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D G Fischer

Publications and source records attributed to D G Fischer.

At least 37 records · Page 2Linked to original sources
PubMed1986

Human monocytes and lymphocytes produce different mixtures of alpha-interferon subtypes.

alpha-Interferon (IFN-alpha) was produced by either peripheral blood lymphocytes or by monocytes and purified by an anti-IFN-alpha affinity column. When these preparations were analyzed by reversed-phase HPLC, a difference in the distribution of IFN-alpha subtypes from the two cell types was found. While the two major subtypes of IFN from induced lymphocytes had apparent molecular weights of 20K and 21K, monocytes produce an additional subtype of molecular weight 26K in large quantities (50%). This subtype had greater activity on human cells than on bovine cells in comparison to other IFN-alpha subtypes.

Animals↗
PubMed1986

The interferon-gamma receptor in human monocytes is different from the one in nonhematopoietic cells.

The receptor for interferon-gamma (IFN-gamma) on peripheral blood monocytes was characterized and was compared with that of human WISH cells. 125I-IFN-gamma was specifically bound to both cells; however, different binding characteristics were obtained. In the case of monocytes, Scatchard analysis gave an upward concave dependency curve, indicating either multiple binding sites or a negative cooperativity among the binding sites. In contrast, a linear Scatchard plot was obtained for the binding in WISH cells. Competition studies gave even more striking differences. Acid-treated IFN-gamma (95% inactivated) effectively competed with 125I-IFN-gamma for binding to the receptor on WISH cells, but not on monocytes. The significance of these differences was evaluated by analyzing the various biological activities of IFN-gamma in these two cell types. IFN-gamma was found to induce an antiviral state in WISH cells, but not in monocytes. Acid-treated IFN-gamma was found to be almost as active as IFN-gamma itself in inducing HLA-DR in WISH cells, but was almost completely inactive as an HLA-DR inducer in monocytes. It is proposed that these variations in biological activity stem from the presence of different receptors for IFN-gamma in monocytes and in WISH cells. Moreover it is suggested that the immunoregulatory functions of IFN-gamma in monocytes are related to the presence of a distinct IFN-gamma receptor in these cells.

Amnion↗
PubMed1985

A bicarbonate-dependent process inhibitable by disulfonic stilbenes and a Na+/H+ exchange mediate 22Na+ uptake into cultured bovine corneal endothelium.

22Na+ uptake into confluent monolayers of cultured bovine corneal endothelial cells was studied in the presence of ouabain (10(-4)M) to inhibit active sodium extrusion. In bicarbonate saline, uptake was reduced to a similar degree either by amiloride (10(-3)M) or by 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS) (10(-3)M). A further reduction was obtained with SITS-pretreated cells in the presence of amiloride. SITS-sensitive uptake was further characterized in saline containing both ouabain (10(-4)M) and amiloride (10(-3)M). It was absolutely dependent on bicarbonate, which could not be substituted by other plasma membrane permeable buffers (50 mM acetate or 25 mM glycodiazine). It was a saturable function of both bicarbonate and sodium concentration. Half-maximal fluxes occurred between 3 and 7 mM HCO3 (at 151 mM Na) and between 35 and 60 mM Na (at 28 mM HCO3). Uptake into sodium-depleted cells was reduced as opposed to sodium-rich cells, and SITS-sensitive 22Na+ efflux out of 22Na+-loaded cells into sodium-free medium was less than efflux into sodium saline, indicating trans-stimulation by sodium. The amiloride-sensitive pathway was studied in the absence of bicarbonate to inhibit uptake via the SITS-sensitive pathway. 22Na+ uptake into sodium-depleted cells increased steeply with extracellular pH in the range between pH 6 and 8 and could be largely blocked by 10(-3), but not by 10(-5) M amiloride. It is concluded that bovine corneal endothelial cells possess at least two distinct pathways for sodium uptake, amiloride sensitive 22Na+ fluxes being mediated by a Na+/H+ antiport, while the SITS-sensitive process is probably identical to a bicarbonate-sodium cotransport system postulated earlier from electrophysiological studies.

4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfo↗
PubMed1985

Increase of vulnerability to lymphotoxin in cells infected by vesicular stomatitis virus and its further augmentation by interferon.

The cytotoxic effect of lymphotoxin (LT) and its modulation by interferon (IFN) was quantitatively assessed in uninfected and vesicular stomatitis virus (VSV)-infected cultured cells. Preparations of human LT, which were depleted of IFN, had a significant cytotoxic effect on VSV-infected HeLa, SV-80, WISH, and Vero cells. IFN, most notably IFN-gamma, further potentiated destruction of the infected cells by these LT preparations, when applied on the cells at sub-antiviral IFN concentrations. In contrast, no cytotoxic effect could be observed in any of the examined cells, when applying LT, IFN, or their combination, in the absence of viral infection. Infected cells in which VSV replication was suppressed by treatment with antiviral concentrations of IFN also resisted destruction by LT. These findings indicate that LT cytotoxicity can be selectively directed against virus-infected cells and that IFN can augment this cell-killing mechanism when failing to exert an antiviral effect.

Animals↗
PubMed1984

Isolation of two discrete human interferon-gamma (immune) subtypes by high-performance liquid chromatography.

A rapid procedure for isolation of two biologically active human interferon-gamma subtypes was developed. Crude interferon-gamma produced in a serum-free culture of peripheral blood mononuclear cells by mitogen stimulation was concentrated and partially purified by chromatography on controlled-pore glass. Following desalting and concentration by ultrafiltration, a step of cation-exchange high-performance liquid chromatography was performed. A linear NaCl gradient (0.01-0.4 M) at pH 7 was employed and four peaks of biological activity eluting at 0.17, 0.20, 0.26 (major peak), and 0.3 M were obtained. The major peak of biological activity coincided with two protein peaks. Analysis of one fraction from the major activity peak by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a protein band having an apparent molecular weight of 26,000, while an adjacent fraction of the same activity peak contained a protein band corresponding to a molecular weight of 21,000. The specific activity of both subtypes was 7-10 X 10(6) units/mg.

Chromatography, High Pressure Liquid↗
PubMed1984

Type I and Type II interferon receptors.

Binding site competition studies of 125I-interferon (IFN)-gamma were performed with homogeneous preparations of IFNs alpha 2, beta, and gamma. It was found that only IFN-gamma could compete for the specific binding site of 125I-IFN-gamma in both WISH and FS11 cells. Thus, a clear distinction between the receptor of IFN- alpha and beta on one hand, and the receptor of IFN-gamma on the other hand, was obtained. This result is unambiguous because all IFN preparations which were used were purified to homogeneity by specific monoclonal antibody immunoaffinity chromatography. We propose to assign the names "Type I" for the receptor of IFN-alpha and IFN-beta, and "Type II" for the specific receptor of IFN-gamma.

Binding, Competitive↗
PubMed1984

Family size and delinquency.

A review of the literature shows that large family size is related to greater delinquency. The relationship remains when a number of variables, i.e., income, socioeconomic status, parental criminality, and family composition, have been controlled. The higher birth rate for lower classes does not appear to be an adequate explanation for this relationship, nor does less close parent-child affectional ties or less parental supervision although all of these may have some influence. The presence of an "infectious example" may partly account for the relationship, as does overcrowding. Large family size is typically associated with the constellation of undesirable family conditions involving poor role models (e.g., poor parental behaviour, parental criminality, sibling delinquency), poor child-rearing practices (e.g., inadequate parental supervision and discipline), and competition for physical (e.g., overcrowding, low income) and psychological (e.g., lack of attention, affection, family interaction) resources. An immediate solution is to reduce the size of families by helping prospective parents plan their families, and for those who wish it, making medical abortions more readily available. The long-range solution is through research to identify variables which significantly influence the relationship between family size and delinquency. Such studies must control for birth order, sibling spacing, siblings' sex, and sex of the delinquents in these families.

Adolescent↗
PubMed1983

Spontaneous production of interferon-gamma and acid-labile interferon-alpha by subpopulations of human mononuclear cells.

A low-density subpopulation of normal human peripheral blood mononuclear leukocytes obtained by percoll gradients was found to produce significant levels (up to 10,000 units/ml) of interferon in the absence of an external inducer. The interferon (IFN) was characterized as a mixture of IFN-gamma (immune) and a pH-sensitive IFN-alpha by neutralization with specific antibodies, by lability to low pH, and by cross-reactivity on bovine cells. Significant levels of IFN were obtained only at high (greater than or equal to 5 X 10(6) cells/ml) cell densities. These levels were not affected by the presence of small T lymphocytes and sharply decreased with cell dilution in a nonlinear fashion. A release of IFN in the absence of an external inducer, indicates additional physiological roles besides its involvement in pathological conditions.

Cells, Cultured↗
PubMed1983

Monoclonal antibodies to human interferon-gamma: production, affinity purification and radioimmunoassay.

Human interferon-gamma (IFN-gamma) purified to electrophoretic homogeneity by a cation exchange h.p.l.c., was used for the development of monoclonal antibodies. Following immunization, spleen lymphocytes of two mice showing the highest binding and neutralizing titers were isolated, fused with NSO mouse myeloma cells and cloned. The screening of hybridomas was based on precipitation of the immune complexes with a second antibody and recovery of the biological activity of IFN-gamma from the precipitate. Twenty nine independent hybridomas secreting antibodies specific to IFN-gamma were obtained. Twelve out of these 29 hybridomas produced antibodies that neutralized the antiviral activity of pure as well as crude IFN-gamma. Moreover, IFN-gamma obtained by various induction procedures was neutralized as well, indicating that these various IFN-gamma subtypes are immunologically cross-reactive. Immune precipitation of partially purified 125I-labelled IFN-gamma by several monoclonal antibodies revealed two protein bands of 26,000 and 21,000 daltons. Immunoaffinity chromatography of IFN-gamma gave a 50-fold purification to a specific activity > or = 4 x 10(7) units/mg. Two of the monoclonal antibodies were found suitable for a sensitive and rapid double antibody solid-phase radioimmunoassay, allowing the detection of IFN-gamma at concentrations of at least 4 ng/ml (150 units/ml) within 8 h.

Animals↗
PubMed1983

Parental supervision and delinquency.

A review of the literature suggests that parental supervision over their children is a significant variable in controlling the amount of delinquent behaviour; high supervision is associated with low delinquency. The relationship remains when variables such as mother's affection, parental conflict, parental aggression, mother's self-confidence, father's deviance, father's absence, father's occupation are controlled. And it appears to be effective under extremely adverse conditions such as poverty and authoritarian and repressive methods of child rearing. Training packages providing basic information about processes of child development and emphasizing positive techniques of child management, with parental supervision as an essential ingredient, need to be further developed and evaluated as a means of reducing delinquency.

Adolescent↗
PubMed1983

Characteristics and requirements of the interaction between human monocytes and tumor cells on the single cell level.

Highly purified (97%-99%) and viable (99%) peripheral blood monocytes obtained by EDTA-reversible adherence to autologous-serum-precoated plastic surfaces could rapidly lyse a variety of tumor cells in a 3-4 hr 51Cr release assay. Using these monocytes as effectors, a short-term agarose/conjugate assay was utilized, permitting us to examine the interaction between fresh human monocytes and neoplastic target cells on a single cell level. That the tumor-bound effector cells were indeed monocytes was confirmed by employing the monocyte-specific monoclonal antibody 61D3, which stained 95%-99% of the mononuclear cells bound to conjugated and killed K562 tumor targets. The binding of monocytes to target cells appeared to be temperature dependent and was extremely rapid, reaching a plateau after 5 min at 30 degrees C. Our findings demonstrated for the first time that only a proportion of human blood monocytes can bind to a particular target cell and that only a fraction of the binding cells have the intrinsic potential to kill those neoplastic targets. The proportion of monocytes capable of binding and killing varies between individuals and also depends on the tumor cell used, indicating heterogeneity in the monocyte and tumor cell populations. The highest proportion of monocytes bind to the human erythromyeloid leukemia K562 cell line (13%-50%). The frequency of monocytes capable of killing K562 tumor cells is relatively low (7%-13%). The system described here should be useful to study the heterogeneity of mononuclear phagocytes and to analyze the molecular basis of the interaction between those effector cells and neoplastic target cells.

Antibodies, Monoclonal↗
PubMed1983

Potentiation of the cytolytic activity of peripheral blood monocytes by lymphokines and interferon.

Human peripheral blood monocytes obtained by EDTA-reversible adherence to plastic surfaces precoated with autologous serum can rapidly lyse a variety of tumor cells. That the effector cells in this system are indeed monocytes has been demonstrated (1). Using a short-term (3 to 4 hr) 51Cr-release assay and the single cell conjugate cytotoxic assay, we studied the effects of lymphokine-rich supernatants containing gamma-interferon and partially purified fibroblast interferon on the monocyte cytolytic activity. Overnight incubation of the monocytes in fetal bovine serum-containing medium resulted in a relatively small decrease in cytotoxic activity compared to the one obtained with monocytes incubated in autologous serum. The addition of lymphokines or interferon under both incubation conditions resulted in augmented activity as measured in the 51Cr-release assay. However, the proportions of binding and cytotoxic monocytes, determined in the single cell conjugate assay, did not increase. These results suggest that augmented activity is not due to recruitment of inactive cells. Kinetics studies of tumor cell lysis indicate the increase in killing efficiency is probably due to both an increase in the rate of killing and in the recycling ability of the cytotoxic cells. Using the conjugate/agarose technique, we also demonstrated that excess tumor cells could impair the lytic machinery of freshly isolated monocytes, whereas monocytes treated with lymphokines or interferon partially lost their sensitivity to this inhibitory effect. The ability of tumor cells to impair the lytic machinery of monocytes could be one of the mechanisms by which tumors escape immunosurveillance.

Cells, Cultured↗
PubMed1983

Erythromyeloid tumor cells (K562) induce PGE synthesis in human peripheral blood monocytes.

Human peripheral blood monocytes were found to spontaneously produce prostaglandin of the E series (PGE) in culture medium (0.5 ng to 3.0 ng/7.5 X 10(5) cells), and the addition of K562 tumor cells enhanced the production by five- to 15-fold after 18 hr of incubation. PGE2 (10(-6) M) inhibited the cytolytic activity of freshly isolated peripheral blood monocytes against K562 target cells by 50%. The PGE production was inhibited by inhibitors of cyclo-oxygenase (indomethacin, aspirin, and ETYA) when present during the incubation. However, pretreatment of monocytes with these cyclo-oxygenase inhibitors was ineffective in preventing PGE production. Kinetic experiments showed that appreciable stimulation of PGE production occurred only after 6 hr of co-culture. Other human tumor cell lines (HSB, SB, and CEM) enhanced PGE production upon co-culture with monocytes but to a lesser extent (twofold to threefold). Monocytes treated with 0.4% formaldehyde or heat (56 degrees C) were not capable of producing PGE when cultured alone or with K526 tumor cells. In contrast, formaldehyde-treated, but not heat-treated, K562 tumor cells were able to induce monocytes to produce PGE. By using a single cell conjugation assay, K562 tumor cells were found to bind equally well to treated or untreated monocytes. In contrast, the lytic activity of treated monocytes against K562 target cells was abolished. The presence of protein synthesis inhibitor, cycloheximide, was found to inhibit PGE production by monocytes cultured alone or with K562 tumor cells. Supernatants from K562 tumor cell cultures were also capable of inducing monocytes to produce PGE, and their effect on PGE production from monocytes was suppressed by cycloheximide. In addition, pretreatment of either K562 tumor cells or monocytes with an irreversible protein synthesis inhibitor, emetine, also suppressed the production of PGE upon co-culture with the untreated counterpart. The production of PGE by monocytes in response to exposure to tumor cells may represent a mechanism whereby tumor cells subvert host immune defense against them.

Cell Line↗
PubMed1982

Spontaneous EEG correlates of intellectual functioning in talented and handicapped adolescents.

EEG correlates of intellectual functioning were investigated in 35 academically talented and 20 academically handicapped adolescents. EEG data from Ertl's Brainwave Analyzer were factor-analyzed and factor scores entered into regression equations predicting four primary mental abilities, verbal, numerical, reasoning, spatial, and two sequential tests of educational progress, reading and mathematics. Analysis indicated that (1) frequency ratio, with relatively greater left-hemisphere activity was the most important EEG variable related to mental functioning in the talented group; (2) while EEG period and alpha ratio were the two most important EEG variables related to intellectual functioning in the mentally handicapped group; (3) hemispheric symmetry was of some importance for both groups, with greater symmetry being associated with superior performance. Contrary to Ertl's neural efficiency theory, (1) neural information transfer rate was significantly positively (not negatively as predicted) related to intellectual performance (for the handicapped group only), and (2) alpha was significantly related to intellectual functioning (for the handicapped group only). Further research is needed to extend and confirm the above findings dealing with persons scoring in the normal IQ range and during mentally active as well as resting conditions.

Adolescent↗
PubMed1981

Regulation of human natural killing. I. The role of monocytes, interferon, and prostaglandins.

We have found that human endogenous natural killer activity as measured in a rapid 51Cr release assay is unaffected by the presence of monocytes. Moreover, stimulation of natural killer cells by poly I:C is independent of monocytes. In contrast, the presence of monocytes in a mixed population of mononuclear cells that have been stimulated by poly I:C suppresses NK activity. The suppression is shown to be partially reversible if indomethacin (10(-6) M) is added to the cultures during stimulation. Culture supernatants of monocytes stimulated with poly I:C are shown to contain PGE1 in a radioimmunoassay, and have NK inhibitory activity comparable to that obtained with exogenous PGE1 added to NK assays at a concentration range of 10(-7) to 10(-9) M. Culture supernatants from poly I:C-stimulated monocytes do not have detectable levels of antiviral activity. In contrast, plastic nonadherent cells stimulated with poly I:C produce significant levels of interferon (100 to 200 U/ml/2 x 10(6) cells) but almost undetectable amounts of PGE. Supernatants of nonadherent cells incubated with indomethacin (10(-6) M) alone augment NK activity. Taken together, the results suggest that stimulation of mononuclear cells with poly I:C is dependent on and regulated by the relative levels of interferon produced by lymphocytes and PGE produced by monocytes.

Cell Adhesion↗