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Biomedical subjects

P Ross

Publications and source records attributed to P Ross.

At least 109 records · Page 6Linked to original sources
PubMed1988

beta-Glucoside Activators of Mung Bean UDP-Glucose: beta-Glucan Synthase : II. Comparison of Effects of an Endogenous beta-Linked Glucolipid with Synthetic n-Alkyl beta-d-Monoglucopyranosides.

n-Alkyl (C(6)-C(12)) beta-d-monoglucopyranosides have been found to be highly potent activators of mung bean beta-glucan synthase in vitro, increasing the V(max) of the enzyme as much as 60-fold and with K(a) values as low as 10 micromolar. Activation is highly specific for the beta-linked terminal glucose residue; other alkyl glycosides such as, octyl-alpha-glucoside, dodecyl beta-maltoside, 6-lauryl sucrose, 6-lauryl glucose, which lack this structure, are ineffective as activators. Based on the similarities in their structure and effects on beta-glucan synthesis under a variety of conditions, it is proposed that the alkyl beta-glucosides are structural analogs of the native glucolipid activator of beta-glucan synthase isolated from mung bean extracts.

Journal Article↗
PubMed1988

Identification of differentiation-specific antigens in psoriatic versus normal skin using monoclonal antibodies.

Human cell hybrids derived from fusions between carcinoma (HeLa) and normal epidermal keratinocytes can be used as immunogens to generate monoclonal antibodies against keratinocyte differentiation-specific antigens. We examined the immunofluorescent staining patterns of these monoclonals in normal human and psoriatic (lesional and uninvolved) skin tissue sections. The immunofluorescent staining patterns indicate that the monoclonal antibodies are recognizing a number of different keratinocyte antigens. Three monoclonals (HLK7, HLK3, and HLK20) displayed different immunofluorescent reactivity in these tissues. These new monoclonal antibodies will be useful tools to study the differentiation abnormalities in psoriasis and may serve as a marker of the psoriatic diathesis.

Antibodies, Monoclonal↗
PubMed1987

T cell antigen receptor phosphorylation induced by an anti-receptor antibody.

In previous studies we demonstrated that the antigen receptor complex on murine T cells is phosphorylated after antigen or mitogen activation. After the clonotypic structures bind antigen, the invariant subunits or CD3 molecules are the target of dual kinase activation. The antigen receptor CD3-gamma-chain subunit is phosphorylated on serine residues by activated protein kinase C and the p21 subunit is phosphorylated by a tyrosine kinase. Herein we demonstrate that another mechanism of receptor activation by the stimulatory monoclonal antibody 145-2C11, which binds the CD3-epsilon chain, results in a similar pattern of kinase activation and receptor phosphorylation.

Animals↗
PubMed1987

T cell receptor tyrosine phosphorylation. Variable coupling for different activating ligands.

We have previously reported (Samelson, L.E., Patel, M.D., Weissman, A.M., Harford, J.B., and Klausner, R.D. (1986) Cell 46, 1083-1090) that T cell activation by antigen is associated with activation of two biochemical pathways. In this scheme two protein kinases are activated by stimulation of the T cell antigen receptor (TCR). These kinases phosphorylate two different chains of the TCR complex. Protein kinase C is responsible for the phosphorylation of the gamma, and, to a lesser extent, the epsilon chains of the receptor on serine residues while the activation of an unidentified tyrosine kinase leads to phosphorylation of the p21 subunit of the receptor on tyrosine residues. In addition to activation by specific antigens, T cells can be functionally activated in vitro by the addition of antibodies that bind either the antigen receptor or the Thy-1 molecule, an entity independent of the receptor. We have used antibodies directed against these molecules and show that they result in the same dual kinase activation observed with antigen stimulation. In addition we have compared the three ligands, antigen, and antibodies directed against the epsilon chain of the TCR or against Thy-1, in terms of how they couple to the two kinase pathways. Activation of phosphatidylinositol breakdown and TCR phosphorylation on serine by all three stimuli are sensitive to cAMP inhibition. In contrast, only antigen-stimulated tyrosine kinase activation is sensitive to cAMP while the two antibody reagents activate the tyrosine kinase in a manner that is entirely insensitive to cAMP inhibition.

Animals↗
PubMed1986

Acoustic emission as a measure of exposure of suspended cells in vitro.

Cell viability, survival, and growth of C1300 mouse neuroblastoma cells were assayed by trypan blue dye exclusion, clonogenesis, and culturing, respectively, after exposure in suspension to therapeutic levels of ultrasound (1 MHz; continuous wave; spatial peak intensity 0.9, 1.7, and 2.6 W/cm2; 5 min at 37 degrees C). Acoustic emission from the cavitating cell suspensions was recorded as the rms value of the half-harmonic and noise components combined. Cell viability and survival appeared better correlated with acoustic emission than with spatial peak intensity, implying that acoustic emission may provide a more direct measure of insult to the cells in a cavitating field than the incident intensity. Biological assay results of growth were well correlated with spatial peak intensity but not with acoustic emission levels, which seems to imply that for this end point incident intensity is a more directly interacting parameter than cavitational activity, provided however that the latter is present. Further refinement of the technique for measuring acoustic emission from cell suspensions should permit separate measurements of the half-harmonic and noise components. When thus refined, it may provide the means to demonstrate cavitational action without resorting to additional experiments to suppress cavitation.

Acoustics↗
PubMed1986

Immunopathology of cutaneous human lupus erythematosus defined by murine monoclonal antibodies.

Skin biopsy specimens obtained from involved skin from sixteen patients with systemic and discoid lupus erythematosus were studied. Murine monoclonal antibodies with a biotin-avidin-horseradish peroxidase staining system were used. The findings consisted of a marked reduction in the number of epidermal Langerhans cells defined by surface antigens, reduced HLA-DR (Ia-like) antigens on the surface of dermal capillary endothelium, and mononuclear cell infiltrates characterized by a predominance of helper T lymphocytes and an increase in the number of mononuclear phagocytic cells. B lymphocytes were rarely identified. The number of T lymphocytes within the dermis correlated inversely with both the number of HLA-DR-positive epidermal Langerhans cells (p less than 0.01) and the HLA-DR staining of dermal capillary endothelium (p less than 0.01). These findings suggest that a T lymphocyte-mediated immune response associated with a reduction in Langerhans cells and capillary endothelium HLA-DR antigens is involved in the inflammatory process of lupus erythematosus skin.

Adult↗
PubMed1986

A novel approach for obtaining and identifying monoclonal antibodies that react with differentiation-specific antigens using human hybrid cells.

HeLa X keratinocyte hybrid cells have been used as immunogens to generate monoclonal antibodies against differentiation-specific antigens. A key feature of the experimental system is that the hybrid cells are undifferentiated in culture and yet terminally differentiate in the mouse. The properties of these cells allow one a facile approach to obtaining and characterizing monoclonal antibodies against differentiation-specific antigens. Use of hybrid cells derived from HeLa X differentiated cell fusions as immunogens should prove to be a general method for identifying differentiation-specific antigens from a variety of differentiated cell types.

Animals↗
PubMed1984

Binding of the estradiol-receptor complex to reconstituted nucleoacidic protein from calf uterus.

Non-histone protein-DNA complexes with acceptor activity for estradiol-receptor complexes were reconstituted from fractionated calf uterine chromatin. Acceptor activity had tissue specificity with target tissue binding exceeding non-target tissue binding. The binding of estradiol-receptor complexes to acceptor sites was dependent on intact non-histone protein-DNA complexes, reconstituted select non-histone proteins, and protein equivalent: DNA reconstitution ratios. [3H]Estradiol-receptor complexes were bound to reconstituted non-histone protein-DNA complexes (i.e., nucleoacidic protein) with a high affinity and with a limited number of binding sites. Fractionation of uterine chromatin non-histone proteins identified two major sets of non-histone proteins which had acceptor activity when reconstituted with DNA. Thus, it seems possible to reconstitute nucleoacidic protein fractions with specific acceptor activity for the calf uterine estrogen receptor.

Animals↗
PubMed1984

Computed tomography appearance of Golden's "S" sign.

The computed tomography version of Golden's "S" sign is strongly suggestive of a centrally obstructing carcinoma. Although more easily seen in the right lung, the "S" sign can be detected in any lobe on computed tomography. The computed tomography appearance of Golden's "S" sign is described and illustrated.

Aged↗
PubMed1984

Control of the humoral immune system within the rabbit oviduct.

Within the oviduct the maternal humoral immune system can react with the sperm on their way to fertilize the ovum and with preimplantation embryos which express paternal surface antigens. The embryo or sperm is destroyed by antibodies plus complement; thus control of the humoral immune system in the oviduct is advantageous. This paper confirms the absence of whole complement in the oviduct as determined by both in vivo and in vitro hemolytic assays. Further, it is established that there exists within oviductal fluid a concentration-dependent inhibition of complement activity. This inhibitor is heat labile and nondialyzable. Utilizing purification by Sephadex G-200 and ion-exchange chromatography, the complement inhibition was attributed to a family of sulfated glycoproteins secreted by the oviductal epithelium.

Animals↗
PubMed1984

Cell proliferation in normal epidermis.

A detailed examination of cell proliferation kinetics in normal human epidermis is presented. Using tritiated thymidine with autoradiographic techniques, proliferative and differentiated cell kinetics are defined and interrelated. The proliferative compartment of normal epidermis has a cell cycle duration (Tc) of 311 h derived from 3 components: the germinative labeling index (LI), the duration of DNA synthesis (ts), and the growth fraction (GF). The germinative LI is 2.7% +/- 1.2 and ts is 14 h, the latter obtained from a composite fraction of labeled mitoses curve obtained from 11 normal subjects. The GF obtained from the literature and from human skin xenografts to nude mice is estimated to be 60%. Normal-appearing epidermis from patients with psoriasis appears to have a higher proliferation rate. The mean LI is 4.2% +/- 0.9, approximately 50% greater than in normal epidermis. Absolute cell kinetic values for this tissue, however, cannot yet be calculated for lack of other information on ts and GF. A kinetic model for epidermal cell renewal in normal epidermis is described that interrelates the rate of birth/entry, transit, and/or loss of keratinocytes in the 3 epidermal compartments: proliferative, viable differentiated (stratum malpighii ), and stratum corneum. Expected kinetic homeostasis in the epidermis is confirmed by the very similar "turnover" rates in each of the compartments that are, respectively, 1246, 1417, and 1490 cells/day/mm2 surface area. The mean epidermal turnover time of the entire tissue is 39 days. The Tc of 311 h in normal cells in 8-fold longer than the psoriatic Tc of 36 h and is necessary for understanding the hyperproliferative pathophysiologic process in psoriasis.

Adult↗
PubMed1984

Oblique hilar tomography and mediastinoscopy. A correlative prospective study in 100 patients with bronchogenic carcinoma.

One hundred patients with bronchogenic carcinoma had oblique hilar tomography preoperatively to evaluate the pulmonary hila. Subsequently, all of these patients underwent mediastinoscopy or thoracotomy or both. Hilar and mediastinal nodes were evaluated for the presence of metastasis. These findings were then correlated with the radiographic findings of oblique hilar tomography. We found oblique hilar tomography to be a useful method of selecting patients for mediastinoscopy. The negative predictive value of oblique hilar tomography for mediastinal involvement was 95 percent, while the positive predictive value was 75 percent. Thus, patients with negative findings on oblique hilar tomography need not undergo mediastinoscopic examination prior to thoracotomy.

Adult↗
PubMed1984

Treatment of femoral fractures with the cast brace.

The authors report a retrospective review of 82 patients with femoral fractures treated nonoperatively by skeletal traction and cast bracing at the University of Alberta Hospital between 1975 and 1979. Fractures were classified as stable or unstable and the position of the fracture was assessed at the time of application of the cast brace and at the time of removal, using angulation, shortening and healing time as criteria for classification of results. Satisfactory results were seen in 88% of patients. At the time of cast brace removal, average knee flexion was 97 degrees, thigh atrophy was 2.5 cm and shortening was 1.4 cm. The unsatisfactory results are analysed and a protocol for successful use of the cast brace is suggested.

Adolescent↗