Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Functional differentiation”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 505 records · Page 28Linked to original sources
PubMed1990

UVB radiation and human monocyte accessory function: differential effects on pre-mitotic events in T-cell activation.

Purified T lymphocytes fail to proliferate in response to antigenic and mitogenic stimuli when cultured in the presence of accessory cells that have been exposed in vitro to sublethal doses of UVB radiation. Because proliferation represents a final stage in the T-cell activation process, the present study was conducted to determine whether T cells were able to progress through any of the pre-mitotic stages when UVB-irradiated monocytes were used as model accessory cells. In these experiments, monoclonal anti-CD3 antibodies were employed as the mitogenic stimulus. Culture of T cells with UVB-irradiated monocytes did allow the T cells to undergo an increase in intracellular free calcium, which is one of the first steps in the activation sequence. The T cells expressed interleukin-2 receptors, although at a reduced level. However, T cells failed to produce interleukin-2 above background levels when they were placed in culture with monocytes exposed to UVB doses as low as 50 J/m2. Incubation of T cells with UVB-irradiated monocytes did not affect the subsequent capacity of T cells to proliferate, since they developed a normal proliferative response in secondary culture when restimulated with anti-CD3 antibodies and unirradiated monocytes. These studies indicate that T lymphocytes become partially activated when cultured with UVB-irradiated monocytes and mitogenic anti-CD3 monoclonal antibodies. In addition, they suggest that interleukin-2 production is the T-cell activation step most sensitive to inhibition when UVB-irradiated monocytes are employed as accessory cells.

Antigens, CD↗
PubMed1977

Morpho-functional differentiation in lobular carcinoma of the breast.

Lobular carcinoma of the breast has been studied using histochemical methods for mucosubstances; immunocytochemical methods for casein and actin; the ruthenium red electronycytochemical method for acid glycoproteins and an immunoelectroncytochemical method for casein. Mucosubstances and casein showed a similar cytoplasmic localization, but casein production was much more intense and also showed a more diffuse cytoplasmic localization. Occasionally casein assumed the form of target-like 'inclusions' as seen characteristically with the mucosubstances. The neoplastic cells were not stained by antisera against actin. Ultrastructurally, some cells showed an intracytoplasmic lumen with microvilli and/or an irregular outline at one extremity which was covered by microvilli. An electron-dense 'fuzz' and casein coated the microvilli of cells exposed respectively to ruthenium red and an anticasein serum followed by peroxidase--anti-peroxidase complexes. It is concluded that lobular carcinoma shows evidence of epithelial rather than myoepithelial differentiation with the emphasis on epithelial secretory cells engaged in intensive milk protein production. All 10 tumours tested for oestrogen receptors were positive in contradistinction to ductal carcinoma with a lower incidence of positivity. It appears that, in addition to distinctive histological and histochemical features, lobular carcinoma has an almost constant endocrine pattern in respect of its oestrogen receptor content.

Actins↗
PubMed1995

Differential functional activities of rainbow trout and human estrogen receptors expressed in the yeast Saccharomyces cerevisiae.

The cDNA of rainbow trout estrogen receptor (rtER), highly and stably expressed in yeast, Saccharomyces cerevisiae, was used to analyse the biological activity of the receptor. The rtER mRNA encoded a 65-kDa protein which was immunorevealed by a specific antibody and migrated with the authentic rtER major protein form detected in trout liver. Yeast rtER bound estradiol with high affinity and the dissociation constant (Kd = 1.35 nM) was very similar to the value measured from trout liver extracts but 3-5-fold higher than the Kd found for human estrogen receptor (hER). This indicates therefore that the rtER has a lower estradiol affinity compared to the human receptor. While the hER Kd remained unchanged at both 4 degrees C or 22 degrees C, it was slightly modified at 30 degrees C. The Kd measured for rtER at 22 degrees C and 30 degrees C were about 2-fold, and 12-fold higher, respectively, than the Kd obtained at 4 degrees C suggesting an alteration of the rtER affinity for its ligand at elevated temperature. To examine the estrogen-receptor-mediated activation of transcription in yeast, reporter plasmids integrated or not in the yeast genome were used. The reporter genes consist of one, two, or three copies of estrogen-responsive elements (ERE) upstream of the yeast proximal CYC1 or URA3 promoters fused to the lacZ gene of Escherichia coli coding for beta-galactosidase. The induction of beta-galactosidase activity for all reporter genes was strictly dependent on the presence of rtER and estrogens. The activation of transcription mediated by rtER responded in an estradiol-dose-dependent manner as in animal cells. However, compared to hER, the estradiol concentration necessary to achieve maximal activation was 10-fold higher. This is probably a consequence of the lower estradiol-affinity for rtER compared to hER. The levels of induction of the reporter genes containing two or three ERE were strongly enhanced compared to the one ERE construct. This is in agreement with the synergistic effect previously described for multiple ERE. The magnitudes of transcriptional induction mediated by rtER and hER were similar when the reporter gene containing three ERE was used but changed when the one ERE construct was used. In this case transcriptional activation indicated by rtER was 10-20 fold lower. This suggests that rtER requires protein/protein interaction for its stabilization on DNA. Antiestrogens were able to bind rtER and promote gene transcription. However, to produce effects comparable to those obtained with estrogens, much higher concentrations were required. This may imply nonetheless that antihormones were capable of provoking efficient interactions of rtER with the transcriptional machinery.

Animals↗
PubMed2003

In vivo dynamic ME-MRI reveals differential functional responses of RA- and area X-projecting neurons in the HVC of canaries exposed to conspecific song.

HVC (nidopallial area, formerly known as hyperstriatum ventrale pars caudalis), a key centre for song control in oscines, responds in a selective manner to conspecific songs as indicated by electrophysiology. However, immediate-early gene induction cannot be detected in this nucleus following song stimulation. HVC contains neurons projecting either towards the nucleus robustus archistriatalis (RA; motor pathway) or area X (anterior forebrain pathway). Both RA- and area X-projecting cells show auditory responses. The present study analysed these responses separately in the two types of HVC projection neurons of canaries by a new in vivo approach using manganese as a calcium analogue which can be transported anterogradely and used as a paramagnetic contrast agent for magnetic resonance imaging (MRI). Manganese was stereotaxically injected into HVC and taken up by HVC neurons. The anterograde axonal transport of manganese from HVC to RA and area X was then followed by MRI during approximately 8 h and changes in signal intensity in these targets were fitted to sigmoid functions. Data comparing birds exposed or not to conspecific songs revealed that song stimulation specifically affected the activity of the two types of HVC projection neurons (increase in the sigmoid slope in RA and in its maximum signal intensity in area X). Dynamic manganese-enhanced MRI thus allows assessment of the functional state of specific neuronal populations in the song system of living canaries in a manner reminiscent of functional MRI (but with higher resolution) or of 2-deoxyglucose autoradiography (but in living subjects).

Acoustic Stimulation↗
PubMed2007

Differential function of Listeria monocytogenes listeriolysin O and phospholipases C in vacuolar dissolution following cell-to-cell spread.

We investigated the role of listeriolysin O (LLO) and the bacterial phospholipases PI-PLC and PC-PLC in cell-to-cell spread of Listeria monocytogenes. We showed that LLO is essential for cell-to-cell spread in primary murine macrophages. Electron micrographs revealed that in the absence of continued LLO expression, bacteria remain trapped in secondary spreading vacuoles having either a double or single membrane. In bacteria lacking PI-PLC and PC-PLC, cessation of LLO expression after initiation of infection resulted in a significant increase in the proportion of bacteria trapped in double-membrane compartments. We propose that the bacterial phospholipases are involved in the dissolution of the inner membrane of the spreading vacuole, yet are not sufficient for disruption of the outer membrane. As a consequence, we identified LLO as a key factor in the disruption of the outer membrane. This model is consistent with the observation that LLO is dispensable for cell-to-cell spread from human macrophages into a cell type in which LLO is not required for vacuolar escape. These data suggest that during human infection, spreading of L. monocytogenes to distant organs is likely to occur even in the absence of LLO expression, and that the bacterial phospholipases may be sufficient to mediate continued cell-to-cell spread.

Bacterial Toxins↗
PubMed1988

Subcellular localization of functionally differentiated microtubules in squid neurons: regional distribution of microtubule-associated proteins and beta-tubulin isotypes.

The subcellular localization of microtubule proteins in the neurons of squid (Doryteuthis bleekeri) was immunologically studied using monoclonal antibodies against the microtubule proteins. We found that (1) the squid neurons contained three kinds of high-molecular-weight microtubule-associated proteins [MAP A of approximately 300 kilodaltons (kD), MAP B of 260 kD, and axolinin of 260 kD] and two kinds of beta-tubulin isotypes (beta 1 and beta 2); (2) the cell body of the squid giant neuron contained MAP A, MAP B, and the two beta-tubulin isotypes (beta 1 and beta 2); (3) axolinin and the beta 1 isotype were present exclusively in the peripheral axoplasm of the giant axon; and (4) a small amount of axolinin, MAP A, and the beta 1 isotype was found in the insoluble aspect of the central axoplasm, whereas the soluble aspect of the central axoplasm contained an abundant amount of MAP A along with the modified form of the beta 1 isotype. The regional difference of the distribution of the microtubule protein components may explain the differences in stability among axonal microtubules. Microtubules in the soluble aspect of the central axoplasm are sensitive to any treatment with colchicine, cold temperature, and high ionic strength but those both in the insoluble aspect of the central axoplasm and in the peripheral axoplasm are highly insensitive to the treatment.

Animals↗
PubMed1989

Regulation of the differentiated functions of Leydig tumor cells by epidermal growth factor.

The three effects of mEGF on MA-10 Leydig tumor cells that have been discussed here are summarized in TABLE 7. The earliest effect of mEGF on MA-10 cells can be detected within 5 min of addition of mEGF and it lasts for about 60 min. During this time mEGF transiently attenuates hCG-stimulated adenylate cyclase activity. Although the magnitude of this effect is small, it can be correlated with a transient attenuation of the hCG-provoked increase in steroid synthesis. At longer times (i.e., 1-8 h) mEGF activates steroid synthesis by a "cAMP-independent pathway" and it potentiates (in a synergistic fashion) the activation of steroidogenesis by hCG, other compounds that activate adenylate cyclase activity, and cAMP analogues. At even longer times (i.e., 8-48 h) mEGF down-regulates the LH/CG receptors and by doing so, limits the steroidogenic response of the cells to hCG. From a biochemical point of view, our data provide an excellent example of those actions of growth factors that are unrelated to the control of cell multiplication, and of the complexity involved even when dealing with a single cell type and a single growth factor. Admittedly we know very little about the molecular basis of the phenomena described herein. Current work in our laboratory, however, is aimed at filling this gap. Among all the questions that we can address, we believe that it is particularly important to characterize the intracellular signaling system(s) activated by mEGF and to determine if a single signaling system is responsible for the diverse biological actions of mEGF in MA-10 cells. From a physiological point of view, our data may also prove important to the understanding of the regulation of testicular functions. There is increasing evidence for the production of EGF (or related peptides such as transforming growth factor alpha) in several tissues, including the testes and ovaries. These findings, together with the results summarized here suggest that EGF (or related peptides) act within the testes in a paracrine, or autocrine fashion and that they may have important modulatory effects on the activation of Leydig cell steroidogenesis by gonadotropins.

Adenylyl Cyclases↗
PubMed1986

Forskolin stimulates cAMP production and the onset of the functional differentiation in the fetal rat thyroid in vitro.

Forskolin, a diterpen stimulating the adenylcyclase induces in vitro an accumulation of cAMP in thyroid glands explanted from 17 day-old rat fetuses. Thyroid glands from 15 day-old fetuses exposed to forskolin exhibit, within 24 hr, an active folliculogenesis and 125I fixation in follicular cavities. The results indicate that cAMP probably activates the onset of both morphological and physiological maturation in the fetal rat thyroid.

Animals↗