF in human plasma. 相似文献
998.
Markus Riederer Kathrin Kurbasik Rainer Steinbrecher Andreas Voss 《Trees - Structure and Function》1988,2(3):165-172
Summary A method for the rapid determination of the lengths and surface areas of very large samples of needles of Picea abies (L.) Karst. using a computer-aided image analysis system was developed. Two independent methods for measuring non-destructively the volumes of individual needles and of all needles attached to a twig were devised. The surface areas and lengths of about 38000 needles sampled from the three youngest needle age-classes (1986, 1985, 1984) of 48 trees approximately 130 years old at four sites in the Fichtelgebirge mountains (N. E. Bavaria, FRG) were measured. The frequency distributions of lengths and areas for each site and age-class are given. Variability of needle size was fairly large. Even though the sites differed in climate, soil, and air pollution levels no consistent effect of these factors on needle size could be detected. Needle lengths and surface areas did not correlate with either the total chlorophyll content of the needles or the degree of crown thinning. The needle surface area (in mm2) of fully developed P. abies needles can be estimated by the empirical equation surface area = 4.440 x needle length -24.8 (r = 0.937), and the needle volume (in mm3) by needle volume = 0.208 x projected needle area
1.353 (r = 0.969). 相似文献
999.
Summary An attempt was made to transfer two sorts of DNA into maize via pollen grains. Controls for both pollen quality and DNA behaviour during the transformation experiments were included. When genomic DNA was used, no transformants were observed among the 1805 seeds screened. With plasmid DNA (harbouring the gene expressing kanamycin resistance in plant cells), three plants with kanamycin resistance were observed among the 1723 seeds screened, although no molecular evidence of transformation was obtained. Experiments indicated that under the conditions used, DNA was being degraded by both pollen and stigma nucleases. Consequently, we attempted to determine protocols which would inhibit these nuclease activities in order to preserve DNA integrity during transformation experiments, thus allowing fertilization. We found that a classic germination medium supplemented by 300 or 600 mM KNO3, or 20% PEG1550 satisfied all these conditions.Abbreviations BK
Brewbaker and Kwack medium
- BKS15
Brewbaker and Kwack medium containing 15% (w/v) sucrose
- EDTA
ethyldiaminetetraacetic acid
- FCR
fluorochromatic reaction
- FP
fertilization percentage
- PEG
polyethylene-glycol 相似文献
1000.