Constancy of exponents of scaling laws describing the droplet-size distribution in vapor-deposited thin films.
Explore the source record for details and available documents.
Journal Article↗
Biomedical subjects
W Li
Publications and source records attributed to W Li.
Mislocalizations of visual elevation and visual vertical induced by visual pitch: the great circle model.
The elevation visually perceived as eye level (VPEL) changes linearly with the pitch of an illuminated visual field. The magnitude of influence is only slightly less when the visual field contains only two dim vertical lines in darkness than when it is complexly structured and normally illuminated. Pitching a visual field consisting of only a single line in darkness produces an influence that is only slightly smaller than the 2-line stimulus. The slopes of the VPEL-vs.-pitch functions for the complex room, 2-line stimulus, and 1-line stimulus are +0.63, +0.56, and +0.52 respectively. Although VPEL is systematically influenced by the pitch of the 2-line stimulus, the orientation of a small line within a frontal plane that is visually perceived as vertical is unaffected. However, when the two lines are pitched by equal amounts in opposite directions, the offset of VPV from true vertical changes linearly with pitch magnitude but VPEL is unaffected. These results are identical to those obtained when the two vertical lines are rolled within the frontal plane, a result that depends on some identities between roll and pitch: roll of two parallel lines in the same direction influences VPV but not VPEL; roll of the two lines in opposite directions influences VPEL but not VPV. The interaction between stimulus conditions and discriminations demonstrates that separate mechanisms are in control of VPEL and of VPV. The slope of the VPEL-vs.-pitch function increases exponentially with line length for the 1-line stimulus (space constant = 15.1 degrees). Summation of influences on VPEL for two lines horizontally separated by 50.3 degrees is as great as for two coextensive lines. The above results are predicted from the Great Circle Model which assumes (1) central projection on a spherical approximation to an erect stationary eye; (2) the sign and magnitude of influence of each line on VPEL and on VPV are determined by the direction and magnitude of the separation between the upper pole of the spherical eye and the intersection of the great circle containing the line's image with the central vertical retinal meridian and with the midfrontal retinal meridian, respectively; (3) the influence of individual nonparallel lines is determined by a weighted average of the influences of individual sets of parallel lines; (4) a generalized version of the Great Circle Model is indicated in which extraretinal signals from head and eye are taken into account.
Curare↗
Visual direction is corrected by a hybrid extraretinal eye position signal.
Explore the source record for details and available documents.
Humans↗
Cysteamine selectively enhances neuropeptide Y2 receptor binding activity.
Affinity labeling of [125I]NPY to the bovine hippocampal NPY receptor has revealed a 50 kDa specific binding protein, the Y2 receptor. Cysteamine (10 microM - 10 mM) specifically enhanced NPY specific labeling of the Y2 receptor without affecting cross-linking efficiency. Several structurally related agents, including reduced glutathione, cysteine, beta-mercaptoethanol and ethanolamine, were without effect on receptor binding. The enhancement of binding by cysteamine could be reversed by washing the membranes. These studies suggest that cysteamine may change the conformation of the NPY Y2 receptor and increase its binding activity.
Animals↗
Two distinct genes encode two major isoelectric forms of insecticyanin in the tobacco hornworm, Manduca sexta.
Insecticyanin is a blue pigment found in the epidermis and hemolymph of the tobacco hornworm, Manduca sexta. Two distinct full-length cDNA species were isolated and shown to encode the two major isoelectric forms of insecticyanin, the a form (INS-a) and b form (INS-b). Sequence analysis of the two cDNA clones, pE1-I1 and Pe3-I2, reveals that both contain an 618-bp open reading frame which predicts an 189-amino-acid protein and an 17-amino-acid signal peptide. Comparison of the deduced INS-a and INS-b proteins show 13 amino acid differences, of which six are conserved. Three amino acid substitutions are also found between the deduced INS-b sequence and the sequenced INS-b protein isolated from the hemolymph. Isolation and characterization of five genomic clones revealed that pE1-I1 and pE3-I2 come from two different genes. Both INS-a and INS-b genes have four exons interrupted by three introns at the same positions. The two genes share 93% nucleotide similarity in the coding region. Moreover, the 'TATA box' and 'CAAT box' are completely conserved in the putative promoter regions of the two genes. Primer extension revealed that both INS-a and INS-b genes begin their transcription at position -52 relative to their translation initiation codon, ATG. We conclude that the two genes are the result of gene duplication.
Amino Acid Sequence↗
Role of sulfhydryl groups in Y2 neuropeptide Y receptor binding activity.
Benextramine, a tetramine disulfide, irreversibly inhibits neuropeptide Y (NPY) binding to the 50-kDa Y2 NPY receptor in bovine hippocampus (Li, W., MacDonald, R. G., and Hexum, T. D. (1991) Eur. J. Pharmacol. 207, 89-91). Evidence is presented that this inhibition occurs through a thiol-disulfide exchange. Treatment of bovine hippocampal membranes with benextramine inhibited NPY affinity cross-linking to the 50-kDa receptor. This inhibition of labeling was not affected by washing the membranes, but could be completely reversed by the addition of several thiol reducing reagents, including reduced glutathione, beta-mercaptoethanol, and cysteine. Benextramine inhibited 70% of NPY-specific labeling and was much more effective than other sulfhydryl reactive agents, such as oxidized glutathione, cystamine, and 5,5'-dithio-bis(2-nitrobenzoic acid). Furthermore, the sulfhydryl-modifying agents N-ethylmaleimide and p-chloromercuriphenyl-sulfonic acid specifically decreased NPY affinity labeling. Finally, NPY labeling of the 50-kDa receptor was reduced by the heavy metal ions Zn2+, Cu2+, and Hg2+. Preincubation with NPY prevented Y2 receptors from being inactivated by either 400 microM N-ethylmaleimide or 1 mM benextramine. These results suggest that one or more benextramine-sensitive sulfhydryl groups on the Y2 receptor are important for NPY binding activity.
Adrenergic alpha-Antagonists↗
Tyrosine phosphorylation of vav proto-oncogene product containing SH2 domain and transcription factor motifs.
Activation of receptor-linked and cytoplasmic protein tyrosine kinases is crucial in the control of normal and abnormal cell growth and differentiation. Some substrates of protein tyrosine kinases such as phospholipase C gamma and ras GTPase-activating protein (GAP) contain sequences homologous to the src protein domains SH2 and SH3 (refs 3-9). The proto-oncogene vav is expressed in haematopoietic cells and its product Vav contains sequence motifs commonly found in transcription factors, such as helix-loop-helix, leucine-zipper and zinc-finger motifs and nuclear localization signals, as well as a single SH2 and two SH3 domains. Here we show that stimulation of T-cell antigen receptor on normal human peripheral blood lymphocytes or on human leukaemic T cells, and the crosslinking of IgE receptors on rat basophilic leukaemia cells, both promote the phosphorylation of tyrosine residues in Vav. Moreover, activation of the receptor for epidermal growth factor leads to marked tyrosine phosphorylation of Vav in cells transiently expressing vav, and Vav associates with the receptor through its SH2 domain. We propose that vav encodes a new class of substrates whose tyrosine phosphorylation may provide a mechanism for direct signal transduction linking receptors at the cell surface to transcriptional control.
3T3 Cells↗
Three-dimensional structure of the ordered phases of Hg on Cu(001).
Explore the source record for details and available documents.
Journal Article↗
Cyclosporin A and FK506 mediate differential effects on T cell activation in vivo.
Modified limiting dilution analysis techniques were used to evaluate the effects of the immunosuppressants cyclosporin A (CsA) and FK506 on alloantigen-induced T cell activation in vivo. Treatment of sponge matrix allograft recipients with either CsA or FK506 inhibited lymphocytic infiltration of the allograft, a process thought to be dependent on local lymphokine production. In addition, both immunosuppressants markedly reduced the absolute number of lymphocytes recovered from the draining lymph nodes (LN) and prevented CTL activation in the LN. However, Ag-primed helper T lymphocytes (HTL) were present in the draining LN of sponge allograft recipients treated with CsA, but not in recipients treated with FK506. T cell depletion experiments were performed to determine the phenotype of primed HTL in the LN of untreated and CsA-treated sponge allograft recipients. In untreated sponge allograft recipients, CD4+ and CD8+ Ag-primed HTL were present in the draining LN in equivalent numbers. In contrast, the majority of primed HTL in the LN of CsA-treated sponge allograft recipients were CD8+, rather than CD4+ T cells. These observations indicate that CsA and FK506 exert distinct in vivo effects at the level of HTL priming, and CD4+ and CD8+ HTL exhibit differential sensitivity to CsA in vivo.
Animals↗
Human prostate cancer model: roles of growth factors and extracellular matrices.
A human prostate cancer model was established by inoculating a prostate specific antigen (PSA)-producing LNCaP cell line with either prostate or bone fibroblasts. Alternatively, this human prostate cancer model can also be established by inoculating LNCaP cells with growth factor(s) (GFs) and extracellular matrix (ECM) immobilized on Gelfoam. The resulting LNCaP tumors were used to evaluate PSA production and excretion in athymic hosts. This model was also employed to examine the biochemical nature of mesenchymal cell-derived growth-promoting protein(s) and to assess the efficacy of potential chemotherapeutic agents. Because of the propensity of human prostate cancer to metastasize to the bone, this study defined a 1.0 M NaCl-eluted fraction, MS1, from the conditioned medium of a bone stromal cell line (MS) by heparin-affinity column chromatography. The growth-promoting activity was assayed both in vivo (e.g., tumor formation) and in vitro (e.g., soft agar colony formation). We found that the growth-promoting activity was trypsin- and heat-sensitive, and partially degraded by acid and dithiothreitol. Immunochemical studies indicated that the polyclonal antibody raised against MS1 blocked the growth-promoting effect elicited by the bone-conditioned media. This growth-promoting factor was found to be immunochemically dissimilar to KGF, HGF, and bFGF. However, addition of bFGF, HGF and NGF, but not aFGF, TGF beta, IGF1, IGF2, PDGF, EGF, TGF alpha and KGF, stimulated anchorage-independent growth of prostate cells, a condition closely parallel to tumor formation in vivo. We found that the MS1 fraction also contained fibronectin and tenascin but not laminin or collagen IV.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
cDNA clone to chick corneal chondroitin/dermatan sulfate proteoglycan reveals identity to decorin.
A 1.6-kb cDNA clone was isolated by screening a library prepared from chick corneal mRNA with a cDNA clone to bovine decorin. The cDNA contained an open reading frame coding for a M(r) 39,683 protein. A 19-amino-acid match with sequence from the N-terminus of core protein from the corneal chondroitin/dermatan sulfate proteoglycan confirmed the clone as a corneal proteoglycan and the homology with human and bovine decorin confirmed its identity as decorin. Structural features of the deduced sequence include a 16-amino-acid signal peptide, a 14-amino-acid propeptide, cysteine residues at the N- and C-terminal regions, and a central leucine-rich region (comprising 63% of the protein) containing nine repeats of the sequence LXXLXLXXNXL/I. Chick decorin contains three variations of this sequence that are tandemly linked to form a unit and three units tandemly linked to form the leucine-rich region. The presence of beta bend amino acids flanking the units may serve to delineate the units as structural elements of the leucine-rich region. Sequence homology within the repeats and the spacing of the repeats suggest that this region arose by duplication. Chick decorin primarily differs from mammalian decorins in the 19-amino-acid sequence that starts the N-terminus of the core protein. Within this region, the serine that serves as a potential acceptor for the chondroitin/dermatan sulfate side chain is preceded by a glycine instead of being followed by a glycine as it is in the mammalian decorins and all other mammalian proteoglycans.
Amino Acid Sequence↗
Neuropeptide Y receptor in bovine hippocampus is a Y2 receptor.
[125I]NPY bound to a single class of saturable binding sites on bovine hippocampus membranes with a KD of 0.1 mM and Bmax of 165 fmol/mg of protein. The rank order of potency of NPY fragments and other structurally related peptides to inhibit [125I]NPY binding was: PYY greater than or equal to NPY much greater than BPP greater than or equal to APP and NPY greater than NPY-(13-36) greater than NPY-(18-36) greater than or equal to NPY-(20-36) much greater than NPY-(26-36) greater than NPY-(free acid). The identity of the NPY binding site was investigated by affinity labeling. Gel electrophoresis followed by autoradiography revealed a band with a mol mass of 50 kDa. Unlabeled NPY or PYY, but not BPP, HPP and APP, inhibited labeling of [125I]NPY to the 50 kDa protein band. Moreover, labeling was inhibited by NPY greater than NPY-(18-36) greater than or equal to NPY-(13-36) greater than or equal to NPY-(20-36) greater than NPY-(26-36) greater than NPY-(free acid). The binding of [125I]NPY and the intensity of the cross-linked band were reduced in parallel by increasing concentrations of unlabeled NPY (IC50 = 0.7 nM and 0.6 mM, respectively). These studies demonstrate that bovine hippocampal membranes contain a 50 kDa [125I]NPY binding site that has the ligand specificity characteristic of the Y2 receptor subtype.
Affinity Labels↗
Effects of sodium arsenite on the cytoskeleton and cellular glutathione levels in cultured cells.
The effects of As3+ (NaAsO2) on the microtubule and microfilament organization, cytoskeletal protein synthesis, cytoskeletal and cytosolic (soluble) protein sulfhydryls, and cellular glutathione (GSH) levels were examined in Swiss 3T3 mouse cells. Exposure of cells to 2.5 microM As3+ for 16 hr resulted in apparent cell retraction and loss of thick cables of actin filaments. However, the cells still retained numerous thinner microfilaments distributed in a disorganized manner. Microtubule organization was relatively undisturbed. At higher doses (greater than or equal to 20 microM), As3+ treatment caused a severe loss of microtubules and the remaining dense finer actin filaments formed smearing clusters in perinuclear areas. Treatment of cells with As3+ also induced a dose-dependent inhibition of cytoskeletal protein synthesis. Furthermore, As3+ exposure enhanced cellular GSH synthesis since the elevated cellular GSH content in As(3+)-treated cells could be abolished by treatment with buthionine sulfoximine, an inhibitor of gamma-glutamylcysteine synthetase required for GSH biosynthesis. As determined by the N-[3H]-ethylmaleimide binding assay, As3+ exposure also increased the amount of protein sulfhydryls in both the cytoskeletal and the cytosolic protein fractions. Moreover, a greater increase in protein sulfhydryls occurred in the cytoskeletal fraction than in the soluble fraction. These results indicate that the cytoskeleton could be a cellular target for injury by As3+ exposure. The elevated cellular GSH content induced by As3+ could provide a protective mechanism against further injury from this metal insult.
Actin Cytoskeleton↗
Bovine major histocompatibility complex class I specific monoclonal antibodies characterized by flow cytometry, one- and two-dimensional electrophoresis, western blot and inhibition of cytotoxic T lymphocyte function.
To identify and characterize the bovine major histocompatibility complex (MHC) class I molecules, a panel of 11 monoclonal antibodies (mAbs) were analyzed. The mAbs reacted with bovine MHC class I antigens, as assessed by flow cytometry and immunoprecipitation followed by one- and two-dimensional gel electrophoresis. Analysis by flow cytometry revealed that class I molecules were expressed less on a class I mutant B-lymphoblastoid cell line than on the parent cell line. The relative molecular weights of the proteins identified by these mAbs were similar to those reported previously for cattle and humans. Nonequilibrium pH gradient two-dimensional gel electrophoresis showed that RH16C recognized four different class I gene products, indicating this mAb reacts with a conserved epitope present on different class I molecules. These mAbs effectively blocked cytotoxic T lymphocyte killing of allogeneic lymphoblasts, suggesting the functional importance of beta-2m in this process. These mAbs should be useful reagents for studying bovine MHC class I molecules.
Animals↗
Inhibition of the growth of human melanoma metastases in nude mice by melanoma-specific murine monoclonal antibody.
The administration of anti-melanoma murine monoclonal antibody (MAB) 16.C8 (IgG2a) to nude mice bearing established human melanoma lung or liver metastases resulted in a significant inhibition of tumour growth. A total dose of 2 mg of affinity purified 16.C8 caused complete inhibition of tumour growth in 89 and 100% of animals in the liver and lung model, respectively. In contrast, a significant tumour growth was found in most control animals which received an irrelevant IgG2a MAB or 2% human serum albumin in Hanks Balanced Salt Solution (HBSS). The MAB was most effective when treatment was started on day 1 or 4 following tumour inoculation. When the 16.C8 MAB treatment was delayed 7 or 14 days, 33 and 67% of 16.C8 treated animals, respectively, developed tumours. The MAB-mediated anti-tumour activity appeared to be dose dependent, and the effect of a suboptimal dose was potentiated by the concomitant administration of recombinant interleukin 2 (rIL-2). Recombinant IL-2 alone in a similar dose did not elicit comparable anti-tumour activity. Moreover, the MAB 16.C8 inhibited tumour growth in irradiated animals which may suggest the involvement of host-radioresistant cellular elements in the 16.C8 antibody-mediated anti-tumour activities in nude mice. These results suggest that MAB 16.C8 alone or combined with rIL-2 may prove useful in the immunotherapy of metastatic melanoma.
Animals↗
Analysis of the Caenorhabditis elegans axonal guidance and outgrowth gene unc-33.
Mutations in the unc-33 gene of the nematode Caenorhabditis elegans lead to severely uncoordinated movement, abnormalities in the guidance and outgrowth of the axons of many neurons, and a superabundance of microtubules in neuronal processes. We have cloned unc-33 by tagging the gene with the transposable element Tc4. Three unc-33 messages, which are transcribed from a genomic region of at least 10 kb, were identified and characterized. The three messages have common 3' ends and identical reading frames. The largest (3.8-kb) message consists of the 22-nucleotide trans-spliced leader SL1 and 10 exons (I-X); the intermediate-size (3.3-kb) message begins with SL1 spliced to the 5' end of exon V and includes exons V-X; and the smallest (2.8-kb) message begins within exon VII and also includes exons VIII-X. A gamma-ray-induced deletion mutation situated within exon VIII reduces the sizes of all three messages by 0.5 kb. The three putative polypeptides encoded by the three messages overlap in C-terminal sequence but differ by the positions at which their N termini begin; none has significant similarity to any other known protein. A Tc4 insertion in exon VII leads to alterations in splicing that result in three approximately wild-type-size messages: the Tc4 sequence and 28 additional nucleotides are spliced out of the two larger messages; the Tc4 sequence is trans-spliced off the smallest message such that SL1 is added 13 nucleotides upstream of the normal 5' end of the smallest message.
Amino Acid Sequence↗
Immunocytochemical localization and messenger ribonucleic acid levels of a progesterone-dependent endometrial secretory protein (cathepsin L) in the pregnant cat uterus.
The purpose of this study was to localize immunocytochemically a progesterone-dependent protein (PDP) and to determine PDP mRNA levels during the initial stage of the implantation period. Uterine tissue was collected from Day 0-18 postcoital animals. The tissue was processed for immunocytochemical localization of PDP, and the endometrial RNA was isolated and analyzed for PDP gene expression by slot-blot hybridization. PDP was detected immunocytochemically as early as Day 5 postcoitus in the epithelial cells of the deep uterine glands, and the intensity of immunostaining appeared to peak by Day 12 postcoitus. PDP was absent in the endometrium obtained from implantation sites after Day 16 postcoitus, but the synthesis of PDP was maintained in the endometrium obtained from nonimplantation sites. Immunogold electron microscopy demonstrated that PDP was present in electron-dense granules of the glandular epithelial cells. PDP mRNA was detectable in the endometrium at Day 5 postcoitus and peaked around Day 10 postcoitus. PDP mRNA was absent in the endometrium from implantation sites after Day 16 postcoitus, but was maintained in the endometrium from nonimplantation sites. In summary, the results of this study illustrate that PDP is synthesized within the epithelial cells of the deep uterine glands, packaged within membrane-bound secretory granules, and released into the uterine lumen. Also, the process of implantation alters the gene expression in a very localized way since PDP mRNA and PDP-positive granules were absent in the endometrial glands obtained from the implantation site within 1-2 days of the onset of implantation, whereas both PDP mRNA and PDP-positive granules were maintained in the endometrial glands from nonimplantation-site regions.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Immunocytochemical analysis of estrogen and progestin receptors in uteri of steroid-treated and pregnant cats.
The purpose of this study was to determine the distribution of estrogen receptors (ER) and progestin receptors (PR) in specific uterine cell populations during various steroid hormone treatment regimens, and to determine if ER and PR distribution in the uterus is altered during implantation and the establishment of pregnancy in the cat. The tissues were processed for indirect immunocytochemical localization of receptors using specific monoclonal antibodies against ER and PR. ER were present in the nuclei of all epithelial cells and stromal fibroblasts in endometrium obtained from ovariectomized animals, whereas PR were only detectable in the nuclei of stromal fibroblasts. There was an apparent increase in the staining intensity and number of nuclei that stained positively for both ER and PR in all cell populations after 14 days of estradiol treatment. The administration of progesterone for 14 and 21 days, in the presence or absence of continuous estradiol, reduced the apparent intensity of staining and the number of nuclei staining positively for both ER and PR. ER were undetectable in the luminal epithelium, but remained in the glandular epithelial cells and stromal fibroblasts, whereas PR were only detectable in stromal fibroblasts. ER and PR localization in the endometrium obtained from estrus animals was similar to that observed in the estradiol-treated animals. A general decrease in intensity of staining for both ER and PR was evident by Day 5 postcoitus in pregnant animals. This decrease in intensity of staining continued until Day 12 postcoitus, when the distributions of ER and PR were similar to those observed in the ovariectomized estradiol-primed, progesterone-treated animals.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗