Polymorphonuclear Peripheral Blood Research Articles

Zinc Enhances Neutrophil Extracellular Trap Formation of Porcine Peripheral Blood Polymorphonuclear Cells through Tumor Necrosis Factor-Alpha from Peripheral Blood Mononuclear Cells

Zinc Enhances Neutrophil Extracellular Trap Formation of Porcine Peripheral Blood Polymorphonuclear Cells through Tumor Necrosis Factor-Alpha from Peripheral Blood Mononuclear Cells

Fucoidan Upregulates Chemotactic Activity of Porcine Peripheral Blood Polymorphonuclear Cells to Interleukin-8 by PI3K Activation

Fucoidan Upregulates Chemotactic Activity of Porcine Peripheral Blood Polymorphonuclear Cells to Interleukin-8 by PI3K Activation

Interaction of Bovine Peripheral Blood Polymorphonuclear Cells and Leptospira Species; Innate Responses in the Natural Bovine Reservoir Host.

Cattle are the reservoir hosts of Leptospira borgpetersenii serovar Hardjo, and can also be reservoir hosts of other Leptospira species such as L. kirschneri, and Leptospira interrogans. As a reservoir host, cattle shed Leptospira, infecting other animals, including humans. Previous studies with human and murine neutrophils have shown activation of neutrophil extracellular trap or NET formation, and upregulation of inflammatory mediators by neutrophils in the presence of Leptospira. Humans, companion animals and most widely studied models of Leptospirosis are of acute infection, hallmarked by systemic inflammatory response, neutrophilia, and septicemia. In contrast, cattle exhibit chronic infection with few outward clinical signs aside from reproductive failure. Taking into consideration that there is host species variation in innate immunity, especially in pathogen recognition and response, the interaction of bovine peripheral blood polymorphonuclear cells (PMNs) and several Leptospira strains was evaluated. Studies including bovine-adapted strains, human pathogen strains, a saprophyte and inactivated organisms. Incubation of PMNs with Leptospira did induce slight activation of neutrophil NETs, greater than unstimulated cells but less than the quantity from E. coli P4 stimulated PMNs. Very low but significant from non-stimulated, levels of reactive oxygen peroxides were produced in the presence of all Leptospira strains and E. coli P4. Similarly, significant levels of reactive nitrogen intermediaries (NO2) was produced from PMNs when incubated with the Leptospira strains and greater quantities in the presence of E. coli P4. PMNs incubated with Leptospira induced RNA transcripts of IL-1β, MIP-1α, and TNF-α, with greater amounts induced by live organisms when compared to heat-inactivated leptospires. Transcript for inflammatory cytokine IL-8 was also induced, at similar levels regardless of Leptospira strain or viability. However, incubation of Leptospira strains with bovine PMNs did not affect Leptospira viability as measured by limiting dilution culture. This is in contrast to previously reported results of innate inflammatory activation by Leptospira in human and other animal models, or the activation and interaction of bovine PMNs with Escherichia coli and other bacterial pathogens. While it could be hypothesized that variations in innate receptor recognition, specifically variance in toll-like receptor 2, could underlie the observed reduction of activation in bovine PMNs, additional studies would be needed to explore this possibility. Reduction in neutrophil responses may help to establish nearly asymptomatic chronic Leptospira infection of cattle. This study emphasizes the importance of studying host-pathogen relationships in the appropriate species as extrapolation from other animal models may be incorrect and confounded by differences in the host responses.

Transdermal toxicity of topically applied anticoagulant rodenticide warfarin in rats.

Occupational/accidental exposure data have showed hemorrhage as a result of transdermal exposure to warfarin, however, other effects are not known. In the present study, the impact of epicutaneous application of 10 μg or 100 μg of warfarin (three times, once a day) on peripheral blood polymorphonuclear (PMN) and mononuclear cells (PBMC) was examined in rats. Both doses resulted in prolongation of prothrombin time and changes in hematologic parameters. Increases in PMN intracellular myeloperoxidase (MPO) activity were seen at higher warfarin dose and both doses resulted in higher percentages of granular CD11b(+) cells. In contrast, a decrease in PMN TNF and IL-6 production (ELISA) and gene expression (RT-PCR) was observed. Epicutaneous application of warfarin resulted in decreased numbers of PBMC, higher numbers of mononuclear CD11b(+) cells, but without effect on PMBC cytokine production. The data obtained showed differential effects of transdermal exposure to warfarin depending on leukocyte type and activity.

Microchimerism and regulation in living related kidney transplant families.

Long-term harmful effects of immunosuppressive drugs and chronic rejection are a persistent impetus to establish methods to induce immunological tolerance to allografts. PCR-based studies have found evidence that humans and other placental mammals can have prolonged extremely low levels of maternal cells as well as other non-self cells, referred to as microchimerism. The persistence of these cells suggests a mechanism for the maintenance of the regulatory T-cell (Treg) responses frequently detected in offspring to non-inherited maternal antigens. We test the hypothesis that the detection of very low copy levels of insertion/deletion (Indel) alleles consistent with non-inherited maternal genes, will correlate with immune regulation to non-inherited maternal antigens as detected by a trans-vivo Delayed-Type Hypersensitivity (tvDTH) assay in kidney transplant recipients, normal donors and their immediate biological family members. Preliminary data reported here compares qPCR amplification of rare DNA templates in the peripheral blood polymorphonuclear (PMN) fraction of cells, with the results of tvDTH assays for linked suppression of recall antigen responses in the presence of non-inherited maternal antigens [NIMA]. The two assays do not show a definitive correlation.

Differential effects of cadmium administration on peripheral blood granulocytes in rats

Infiltration of circulatory inflammatory cells is a common histopathological finding in target organs following cadmium administration, but there is paucity of data concerning their activity. In this study, the effects of sublethal (1mg/kg) cadmium on peripheral blood polymorphonuclear (PMN) cells were examined 48h following administration in rats, when tissue (liver and lung) infiltration of these cells was observed. Cadmium administration resulted in systemic inflammatory cytokine and acute phase response with an increase in circulatory neutrophil numbers and cells that express CD11b molecules. Rise in basic aspects of oxidative activity including intracellular myeloperoxidase (MPO), reactive oxygen (nitroblue tetrazolium/NBT cytochemical assay) and nitrogen (Griess assay) species production was observed in PMNs from cadmium-administered rats. A decrease in levels of mRNA for IL-1β, TNF-α and IL-6 was noted, but production of these cytokines was affected differentially. Described effects of cadmium on PMNs add further to the understanding of inflammatory potential of this environmental contaminant.

AB0076 Synovial fluid mediates the capacity of microcrystals to induce inflammation

BackgroundMonosodium urate (MSU), calcium pyrophosphate dihydrate (CPPD) and basic calcium phosphate (BCP) crystals, are able of activating the NLRP3 inflammasome to induce production of IL-1β. Moreover, it has now emerged...

Systemic immunomodulatory effects of topical dinitrochlorobenzene (DNCB) in rats. Activity of peripheral blood polymorphonuclear cells

Topical application of dinitrochlorobenzene (DNCB) is employed in the immunotherapy of skin diseases. Activation of T-cell mediated immune responses (Th1/type1) is the supposed mechanism of the clinical effect of DNCB, but there are no data concerning innate/inflammatory mechanisms. In this study, the effect of repeated topical DNCB application on peripheral blood polymorphonuclear (PMN) leukocytes has been examined in two rat strains which differ in the propensity to mount Th1/type1 or Th2/type2 responses. The dynamics of changes in PMN numbers and effector activities (respiratory burst, nitric oxide production and myeloperoxidase content), as well as in adhesion and TNF-α production following the rat skin sensitization with low (0.4%) and high (4%) DNCB doses were measured. Both priming and activation of PMNs were observed following skin sensitization with DNCB, with dose-dependent as well as time-dependent differences in some PMN activities. Obtained data might be relevant for understanding the immune mechanisms of topical DNCB therapy.

Abacavir and didanosine induce the interaction between human leukocytes and endothelial cells through Mac-1 upregulation

Abacavir and didanosine are nucleoside reverse transcriptase inhibitors (NRTI) widely used in therapy for HIV-infection but which have been linked to cardiovascular complications. The objective of this study was to analyze the effects of clinically relevant doses of abacavir and didanosine on human leukocyte-endothelium interactions and to compare them with those of other NRTIs. The interactions between human leukocytes - specifically peripheral blood polymorphonuclear (PMN) or mononuclear (PBMC) cells - and human umbilical vein endothelial cells were evaluated in a flow chamber system that reproduces conditions in vivo. The expression of adhesion molecules was analyzed by flow cytometry. Abacavir induced a dose-dependent increase in PMN and PBMC rolling and adhesion. This was reproduced by didanosine but not by lamivudine or zidovudine. Both abacavir and didanosine increased Mac-1 expression in neutrophils and monocytes, but produced no effects on either lymphocytes or the expression of endothelial adhesion molecules. The PMN/PBMC rolling and adhesion induced by abacavir or didanosine did not occur when antibodies against Mac-1 or its ligand ICAM-1 were blocked. Abacavir induces significant human leukocyte accumulation through the activation of Mac-1, which in turn interacts with its endothelial ligand ICAM-1. The fact that didanosine exhibits similar effects and that lamivudine and zidovudine do not points to a relationship between the chemical structure of NRTIs and the induction of leukocyte/endothelial cell interactions. This mechanism may be especially relevant to the progression of the vascular damage associated with atherosclerosis and myocardial infarction in abacavir and didanosine-treated patients.

Gastrin induces the interaction between human mononuclear leukocytes and endothelial cells through the endothelial expression of P-selectin and VCAM-1

Gastric mucosal inflammation is frequently associated with hypergastrinemia, and a correlation exists between the level of gastrin and degree of gastritis. We have previously observed that gastrin promotes leukocyte-endothelial interactions and contributes to Helicobacter-induced inflammation in the rat mesentery. In the present study, we aimed to evaluate a possible proinflammatory activity of gastrin in humans. The interaction between human leukocytes [U-937 cells, peripheral blood polymorphonuclear (PMN), and peripheral blood mononuclear (PBMC) cells] and human umbilical vein endothelial cells (HUVEC) was analyzed in static and dynamic conditions. The endothelial expression of adhesion molecules [P-selectin, E-selectin, intercellular adhesion molecule-1, vascular cell adhesion molecule (VCAM)-1] was analyzed by flow cytometry and fluorescent microscopy screening. Gastrin increased the static adhesion of U-937 cells to HUVEC (1 h; 10(-9) M: 122 +/- 9%; 10(-8) M: 143 +/- 17%; 10(-7) M: 162 +/- 14% vs. control, all P < 0.05). Incubation of HUVEC with gastrin (4 h) also increased PBMC rolling (vehicle: 63 +/- 12; 10(-9) M: 109 +/- 29; 10(-8) M: 141 +/- 24; 10(-7) M: 261 +/- 16 leukocytes/min, P < 0.05) and adhesion (vehicle: 3 +/- 2, 10(-9) M: 11 +/- 4, 10(-8) M: 17 +/- 5, 10(-7) M: 15 +/- 5 leukocytes/mm(2), all P < 0.05) in the parallel-plate flow chamber. Treatment of PBMC with gastrin had no effects. The cholecystokinin (CCK)-2 receptor antagonist (L-365,260, 10(-7) M) prevented the effects of gastrin. P-selectin and VCAM-1 expression were enhanced by gastrin, and neutralizing antibodies against these molecules prevented PBMC rolling and adhesion. Gastrin did not affect the interactions between HUVEC and PMN. Gastrin induces interactions between human mononuclear leukocytes and endothelial cells through the activation of CCK-2 receptors and the enhancement of endothelial P-selectin and VCAM-1.

Secreted tumor necrosis factor-α by human myeloid cells: a valuable parameter for evaluation of endotoxin contamination in vitro

Myeloid cells respond to external stimuli such as gram negative bacterial lipopolysaccharides (LPS) or endotoxin by producing a large array of intermediates and proteins, including the pro-inflammatory cytokines such as, tumor necrosis factor-α (TNF-α), free radicals, nitric oxide, and other intermediates. The aim of this research was to investigate the response of human myeloid cells to endotoxin, and correlate secreted TNF-α concentration with endotoxin exposure. For this purpose, human myeloid cell lines such as, U937, HL-60 (undifferentiated and differentiated) and the human peripheral blood Mononuclear (hpMN) and Polymorphonuclear (hpPMN) cells were treated by bacterial endotoxin in a dose and time dependent manner. Then the cells were isolated from supernatants. The nitro-blue tetrazolium (NBT) reduction potential of isolated cells was quantitatively assessed. The secreted TNF-α was assessed by the ELISA and TNF-α dependent L929 cells cytotoxicity methods. The hpPMN, hpMN, and differentiated U937 cells showed a higher ability to reduce NBT in response to endotoxin. The amount of produced TNF-α by hpPMN and hpMN cells were higher than that of other cells (Up to 300 pg/ml at 15 min and 6000 pg/ml at 24 hrs in response to 10 ng/ml of endotoxin, r = 0.974).The results of this study indicated that, human myeloid cells specially the hpPMN and hpMN cells provide a useful in vitro system for evaluating the endotoxin contamination in culture medium. In response to endotoxin, these cells synthesize and secrete TNF-α in a dose and time dependent manner.

Effect of a Short‐Term Infusion with Soybean Oil‐Based Lipid Emulsion on Phagocytic Responses of Canine Peripheral Blood Polymorphonuclear Neutrophilic Leukocytes

The use of soybean oil-based lipid emulsion (SO-based LE) in parenteral nutrition has been reported to impair neutrophil functions in humans and rodents. As yet, little is understood about the effects of SO-based LE on canine immune responses. A short-term infusion with SO-based LE affects the phagocytic responses of canine peripheral blood polymorphonuclear neutrophilic leukocytes (PMNs). Twenty-four healthy Beagle dogs. Experimental study. Dogs were randomly assigned into groups of six and administered a 2-hour IV infusion with 0.9% NaCl solution or sufficient SO-based LE (INTRALIPOS 20%) to supply 40, 100, and 200% of the basal energy requirement (BER). PMN functions were determined after collecting blood samples before, immediately after, and 24 hours after the infusion. None of the treatments significantly affected the phagocytic capacity of PMNs or circulating leukocyte numbers. The infusion providing 200% of BERs significantly reduced PMN oxidative burst activity, filamentous actin polymerization, and Cdc42 Rho guanosine triphosphatase activity immediately after its delivery. However, these functions were restored to pre-infusion values 24 hours after the infusion. The lower calorie infusions did not have these effects. These results suggest that short-term infusions with a supraphysiological dose of SO-based LE may decrease the immune functions of canine PMNs. However, more long-term studies will be needed to extrapolate the effect of SO-based LE with clinically relevant doses in a practical situation.

Systemic Immunity-Enhancing Effects in Healthy Subjects Following Dietary Consumption of the Lactic Acid Bacterium Lactobacillus rhamnosus HN001

Objective: To determine the effects of the probiotic lactic acid bacterium, Lactobacillus rhamnosus HN001, on natural cellular immunity when delivered orally in normal low-fat milk (LFM) or lactose-hydrolyzed low-fat milk (LFM-LH).Design: A three stage, pre-post intervention trial, spanning nine weeks.Setting: Taipei Medical College Hospital, Taipei, Taiwan.Subjects: Fifty-two healthy middle-aged and elderly volunteers (17 males, 35 females; median age 63.5, range 44–80).Interventions: Stage 1 (run-in diet): 25g/200 mL reconstituted LFM powder, twice daily for 3 weeks. Stage 2 (probiotic intervention): LFM or LFM-LH, supplemented with 109 CFUs/g L. rhamnosus HN001 in each case, for 3 weeks. Stage 3 (wash-out): LFM for 3 weeks.Measures of Outcome: In vitro phagocytic capacity of peripheral blood polymorphonuclear (PMN) leukocytes; in vitro tumoricidal activity of natural killer (NK) leukocytes.Results: Immunological responses were unaffected by the run-in diet of LFM alone. In contrast, the relative proportion of PMN cells showing phagocytic activity increased by 19% and 15%, respectively, following consumption of HN001 in either LFM or LFM-LH; the relative level of NK cell tumor killing activity increased by 71% and 147%. In most cases these levels declined following cessation, but remained above baseline.Conclusions: Dietary consumption of L. rhamnosus HN001, in a base of low-fat milk or lactose-hydrolyzed low-fat milk, appears to enhance systemic cellular immune responses and may be useful as a dietary supplement to boost natural immunity.

Phorbol 12-myristate 13-acetate induced cell death of porcine peripheral blood polymorphonuclear leucocytes.

Polymorphonuclear leucocytes (PMNs) circulating in mammalian peripheral blood are terminally differentiated cells, and once isolated in serum-free medium, they undergo apoptosis within 1 or 2 days. In this study, we studied the effects of phorbol myristate acetate (PMA) on the viability of porcine PMNs in vitro. PMA is known to suppress apoptosis in many cell types. PMA but not dioctanoyl glycerol (DOG) induced morphological degeneration and cell death within 3 to 5 hours as assessed by light microscopy observation and the MTT viability assay. This occurred despite the fact that DNA fragmentation associated with "spontaneous apoptosis" was not observed. Morphological degeneration and death were not due to the oxidative damage from superoxides or its metabolites produced by polymorphonuclear leucocytes, because PMA and DOG similarly stimulated superoxide production. Several other inactive phorbol derivatives tested did not cause cell death, suggesting that the toxicity of PMA did not result from non-specific effect of the reagent.

Nitric Oxide Production by Human Peripheral Blood Polymorphonuclear Leucocytes

1. We describe a rapid and reliable technique for the assessment of basal nitric oxide release in clinical situations, using peripheral blood polymorphonuclear leucocytes isolated by a single-step density gradient procedure. The assay is based on the quantitative conversion of oxyhaemoglobin to methaemoglobin by nitric oxide. We have further examined the ability of these cells to respond to various stimuli. 2. Basal (unstimulated) nitric oxide release occurred, which was augmented by superoxide dismutase. The mean value for healthy subjects was 283 +/- 96.7 pmol min-1 10(-6) cells. 3. Both phorbol myristate acetate and N-formyl-methionyl-leucylphenylalanine induced further release of nitric oxide, which was increased by preincubation with lipopolysaccharide, interleukin-6 and interferon-gamma. 4. Preincubation of cells with NG-monomethyl-L-arginine or L-canavanine sulphate inhibited nitric oxide production. 5. The procedure provides a valuable tool for monitoring nitric oxide up-regulation in clinical situations.

Granulocyte colony-stimulating factor potentiates anti-Candida albicansgrowth inhibitory activity of polymorphonuclear cells

Granulocyte colony-stimulating factor (G-CSF) stimulates a subset of granulocyte colony forming cells and when administered to neutropenic individuals results in recovery of blood neutrophil numbers to normal levels. Therefore, G-CSF may be a useful therapeutic agent for infections in immunocompromised hosts. However, to date there has been only limited information that G-CSF activates the antimicrobial activity of neutrophils. In the present study, we found that recombinant G-CSF promotes the anti-Candida albicans activity of normal human blood polymorphonuclear (PMN) cells in vitro using both a 3H-glucose uptake procedure and a Candida colony counting assay. As little as 0.1 ng/ml G-CSF induced significant anti-Candida activity in the PMN cultures. G-CSF treatment also enhanced superoxide anion production by the PMNs in response to f-MLP as determined by the superoxide dismutase inhibitable cytochrome C reduction method. Such results show that G-CSF can promote the antimicrobial activity of peripheral blood PMNs against C. albicans.

Granulocyte colony-stimulating factor potentiates anti- Candida albicans growth inhibitory activity of polymorphonuclear cells

Granulocyte colony-stimulating factor (G-CSF) stimulates a subset of granulocyte colony forming cells and when administered to neutropenic individuals results in recovery of blood neutrophil numbers to normal levels. Therefore, G-CSF may be a useful therapeutic agent for infections in immunocompromised hosts. However, to date there has been only limited information that G-CSF activates the antimicrobial activity of neutrophils. In the present study, we found that recombinant G-CSF promotes the anti- Candida albicans activity of normal human blood polymorphonuclear (PMN) cells in vitro using both a 3H-glucose uptake procedure and a Candida colony counting assay. As little as 0.1 ng/ml G-CSF induced significant anti-Candida activity in the PMN cultures. G-CSF treatment also enhanced superoxide anion production by the PMNs in response to f-MLP as determined by the superoxide dismutase inhibitable cytochrome C reduction method. Such results show that G-CSF can promote the antimicrobial activity of peripheral blood PMNs against C. albicans.

Changes in free amino acids in Peripheral Blood (PB) lymphocytes and Polymorphonuclear (PMN) leukocytes after treatment with diazepam

The effect of single and chronic (15 days) i.p. injections (1.0 and 8.0 mg/kg) of diazepam (DZ) on free amino acid profile in peripheral blood (PB) lymphocytes and polymorphonuclear (PMN) leukocytes of male Wister Albino rats were investigated. Depletion of some free amino acids was observed in the lymphocytes (mixed T- and B-lymphocytes) and PMN leukocytes (91–95%) neutrophils especially after chronic DZ-treatment. A dose-dependent depletion in the lymphocyte amino acids, Tau, Gly, Ala, Met and Ile, was found after both acute and chronic DZ-treatment. A similar depletion of Tau, Asp, Glu and Met appeared in the PMN leukocytes after single doses as well as chronic DZ-treatment. These results suggest that administration of 1.0 – 8.0 mg/kg of DZ in single dose or after chronic administration may interfere with the transport of certain important amino acids and/or protein turnover in PB lymphocytes and PMN leukocytes. On the other hand, the basic amino acids Lys, His and Arg were significantly increased in PMN leukocytes after chronic administration of 1.0 mg/kg DZ. It was suggested that the increased levels of the basic amino acids in the neutrophils may interact with the intracellular changes in pH that normally accompany the respiratory burst.

Correlation of quantitative human cytomegalovirus pp65-, p72- and p150-antigenemia, viremia and circulating endothelial giant cells with clinical symptoms and antiviral treatment in immunocompromised patients

Human cytomegalovirus (HCMV) replication in peripheral blood polymorphonuclear (PMNL) and mononuclear (MNL) leukocytes was investigated by quantitative determination of pp65-, p72- and p150-antigenemia and viremia in 7 (4 heart or heart-lung transplanted and 3 AIDS) immunosuppressed patients. These parameters were correlated with appearance of clinical symptoms and with their disappearance following antiviral treatment. Onset and progression of HCMV infection was associated to increasing levels of pp65-, p72- and p150-antigenemia and viremia, and a significant correlation was found between antigenemia and viremia in both PMNL and MNL. pp65-antigenemia showed absolute levels higher than p72- and p150-antigenemia both in PMNL and MNL, but PMNL showed figures consistently higher than MNL for all 3 viral proteins. levels of p150-antigenemia and viremia >100 were associated to clinical symptoms in patients with peak of infection within 40 days after transplantation. In addition, number of HCMV-infected circulating giant cells (CGC) progressively increased in the presence of an organ syndrome. Antiviral treatment with either foscarnet or ganciclovir induced rapid disappearance of p150-positive PMNL and MNL as well as CGC, followed by disappearance of p72-positive leukocytes within a few days. pp65-positive cells were the last to disappear. Reported data suggest that viral replication may occur not only in MNL, but also in PMNL. Interaction between HCMV-infected circulating leukocytes and CGC may represent one of the major pathogenetic pathways for the development and dissemination of HCMV infection in immunocompromised patients.

Leukotriene B4 and tumor necrosis factor release from leukocytes: effect of peritoneal dialysate.

The effect of peritoneal dialysate on the capacity of peripheral blood polymorphonuclear (PMNL) and mononuclear leukocytes (MNC) to release leukotriene B4 (LTB4) and tumor necrosis factor alpha (TNF alpha) was investigated in vitro. Following density gradient separation, aliquots of 5 x 10(6) PMNL or MNC were incubated in peritoneal dialysis fluid containing 1.5% glucose or Hanks' buffer (= control) for 1-2 h at 37 degrees C. TNF alpha and LTB4 production was stimulated with Escherichia coli lipopolysaccharide (LPS) and calcium ionophore A23187, respectively. MNC incubated in buffer and LPS produced (mean +/- SD) 1,006 +/- 522 pg TNF alpha/5 x 10(6) cells; no significant amounts of TNF alpha were detectable in the presence of dialysate. An inhibition of TNF alpha release was also observed in MNC exposed to bicarbonate-buffered dialysates (pH 7.40) and 4.25% and 1.5% glucose solution with physiologic osmolality. Incubation of PMNL in Hanks' buffer followed by A23187 stimulation led to production of 29.1 +/- 19.2 ng LTB4/5 x 10(6) cells, whereas glucose-incubated cells were refractory to ionophore stimulation (less than 0.1 ng LTB4/5 x 10(6) cells). The failure of dialysate-exposed leukocytes to release inflammatory mediators in response to adequate stimuli may contribute to the impairment of cellular host defense in the setting of continuous ambulatory peritoneal dialysis.