Regulation of fibronectin receptor distribution by transformation, exogenous fibronectin, and synthetic peptides

Recent studies have shown that fibronectin and its 140K membrane receptor complex are spatially associated with microfilaments to form cell surface linkage complexes which are thought to mediate adhesive interactions between fibroblasts and their substrata. We examined the regulation of the organization of these cell surface structures in transformed and fibronectin-reconstituted cells as well as in cells treated with a competitive synthetic peptide inhibitor of fibronectin binding to its receptor. Correlative localization experiments with interference reflection microscopy and double-label or triple-label immunofluorescence revealed a concomitant loss of fibronectin, 140K receptor, and alpha-actinin colocalization at cell substratum extracellular matrix contact sites after transformation of chick fibroblasts by wild-type or temperature-sensitive Rous sarcoma viruses (RSV). Western and dot immunoblot analyses established that although similar total quantities of intact 140K molecules were present in the transformed cell cultures, significantly more was released into the culture medium of transformed cells. The 140K molecules on transformed cells were available for interaction with exogenously added fibronectin, which could reconstitute fibronectin-140K linkage complexes. In such fibronectin reconstitution experiments, many cells expressed both fibronectin-140K-actin linkage complexes and RSV pp60src, indicating that the morphological reversion could occur even in the continued presence of RSV transformation. The synthetic peptide Gly-Arg-Gly-Asp-Ser derived from the sequence of the cell-binding region of fibronectin could also prevent the organization of fibronectin-140K linkage complexes. Our results suggest that fibronectin interaction with cells regulates the organization of fibronectin receptor complexes and cytoskeletal components at the cell surface.

[Mechanism of cell damage by hematoporphyrin derivatives (HPD) plus light--I. Photooxidation of hepatoma cell membrane by HPD plus light]

Ascitic hepatoma cells of mice were incubated with three HPD. After the cell-bound HPD was treated by visible light, the product of membrane lipid peroxidation--malondialdehyde (MDA) was determined. The results showed that the MDA level increased with HPD concentration and exposure time, but it was unchanged in the control. Beta-carotene, a quencher of singlet oxygen, could inhibit the lipid photooxidation of the membrane of cell-bound HPD resulting in a decrease of MDA level which decreased with increase of beta-carotene concentration. Adding vitamin E in vitro and vivo, formation of the product of membrane lipid peroxidation of cell-bound HPD by light was inhibited and the MDA level decreased with the increase of vitamin E concentration. These results show that the singlet oxygen, produced by HPD bound cells following light activation, reacts directly with the polyunsaturated fatty acids on cell membrane to produce lipid peroxides leading to cellular damage.

Anti-tumor properties of lymphocytes activated by the oxidizing mitogens

Human peripheral blood mononuclear cells when activated with the oxidizing mitogens, neuraminidase/galactose oxidase or sodium periodate, express cytolytic activity for freshly isolated tumor cells and for a variety of cell lines, including NK-resistant solid tumor lines. Normal lymphoid cells are not targets for cytotoxicity and do not inhibit lysis of susceptible targets mediated by the oxidizing mitogen-activated mononuclear cells. The cytotoxic response is rapidly generated and reaches peak levels at 48 hr. The oxidizing mitogens induce expression of IL 2 receptors on peripheral blood mononuclear cells. Combined treatment of cells with IL 2 and the oxidizing mitogens results in a marked enhancement of cytotoxicity. Enhancement is achieved at levels of IL 2 that alone result in minimal generation of cytotoxic cells. Growth of a human renal cancer cell line in nude mice was inhibited when the renal cancer cells were injected together with oxidizing mitogen-activated human mononuclear cells. These studies indicate that oxidizing mitogen-activated cells provide a potentially valuable source of material for the adoptive immunotherapy of tumors.

Anti-tumor properties of lymphocytes activated by the oxidizing mitogens

Human peripheral blood mononuclear cells when activated with the oxidizing mitogens, neuraminidase/galactose oxidase or sodium periodate, express cytolytic activity for freshly isolated tumor cells and for a variety of cell lines, including NK-resistant solid tumor lines. Normal lymphoid cells are not targets for cytotoxicity and do not inhibit lysis of susceptible targets mediated by the oxidizing mitogen-activated mononuclear cells. The cytotoxic response is rapidly generated and reaches peak levels at 48 hr. The oxidizing mitogens induce expression of IL 2 receptors on peripheral blood mononuclear cells. Combined treatment of cells with IL 2 and the oxidizing mitogens results in a marked enhancement of cytotoxicity. Enhancement is achieved at levels of IL 2 that alone result in minimal generation of cytotoxic cells. Growth of a human renal cancer cell line in nude mice was inhibited when the renal cancer cells were injected together with oxidizing mitogen-activated human mononuclear cells. These studies indicate that oxidizing mitogen-activated cells provide a potentially valuable source of material for the adoptive immunotherapy of tumors.

Chronic measurement, using a Doppler probe, of uterine artery flow in the gravid guinea-pig

A chronic animal model is described which permits for the first time the continuous measurement of uterine artery blood flow velocity in the pregnant guinea-pig by using a miniaturized Doppler flow probe. Preliminary validation revealed that alterations in actual blood flow are directly and proportionally related to the change in the Doppler shift (r = 0.984) from 0 to 100 ml/h. The velocity signal baseline was as stable as that of systemic blood pressure. Depending upon the individual animal's flow velocity, a deviation of 2-5% from baseline was statistically significant. With experience, greater than 90% of preparations were successful and a 30-day interval was often available for study. Uterine artery flow velocity increased steadily between 45 and 55 days of gestation. Instrumentation did not result in fetal growth retardation. A reduction in flow velocity occurred during general anaesthesia using ketamine and the antianxietal xylazine. In agreement with the reports of other investigators using a different model, both hydralazine and angiotensin II increased uterine blood velocity and adrenaline reduced it.

Quantitation of myelination and demyelination by the measurement of myelin basic protein by ELISA

Utilizing a competitive inhibition enzyme-linked immunosorbent assay (ELISA) we measured the amount of myelin basic protein (MBP) in brain, liver, and kidney of newborn mouse and compared these values with myelinated cerebellar explant cultures under various conditions. Explant cultures demyelinated with anti-myelin serum showed a 90% decrease in MBP when compared with controls. These results correlated with myelination and demyelination as observed by light microscopy. Newborn tissues including brain showed only negligible activity for MBP. This technique provides a sensitive and objective method for quantitating in-vitro demyelination.

Rhodopsin's amino terminus is a principal antigenic site

Antisera and monoclonal antibodies to rhodopsin were examined for their binding specificity to rhodopsin by using peptides from the rhodopsin sequence as competitors for antibody binding to rhodopsin in an enzyme-linked immunoassay. Monoclonal antibodies tested were raised in mice against bovine and rat rhodopsin. Antisera tested were raised in sheep against bovine rhodopsin and in rabbits against human rhodopsin. Peptides were synthesized from the bovine rhodopsin sequences 2-32, 1-12, 13-23, 24-34, 5-11, 231-252 and 331-348 for use as competitors in the immunoassay. A mixture of soluble CNBr peptides, and the purified CNBr peptide representing the sequence 2-39 were also employed. The monoclonal antibodies were all anti-amino-terminal in their binding specificity, although each recognized slightly different regions of the amino terminus. Each of the three antisera was predominantly directed against rhodopsin's amino terminus. We conclude that the amino-terminal 30 or more amino acids, and particularly the amino-terminal 15 amino acids, represent a principal antigenic region of the rhodopsin molecule.

Serum insulin and blood pressure in an obese population

Serum insulin has been implicated as a determinant of blood pressure (BP) level in obese hypertensive individuals. We examined the relationships among fasting insulin, mean arterial pressure (MAP), body composition, and fat distribution in 204 subjects unselected for glucose tolerance. All met the criteria of taking no oral hypoglycemic agents, insulin or antihypertensive medications. 95 percent were considered obese and 78 percent were female. Mean age was 39 years (range 15-71), percent ideal body weight (IBW) 171 percent (109-332), BP 125/81 mmHg (80-181/50-110) and fasting insulin 44 microU/ml (4-196). Lean body mass (LBM) and body fat were measured by tritium dilution. The correlation coefficient between insulin and MAP was 0.32 (P less than 0.0001). Both insulin and MAP correlated highly with percentage IBW, percentage body fat, fat mass, LBM, body build and upper fat pattern. Controlling for these variables simultaneously eliminated the association between insulin and BP. By contrast, the correlations between MAP and measures of body composition and fat distribution retained significance after controlling for insulin level. These findings suggest that measures of body composition and fat distribution have a relationship with BP that is not entirely accounted for by serum insulin level, and the relationship between serum insulin and BP is indirect and largely accounted for by their mutual association with measures of body composition and fat distribution.

Body composition studies in patients with the acquired immunodeficiency syndrome

Body composition studies were performed in 33 patients suffering from the acquired immunodeficiency syndrome (AIDS). Studies included measurements of total body potassium, fat, and total body and extracellular water volumes plus serum retinol binding protein concentration, iron binding capacity, and albumin concentration. AIDS patients were underweight (p less than 0.001) and were depleted of potassium (p less than 0.001) with the lowest values occurring in patients close to death at the time of study. Body fat contents also were reduced. Intracellular water volumes were decreased in the AIDS patients (p less than 0.001) with a relative increase in extracellular water volume (p less than 0.001). Serum protein concentrations were decreased in the AIDS patients. Longitudinal studies did not demonstrate tissue repletion in patients with AIDS, despite apparent clinical stability. These studies demonstrate that severe, progressive malnutrition occurs in patients with AIDS. If malnutrition can be shown to have a deleterious effect upon the disease course, therapy of malnutrition may play an important role in the treatment of this disorder.