Search PubMed⌕ Search

Biomedical subjects

D W Barnes

Publications and source records attributed to D W Barnes.

At least 55 records · Page 3Linked to original sources
PubMed1987

Extended culture of mouse embryo cells without senescence: inhibition by serum.

Mouse embryo cells cultured in vitro in serum-supplemented media undergo growth crisis, resulting in the loss of genomically normal cells prior to the appearance of established, aneuploid cell lines. Mouse embryo cells established and maintained for multiple passages in the absence of serum did not exhibit growth crisis or gross chromosomal aberration. Cells cultured under these conditions were dependent on epidermal growth factor for survival. Proliferation was reversibly inhibited by serum or platelet-free plasma, suggesting that mouse embryo cultures maintained by conventional procedures are under the influence of inhibitory factors.

Animals↗
PubMed1986

Immunosuppression without liver induction by subchronic exposure to 2,7-dichlorodibenzo-p-dioxin in adult female B6C3F1 mice.

The overall objective of this investigation was to begin to characterize the structure-activity relationship associated with dioxin-induced suppression of humoral immunity. Subchronic exposure (14 days) to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the prototype of the class, produced a suppression of the antibody responses to both sheep erythrocytes, a T-dependent antigen, and dinitrophenyl-Ficoll, a T-independent antigen. Surprisingly, similar results were observed with 2,7-dichlorodibenzo-p-dioxin (DCDD), a dioxin congener lacking affinity for the Ah receptor. In contrast, subchronic exposure to octachlorodibenzo-p-dioxin (OCDD), another dioxin congener without affinity for the Ah receptor, was devoid of activity. Subchronic exposure to 2,3,7,8-TCDD, but not 2,7-DCDD, produced an induction of several liver parameters including: liver weight, amount of microsomal protein, amount of cytochrome P-450, activity of aminopyrine-N-demethylase and activity of aryl hydrocarbon hydroxylase. Subchronic exposure to 2,3,7,8-TCDD or 2,7-DCDD produced no marked changes in thymus weight. Acute exposure to 2,3,7,8-TCDD also produced suppression of the antibody response in the absence of effects on the thymus.

Animals↗
PubMed1986

Induction of hypoxia in normal and malignant tissues by changing the oxygen affinity of hemoglobin--implications for therapy.

The drug BW12C, which increases the oxygen affinity of hemoglobin, reduces oxygen availability to tissues. This results in protection against radiation damage to the hemopoietic system and epidermal Langerhans cells in CBA mice. The drug also protects against beta-irradiation damage in pig epidermis. BW12C increases the hypoxic cell fraction in tumors and histological examination of an experimental T cell lymphoma shows that the induced hypoxia leads to tumor necrosis.

Aldehydes↗
PubMed1986

Binding of Staphylococcus aureus by human serum spreading factor in an in vitro assay.

Human serum spreading factor, an animal cell adhesion-promoting glycoprotein, bound Staphylococcus aureus in an assay in which association of bacteria to protein-precoated microtiter wells was quantitated. Interaction of human serum spreading factor with S. aureus suggests that this protein may play a role in host defenses and in the invasiveness and pathogenicity of microbial infections.

Antibodies, Monoclonal↗
PubMed1986

CNS diseases associated with varicella zoster virus and herpes simplex virus infection. Pathogenesis and current therapy.

In recent years, herpes simplex virus has been recognized as an important CNS pathogen in neonates and adults. The recent development of effective antiviral therapy has substantially reduced the excessive morbidity and mortality associated with these infections. For neonatal herpes simplex infections, the current drug of choice is vidarabine. The results of ongoing clinical trials comparing vidarabine with acyclovir in neonatal herpes may lead to a change in the recommended therapy. In the adult, the therapy of choice for herpes simplex encephalitis is acyclovir. Although effective, the present therapies for herpes simplex infections of the CNS leave much room for improvement. In addition to the development of more effective antiviral drugs and less invasive diagnostic techniques, prevention of these often devastating infections will be important in reducing morbidity and mortality. The CNS diseases associated with varicella and herpes zoster may have a different pathogenesis. The implication for therapy in these diseases favors nonspecific supportive therapy in the varicella-associated syndromes. The few anecdotal reports of the use of vidarabine and acyclovir in herpes zoster encephalitis and the histopathologic evidence suggesting viral invasion of the CNS in many cases of zoster-associated neurologic syndromes makes the use of specific antiviral therapy in zoster encephalomyelitis more rational. However, appropriate therapeutic recommendations will have to be based on controlled clinical trials that have not yet been performed.

Central Nervous System Diseases↗
PubMed1985

Heparin-binding properties of human serum spreading factor.

Human serum spreading factor (SF) is a blood glycoprotein that promotes attachment and spreading and influences growth, migration, and differentiation of a variety of animal cells in culture. SF purified from human plasma or serum by chromatographic methods reported previously (Barnes, D. W., and Silnutzer, J. (1983) J. Biol. Chem. 258, 12548-12552) does not bind to heparin-Sepharose under conditions of physiological ionic strength and pH. In a further examination of the heparin-binding properties of human serum SF, we found that exposure of purified SF to 8 M urea altered several properties of the protein, including heparin affinity, and these alterations remained after removal of the urea from SF solutions. Urea-treated SF bound to heparin under physiological conditions, and salt concentrations of 0.4 M or higher were required for elution of urea-treated SF from heparin-Sepharose at pH 7.0. The alteration of heparin-binding properties of SF also was observed upon exposure of the protein to heat or acid. Treatment of SF with urea, heat, or acid resulted additionally in greatly decreased cell spreading-promoting activity of the molecule. The decreased biological activity was associated with a reduced ability of the treated SF to bind to the cell culture substratum, a prerequisite for the attachment-promoting activity of the molecule. Experiments examining the heparin-binding properties of native SF in unfractionated human plasma indicated that the major portion of SF in blood did not bind to heparin under conditions of physiological ionic strength and pH.

Blood Proteins↗
PubMed1985

Human spreading factor: synthesis and response by HepG2 hepatoma cells in culture.

Human serum spreading factor (SF) is a cell adhesion and spreading-promoting glycoprotein purified from serum or plasma that mediates effects in a wide variety of animal cell culture systems. HepG2 human hepatoma cells were found to synthesize and secrete SF into culture medium. Quantitative immunoassay of the protein indicated a concentration of about 1 microgram/ml in 48 hr-conditioned medium from confluent cultures. Although fibronectin also was synthesized and secreted into the culture medium, HepG2 cell spreading was observed in response to human serum SF, but not in response to human plasma fibronectin. Immunoprecipitation of SF from culture medium of cells metabolically-labeled with leucine, fucose or glucosamine identified a single form of the molecule of approximately 70,000 daltons. Treatment of cultures with tunicamycin inhibited incorporation of fucose and glucosamine into immunoprecipitated SF, but did not prevent synthesis and secretion of the protein. Electrophoretic analysis and cell spreading assays showed that SF secreted by tunicamycin-treated HepG2 cells was of molecular weight (mw) approximately 60,000, and was biologically active.

Carcinoma, Hepatocellular↗
PubMed1985

Effects of fibronectin-related peptides on cell spreading.

Four synthetic peptides related in amino acid sequence to the area of the fibronectin molecule thought to be involved in cell binding were tested for the ability to inhibit cell spreading promoted by several different attachment factors. Effects of the peptides were assayed on a number of cell types. For all cell types tested, peptides effective at inhibiting fibronectin-promoted cell spreading were found also to inhibit cell spreading promoted by human serum spreading factor (SF). These peptides were also capable of inhibiting to a lesser extent cell spreading promoted by other attachment factors, although this phenomenon was dependent on the cell type examined.

Cell Adhesion↗
PubMed1985

Selection of transformed cells in serum-free media.

NIH3T3 cells grow in a serum-free basal nutrient medium supplemented with fibronectin, transferrin, insulin, epidermal growth factor (EGF) and high density lipoprotein (HDL). The individual omission from the serum-free medium of insulin, EGF, or HDL results in greatly reduced cell growth. These growth-restrictive conditions can be used to select for cells transformed with SV40, the polyomavirus middle T antigen gene, the activated human ras gene, and the mouse c-myc gene.

Animals↗
PubMed1985

Immunotoxicological investigations in the mouse: general approach and methods.

The adverse effects of chemicals on the lymphoreticular system have generated considerable toxicological interest. In this series of papers, the effects of selected environmentally relevant compounds are reported. This first paper describes the methods and general approach used in judging a chemical's potential risk to the immune system. Risk evaluation was approached utilizing acute, 14- and 90-day studies. Both sexes of the CD-1 random-bred mouse were employed. The immune system was evaluated against a background of more standard toxicological parameters, which included fluid consumption, body and organ weights, hematology, serum and liver chemistries, hepatic microsomal enzyme activities and blood coagulation. Bone marrow status was evaluated by assessing DNA synthesis. Humoral immunity was evaluated by determining the number of IgM spleen antibody-forming cells (AFC) to sheep erythrocytes (sRBC), the serum antibody level to sRBC, and spleen lymphocyte response to the B cell mitogen, lipopolysaccharide (LPS). The status of cell-mediated immunity was assessed by quantitating the delayed type hypersensitivity (DTH) response to sRBC, proliferation of the popliteal lymph node, and the spleen cell response to the T lymphocyte mitogen, Concanavalin A (Con A). Macrophage function was evaluated by measurement of the vascular clearance rate and distribution of radiolabeled sRBC in the liver, spleen, lungs, and thymus, and recruitability, adherence, chemotaxis, and phagocytic activity of peritoneal exudate cells (PEC). Historical control data from six 14- and 90-day studies conducted over a one year period are given. The data resulting from these types of studies can provide a basis for the initial evaluation of a chemical's adverse effect on the immune system.

Animals↗
PubMed1985

Toxicology of 1,1,2-trichloroethane in the mouse.

1,1,2-Trichloroethane (TCE) was administered to male and female CD-1 mice to evaluate its effect on standard toxicological parameters. Following determination of the acute LD50 (378 mg/kg in males and 491 mg/kg in females), and a 14-day range-finding study, a 90-day drinking water study was performed in which the doses consumed were 4.4, 46, and 305 mg/kg for males and 3.9, 44, and 384 mg/kg for females. The liver was a target of TCE toxicity in both sexes as demonstrated by dose-dependent alterations in hepatic microsomal enzyme activities and serum enzyme levels. The erythroid element of the female mice was also affected, as indicated by significantly decreased hematocrit and hemoglobin levels.

Animals↗
PubMed1985

Toxicology of trans-1,2-dichloroethylene in the mouse.

Trans-1,2-dichloroethylene (DCE) was administered to male and female CD-1 mice in order to evaluate its effects on standard toxicological parameters. Following an acute LD50 determination (2122 mg/kg in males and 2391 mg/kg in females) and a 14-day range-finding study, a 90-day drinking water study was performed using levels of DCE calculated to deliver approximately 1/100, 1/10, and 1/5 the LD50. Various toxicological assessments were made, including body and organ weights, hematology, serum chemistries, and hepatic microsomal activities. Few alterations were observed in either sex following 90 days of exposure. The most noteworthy changes occurred in the males exposed to the highest level of DCE, where there was a significant decrease in glutathione levels, and in the females exposed to all three DCE levels, where there was a significant decrease in aniline hydroxylase activity. These data served as background for the immunotoxicological evaluation presented in the following manuscript.

Animals↗
PubMed1985

Stimulation of haptotaxis and migration of tumor cells by serum spreading factor.

A central feature of tumor metastasis is the migration of malignant cells through interstitial tissues and vascular structures as they spread throughout the body. Various components of the extracellular matrix and of basement membranes, consisting of genetically distinct collagens, proteoglycans, and noncollagenous glycoproteins, are known to modulate certain aspects of cell behavior, including cell movement. Serum spreading factor is a glycoprotein component of human serum that is also found in interstitial tissues. Two native forms are seen in human serum, a Mr 65,000 and a Mr 75,000 component. Spreading factor promotes substratum attachment and spreading of diverse cell types, including epithelial and fibroblastic cells, and will affect the growth rate and differentiation of cells in serum-free culture media. Serum spreading factor was shown to promote the directed migration of the following tumor cell lines in modified Boyden chamber assays: murine melanoma K-1735 (clones M2, M4, and 16); human breast carcinoma MCF-7; and human fibrosarcoma HT-1080. The stimulation of movement occurred over a concentration range of 0.5 to 50 micrograms of serum spreading factor per ml with a maximum response between 5 and 10 micrograms/ml. The maximal response varied with the cell line and ranged from 5- to 50-fold greater migration than control. A monoclonal antibody to spreading factor, previously shown to inhibit the attachment and spreading-promoting activity, abrogated this migration response. Experiments using filters that were precoated with spreading factor indicated that cells could migrate on an insolubilized layer of this protein by haptotaxis. Tumor cell migration to spreading factor in vitro suggests a possible role for this protein in the phenotypic behavior of metastatic cells.

Animals↗
PubMed1984

A biologically active thrombin cleavage product of human serum spreading factor.

Purified human serum spreading factor preparations consisting of two immunologically-related, biologically-active proteins of molecular weights approximately 65,000 and 75,000 were incubated with purified hydrolytic enzymes: papain, neuraminidase and thrombin. Biologically active products of the enzymatic digestions were obtained in each case. Digestion of serum spreading factor preparations with thrombin produced a single active form of molecular weight approximately 57,000. Generation of a single molecular weight form of serum spreading factor by thrombin cleavage of the two higher molecular weight forms should simplify studies of the biochemistry and biology of this protein, and may represent a reaction of physiological significance.

Biological Assay↗
PubMed1984

Growth characteristics of A431 human epidermoid carcinoma cells in serum-free medium: inhibition by epidermal growth factor.

A431 human epidermoid carcinoma cells in culture may be grown in the absence of serum in a one to one mixture of Ham's F12 and Dulbecco-modified Eagle's medium supplemented with 10 micrograms/ml bovine insulin, 10 micrograms/ml human transferrin, 5 micrograms/ml human cold-insoluble globulin and 0.5 mM ethanolamine. Growth rate of the cells in this serum-free medium is essentially identical to that of cells in medium containing 10% fetal calf serum. Addition of epidermal growth factor at concentrations which are stimulatory for the growth of other cell types in culture causes and inhibition of A431 cell growth in both serum-free and serum-containing medium. The inhibitory effect of epidermal growth factor is reversible upon replacement of epidermal growth factor-containing medium with medium containing no epidermal growth factor. Simultaneous addition to the medium of antibody to epidermal growth factor along with epidermal growth factor prevents the inhibitory effect.

Carcinoma, Squamous Cell↗
PubMed1984

Glass-bead affinity chromatography of cell attachment and spreading-promoting factors of human serum.

The glass-binding properties of a number of purified glycoproteins capable of promoting attachment and spreading of a variety of types of animal cells in culture have been examined. Two such factors in human serum, fibronectin and serum spreading factor, exhibited strong affinities for glass beads and could be eluted from glass-bead columns under similar conditions. A number of other glycoproteins of human serum that do not promote cell adhesion did not bind to glass beads under conditions that resulted in binding of serum spreading factor or fibronectin. At a sufficiently low ratio of serum volume to glass-bead volume, human serum could be simultaneously depleted of serum spreading factor, fibronectin, and cell spreading-promoting activity by glass-bead affinity chromatography. Laminin, another cell spreading-promoting glycoprotein, possessed glass-binding properties similar to those of serum spreading factor and fibronectin while chondronectin, a fourth cell spreading-promoting factor of more limited specificity of biological activity and distribution in vivo, did not exhibit a strong interaction with glass beads under the same conditions. These observations suggest that glass-bead column affinity chromatography may prove useful as a general method for isolation and study of glycoprotein factors promoting attachment and spreading of cells in culture.

Animals↗
PubMed1984

Naphthalene toxicity in CD-1 mice: general toxicology and immunotoxicology.

Random bred CD-1 mice were used to evaluate the acute oral toxicity and subchronic toxicity of naphthalene administered in corn oil. The acute oral LD50 of naphthalene was 533 and 710 mg/kg in male and female mice, respectively. Subchronic toxicity was evaluated with 14- and 90-day daily oral gavage studies. Doses utilized in the 14-day study were 27, 53, and 267 mg/kg, with the latter representing one-half of the male LD50. Both males and females demonstrated a 5-10% mortality and depressed body weight at the high dose only. Males had decreased thymus weights, and females had decreased spleen and increased lung weights at the high dose only. Other organ weights were unaffected at any dosage level. Serum enzyme and electrolyte levels were not altered in a dose-related manner. To assess the potential immunotoxicity of naphthalene the following screen was utilized: humoral immune response, response to mitogens, delayed hypersensitivity response, popliteal lymph node response, bone marrow stem cell number, and DNA synthesis. No evidence of immunotoxicity was demonstrated. The 90-day study employed daily oral doses of 5.3, 53, and 133 mg/kg. There was no treatment-related mortality in either sex, nor was body weight affected. Organ weights were not affected in males, and females showed reduced spleen weights only at the high dose. Serum enzyme and electrolyte levels, as well as the immunotoxicity screen, indicated that naphthalene doses up to one-fourth the LD50 for 90 days failed to elicit consistent statistically significant and biologically relevant compound-related effects. A screen of the effects of the 90-day naphthalene treatment on various aspects of the hepatic drug metabolizing system indicated no alterations, with the exception of a specific dose-related inhibition of aryl hydrocarbon hydroxylase activity in both male and female mice.

Animals↗