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Biomedical subjects

D A Bass

Publications and source records attributed to D A Bass.

At least 73 records · Page 4Linked to original sources
PubMed1981

1-O-Alkyl-sn-glyceryl-3-phosphorylcholines: a novel class of neutrophil stimulants.

1-O-Alkyl-2-O-acetyl-sn-glyceryl-3-phosphorylcholine aggregates and degranulates platelets and polymorphonuclear neutrophils. Here, the bioactivities of this platelet-activating factor, its 2-O-ethyl, and its 2-lyso derivatives were examined further. Each phospholipid aggregated and degranulated rabbit platelets and neutrophils with relative potencies of about 10,000 1,000, and 1, respectively. For rabbit neutrophils, and 2-O-acetyl compound was active in nanomolar and lower concentrations; required extracellular calcium and magnesium in order to induce aggregation; and required extracellular calcium and cytochlasin B in order to induce optimal degranulation. Furthermore the 2-O-acetyl and 2-O-ethyl compounds, in concentrations about tenfold higher than those required for rabbit neutrophils, aggregated and degranulated human neutrophils. With reference to these human neutrophil responses, degranulation required, and aggregation was dramatically enhanced by, cytochalasin B. The lysoanalog was unable to induce these response in the human cells. Thus, these lipids represent a novel class of neutrophil stimulants that closely resemble certain chemotactic factors (eg, C5a and synthetic oligopeptides) in their ability to aggregate and degranulate neutrophils and in the influences which calcium, magnesium and cytochalasin B have on their bioactions. Because platelet-activating factor circulates in the blood of rabbits and, perhaps, humans during anaphylaxis and is suspected of being involved in other syndromes such as serum sickness, this lipid may have unique biologic significance: it may act to recruit platelets and neutrophils into the lesions of these and similar pathologic syndromes.

Animals↗
PubMed1980

Role of arachidonic acid in stimulation of hexose transport by human polymorphonuclear leukocytes.

Whereas insulin does not stimulate hexose transport in polymorphonuclear leukocytes, we recently reported that C5a causes the leukocytes to take up 2-[(3)H]deoxyglucose. We now find that fMet-Leu-Phe, in a concentration-related manner with an EC(50) (concentration producing 50% of stimulatory activity) of 1.2 nM, causes a 5.5-fold stimulation of deoxyglucose uptake. Moreover, arachidonic acid (5,8,11,14-eicosatetraenoic acid) similarly stimulated deoxyglucose uptake with an EC(50) of 0.6 muM. Stimulation by arachidonic acid exhibited structural specificity; five structural analogues of arachidonic acid, including arachidonyl alcohol, 8,11,14-eicosatrienoic acid, 11,14,17-eicosatrienoic acid, 5,8,11,14-eicosatetraynoic acid, and arachidic acid, did not stimulate deoxyglucose uptake. Release and metabolism of arachidonic acid may also be involved in the stimulation of deoxyglucose uptake by fMet-Leu-Phe. Inhibitors of arachidonic acid metabolism (5,8,11,14-eicosatetraynoic acid, nordihydroguaiaretic acid, indomethacin, aspirin, and benzylimidazole) caused parallel changes in the responses to both arachidonic acid and fMet-Leu-Phe. Stimulation of deoxyglucose uptake of polymorphonuclear leukocytes by chemotactic factors or arachidonic acid had the characteristics of carrier-facilitated hexose transport. The response was saturable with increasing concentrations of stimulant or substrate (deoxyglucose). It was stereospecific (inhibited by D-glucose but not by L-glucose) and was inhibited in resting and stimulated cells by 5 mug of cytochalasin B per ml. It was separable from the stimulation of oxidative metabolism; it occurred normally in polymorphonuclear leukocytes from a patient with chronic granulomatous disease (these are incapable of an oxidative metabolic response to membrane stimuli). Thus, stimulation of polymorphonuclear leukocytes is associated with enhanced hexose transport. Moreover, carrier-facilitated hexose transport and arachidonic acid metabolism may be linked, at least in these leukocytes: arachidonic acid mimies the stimulatory effects of chemotactic factors, and blockade of arachidonic acid metabolism inhibits the stimulation of hexose transport by these agents.

Arachidonic Acids↗
PubMed1980

Eosinopenia of acute infection: Production of eosinopenia by chemotactic factors of acute inflammation.

One distinctive aspect of the response to acute inflammation involves a rapid and persistent decrease in the numbers of circulating eosinophils, yet the mechanisms of this eosinopenia are undefined. One possibility is that the abrupt eosinopenia may be the result of release of small amounts of the chemotactic factors of acute inflammation into the circulation. These studies were designed to examine the numbers of circulating eosinophils after an intravenous injection of zymosan-activated serum, partially purified C5a or the synthetic peptide, N-formyl-methionyl-leucyl-phenylalanine. Each of these factors caused a virtual disappearance of circulating eosinophils within 1 min, a transient return of eosinophils to approximately 50% of control levels after 10-90 min, and a subsequent decrease which persisted for 5 h. In contrast, the numbers of circulating heterophils, although dropping transiently, rapidly returned and rose to elevated levels for 6 h after injection. The response was not caused by adrenal mediation as it occurred normally in adrenalectomized rabbits. Two chemotaxins of allergic inflammation, histamine and the tetrapeptide valine-glycine-serine-glutamic acid, did not cause significant eosinopenia. Circulating granulocytes of patients undergoing hemodialysis, which has been reported to activate complement, demonstrated similar eosinopenic and neutropenic-neutrophilic responses. Thus, in rabbits and in man, intravascular activation or injection of chemotactic factors (C5a or N-formyl-methionyl-leucyl-phenylalanine) causes a brief, nonspecific granulocytopenia followed by a prolonged eosinopenic-neutrophilic response analogous to that seen during acute infection.

Animals↗
PubMed1980

Comparison of human eosinophils from normals and patients with eosinophilia.

Previous studies of the biochemistry and physiology of eosinophils have relied upon cells obtained from patients with eosinophilia (EE). It is unknown whether such cells might have been activated or partially exhausted by the pathological state causing eosinophilia. We examined cell surface charge, membrane transport of deoxyglucose, activation of lyso-somal acid phosphatase, and oxidative metabolism to provide a profile to compare EE with purified normal eosinophils (NE) and normal neutrophils. Eosinophils or neutrophils were obtained in >95% purity from normal individuals and patients with eosinophilia of diverse etiologies. Cell surface charge was determined by electrophoretic mobility in micromoles per second per volt per centimeter. Normal eosinophils demonstrated a surface charge of 2.46+/-0.03. Stimulation of the cells by zymosan-activated serum (ZAS) reduced the surface charge to 1.82+/-0.02. In contrast, the charge of "resting" EE was already reduced (1.89+/-0.05) and was not altered by ZAS. Resting and stimulated neutrophils had a charge of 1.98+/-0.01 and 1.69+/-0.02, respectively. Uptake of [(3)H]2-deoxyglucose has been shown to reflect carrier-facilitated hexose transport in granulocytes. Deoxyglucose uptake by resting NE and NE stimulated by ZAS was 2.40+/-0.40 and 5.44+/-0.39 (cpm x 10(-3)/2 x 10(5) eosinophils), respectively. Resting and stimulated EE demonstrated deoxyglucose uptake of 7.55+/-0.58 and 15.3+/-0.6, respectively.Lysosomal acid phosphatase was determined by an electron microscopic cytochemical technique. In normal eosinophils and neutrophils, lysosomal acid phosphatase in mature cells is held in a latent form. Normal eosinophils demonstrated weakly positive acid phosphatase activity in 7.8+/-1.2% of the specific granules. Normal eosinophils, stimulated by opsonized staphylococci or the calcium ionophore A23187, develop rapid activation of acid phosphatase in approximately 80% of the granules throughout the cells. Resting EE were usually already activated and demonstrated acid phosphatase in 48.6+/-8.6% of the granules (range, 2-95% granules positive; significant activation was observed in preparations in EE from 11 of 15 patients). Oxidative metabolism was monitored by measurement of the hexose monophosphate shunt (HMPS) (metabolism of 1-[(14)C]glucose to (14)CO(2)). Previous studies demonstrated that resting EE have an HMPS activity which is nearly that of stimulated neutrophils, yet EE remain capable of further 7-10-fold increase when stimulated by opsonized zymosan. In contrast, the HMPS of NE (resting and stimulated) was not significantly different from that of neutrophils. Thus eosinophils obtained from patients with eosinophilia appear significantly activated when compared with normal eosinophils by the criteria of surface charge, activation of lysosomal acid phosphatase, membrane hexose transport, and hexose monophosphate shunt activities.

Acid Phosphatase↗
PubMed1980

Functional and metabolic studies of polymorphonuclear leukocytes in the congenital Pelger-Huet anomaly.

Polymorphonuclear leukocytes (PMNL) from two individuals with congenital Pelger-Huet anomaly (PHA) were examined to determine whether functional or metabolic defects accompanied the known morphological abnormality. No abnormalities of the PHA cells, as compared to normal control cells, were found when tested for quantitative leukocyte enzyme activities, nitroblue tetrazolium reduction, hexose monophosphate shunt activity, superoxide production, generation of chemiluminescence, or iodination. The PHA cells, as compared to normal PMNL, demonstrated normal chemotaxis and random migration, as well as bactericidal activity.

Adult↗
PubMed1980

Differential regulation of spleen cell-mediated eosinophil and neutrophil-macrophage production.

Nonadherent spleen cells of mice infected with Trichinella spiralis released growth stimulatory factors (GSFs) in vitro when challenged with excretory/secretory products of muscle stage larvae. The assay of GSF was based on proliferation of normal, nonadherent syngeneic marrow cells in liquid tube cultures. Media conditioned for 1 day by challenged spleen cells stimulated eosinophil production but failed to stimulate production of other cell types. In contrast, media conditioned for 5 days supported eosinophil, neutrophil, and macrophage production. The kinetics of cell production were also different. Eosinophil production started within 1 day, reached a peak at day 2, and was down to control levels by day 4. In contrast, neutrophil/macrophage production began between 2 and 4 days and reached a peak at 6--8 days. The short duration of eosinophil production was evidently due to depletion of growth-factor-responsive cells.

Animals↗
PubMed1980

Stimulation of eosinophil production in vitro by eosinophilopoietin and spleen-cell-derived eosinophil growth-stimulating factor.

Eosinophilopoietin (EPP) was previously characterized by the ability to stimulate eosinophil production in vivo, but these studies could not ascertain whether EPP had a direct effect on the bone marrow or acted indirectly by causing release of eosinophilopoietic activity by other tissues. The present studies demonstrate that EPP stimulates eosinophil growth in liquid culture of mouse bone marrow in vitro. The timing of stimulation by EPP in vivo and in vitro were parallel, with maximal eosinophil growth after 48 hr. Moreover, EPP appears similar to, and possible identical with, the eosinophil growth-stimulating substance (EO-GSF) released by antigenic stimulation of immune nonadherent spleen cells. Both EPP and EO-GSF are of low molecular weight, both produce stimulation of eosinophil growth with identical kinetics, and both produced similar dose-response curves in the liquid culture system.

Animals↗
PubMed1980

Phorbol myristate acetate: in vivo effects upon neutrophils, platelets, and lung.

Phorbol myristate acetate is a potent aggregator of platelets. It was found that it was similarly potent in aggregating neutrophils and in producing striking thrombocytopenia and neutropenia when infused intravenously into rabbits. Aggregation and cytopenia were further correlated in that both types of responses developed abruptly and persisted for more than 90 minutes. Animals infused with 40 microgram/kg of the phorbol ester exhibited moderately severe respiratory distress. Their respiratory rate doubled shortly after the infusion, and this tachypnea persisted for more than 2 hours. At necroscopic examination, the lungs of these rabbits contained two outstanding abnormalities: numerous foci of alveolar hemorrhage and extensive intravascular accumulations of platelets and neutrophils. Thus, these animals had evidence of increased permeability and potential occlusion of the pulmonary microvasculature. Increased permeability, occlusion of lung blood vessels, or the occurrence of both processes was further indicated in studies on animals pre-infused with the plasma protein marker 125I-albumin: animals infused with the phorbol ester had a significantly increased amount of this label in their lungs in spite of thorough postmortem perfusion of their pulmonary vasculature with saline and fixative. We conclude that phorbol myristate acetate has actions in vivo that resemble those of a variety of other platelet (eg, arachidonic acid) and neutrophil (eg, chemotactic factors) aggregating agents that cause cytopenia and lung dysfunction. However, compared with these other agents, the phorbol ester produces respiratory distress of intermediate severity and greater duration. The drug, therefore, induces a syndrome that more closely resembles that seen in a variety of clinical and experimental conditions that associate shocklike states with cytopenia and lung dysfunction. It may serve as a useful tool in the study of the pathophysiology of these states as well as in those produced by other aggregating agents.

Animals↗
PubMed1979

Enhancement of hexose uptake in human polymorphonuclear leukocytes by activated complement component C5a.

The polymorphonuclear leukocyte (PMNL) depends on glucose as a source of energy for motility, chemotaxis, phagocytosis, and bactericidal activity. Activated complement (C5a) at low concentrations stimulates carrier-mediated carbohydrate transport in PMNLs as measured by the uptake of 2-deoxy-D-[(3)H]glucose. Human PMNLs were preincubated at 37 degrees C for 15 min with zymosan-activated human serum or various purified preparations of human C5a. A concentration-dependent increase in deoxyglucose transport (>700% of control) into PMNLs occurred with all test substances. Reaction was linear for 30 min, and uptake of deoxyglucose followed saturation kinetics. C5a caused a decrease in the K(m) for deoxyglucose, from 0.53 to 0.11 mM, without altering the V(max) (44 nmol/30 min per 5 x 10(6) PMNLs in control and 46.6 with C5a). The optimal concentration of C5a for enhanced carrier-mediated transport of deoxyglucose was similar to that which promoted optimal chemotaxis. Activated serum from C5-deficient mice had little or no effect on deoxyglucose transport whereas that from normal syngeneic mice enhanced deoxyglucose transport. C5a did not enhance deoxyglucose transport into isolated erythrocytes, platelets, or lymphocytes. The deoxyglucose within the cell was primarily in the phosphorylated form, and hexokinase activity was not increased in PMNLs stimulated with C5a, indicating that hexokinase was not rate limiting and that enhanced transport was the mechanism of the C5a activity. Insulin at physiologic concentration (10 ng/ml) had no effect on deoxyglucose transport in PMNL and did not act as a competitive inhibitor of C5a. This insulin-like bioactivity could be detected with the amount of C5a that would be present after activation of 0.1-0.5% of the C5 in 1 ml of serum. This suggests that uptake of [(3)H]deoxyglucose by PMNLs might serve as a highly sensitive test for activation of the fifth component of complement.

Biological Transport↗
PubMed1979

Altered neutrophil migration during bacterial infection associated with a serum modulator of cellular motility.

The motility of polymorphonuclear leukocytes (PMNLs) from 25 patients with bacterial infection was assessed by using the migration-under-agarose assay. A spectrum of responses was observed. Random and directional motility stimulated by C5a or pressed in parallel. These responses contrasted with those of normal PMNLs preincubated with either FMLP or C5a; preincubation with one chemotaxin inhibited a subsequent response to the same stimulus but did not inhibit the response to the other. The parallel responses of patient PMNLs to C5a and FMLP suggest that the altered motility reflects a perturbation independent of a specific chemotactic receptor. Heat-inactivated serum from patients with bacterial infection, when preincubated with normal PMNLs, resulted in significant enhancement of both random and directional migration. The data indicate that bacterial infection is associated with appearance of a modulator of neutrophil motility.

Adult↗
PubMed1979

Dissociation of leukocyte alkaline phosphatase from the bactericidal activity of neutrophils.

We have identified an apparently healthy individual with no history of repeated infections whose neutrophils were virtually devoid of alkaline phosphatase activity by either spectrophotometric or histochemical assay. His cells showed normal bactericidal activity toward both Staphylococcus aureus and Escherichia coli when tested in vitro. We have also demonstrated that L-p-bromolevamisole, a potent inhibitor of alkaline phosphatase in many tissues, is likewise an effective inhibitor of the neutrophilic enzyme. Concentrations of this compound which caused nearly complete inhibition of the neutrophilic enzyme did not impair the ability of intact cells to kill bacteria. These results suggest that leukocyte alkaline phosphatase is not required for the normal bactericidal activity of neutrophils.

Alkaline Phosphatase↗
PubMed1979

Eosinophils versus neutrophils in host defense. Killing of newborn larvae of Trichinella spiralis by human granulocytes in vitro.

Eosinophil leukocytes have been reported to have a major role in host defense against invasive, migratory phases of helminth infestations, yet the relative larvicidal abilities of eosinophils and neutrophils have not been thoroughly examined. This study examined the killing of newborn (migratory phase) larvae of Trichinella spiralis during incubation by human granulocytes in vitro. The assay employed cultue of larvae with cells, sera, and reagents in microtiter wells with direct counting of surviving larvae after incubation. Killed larvae appeared to be lysed. Verification of the microplate assay was obtained by demonstrating complete loss of infectivity of larvae incubated with leukocytes and immune serum. In the presence of optimal immune serum concentrations, purified neutrophils or eosinophils achieved >/=95% killing of larvae at cell:larva ratios of 2,000:1 or greater. Fresh normal serum prompted slight (19%) killing by leukocytes at a cell:larva ratio of 9,000:1. Cells plus heat-inactivated normal serum and all sera preparations in the absence of leukocytes killed <8% of the larvae. The activity of immune serum was opsonic. Cells adhered to larvae that had been preincubated in immune serum, and immunofluorescent studies indicated that such preopsonized larvae were coated with immunoglobulin (Ig)G. However, preopsonized larvae lost opsonic activity and surface IgG during incubation for 3 h in medium lacking immune serum. The rate of killing was dependent on the cell:larva ratio; at high leukocyte concentrations (4,200:1), 99% were killed within 7 h; at lower cell:larva ratios, killing increased steadily during a 20-h incubation period. Killing was inhibited by 20 mug catalase, 5 mug/ml cytochalasin B, or 5muM colchicine, but was unchanged by superoxide dismutase and was enhanced by azide or cyanide. Leukocytes from a patient with chronic granulomatous disease, lacking ability to mount a normal oxidative response, demonstrated a markedly suppressed larvicidal effect. The data indicate that neutrophils are at least as effective as eosinophils in the killing of newborn larvae of T. spiralis. The killing appeared to be mediated by the oxidative metabolic burst with its generation of hydrogen peroxide.

Animals↗
PubMed1979

Mechanisms of killing of newborn larvae of Trichinella spiralis by neutrophils and eosinophils. Killing by generators of hydrogen peroxide in vitro.

Eosinophil and/or neutrophil leukocytes appear to have important roles in host defense against invasive, migratory helminth infestations, but the mechanisms of larval killing by leukocytes are uncertain. This study examines killing of newborn (migratory phase) larvae of Trichinella spiralis during incubation with granule preparations of human eosinophils or neutrophils and generators of hydrogen peroxide (glucose-glucose oxidase) (G-GO) or superoxide and hydrogen peroxide (xanthine-xanthine oxidase). Larvae were killed by either hydrogen peroxide-generating system in a concentration-dependent manner. Direct enumeration of surviving larvae after incubation in microtiter wells containing the appropriate reagents was used in assess larval killing. Verification of the microplate assay was demonstrated by complete loss of larval ability to incorporate [(3)H]deoxyglucose and loss of infectivity after incubation in comparable concentrations of G-GO. Larvae were highly sensitive to oxidative products; significant killing occurred after incubation with 0.12 mU glucose oxidase and complete killing occurred with 0.5 mU. Comparable killing of bacteria required over 60 mU glucose oxidase. At 5 mU glucose oxidase, killing was complete after 6 h of incubation. Killing by G-GO was inhibited by catalase but not by boiled catalase or superoxide dismutase and was enhanced by azide. Addition of peroxidase in granule pellet preparations of eosinophils or neutrophils did not enhance killing by G-GO. These data indicate a remarkable susceptibility of newborn larvae of T. spiralis to the hydrogen peroxide generated by neutrophil and eosinophil leukocytes.

Animals↗