Proteases have been used as a tool to investigate the role of surface molecules in fibronectin-mediated cell adhesion. Proteolytic digestion of membrane-proteins by pronase (1 mg/ml for 20 rain at 37°C) completely inhibited adhesion of baby hamster kidney (BHK) fibroblasts on fibronectin-coated plastic dishes. Various degrees of inhibition were also obtained after treatment with proteinase K, chymotrypsin, papain, subtilopeptidase A, and thermolysin.Protein synthesis was required to restore the adhesive properties of pronase-treated cells, showing the protein nature of the molecules involved in adhesion to fibronectin.A peculiar feature of these proteins was their resistance to cleavage by trypsin. After prolonged trypsin treatment (1 mg/ml for 20 min at 37°C), cells adhered and spread on fibronectin-coated dishes, even when protein synthesis was inhibited by 4/~M cycloheximide. Under these conditions only three glycoproteins (gp) of molecular weight 130,000, 120,000, and 80,000 were left on the cell surface. These were precipitated by a rabbit antiserum against BHK cells that also inhibited adhesion of trypsin-treated cells, gp120 and gp80 were left at the cell surface after mild pronase digestion (0.2 mg/ml for 20 min at 37°C), under conditions not affecting adhesion. These data suggest that these glycoproteins may be involved in fibronectinmediated cell adhesion in some as yet unknown way.Adhesion of fibroblasts to a growth substratum is mediated by fibronectin, a high molecular weight glycoprotein of the pericellular matrix (1-3). Fibronectin is organized in domains with distinct biological properties (4-6). A restricted region near the N-terminal end of the molecule contains a binding site for collagen (7,8); on the C-terminal side, two regions with binding properties for glycosaminoglycans and the cell surface, respectively (9, 10), have been identified.Interaction of fibronectin with the cell membrane can be studied by measuring the adhesion of fibroblasts to fibronectincoated substrata (11). This system has already been employed in an attempt to elucidate the nature of the cell surface molecules involved. It has been reported that ricin-resistant baby hamster kidney (BHK) cell variants adhere poorly to fibronectin-coated dishes, suggesting that cell surface acceptors for ricin agglutinin are involved in the interaction with fibronectin (12). By means of reversible cross-linking experiments, a glycoprorein with a molecular weight of 47,000 was found to be in

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A significant portion of our study population had low regard for patients with substance use. Future research is needed to determine significant contributing factors and develop interventions to mitigate negative attitudes among ED physicians toward patients with substance use disorder.

This randomized, open-labeled, multicenter study was designed to assess safety and pharmacokinetics of dronabinol (Marinol) tablets and megestrol acetate (Megace) micronized tablets, alone and in combination, for treatment of HIV wasting syndrome. Weight and quality of life data were also collected. Fifty-two patients (mean CD4+ count, 59 cells/microliter) were randomized to one of four treatment arms: dronabinol 2.5 mg twice/day (D); megestrol acetate 750 mg/day (M750); megestrol acetate 750 mg/day+dronabinol 2.5 mg twice/day (M750+D); or megestrol acetate 250 mg/day+dronabinol 2.5 mg twice/day (M250+D). After therapy initiation, 47 patients returned for at least one visit, and 39 completed the planned 12 weeks of study visits. Occurrence of adverse events, drug discontinuation, new AIDS-defining conditions, or CD4+ T lymphocyte changes were not statistically significantly different among arms. Serious adverse events assessed as related to dronabinol included CNS events (e.g., confusion, anxiety, emotional lability, euphoria, hallucinations) and those assessed as related to megestrol acetate included dyspnea, liver enzyme changes, and hyperglycemia. The mean weight change +/- SE over 12 weeks was as follows: D, -2.0 +/- 1.3 kg; M750, +6.5 +/- 1.1 kg; M750+D, +6.0 +/- 1.0 kg; and M250+D, -0.3 +/- 1.0 kg (difference among treatment arms, p = 0.0001). Pharmacokinetic parameters measured after 2 weeks of therapy for M750 were Cmax = 985 ng/ml and AUC = 22,487 ng x hr/ml, and for dronabinol and its active metabolite (HO-THC), respectively, were Cmax = 2.01; 4.61 ng/ml and AUC = 5.3; 23.7 ng x hr/ml. For megestrol acetate, but not dronabinol, there was a positive correlation at week 2 between both Cmax and AUC with each of the following: (1) weight change, (2) breakfast visual analog scale for hunger (VASH) score, and (3) dinner VASH score.

The Triton X-100-insoluble skeleton of baby hamster kidney BHK cells consists of the nucleus, intermediate-size filaments, and actin fibers. By transmission electron microscopy, membrane fragments were found to be associated with these insoluble structures. When radioiodinated or [3H]glucosamine-labeled cells were extracted with 0.5% Triton, most plasma membrane glycoproteins were solubilized except for a glycoprotein with a molecular weight of 85,000 (gp85) that remained associated with the insoluble skeletons . Immunoprecipitation with a specific antiserum indicated that the gp85 is not a proteolytic degradation product of fibronectin, an extracellular matrix glycoprotein insoluble in detergent .A monoclonal antibody of BHK cells specific for gp85 was produced . Immunofluorescence analysis with this monoclonal antibody indicated that gp85 is not associated with the extracellular matrix, but is confined to the cell membrane . Both in fixed and unfixed intact cells, fluorescence was concentrated in dots preferentially aligned in streaks on the cell surface . Gp85 was found to behave as an integral membrane protein interacting with the hydrophobic core of the lipid bilayer since it was extracted from membrane preparations by ionic detergents such as SDS, but not by 0.1 N NaOH (pH 12) in the absence of detergents, a condition known to release peripheral molecules . Association of gp85 with the cell skeleton was unaffected by increasing the Triton concentration up to 5%, but it was affected when actin filaments were dissociated or when a protein-denaturing agent (6 M urea) was used in the presence of Triton, suggesting that protein-protein interactions are involved in the association of gp85 with the cell skeleton . We conclude that gp85 is an integral plasma membrane glycoprotein that might have a role in cell surface-cytoskeleton interaction .When nucleated cells in culture are extracted with non-ionic detergents, most cellular components, including membranebound organelles, are solubilized . However, intermediate filaments and actin fibers are left as an insoluble residue that retains the three-dimensional organization of the intact cell cytoskeleton (1-3) . Moreover, cytoskeleton-associated molecules, known to play a role in actin-plasma membrane interaction, have been detected in the detergent-insoluble cell fraction . These include the two subunits of spectrin, ankyrín, a polypeptide termed band 4 .1 in erythrocytes (4-7), fimbrin (8), villin (9), vinculin (10), c actinin (11), and spectrin-like molecules (12, 13) in nucleated cells . In addition, one integral membrane glycoprotein, band III, has been reported to remain associated to the erythrocyte submembranous cytoskel-512 eton after detergent extraction (14) . This glycoprotein represents the membrane attachment protein for spectrin-ankyrin complexes .In this paper, we identified, by means of a monoclonal antibody, a cell surface integral membrane glycoprotein of 85,000 mol wt (gp85) associated to the Triton-insoluble skeleton . The detergent inso...