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Biomedical subjects

R D Nelson

Publications and source records attributed to R D Nelson.

At least 109 records · Page 6Linked to original sources
PubMed1979

Chemotactic deactivation of human neutrophils: possible relationship to stimulation of oxidative metabolism.

Neutrophils preexposed to high concentrations of activated complement or synthetic N-formyl methionyl peptides are inhibited in their subsequent spontaneous and chemotactic migratory responses. We have considered the possibility that a part of this nonspecific loss of migratory function may be attributable to the interaction of the leukocytes with reactive forms of oxygen deriving from the cytotaxin-induced burst of oxidative metabolic activity. For these studies we have assessed the effect of preexposure of neutrophils from patients with chronic granulomatous disease to cytotaxins on their subsequent migratory responses. We find that these responses are not altered by preexposure to either cytotaxin. Thus, there appears to be a functional relationship between deactivation and the ability of the normal neutrophil to undergo a cytotaxin-induced respiratory burst.

Blood↗
PubMed1979

Human neutrophil migratory function: modulatory effect of interactions with opsonized particles.

Human polymorphonuclear neutrophils preexposed to cytotaxin or to phagocytizable particles exhibited reduced spontaneous and chemotactic migratory responses. This influence of cytotaxin appears to be related to toxic effects of by-products of hexose monophosphate shunt stimulation. To determine whether a phagocytic stimulus may inhibit subsequent neutrophil migratory functions by the same mechanism, we assessed spontaneous and chemotactic migratory functions of neutrophils from individuals with chronic granulomatous disease exposed to antibody-opsonized sheep erythrocytes. Our results showed that phagocytosis of such particles did not alter these migratory responses of chronic granulomatous disease neutrophils and suggest that phagocytic stimulation of normal neutrophils may modulate migratory function by some mechanism dependent upon hexose monophosphate shunt stimulation.

Cell Movement↗
PubMed1979

Cytotaxin receptors of neutrophils: evidence that F-methionyl peptides and pepstatin share a common receptor.

Pepstatin, a chemotactic microbial pentapeptide, competes with f-Met-Leu-[3H]Phe for binding to human neutrophils. Furthermore, porcine neutrophils, which neither specifically bind nor respond chemotactically to the synthetic f-methionyl peptides, also fail to respond chemotactically to pepstatin. These results suggest that pepstatin shares a receptor on the neutrophil with f-methionyl peptides, despite their completely different amino acid compositions. The specificity of this cytotaxin receptor may therefore be broader than expected and depend on ligand characteristics distinct from primary structure.

Animals↗
PubMed1979

Mechanisms of the adjuvant effect of hemoglobin in experimental peritonitis. V. The significance of the coordinated iron component.

Adjuvant effects of hemoglobin, methemoglobin, hematin, and ferric nitrilotriacetate (FENTA) on the lethality of E. coli peritonitis in rats were compared. The functional importance of coordinated iron was affirmed by the findings that: (1) hematin simulated the hemoglobin effect when administered on an iron-equivalent basis and (2) hematoporphyrin was inactive at the same levels as hematin. The effects of hemoglobin and methemoglobin were virtually identical, suggesting that the oxidation state of the metallic center is immaterial, and analyses of peritoneal contents during lethal peritonitis promoted by either adjuvant revealed insignificant interconversions of these compounds. Saturation of systemic iron-binding capacity could not be detected during lethal E. coli--hemoglobin peritonitis and deliberate saturation of systemic transferrin by infusions of intravenous FENTA did not enhance the adjuvant effect of hemoglobin. The adjuvant effect of intraperitoneally administered FENTA was effectively nullified by simultaneous intraperitoneal deferoxamine injection, but the same maneuver had no effect on hemoglobin potency. Thus the adjuvant effect of hemoglobin in experimental peritonitis is functionally dependent on the iron component but cannot be explained by a non-heme iron flux. These characteristics suggest that adverse interactions of coordinated iron species with host defense chemistry will be fruitful subjects for future study.

Animals↗
PubMed1978

Phagocytosis of Candida albicans by human leukocytes: opsonic requirements.

The kinetics of phagocytosis of Candida albicans by human polymorphonuclear leukocytes was studied. The basis for these studies was a phagocytic assay with use of C. albicans radiolabeled with [3H]adenine. After incubation of leukocytes with C. albicans, extracellular C. albicans was separated from phagocytes by centrifugation through Ficoll-Hypaque suspensions (specific density, 1.175 g/cm3). Recovery of leukocytes by this technique was greater than or equal to 85%. The initial rate of phagocytosis was more rapid than that previously reported for bacteria. Ethylenediaminetetraacetate, vinblastine, ethylmaleimide, NaF, and ice bath temperature completely inhibited phagocytosis. Colchicine had no effect, and NaN3 was partially inhibitory. Pooled sera possessed low titers (greater than or equal to 1:40) of heat-stable opsonins. The opsonic activity of pooled sera was shown to depend primarily upon complement activated through both the alternative and classical pathways. Decomplemented hyperimmune sera were opsonic at high dilutions (greater than or equal to 1:160), and complement amplified the initial rate of ingestion seen with hyperimmune sera.

Candida albicans↗
PubMed1978

Chemokinetic and chemotactic factors in psoriasis scale extracts.

Soluble solutions of psoriasis scale were prepared by extracting scales in 6 m urea and removing urea by dialysis. Extracts were tested for chemokinetic and chemotactic activity for human polymorphonuclear leukocytes and mononuclear cells in vitro using the migration under agarose assay. Five of 6 extracts demonstrated significant chemotactic activity for polymorphonuclear leukocytes, and 4 or 6 were also chemotactic for mononuclear cells. All extracts augmented random migration of polymorphonuclear leukoyctes (chemokinesis). Checkerboard epxeriments showed extracts were truly chemotactic as well as chemokinetic. The kinetics of polymorphonuclear leukocyte and mononuclear cell chemotaxis toward psoriasis scale extracts were similar to kinetics of chemotaxis toward a bacteria-derived chemotactic factor and zymosan-activated serum. Since zymosan-activated serum and purified C5a were not chemokinetic, psoriasis scale extract was more like a bacteria-culture supernate than these complement factors in augmenting random migration of polymorphonuclear leukocytes. Substances in psoriasis scale may be capable of influencing the inflammatory response.

Cell Movement↗
PubMed1978

Chemotactic deactivation of human neutrophils: evidence for nonspecific and specific components.

Human polymorphonuclear neutrophils have been preexposed to activated complement as zymosan-activated serum (ZAS) or to the chemotactic oligopeptide N-formyl methionylphenylalanine (F-Met-Phe). Spontaneous migration and chemotactic responses toward the deactivating and other cytotaxins were monitored after washing and resuspension of cells in cytotaxin-free medium. Two patterns of deactivation were observed. Preexposure of the leukocytes to high doses of ZAS or F-Met-Phe decreased all subsequent migratory responses. Preexposure of the leukocytes to lower doses of ZAS or F-Met-Phe decreased only a subsequent chemotactic response to the deactivating cytotaxin. These results suggest two mechanisms, or components, of chemotactic deactivation.

Cell Movement↗
PubMed1977

Chemiluminescence response of human leukocytes: influence of medium components on light production.

Light-producing reactions have been reported to occur after phagocytosis of opsonized particles by human polymorphonuclear neutrophils, eosinophils, and monocytes. Such chemiluminescence appears to be related to the generation of singlet oxygen, superoxide, and hydroxyl radicals, which have also been implicated as microbicidal agents. In examining the influences of various medium components on leukocyte chemiluminescence, we have observed that the amount of light measured is increased by addition of soluble protein, the amino acids tyrosine and tryptophane, or excess zymosan to the reaction medium. These agents appear to produce their effect not by increasing the rate of phagocytosis, but by providing substrate for secondary light-producing reactions. Polystyrene particles do not provide a suitable substrate for such secondary light-producing reactions. This is evidenced by the failure of ingested latex to stimulate high levels of chemiluminescence in the cellular system and their failure to augment light production in two noncellular chemiluminescent reactions. Some of the light generated in the cellular chemiluminescence response may derive from secondary reactions, which occur outside of the phagocyte. Support for this phenomenon is provided by two experiments. In one, addition of supplementary, nonopsonized zymosan to the reaction, after phagocytosis of opsonized zymosan is complete, resulted in an increased level of chemiluminescence. In another, addition of nonopsonized zymosan, together with latex particles, resulted in a significant increase in chemiluminescence. The results of the latter experiment also support our hypothesis that latex does not provide an appropriate substrate for secondary light-producing reactions. These observations suggest that leukocytes activated by phagocytosis generate electronically activated radicals which act intra- and extracellularly and that the amino acids tyrosine and trytophane may provide one substrate through which these agents act.

Culture Media↗
PubMed1976

Chemiluminescence response of phagocytizing human monocytes.

Chemiluminescence (CL) occurs as a consequence of phagocytosis of bacteria or inert particles by human polymorphonuclear neutrophils. This phenomenon appears to be related to the production of singlet oxygen and/or electronically excited carbonyl groups which relax with light emission. We report that human monocytes also produce CL after phagocytosis of opsonized bacteria, fungi, or zymosan particles. Monocytes produce approximately one-third of the CL produced by polymorphonuclear neutrophils for all three particles, reflecting possible metabolic differences between cells of these types. Addition of exogenous superoxide dismutase reduced the peak production of CL by 65% for cells of both types, whereas raising the temperature of the cultures from 25 to 37 C approximately doubled the peak CL responses.

Candida albicans↗
PubMed1976

Chemotaxis of human polymorphonuclear neutrophils under agarose: morphologic changes associated with the chemotactic response.

Studies of morphologic changes of leukocytes responding to a chemotaxin gradient have been limited due, in part, to difficulties encountered with detailed electron microscopic analysis of cells migrating through membrane filters or on glass slides. The recently developed migration under agarose method provides a new opportunity to view and compare morphologies of cells migrating spontaneously and in response to a chemotaxin gradient. The present report describes the morphologic features we have observed by scanning electron microscopy of human polymorphonuclear leukocytes both spreading on a cover slip and migrating under agarose. We demonstrate that cells migrating under agarose exhibit a morphology that differs distinctly from that of cells spreading on a cover slip and, further, that the cytoplasmic periphery of cells responding to a chemotactic gradient under agarose becomes very irregular due to the formation of blebs or small pseudopodium-like structures.

Chemotaxis, Leukocyte↗
PubMed1975

Chemotaxis under agarose: a new and simple method for measuring chemotaxis and spontaneous migration of human polymorphonuclear leukocytes and monocytes.

A variety of methods have been devised for the study of spontaneous and directed cell migration. Among these, the membrane filter method introduced by Boyden in 1962, with its more recent modifications, has become the technique of choice for studies of leukocyte migration in vitro. This method, however, cannot be applied without alteration to studies of chemotaxis and spontaneous migration of cells of different types. We describe in this report a new and simple method for studying human leukocyte chemotaxis, in vitro, which is based upon migration of cells under agarose gel. This method has application to both polymorphonuclear leukocytes and monocytes, permits measurement of both chemotaxis and spontaneous migration, requires fewer cells per test, and is rapid, simple, reproducible, and inexpensive to set up.

Cell Movement↗
PubMed1975

Macrophage requirement for production of guinea pig migration inhibitory factor (MIF) in vitro.

Methods devised for generation and assay of migration inhibitory factor (MIF) on a reduced scale have permitted the performance of experiments which demonstrate that glass bead column-purified guinea pig lymph node lymphocytes do not produce MIF or proliferate in response to antigen. Evidence that the macrophage is the essential cellular element eliminated by the purification procedure is demonstrated by the restoration of both lymphocyte responses upon addition of 5% macrophages to the purified lymphocytes. Autologous, immune and syngeneic, non-immune peritoneal exudate macrophages were equally effective in restoring MF production by purified lymphocytes. Supernatants which inhibited the migration of peritoneal exudate macrophages had only minimal or no effect on the migration of alveolar macrophages, confirming that the inhibitory effects studied were attributable to MF and not cytophilic antibody.

Animals↗
PubMedDate not supplied

Thermal injury, the inflammatory process, and wound dressing reduce human neutrophil chemotaxis to four attractants.

The purpose of this study was to assess the influence of thermal injury and the inflammatory process on chemotactic responses of neutrophils to four attractants (N-formyl-methionyl-leucyl-phenylalanine, the complement fragment C5a, interleukin-8, and leukotriene B4) under agarose, expression of Mac-1 (CD11b/CD18) adherence receptors on the cell surface, and polymerization of actin in the cell cytoplasm. Circulating neutrophils were isolated from peripheral blood, and exudate neutrophils from fluid collecting under two different wound dressings applied to abrasion sites of healthy subjects and to skin graft donor sites of patients with burns. Burn injury reduced the chemotactic responses of circulating neutrophils to all four attractants, suggesting a "global" defect in chemotactic function. Patient-exudate neutrophils collected under Tegaderm exhibited further decrements in all chemotactic responses, and patient-exudate neutrophils collected under Biobrane were nonmotile. The exudate neutrophils collected under Biobrane expressed high levels of Mac-1 receptors and irreversibly polymerized actin, which may contribute to the nonmotility of these exudate cells.

Actins↗
PubMedDate not supplied

Targeting collecting tubules using the aquaporin-2 promoter.

The aquaporin-2 promoter has been used to drive Cre recombinase expression in order to achieve renal collecting duct principal cell specific gene deletion. This technique requires two lines of mice: one transgenic mouse line containing a cell-specific promoter driving Cre recombinase expression and the other line, engineered using gene targeting strategies, that contains a lox-flanked target gene of interest. Mating of these two mouse lines permits cell-specific deletion of the target gene. This method could ultimately be used to obtain targeted deletion of any gene in any cell type in the kidney for which a specific promoter has been identified. The applications of this technology, as well as its strengths and weaknesses, are discussed with particular reference to the kidney.

Animals↗