Thin film piezoelectric response characterisation using atomic force microscopy with standard contact mode imaging

This article introduces a technique for observing and quantifying the piezoelectric response of thin films, using standard atomic force microscopes (AFMs). The technique has been developed and verified using strontium-doped lead zirconate titanate (PSZT) thin films, which are known for their high piezoelectric response. Quantification of the electro-mechanical voltage coefficient d(33) (pm/V) is made directly based on the applied peak-to-peak voltage and the corresponding peak-to-peak displacement in the obtained scan image. Under the proposed technique the AFM is configured in contact mode, where the silicon nitride tip is set to follow the film displacement at a single point. A known sinusoidal voltage is applied across the film and the displacement determined as a function of time, rather than the typical AFM measurement of displacement versus tip position. The resulting raster image contains several bands, which are directly related to the AFM scan frequency and the applied sinusoidal voltage and its frequency. Different combinations of the AFM scan frequency and the applied sinusoid frequency have been used to characterise the PSZT thin films, with estimated values of d(33) between 109 and 205 pm/V.

Characterisation of nickel silicide thin films by spectroscopy and microscopy techniques

This article discusses the formation and detailed materials characterisation of nickel silicide thin films. Nickel silicide thin films have been formed by thermally reacting electron beam evaporated thin films of nickel with silicon. The nickel silicide thin films have been analysed using Auger electron spectroscopy (AES) depth profiles, secondary ion mass spectrometry (SIMS), and Rutherford backscattering spectroscopy (RBS). The AES depth profile shows a uniform NiSi film, with a composition of 49-50% nickel and 51-50% silicon. No oxygen contamination either on the surface or at the silicide-silicon interface was observed. The SIMS depth profile confirms the existence of a uniform film, with no traces of oxygen contamination. RBS results indicate a nickel silicide layer of 114 nm, with the simulated spectra in close agreement with the experimental data. Atomic force microscopy and transmission electron microscopy have been used to study the morphology of the nickel silicide thin films. The average grain size and average surface roughness of these films was found to be 30-50 and 0.67 nm, respectively. The film surface has also been studied using Kikuchi patterns obtained by electron backscatter detection.

Heparin-induced thrombocytopenia complicating hemodialysis

Hemodialysis complicated by heparin-induced thrombocytopenia (HIT) is a rare event requiring anticoagulation with direct-thrombin inhibitors. Contaminant calcific uremic arteriolopathy (calciphylaxis) further complicates this situation due to the possibility that warfarin anticoagulation may exacerbate skin necrosis. The authors report a patient with renal failure and calciphylaxis who developed HIT after starting hemodialysis. She was successfully treated with Argatroban.

Reversible renal allograft dysfunction and proteinuria from nutcracker-like syndrome: a case report

A 27-year-old Hispanic man with hypertension and renal failure was on hemodialysis for 4 years prior to receiving a living donor renal transplant from his 19-year-old sister. His serum creatinine decreased to 1.7 mg/dL at 3 weeks posttransplant with a urine protein creatinine ratio (UP) of 0.1 (g/g). Over the next 2 months, he experienced repeated episodes of allograft dysfunction with elevation of creatinine and proteinuria levels, associated with a lymphocele. Doppler studies of the allograft revealed renal vein compression. His symptoms responded to aspiration of the fluid collection, resolving completely with surgical drainage. We believe that the episodes of allograft dysfunction and proteinuria were related to recurrent lymphocele, causing a nutcracker-like syndrome.

Morphine priming rescues high-dose morphine-induced biological perturbations

In in vitro studies, macrophage morphine priming (MP; preincubation with low-dose morphine) attenuated the effects of high-dose morphine (HDM) on macrophage capabilities of killing and containment of phagocytosed bacteria. In in vivo studies, mice received either normal saline (control), HDM, or MP twice daily for 10 consecutive days. All HDM-treated mice showed a significant peritoneal bacterial leak; none of the control and only 2 of 12 mice receiving MP showed peritoneal bacterial leak. HDM-treated mice showed decreased macrophage migration into the peritoneal cavity; however, MP inhibited this effect. In in vitro studies, macrophages and bone-marrow cells harvested from HDM-treated mice showed not only enhanced apoptosis but also decreased migration across the filter of a Boyden chamber; nevertheless, MP inhibited these effects of HDM. MP also attenuated the proapoptotic effect of HDM; however, this effect was prevented by treatment with pyrrolidine derivative of dithiocarnamate, an inhibitor of nuclear factor- kappa B. These results suggest that MP provides protection against HDM-induced degradation of the host defense barrier through preservation of macrophage function.

Denture-induced fibrous hyperplasia. Treatment with carbon dioxide laser and a two year follow-up

Denture-induced fibrous hyperplasia (DIFH) is a persistent lesion caused mostly by the prolonged wear of an ill-fitting, over-extended denture. Although the condition frequently coexists with denture stomatitis, it is a distinct entity with a different protocol for management. The article describes successful treatment for a case of DIFH using carbon dioxide laser and a two year follow-up. The inherent advantages of using carbon dioxide laser over conventional surgical techniques are discussed.

Dialysis Membrane-Induced Oxidative Stress: Role of Heme Oxygenase-1

Dialysis membranes have been reported to induce monocyte apoptosis. We studied the role of oxidative stress in the induction of dialysis membrane-induced monocyte apoptosis. Superoxide dismutase, a superoxide scavenger, prevented dialysis membrane-induced monocyte apoptosis. Similarly, other antioxidants also inhibited dialysis membrane- induced apoptosis. In addition, the interaction of dialysis membranes with monocytes was associated with the generation of molecules leading to oxidative stress such as superoxide and TBARS. Interestingly, pre-induction of heme oxygenase (HO)-1 by hemin prevented dialysis membrane-induced monocyte apoptosis, whereas inhibition of HO-1 activity (treatment with tin protoporphyrin, SN-P) enhanced dialysis membrane-induced monocyte apoptosis. We suggest that oxidative injury associated with dialysis membrane and monocyte interaction plays a role in monocyte injury. Pre-induction of HO-1 may attenuate dialysis membrane-induced monocyte apoptosis.

Morphine-induced degradation of the host defense barrier role of intestinal mucosal injury

The effect of morphine on intestinal ulcer formation and on the degradation of the host defense barrier was studied. Mice receiving morphine (MRM) showed mucosal ulcer formation in the ileum and in the upper third of the colon. In in vitro studies, morphine enhanced apoptosis of cultured human colonic cells (HCC). Nitric oxide synthase (NOS) inhibitors attenuated the proapoptotic effect of morphine. Moreover, morphine stimulated NO generation by HCCs. MRM also showed a breach in the host defense barrier as well as injury to peritoneal macrophages. Although NOS inhibitors completely prevented morphine-induced intestinal ulcer formation, it provided only partial protection against a breach in the host defense barrier and peritoneal macrophage injury. Propranolol did not inhibit the induction of intestinal ulcer formation in MRM; nevertheless, propranolol prevented a breach in the host defense barrier as well as macrophage injury in MRM, whereas hemin exacerbated macrophage injury as well as the breach in the host defense barrier of MRM. These findings suggest that morphine-induced intestinal injury is mediated through NO generation. However, the degradation of the host defense barrier correlates with macrophage injury, but not intestinal injury.

Hepatocyte Growth Factor Modulates H2O2-Induced Mesangial Cell Apoptosis through Induction of Heme Oxygenase-1

Oxidative stress plays an important role in the induction of mesangial cell (MC) injury. In the present study, we evaluated the molecular mechanism involved in hydrogen peroxide (H2O2)-induced MC apoptosis. In addition, we examined the role of heme oxygenase-1 (HO-1) in hepatocyte growth factor (HGF)-modulated, H2O2-induced MC injury. H2O2 promoted (p < 0.001) mouse MC (MMC) apoptosis. This effect of H2O2 was associated with translocation of cytochrome c from the mitochondrial to the cytosolic compartment. In addition, a caspase-9 inhibitor partially attenuated this effect of H2O2. These findings suggest that H2O2-induced MMC apoptosis is mediated through the mitochondrial pathway. HGF not only prevented H2O2-induced MMC apoptosis, but also inhibited H2O2-induced translocation of cytochrome c from the mitochondrial to the cytosolic compartment. HGF also promoted the expression of HO-1 by MMCs; interestingly, hemin inhibited (p < 0.001) H2O2-induced MMC apoptosis. On the other hand, zinc protoporphyrin inhibited the protective influence of HGF on H2O2-induced MMC apoptosis. These findings suggest that H2O2-induced apoptosis occurs through the mitochondrial pathway. HGF provides protection against H2O2-induced MMC apoptosis through induction of HO-1.

Morphine-induced macrophage apoptosis: oxidative stress and strategies for modulation

Occurrence of macrophage apoptosis has been implicated for the altered immune function found in an opiate milieu. In the present study, we evaluated the role of oxidative stress in morphine-induced macrophage apoptosis. Morphine promoted the apoptosis of macrophages. This effect of morphine was associated with the production of superoxide and nitric oxide (NO). Antioxidants provided protection against morphine-induced macrophage injury. In addition, diphenyleneiodonium chloride, an inhibitor of reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation, attenuated the proapoptotic effect of morphine. Antitransforming growth factor-beta (anti-TGF-beta) antibody and propranolol (an inhibitor of the phospholipase D pathway) inhibited morphine-induced superoxide generation as well as apoptosis. N'-Tetraacetic acid tetra (acetoxymethyl) ester, a calcium-chelating agent, inhibited morphine-induced apoptosis, whereas thapsigargin (a calcium agonist) stimulated macrophage apoptosis under basal as well as morphine-stimulated states. These studies suggest that morphine-induced macrophage apoptosis is mediated through downstream signaling involving TGF-beta and NO production. Moreover, there is NADPH oxidation activation involving phospholipase D and Ca(2+), leading to the generation of superoxide. In in vivo studies, administration of N-acetyl cysteine and preinduction of heme oxygenase activity and epoetin alpha prevented morphine-induced peritoneal macrophage apoptosis, thus further confirming the role of oxidative stress in morphine-induced macrophage apoptosis.

Protease inhibitors modulate apoptosis in mesangial cells derived from a mouse model of HIVAN11See Editorial by Foster, p. 1105

BACKGROUND

Oxidative stress as well as opiate addiction has been shown to play a role in the development of complications associated with human immunodeficiency virus (HIV) infection.

METHODS

We studied the occurrence of apoptosis in mesangial cells derived from control (NTrMC) mice and mice transgenic for HIV-1 genes (HTrMC) under basal and morphine-stimulated states (MSS). We evaluated the effect of free radical scavengers and antioxidants on HTrMC apoptosis and production of superoxide under basal and MSS. In addition, we examined the effect of protease inhibitors (PI) on apoptosis of NTrMCs/HTrMCs as well as morphine-induced superoxide dismutase (SOD) and nicotinamide adenine dinucleotide phosphate (reduced form) (NADPH) oxidase activation.

RESULTS

HTrMCs showed greater apoptosis when compared with NTrMCs. Morphine triggered (P < 0.001) apoptosis of both NTrMCs and HTrMCs. Both antioxidants and free radical scavengers inhibited apoptosis of NTrMCs and HTrMCs under both basal and MSS. Morphine stimulated the production of superoxide by NTrMCs as well as by HTrMCs. Nevertheless, HTrMCs produced a greater (P < 0.001) amount of superoxide when compared with NTrMCs both under basal and MSS. PIs such as saquinavir and Indinavir inhibited HTrMC apoptosis in a dose-dependent manner. Saquinavir also protected HTrMCs against the proapoptotic effect of morphine. Moreover, saquinavir inhibited the production of superoxide by HTrMCs under both basal and MSS. Saquinavir also attenuated the morphine-induced expression of SOD and NADPH oxidase (Gp91phox) by HTrMCs. Interestingly, hemin exacerbated morphine-triggered HTrMC apoptosis.

CONCLUSION

Oxidative stress seems to play a role in the accelerated rate of HTrMC apoptosis both under basal and MSS. Saquinavir may be inhibiting HTrMC apoptosis by mitigating oxidative stress.

Role of oxidative stress and heme oxygenase activity in morphine-induced glomerular epithelial cell growth

Opiate addiction has been reported to contribute to the progression of renal injury. In addition, opiate addiction is a major risk factor for the development of human immunodeficiency virus-associated nephropathy. In the present study, we evaluated the effects of morphine, an active metabolite of heroin, on glomerular epithelial cell (GEC) growth and the involved molecular mechanism. At lower concentrations, morphine promoted GEC proliferation; however, at higher concentrations, morphine triggered apoptosis. Antioxidants inhibited morphine-induced proliferation as well as apoptosis. Similarly, free radical scavengers prevented morphine-induced GEC proliferation and apoptosis. Because proliferative and proapoptotic effects of morphine were inhibited by free radical scavengers as well as antioxidants, it appears that these effects of morphine are mediated through oxidative stress. Hemin, an inducer of heme oxygenase (HO) activity, inhibited GEC proliferation and promoted GEC apoptosis under basal and morphine-stimulated conditions. On the other hand, zinc protoporphyrin, an inhibitor of HO activity, promoted GEC proliferation and inhibited GEC apoptosis under basal as well as morphine-stimulated conditions. These findings suggest that HO activity is directly related to GEC apoptosis and inversely related to GEC proliferation. Morphine, de novo, had bimodal effects on HO activity: lower concentrations increased and higher concentrations decreased HO activity. It appears that HO activity may be modifying morphine-induced GEC growth.

Angiotensin II induces apoptosis in renal proximal tubular cells

ANG II has been demonstrated to play a role in the progression of tubulointerstial injury. We studied the direct effect of ANG II on apoptosis of cultured rat renal proximal tubular epithelial cells (RPTECs). ANG II promoted RPTEC apoptosis in a dose- and time-dependent manner. This effect of ANG II was attenuated by anti-transforming growth factor (TGF)-beta antibody. Moreover, TGF-beta triggered RPTEC apoptosis in a dose-dependent manner. ANG II also enhanced RPTEC expression of Fas and Fas ligand (FasL); furthermore, anti-FasL antibody attenuated ANG II-induced RPTEC apoptosis. In addition, ANG II increased RPTEC expression of Bax, a cell death protein. Both ANG II type 1 (AT(1)) and type 2 (AT(2)) receptor blockers inhibited ANG II-induced RPTEC apoptosis. SB-202190, an inhibitor of p38 MAPK phosphorylation, and caspase-3 inhibitor also attenuated ANG II-induced RPTEC apoptosis. ANG II enhanced RPTEC heme oxygenase (HO)-1 expression. Interestingly, pretreatment with hemin as well as curcumin (inducers of HO-1) inhibited the ANG II-induced tubular cell apoptosis; conversely, pretreatment with zinc protoporphyrin, an inhibitor of HO-1 expression, promoted the effect of ANG II. These results suggest that ANG II-induced apoptosis is mediated via both AT(1) and AT(2) receptors through the generation of TGF-beta, followed by the transcription of cell death genes such as Fas, FasL, and Bax. Modulation of tubular cell expression of HO-1 has an inverse relationship with the ANG II-induced tubular cell apoptosis.

Ethanol promotes T cell apoptosis through the mitochondrial pathway

Clinical reports suggest that acute ethanol intoxication is often associated with lymphopenia. Previously, ethanol was reported to invoke thymocyte apoptosis. We studied the effect of ethanol on T cell apoptosis. In addition, we evaluated the molecular mechanism of ethanol-induced T cell apoptosis. Human T cells harvested from healthy subjects after an alcohol drinking binge showed enhanced T cell apoptosis (before, 0.4 +/- 0.2% versus after, 19.6 +/- 2.5% apoptotic lymphocytes/field; P < 0.001). In in vitro studies, ethanol in a concentration of 50 mm and higher enhanced the apoptosis of Jurkat cells. DNA isolated from ethanol-treated Jurkat cells displayed integer multiples of 180 base pairs. Ethanol decreased Jurkat cell expression of Bcl-2, whereas ethanol increased Jurkat cell expression of Bax. Jurkat cells treated with ethanol also showed translocation of cytochrome C into cytosol. Moreover, a caspase-9 inhibitor partially inhibited ethanol-induced Jurkat cell apoptosis. In in vivo studies, after binge drinking, T cell expression of Bcl-2 also decreased. In addition, binge drinking induced the cleavage of caspase-3, suggesting activation of caspase-3 in T cells. These results suggest that ethanol promotes T cell apoptosis through the activation of intrinsic or mitochondrial pathway.

Role of heme oxygenase-1 in morphine-modulated apoptosis and migration of macrophages

We examined the role of heme oxygenase (HO)-1 in morphine-induced decrease in macrophage migration. Morphine promoted expression of HO-1 in murine macrophages. Morphine-receiving mice (MRCs) showed decreased (P<.001) macrophage migration and increased (P<.001) occurrence of macrophage apoptosis. In in vitro studies, peritoneal macrophages harvested from MRCs also showed decreased (P<.001) migration, compared with those from control mice. Bone marrow cells isolated from MRCs showed not only decreased (P<.001) migration but also increased apoptosis. Pretreatment of MRCs with hemin not only decreased migration of macrophages further but also enhanced the apoptosis of peritoneal macrophages. On the other hand, pretreatment of MRCs with zinc protoporphyrin attenuated the effect of morphine on both macrophage migration and the occurrence of apoptosis. In in vitro studies, pretreatment of macrophages with hemin exacerbated morphine-induced apoptosis, whereas pretreatment with zinc protoporphyrin attenuated morphine-induced macrophage apoptosis.

Monocyte apoptosis in dialysis patients is Fas ligand-mediated

BACKGROUND

The mononuclear phagocyte system plays an important role in host defense. Since dialysis patients have been reported to show enhanced leukocytes apoptosis, we evaluated the mechanism of increased apoptosis of monocytes in dialysis patients.

METHODS

Apoptotic studies were carried out on monocytes isolated from dialysis patients as well as healthy subjects. The effect of dialysis sera and membranes was evaluated on monocyte apoptosis as well as monocyte expression of proapoptotic proteins such as Fas and FasL. To confirm the role of FasL, we evaluated the effect of activated secretory products on T cell apoptosis. In addition, we studied FasL content of dialysis sera and supernatants of activated monocytes.

RESULTS

Monocytes isolated from dialysis patients (MDP) showed a greater magnitude of apoptosis when compared to monocytes isolated from healthy subjects (MHS) (MHS, 3.6 +/- 1.1% vs. MDP, 24.3 +/-1.4%). Sera of hemodialysis patients (SHD) promoted (p < 0.001) apoptosis of MHS when compared to pooled control sera (HPS) (HPS, 0.8 +/- 0.5% vs. SHD, 11.5 +/- 0.5% apoptotic cells/field). Dialysis membranes, cellulose acetate membranes in particular, promoted monocyte apoptosis. Interestingly, anti-FasL antibodies partly inhibited dialysis sera-induced monocyte apoptosis. Dialysis membranes also modulated monocyte expression of both Fas and FasL. Secretory products of activated monocytes also promoted T cell apoptosis. Dialysis sera and activated monocyte secretory products showed increased FasL content.

CONCLUSIONS

These results suggest that dialysis patients have an increased rate of monocyte apoptosis, which is mediated through a uremic milieu (serum factors). One of these serum factors seems to be FasL. In addition, dialysis membranes seem to promote apoptosis independent of the uremic milieu. The present study provides a mechanistical insight into the enhanced apoptosis of monocytes in dialysis patients.

Angiotensin II-induced mesangial cell apoptosis: role of oxidative stress

BACKGROUND

Angiotensin II (ANG II) has been shown to play a role in the induction of glomerular injury. In the present study, we evaluated the effects of ANG II on mesangial cell apoptosis and the involved molecular mechanism.

MATERIALS AND METHODS

The effect of ANG II on apoptosis of mouse mesangial cells (MC) was evaluated by morphologic, DNA fragmentation and TUNEL assays. To evaluate the role of oxidative stress and involved mechanisms, we studied the effect of antioxidants, anti-TGF-beta antibody, inhibitors of nitric oxide synthase and modulators of cytosolic calcium/heme oxygenase (HO) activity. In addition, we studied the effect of ANG II on the generation of reactive oxygen species (ROS) by MCs.

RESULTS

ANG II promoted apoptosis of MCs in a dose dependent manner. This effect of ANG II was not only associated with ROS production, but also inhibited by antioxidants. Both Anti-TGF-beta antibody and propranolol inhibited ANG II-induced ROS generation and apoptosis. BAPTA inhibited both ANG II- and TGF-beta-induced apoptosis. On the other hand, thapsigargin stimulated MC apoptosis under basal as well as ANG II/TGF-beta stimulated states. ANG II receptor types 1 and 2 antagonists attenuated the proapoptotic effect of ANG II. Hemin inhibited but zinc protoporphyrin enhanced the proapoptotic effect of ANG II. Propranolol increased HO activity; whereas pre-treatment with propranolol prevented ANG II-induced apoptosis.

CONCLUSIONS

ANG II promotes MC apoptosis. This effect of ANG II is mediated through downstream signaling involving TGF-beta, phospholipase D, and Ca(2+), contributing to the activation of NADPH oxidase and generation of ROS. HO activity plays a modulatory role in ANG II- induced MC apoptosis.

Role of p38 mitogen-activated protein kinase phosphorylation and Fas-Fas ligand interaction in morphine-induced macrophage apoptosis

In this study, we evaluated the molecular mechanisms involved in morphine-induced macrophage apoptosis. Both morphine and TGF-beta promoted P38 mitogen-activated protein kinase (MAPK) phosphorylation, and this phosphorylation was inhibited by SB 202190 as well as by SB 203580. Anti-TGF-beta Ab as well as naltrexone (an opiate receptor antagonist) inhibited morphine-induced macrophage P38 MAPK phosphorylation. Anti-TGF-beta Ab also attenuated morphine-induced p53 as well as inducible NO synthase expression; in contrast, N(G)-nitro-L-arginine methyl ester, an inhibitor of NO synthase, inhibited morphine-induced P38 MAPK phosphorylation and Bax expression. Morphine also enhanced the expression of both Fas and Fas ligand (FasL), whereas anti-FasL Ab prevented morphine-induced macrophage apoptosis. Moreover, naltrexone inhibited morphine-induced FasL expression. In addition, macrophages either deficient in FasL or lacking p53 showed resistance to the effect of morphine. Inhibitors of both caspase-8 and caspase-9 partially prevented the apoptotic effect of morphine on macrophages. In addition, caspase-3 inhibitor prevented morphine-induced macrophage apoptosis. These findings suggest that morphine-induced macrophage apoptosis proceeds through opiate receptors via P38 MAPK phosphorylation. Both TGF-beta and inducible NO synthase play an important role in morphine-induced downstream signaling, which seems to activate proteins involved in both extrinsic (Fas and FasL) and intrinsic (p53 and Bax) cell death pathways.

Lymphopenia in dialysis patients: a preliminary study indicating a possible role of apoptosis

Lymphopenia is a common finding in dialysis patients. Since infection rate and mortality associated with infection are high in dialysis patients, lymphopenia may be one of the contributing factors. In the present study, we evaluated the mechanism responsible for lymphopenia in these patients. Lymphocytes isolated from dialysis patients showed increased apoptosis (p < 0.001) when compared to lymphocytes isolated from healthy subjects (healthy subjects, 0.5 +/- 0.2% vs. dialysis patients, 8.8 +/- 0.7% apoptotic cells/field). Sera from dialysis patients promoted lymphocyte apoptosis in a time- and dose-dependent manner. These sera also enhanced lymphocyte DNA fragmentation into multiple integers of 180 base pairs in the form of a ladder pattern. Cellulose acetate membranes promoted T cell apoptosis when compared to polysulfone membranes and to control. Cellulose acetate dialysis membranes also appear to promote lymphocyte FasL expression. Similarly, dialysis sera enhanced T cell Fas as well as FasL expression. Neither the cellulose acetate nor polysulfone membranes could induce FasL expression on B cells. Similarly, dialysis sera failed to induce FasL expression on B cells. On the other hand, anti-FasL antibodies attenuated dialysis sera-induced apoptosis in T as well as B cells. Interestingly, dialysis serum showed a 5-fold increase in FasL content when compared with control serum. These results suggest that dialysis-associated factors can induce autocrine death in T cells but the help of activated T cells is required to induce death in B cells.

Morphine-induced degradation of the host defense barrier: role of macrophage injury

The effect of morphine on the degradation of the host defense barrier in rats and mice was studied. Mice received either 3 or 11 doses of morphine. Mice receiving 11 doses of morphine showed gram-negative bacteremia and bacterial growth in samples of peritoneal fluid (PF), liver, spleen, kidneys, heart, and lungs; PF and tissue samples from only 1 control mouse showed bacterial growth, and no control mice had bacteremia. Mice receiving 11 doses also had suppressed bone marrow macrophage colony formation. Monocytes and peritoneal macrophages harvested from morphine-treated mice showed greater injury than did those from control mice. Pretreatment of mice with naloxone inhibited morphine-induced macrophage injury and degradation of the host defense barrier. In in vitro studies, morphine attenuated the killing of bacteria phagocytosed by macrophages and also facilitated their escape. This study indicates that morphine-induced monocyte and macrophage injury may be linked to degradation of the host defense barrier.

Dialysis membrane-induced neutrophil apoptosis is mediated through free radicals

Patients on hemodialysis are prone to infection. Neutrophils are the host's first line of defense against certain invading pathogenic microorganisms. Since apoptotic neutrophils are functionally compromised we examined the effect of dialysis membranes on neutrophil apoptosis. Dialysis patients showed greater (p < 0.001) neutrophil apoptosis when compared with control subjects. Cellulose acetate membranes directly promoted (p < 0.001) neutrophil apoptosis. Cellulose acetate membrane-treated neutrophils exhibited greater apoptosis (p < 0.01) when compared with polysulfone membrane-treated neutrophils. Superoxide dismutase (SOD) partly inhibited the cellulose acetate membrane-induced neutrophil apoptosis, whereas both catalase and dimethylthiourea (DMTU) inhibited the polysulfone membrane-induced neutrophil apoptosis. Similarly, L-NAME, a nitric oxide synthase inhibitor, attenuated both the cellulose acetate and the polysulfone membrane-induced neutrophil apoptosis. In addition, cellulose acetate and monocyte interaction products promoted (p < 0.001) neutrophil apoptosis. These results suggest that dialysis membranes can promote neutrophil apoptosis directly as well as through their interaction with monocytes. The direct effect of dialysis membranes seems to be mediated partly through the generation of reactive oxygen species.

Fas-mediated apoptosis of neutrophils in sera of patients with infection

In the presence of infection, neutropenia is considered to be a marker of poor prognosis; conversely, neutrophilia may not be a determinant of a better prognosis. Since apoptotic neutrophils are compromised functionally, we evaluated the effect of infection on neutrophil apoptosis. The rate of apoptosis was greater for neutrophils isolated from patients with infection than for healthy controls. Escherichia coli did not directly modulate the rate of neutrophil apoptosis. However, sera from infected patients promoted (P < 0.001) neutrophil apoptosis. Interestingly, the sera of patients with different types of infection (gram negative, gram positive, or culture negative) exerted a more or less identical response on neutrophil apoptosis. Sera of infected patients showed a fivefold greater content of FasL compared to controls. Moreover, anti-FasL antibody partly attenuated the infected-serum-induced neutrophil apoptosis. In in vitro studies, E. coli enhanced monocyte FasL expression. Moreover, conditioned media prepared from activated macrophages from control mice showed enhanced apoptosis of human as well as mouse neutrophils. On the contrary, conditioned media prepared from activated macrophages isolated from FasL-deficient mice induced only a mild degree of neutrophil apoptosis. These results suggest that neutrophils in patients with infection undergo apoptosis at an accelerated rate. Infection not only promoted monocyte expression of FasL but also increased FasL content of the serum. Because the functional status of apoptotic cells is compromised, a significant number of neutrophils may not be participating in the body's defense. Since neutrophils play the most important role in innate immunity, their compromised status in the presence of infection may transfer the host defense burden from an innate response to acquired immunity. The present study provides some insight into the lack of correlation between neutrophilia and the outcome of infection.