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Biomedical subjects

B Arnold

Publications and source records attributed to B Arnold.

At least 127 records · Page 7Linked to original sources
PubMed1979

Lysolecithin analogs as adjuvants in delayed-type hypersensitivity in mice. I. Characterization of the adjuvant effect.

The adjuvant activity of 5 different lysolecithin analogs (LLA) has been studied in delayed-type hypersensitivity (DTH) using fowl gamma globulin, bovine serum albumin and the terpolymer L-glutamic acid 60-L-alanine30-L-tyrosine10(GAT), as antigens. Increased DTH responses, by factors of 1.8--2.0 in CBA and BALB/c mice, showed that LLA are immunopotentiators if given intraperitoneally (i.p.) or subcutaneously (s.c.) together with the antigen. The concentration range, within which LLA are active, is limited to 10--20 micrograms/mouse s.c. and 100--300 micrograms/mouse i.p. Adjuvanticity was tested as a function of the LLA structure. The most pronounced immunopotentiation was obtained with racemic 1-octadecyl-2-methylglycero-3-phosphorylcholine (ET18-O-CH3). The LLA became less active with decreasing numbers of C atoms in the alkyl chain.

Adjuvants, Immunologic↗
PubMed1979

Lysolecithin analogs as adjuvants in delayed-type hypersensitivity in mice. II. Studies on the mode of action.

Lysolecithin analogs (LLA) possess adjuvant activity in delayed-type hypersensitivity (DTH). To elucidate their mode of action, we studied the influence of LLA on the recruitment of hemopoietic progenitor cells and on the induction and transfer of DTH. Whereas the number and composition of colony-forming cells (CFC) in the bone marrow remained unaltered in LLA-treated mice, the number of CFC in the spleen was augmented severalfold, and the content of macrophage progenitors was remarkably increased. DTH was induced with macrophages from peritoneal cells (PC) pulsed with keyhole limpet hemocyanin (KLH). A more marked DTH response was obtained with KLH-pulsed PC from LLA-treated mice than from mice given phosphate-buffered saline (PBS). On the other hand, there was no difference in the DTH response following adoptive transfer of sensitized cells to naive mice pretreated either with PBS or LLA. It is concluded that the adjuvant effect of LLA can be accounted for partly in terms of their effects on macrophage progenitors and partly in terms of a more effective T cell activation by antigens associated with LLA-derived macrophages.

Adjuvants, Immunologic↗
PubMed1979

An improved method for selecting T-cell hybridomas by the fluorescence-activated cell sorter.

A two-step sorting procedure with the fluorescence-activated cell sorter (FACS) is described to select T cell hybridomas from cell populations obtained from the fusion of activated T cells and T- lymphoma cells. Cells are first sorted on the basis of differences in cell-surface antigens. After a period of growth in culture, the cells are then stained with the DNA-labeling dye dis-benzimidazole 33258 Hoechst and sorted on the basis of their DNA content. From 15 to 25% of the resulting cell clones, growing out of limiting dilutions, were hybrid lines as judged by chromosome analysis.

Animals↗
PubMed1978

Distribution and metabolism of synthetic alkyl analogs of lysophosphatidylcholine in mice.

Stability, distribution and metabolic fate of alkyl analogs of lysophosphatidylcholine have been studied in mice. Analogs employed were 1-hexadecyl- and 1-dodecyl-propanediol-3-phosphorylcholine (2-deoxy-lysophosphatidylcholine) and rac-1-octadecyl-2-methyl-glycero-3-phosphorylcholine (2-methoxy-lysophosphatidylcholine). It is demonstrated that (1) the half-life of these compounds in the organism was increased to the order of days as compared to minutes or hours for natural lysophosphatidylcholine, (2) the analogs were slowly degraded in vivo with partial incorporation of the hydrophobic part into neutral lipids and phosphatidylcholine. Deoxy analogs were apparently degraded faster than methoxy derivatives, and (3) due to this metabolism, accumulation of these compounds, even after repeated injections, did not occur in mice. Intravenous and intraperitoneal injections led to rapid and complete distribution of the lysolipids with slight enrichment in liver, kidneys and intestine. Subcutaneous or oral application resulted in a similar distribution, however, remarkable depot effects at the sites of administration were observed. Experiments with tumor-bearing mice indicated a reduced metabolic turnover and thus a slight enrichment of ether-lysophosphatidylcholine analogs in tumor tissue.

Animals↗
PubMed1978

Relation of cytolytic activity of an ether-deoxy lysophosphatidylcholine analog to available membrane surface. Comparison of normal and tumor cells from mice.

1-Hexadecylpropanediol-3-phosphorylcholine, an ether-deoxy analog of lysophosphatidylcholine, has been employed to study the sensitivity of various types of mouse cells with respect to changes in membrane permeability induced by lysophosphatidylcholine. Cells used included erythrocytes, thymocytes, spleen cells and macrophage, as well as 4 different tumors (2 lymphomas, 1 Ehrlich acites and 1 methylcholanthren-induced fibrosarcoma). The sensitivity to the lysophosphatide (on a per-cell basis) of the above cell types varied by a factor of 65. When lytic concentrations were related to available membrane surface, this variation was reduced to a factor of 2.5. No principal difference was observed between the sensitivity of normal versus tumor cell membranes with respect to lysophosphatidylcholine lysis. Membrane surface, available for lysophosphatidylcholine, has been estimated from binding equilibria of 14C-labelled deoxy-lysophosphatidylcholine to the cells under standardized conditions. This method is based on the finding that binding equilibria of lysophospholipids to cells are predominantly determined by the available membrane surface.

Animals↗
PubMed1977

Left atrial pressure and sodium balance in conscious dogs on a low sodium intake.

10 conscious chronically prepared dogs were used. After recovery from thoracotomy (catheter into the left atrium, nylon purse string around the mitral annulus) they were kept chronically on a low sodium intake (less than 0.5 meq Na/kg bw daily). On 51 days left atrial pressure (LAP) was increased for 60 min about 10 cm H2O once daily by tightening the purse string (distension period: DP). During (DP) urine volume (V) increased about threefold, and sodium excretion (ENa) about sixfold. The amount of renal sodium loss on the days when LAP was increased exceeded the daily intake considerably. The application of DOCA (15 mg i.m.) did not diminish ENa during DP and 60 min therere increased by about 15 mm Hg. The data suggest that stimulation of intrathoracic receptors by a reversible mitral stenosis augments renal sodium excretion even in a state of a highly stimulated tubular sodium resorption.

Animals↗
PubMed1977

Quantitative studies on lysolecithin-mediated hemolysis. Use of ether-deoxy lysolecithin analogs with varying aliphatic chain-lengths.

The process of lysolecithin-mediated hemolysis has been investigated by use of various ether-deoxy lysolecithin analogs (1-alkyl-propanediol-3-phosphorylcholine) with alkyl residues of 10-22 carbon atoms. Hemolytic activities were defined either as molar amounts to be added for 50% lysis (L50) or as cell-bound amounts at 50% lysis (A50). It was found, that in contrast to L50, A50 values are independent of experimental conditions. Moreover, L50 values primarily reflect the binding affinities, while A50 values give more accurate information on the actual membrane-disturbing potential. The strongest hemolytic C16-lysolecithin analog required 2 - 10(7) or 5 - 10(7) molecules bound per cell for 50% lysis at 0 or 37degrees C, respectively, corresponding to about 10 or 25% of the total membrane phospholipids. Evidence is presented, indicating that (a) lysophosphatides bind to cells below their critical micelle concentration, (b) micelles themselves are not generally necessary for cell lysis. Red cells of different species (man and cattle) as well as at varying temperatures exhibit significantly different sensitivities in terms of L50 and A50 values. These differences, however, depend on the degree of hydrophobicity of the lysolecithins and disappear in the case of lysolipids having C10 or C12 aliphatic residues. The data are in agreement with our hypothesis that cellular sensitivity to lysolecithin lysis may be determined by the degree of segregation of lysolecithin-rich areas within the membrane lipid phase.

Animals↗
PubMed1976

Quantitative studies on lysolecithin mediated hemolysis. Benzylated lysolecithin as a probe to study effects of temperature and red cell species on the hemolytic reaction.

The slow reacting hemolytic lysolecithin analog 1-octadecyl-2-benzyl-glycero-3-phosphorylcholine has been employed for a detailed study of the process of lysolecithin induced hemolysis. Using a radiolabelled analog we found that the different sensitivities of red cells from different species (chicken, man, cattle) are not paralleled by the binding affinities of lysolecithin. Moreover, lysophosphatide binding to the cells is reduced at low temperatures while the hemolytic activity increases. In contrast to continuous changes of lytic activity and binding between 0 and 37 degrees C, the velocity of the hemolytic reaction with human erythrocytes is extraordinarily fast at 10 degrees C. Experiments in sucrose containing buffer indicated principally different lysis mechanisms below and above 15 degrees C. We have further shown that cells loaded sublytically with the lysolecithin at 37 degrees C undergo spontaneous lysis upon cooling to 0 degrees C. The degree of lysis under these conditions, however, is diminished with increasing amounts of cell-bound lysolipid. Determinations of membrane microviscosities by means of fluorescence polarization revealed some qualitative relations between membrane fluidity and sensitivity to lysolecithin. The data are discussed on the basis of recent reports indicating that lysolecithin-distribution in mixed lipid phases may be heterogeneous depending on lipid composition and temperature.

Animals↗
PubMed1976

Teaching nuns' perceptions of white and black pupils as a function of authoritarianism and other factors.

A sample of 283 teching nuns described the White Pupil, the Black Pupil, and the Ideal Pupil on an adjective description form. A Prejudice score was computed by subtracting the Ideal minus Black differences summed across 52 items from the Ideal minus White differences. Analyses based on 269 subjects revealed that neither age nor amount of prior contact with minorities predicted level of prejiduce. However, high and low-F-scale scorers differed significantly on the Prejudice score and on selected pupil perception factors. Implications in regard to training programs on racial attitudes were discussed.

Black or African American↗
PubMed1976

Molecular aggregation of the slow reacting hemolytic lysolecithin analog 1-octadecyl-2-benzyl-glycero-3-phosphorylcholine in aqueous solution.

An attempt has been made to relate the retarded adsoprtion to red cells of the slow reacting hemolytic phosphatide Rac. 1-octadecyl-2-benzyl-glycero-3-phosphorylcholine (benzyl-lysolecithin) to its aggregation status in aqueous solution. Light scattering measurements indicate a critical micelle concentration at 37 degrees of less than 2 X 10(-6) M. The micellar weight as determined by angle dependent light scattering is 6 X 10(7) with about 97 000 molecules per micells. The aggregates, which according to electron-microscopic observations are more similar to lecithin-liposomes than to usual lysolecithin-micelles, undergo a phase transition at 14 degrees from a tightly packed liquid-crystalline state to the more loose structure of a gel phase with increased mobility of the aliphatic chains. The enthalpy of transition is 4.2 kcal/mole. These changes of the micellar structure are reflected in the binding kinetics of benzyl-lysolecithin to red cells in that the binding rate is rather constant below, but strongly increasing above the transition temperature. It is concluded that the unusual micellar structure is responsible for the retarded adsorption of this lysolecithin analog to red cells and that the rate of adsorption is probably determined by the rate of escape of single lysophosphatide molecules from the micelles.

Binding Sites↗
PubMedDate not supplied

Expansion of CD3+CD56+ lymphocytes correlates with induction of cytotoxicity by interleukin-2 gene transfer in human breast tumor cultures.

BACKGROUND: Mice immunized with murine mammary carcinoma cells genetically engineered to secrete interleukin-2 (IL-2) are rendered resistant to subsequent challenge with unmodified tumor cells, and in the case of mice bearing established tumors, the rate of development of pulmonary metastases is reduced. Despite these encouraging animal results, little is known about the induction of antitumor immunity by IL-2 gene transfer in human breast cancer. METHODS: Adenovirally mediated IL-2 gene transfer was performed in 12 tumor fragment cultures established from seven primary breast cancers. Autologous tumor infiltrating lymphocytes (TILs) or peripheral blood mononuclear cells (PBMCs) were cocultured with transduced tumor fragments, and changes in phenotype and cytotoxicity were measured. RESULTS: IL-2 was never detectable in the untransduced cultures, but it peaked at 5.0-1,324.8 ng/ml in the transduced cultures. Lymphocyte counts declined in all untransduced cultures, but they increased two- to sevenfold in four transduced cultures. CD4:CD8 ratios decreased from a mean of 2.11 at baseline to 1.27 after stimulation in coculture (p = 0.03). Expansion of lymphocytes expressing the natural killer cell phenotype (CD3-CD56+) occurred in only one culture, but the CD3+CD56+ population increased in four of six cultures. Lymphocytes from four of 10 cocultures generated significant cytotoxicity against allogeneic breast cancer cells. Induction of cytotoxicity correlated with expansion of the CD3+CD56+ phenotype (R2 = 0.805, p = 0.02). CONCLUSIONS: IL-2 gene expression by human breast cancer causes expansion of CD3+CD56+ cytotoxic-lymphocytes. This phenotype is consistent with that of a non-major histocompatibility complex (MHC)-restricted cytokine induced killer cell population previously described.

Adult↗
PubMedDate not supplied

Alpha B-crystallin in the mammalian inner ear.

To study the distribution of alpha B-crystallin, formalin-fixed preparations of the inner ear of the rat, cynomolgus monkey, rhesus monkey and human were stained immunohistochemically for alpha B-crystallin. In all cochleae investigated, intense staining for alpha B-crystallin was found in the inner and outer pillars as well as in the cells of Hensen and Claudius. In the primate inner ear, alpha B-crystallin was also present in the polygonal epithelial cells of Reissner's membrane, the interdental cells and some fibrocytes of the spiral limbus, epithelial cells of the outer spiral sulcus and the Schwann cells of the 8th nerve. In the primate stria vascularis, alpha B-crystallin was mainly seen in the basal cell layer and the adjacent cells of the connective tissue layer. alpha B-crystallin was found to be present in a large variety of cells in the inner ear surrounding the scala media.

Aged↗