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Biomedical subjects

L A Boxer

Publications and source records attributed to L A Boxer.

At least 163 records · Page 9Linked to original sources
PubMed1981

Membrane fluidity changes accompanying phagocytosis in normal and in chronic granulomatous disease polymorphonuclear leukocytes.

We have studied membrane fluidity changes in polymorphonuclear leukocytes (PMN) during phagocytosis. Membrane fluidity was assessed by electron spin resonance (ESR) using a nitroxide-substituted stearic acid analog (5DS) as a spin probe. PMN from normal subjects and from 3 CGD patients (2 males, 1 female) were incubated in Kreb's Ringers phosphate with or without opsonized zymosan. ESR spectra were obtained and the order parameter (S), which is inversely related to membrane fluidity, was calculated. Without zymosan addition, S for normal (0.638) and for CGD (0.635) were not significantly different (p less than 0.35). The S values indicate that under resting conditions the molecular environment of the CGD membrane is similar to that of normal PMN membranes. However, with addition of opsonized zymosan, the normal, but not the CGD, PMN showed a significant increase (CGD, S = 0.638; normal, S = 0.647; p less than 0.001). This change in S for the normals is consistent with a more restricted movement of 5DS. Treatment of normal PMN with a mixture of scavengers specific for H2O2 (catalase, 1600 U/ml), O2-.(superoxide dismutase, 100 micrograms/ml), and for HO., (sodium benzoate, 1mM) during zymosan stimulation gave S values similar to those of resting cells. Catalase alone also lowered S value, suggesting that H2O2 was instrumental in causing the initial S value increase. This idea was supported by studies in which CGD cells were incubated with zymosan in the presence of glucose oxidase, an enzyme that catalyzes glucose oxidation resulting in the direct reduction of molecular oxygen to H2O2. Our results indicate that reduced O2 by-products, particularly H2O2, can cause altered biophysical properties of PMN membrane during phagocytosis.

Granulomatous Disease, Chronic↗
PubMed1981

Cell elastimetry in the detection of antineutrophil antibodies.

Cell elastimetry has been applied to the measurement of antineutrophil antibodies. This technique measures, under direct visualization, the negative pressure required of aspirate PMNs into small-pored pipettes. Two groups of studies were carried out: (A) In the first group of studies, normal PMNs were incubated with 1 of 8 known antineutrophil serums. Each serum significantly decreased membrane deformability--i.e., cells became more rigid. The study was conducted in an entirely blind fashion. Randomly coded serums from patients and controls were studied for deformability by observers unaware of the code. (B) In the second group of studies, sera containing immune complexes were incubated with normal PMNs. No significant effects were noted upon deformability. As a single cell assay that partially reflects membrane rigidity, elastimetry may, therefore, have potential in the further characterization of mechanisms by which such antineutrophil antibodies compromise neutrophil functions.

Adult↗
PubMed1980

Childhood neutropenia.

Neutropenia can occur because of abnormalities of marrow stem cell development, poor release of polymorphonuclear leukocytes from the marrow reserve, or decreased survival of polymorphonuclear leukocytes. Some of the more important clinical entities are discussed.

Aging↗
PubMed1980

Effectiveness of enteral and parenteral nutrition in the nutritional management of children with Wilms' tumors.

The effectiveness of enteral and parenteral feeding in supporting a satisfactory nutrition status and/or reversing protein-energy malnutrition was evaluated in nine children, ages 1 to 7 years (eight female), with Wilms' tumors. At the onset of treatment, eight patients received comprehensive enteral nutrition (CEN) which included intense nutritional counseling and oral supplements while one received total parenteral nutrition (TPN). Despite CEN, the initial, intense treatment period was associated with a decreased energy intake (64 +/- 27% Recommended Dietary Allowances), dramatic weight loss (22 +/- 7% by 26 +/- 17 days from the beginning of treatment), decreased skinfold thickness (< 10th percentile), and decreased albumin concentrations (< 3.2 g/dl). Four of those who initially received CEN subsequently required TPN. A total of five patients received TPN for a mean of 31 days (range 11 to 60); kcal averaged 105 +/- 9% Recommended Dietary Allowances during weight gain. At onset of TPN, the mean albumin, transferrin, total lymphocyte count were 3.02 +/- 0.45 g/dl, 155 +/- 40 mg/dl, and, 655 +/- 437/mm3, respectively; all children had abnormal anthropometric measurements and anergy to recall skin test antigens. TPN for 28 or more days supported weight gain (+ 2.44 kg), increased serum albumin (+ 0.58 +/- 0.47 g/dl) and transferrin (+ 76 +/- 34 mg/dl), and reversed anergy despite low total lymphocyte counts. During maintenance treatment, nutritional status was maintained or restored with CEN in the group who responded. These preliminary data document the severity of protein-energy malnutrition which accompanies initial, intense treatment of children with Wilms' tumors, the nutritional and immunological benefits of TPN during continuing intense treatment and the effectiveness of CEN in maintaining a satisfactory nutritional status during maintenance treatment.

Body Height↗
PubMed1980

Diminished polymorphonuclear leukocyte adherence. Function dependent on release of cyclic AMP by endothelial cells after stimulation of beta-receptors by epinephrine.

To investigate the biochemical and cellular basis for the rise in polymorphonuclear leukocyte (PMN) count during epinephrine administration, PMN from subjects receiving epinephrine were studied for their capacity to adhere to nylon wool fibers and endothelial cell monolayers. After administration of epinephrine, the PMN count increased by 80% at 5 min, and isolated PMN adherence to nylon fibers fell from a base line of 44+/-2-18+/-3%. In contrast, when subjects were infused with the beta-antagonist propanolol before receiving epinephrine, the PMN count failed to rise and PMN adherence was normal. Exposure of PMN endothelial cell monolayers to 0.1 muM epinephrine led to diminished PMN adherence that could be blocked by 10 muM propanolol but not by 10 muM phentolamine. Sera obtained from subjects 5 min after receiving epinephrine or from supernates derived from endothelial cell monolayers exposed to 90 nM epinephrine inhibited PMN adherence to nylon fibers. Addition of anticyclic AMP antisera but not anticyclic guanosine monophosphate antisera to the postepinephrine sera or to the postepinephrine supernate derived from the endothelial cell monolayers abolished their inhibitory effect of PMN adherence to nylon fibers. In contrast, direct exposure of PMN to epinephrine failed to affect their adherent properties. Because it has been previously shown that endothelial cells contain beta-receptors and respond to catecholamines by raising their intracellular concentrations of cyclic AMP, and that PMN adherence is attenuated by cyclic AMP, it would appear that diminished PMN adherence after epinephrine administration is mediated through endothelial cell beta-receptor activity, which in turn impairs PMN margination in vivo and could account for the rise in circulating PMN.

Cell Adhesion↗
PubMed1980

Inhibition of polymorphonuclear leukocyte adherence by prostacyclin.

The adherence of human PMNs to nylon fibers or endothelial cells is inhibited by exposure in vitro of the phagocytic cells to PGl2. The impaired adherence is transient and correlates with a rise in intracellular levels of cyclic AMP. Similarly, stimulation of human endothelial cells with sodium arachidonate, a precursor of PGl2, leads to impaired PMN adherence. On the other hand, PGl2 failed to alter O2- release and the bactericidal capacity of the PMNs. These findings suggest that PGl2 may play a role in regulating PMN adhesiveness to endothelial cells without compromising host defense.

Cell Adhesion↗
PubMed1980

Differences in polymorphonuclear leukocyte aggregating responses among several species in response to chemotactic stimulation.

We investigated some of the metabolic requirements for FMLP-induced aggregation, monitored spectrophotometrically at 37 degrees C in human, rabbit, and guinea pig p]olymorphonuclear leukocytes. Exposure of guinea pig polymorphonuclear leukocytes to the anaerobic glycolytic inhibitors 5 mM 2-deosy-glucose and 5 mM iodoacetamide inhibited aggregation, whereas 1 mM KCN was without effect. Ca++ and Mg++ were required for optimal aggregation; Mg++ alone partially supported aggregation, whereas Ca++ alone failed to do so. Verapamil, a divalent cationic blocker, inhibited polymorphonuclear leukocyte aggregation of all species in a dose-dependent fashion in the presence of Ca++ and Mg++ and blocked pseudopodia formation as monitored by transmission electron microscopy. Rabbit polymorphonuclear leukocytes were most response to FMLP and aggregated at concentrations as low as 2 x 10(-13)M in the presence of cytochalasin B. Cytochalasin B enhanced aggregation of both human and rabbit polymorphonuclear leukocytes but not guinea pig polymorphonuclear leukocytes in the presence of divalent cations. Unlike polymorphonuclear leukocytes from other species, cytochalasin B rabbit pretreated polymorphonuclear leukocytes aggregated even in the absence of divalent cations, and this response was completely blocked by verapamil. Human and guinea pig polymorphonuclear leukocytes demonstrated aggregatiopn responses only to concentrations as low as 2 x 10(-10)M FMLP. These studies show the unique aggregating responses of rabbit, human, and guinea pig polymorphonuclear leukocytes to FMLP and indicate the requirement for divalent cation transport and formation of pseudopia in this response for all species.

Animals↗
PubMed1980

Congenital dysgranulopoietic neutropenia: clinical, serologic, ultrastructural, and in vitro proliferative characteristics.

Six children with severe congenital neutropenia and repeated life-threatening infections were investigated by examining clinical features and myeloid cell ultrastructure, cytochemistry, and in vitro proliferation. Despite the presence of neutropenia, normal numbers of colony-forming cells (CFC) were present in blood and marrow specimens, and colony-stimulating activities (CSA) from blood cells and serum were normal or slightly increased in all patients. In vitro maturation of the progenitors to neutrophils was also uniformly present in the colonies. No patients had demonstrable antineutrophil antibodies or serum inhibitors of myelopoiesis. Serum lysozyme levels were normal. Ultrastructural and cytochemical studies of directly sampled marrow cells revealed several abnormalities in most neutrophilic myeloid cells from each of the patients consistent with an intrinsic myeloid precursor cell defect. These included (1) the defective synthesis or degeneration of primary granules, (2) an absence or marked decrease of secondary granules in the few late neutrophils observed in the bone marrow, and (3) the presence of autophagy. Phagocytosis of intact myeloid cells with subsequent degeneration was not observed; however, neutrophil debris was evident in phagocytic vacuoles of marrow macrophages. Our demonstration of ultrastructurally dysmorphic neutrophilic granulocytes, intramedullary cell lysis, normal stem cell numbers, and negative serology is comparable to similar observations of erythroid cells from patients with congenital dyserythropoietic anemia. We therefore hypothesize that the dysgranulopoiesis in these children results in neutropenia and propose the descriptive name congenital dysgranulopoietic neutropenia.

Agranulocytosis↗
PubMed1979

Protection of granulocytes by vitamin E in glutathione synthetase deficiency.

The administration of vitamin E (alpha-tocopherol) was found to improve polymorphonuclear leukocyte function in an infant with congenital deficiency of glutathione synthetase activity. Before therapy with vitamin E the abnormal leukocytes exposed to phagocytic challenge showed oxidant damage. They released 60 per cent more hydrogen peroxide than did normal leukocytes, iodinated only 20 to 25 per cent of the normal number of particles, and were unable to kill bacteria as effectively as normal leukocytes although the rates of phagocytosis were normal. These functional abnormalities disappeared when the patient was placed on 400 IU of alpha-tocopherol daily for three months. Associated with the functional improvement was a normalization of microtubule assembly during phagocytic challenge.

Blood Bactericidal Activity↗
PubMed1979

Enhancement of chemotactic response and microtubule assembly in human leukocytes by ascorbic acid.

The incubation of human leukocytes with ascorbic acid increased chemotaxis of the cells. In addition, ascorbic acid promoted the assembly of intracellular polymorphonuclear leukocyte (PMN) with colchicine blocked the effect of ascorbic acid on promoting microtubule assembly. Not only did ascorbic acid promote the assembly of microtubules in vivo, but it enhanced the assembly of bovine brain tubulin into microtubules in vitro as quantitated by a glass-fiber filtration assay and by promotion of viscosity changes. The enhancement in leukocyte mobility by ascorbate at concentrations achievable in normal tissues correlates with its ability to assemble microtubule organelles.

Ascorbic Acid↗
PubMed1979

Infectious mononucleosis with severe neutropenia and opsonic antineutrophil activity.

Severe granulocytopenia is an uncommon complication of infectious mononucleosis, only 18 cases having been reported previously. Our review and experience with this case would indicate that (1) severe granulocytopenia is usually diagnosed at about the third or fourth week of illness, (2) bone marrow examination most commonly reveals lack of mature neutrophil precursors in the myelocytic series, (3) the duration of usually short, lasting about a week, and (4) most patients recover without treatment. The laboratory findings in our case suggests that the neutropenia may be antibody mediated.

Adolescent↗
PubMed1979

Oxidative damage to neutrophils in glutathione synthetase deficiency.

Several episodes of neutropenia were observed in a child with glutathione synthetase deficiency (5-oxoprolinuria). Studies of the patient's glutathione-deficient neutrophils were undertaken to examine the responses of the cells to oxidative stress associated with phagocytosis. The patient's neutrophils contained 10--20% of normal glutathione content. Circulating neutrophils in infection-free periods appeared less mature than normal by morphologic criteria, suggesting increased cell turnover. The cells ingested particles, responded to chemotactic stimuli, and oxidized 1-14C glucose normally. However, following ingestion of particles, the cells accumulated excess hydrogen peroxide compared with normal cells, and showed impaired protein iodination and bacterial killing. Electron micrographs revealed damage to microtubules and membranous structures in the patient's neutrophils during phagocytosis. The level of glutathione in the cells appears inadequate to protect against peroxide generated during normal cell function, and the cells are thus damaged and rendered less effective in bacterial killing. The data provide evidence for a protective role of glutathione in normal neutrophil function.

Chemotaxis, Leukocyte↗
PubMed1979

Impaired microtubule assembly and polymorphonuclear leucocyte function in the Chediak-Higashi syndrome correctable by ascorbic acid.

It was previously shown that the abnormal surface characteristics and defective bactericidal function of polymorphonuclear leucocytes (PMN) in the Chediak-Higashi syndrome (CHS) are correlated with impaired microtubule assembly, and in one patient direct electron microscopic evidence for an anomaly in microtubule assembly following surface membrane activation by concanavalin A (Con A). We show that very few microtubules are visible in CHS leucocytes from two additional patients under conditions where normal PMNs contain abundant microtubules, and that both in vivo and in vitro exposure of the CHS leucocytes to ascorbic acid promotes the assembly of microtubules. This agent, which normalizes chemotaxis and degranulation in CHS leucocytes, is shown also to correct granulocyte adherence in these leucocytes. It is suggested that the improved clinical course of patients with CHS following treatment with ascorbic acid is related at least in part to improvement of microtubule assembly and PMN function by the ascorbic acid.

Ascorbic Acid↗
PubMed1979

Hemoglobin Indianapolis (beta 112[G14] arginine). An unstable beta-chain variant producing the phenotype of severe beta-thalassemia.

Hemoglobin (Hb) Indianapolis is an extremely labile beta-chain variant, present in such small amounts that it was undetectable by usual techniques. Clinically, it produces the phenotype of severe beta-thalassemia. Biosynthetic studies showed a beta:alpha ratio of 0.5 in reticulocytes and about 1.0 in marrow after a 1-h incubation. These results, similar to those seen in typical heterozygous beta-thalassemia, suggested that betaIndianapolis was destroyed so rapidly that its net synthesis was essentially zero. To examine the kinetics of globin synthesis, reticulocyte incubations of 1.25--20 min were performed with [3H]leucine. The betaIndianapolis:beta A ratio at 1.25 min was 0.80 suggesting that beta Indianapolis was synthesized at a near normal rate. At 20 min, this ratio was 0.46 reflecting rapid turnover of beta Indianapolis. The erythrocyte ghosts from these incubations contained only betaIndianapolis and alpha-chains, and the proportion of betaIndianapolis decreased with time, indicating loss of betaIndianapolis. Pulse-chase studies showed little change in beta A:alpha ratio and decreasing betaIndianapolis:alpha and betaIndianapolis:beta A with time. The half-life of betaIndianapolis in the soluble hemoglobin was approximately equal to 7 min. There was also rapid loss of beta Indianapolis from the erythrocyte membrane. From these results, it may be inferred that betaIndianapolis is rapidly precipitated from the soluble cell phase to the membrane, where it is catabolized. Heterozygotes for beta 0-thalassemia usually have minimal hematologic abnormalities, whereas heterozygotes with betaIndianapolis, having a similar net content of beta-chain, have severe disease. The extremely rapid precipitation and catabolism of betaIndianapolis and the resulting excess of alpha-chains, both causing membrane damage, may be responsible for the severe clinical manifestations associated with this variant. It seems likely that other, similar disturbances in the primary sequence of globin polypeptide chains may produce clinical findings similar to those seen with hemoglobin Indianapolis and thus produce the phenotype of severe beta-thalassemia.

Adolescent↗