General tissue reactions and implications for radiation protection

Non-cancer effects and risks at low doses from ionising radiation are controversial topics within the field of radiation protection. These issues are discussed in International Commission on Radiological Protection (ICRP) Publication 118, 'ICRP statement on tissue reactions'. Both non-cancer effects and risks are expected to become increasingly important to the system of radiation protection. Before this can happen, several factors must be considered: thorough characterisation of the relationship between dose and risk; verification of the biological mechanisms for any noted excess risk; and adjustment of noted excess risks through the use of a detriment factor. It is difficult to differentiate the relatively small risks associated with radiation from other risk factors in the low-dose region of the dose-response curve. Several recent papers have indicated the possibility of a non-linear dose-response relationship for non-cancer effects. In addition, there are still many uncertainties associated with the biological mechanisms for non-cancer effects. Finally, it is essential to consider the incorporation of detriment into a well-defined system of radiological protection. Given the recent interest in non-cancer effects, it is essential to facilitate discussions in order to define dose limits more clearly within the existing system of radiation protection for both cancer and non-cancer effects.

Gene expression profiling of lung myofibroblasts reveals the anti-fibrotic effects of cyclosporine

Cyclosporine, a calcineurin inhibitor, is a potent immunosuppressive agent that acts chiefly through the inactivation of T-lymphocytes. Several clinical studies have demonstrated the effectiveness of cyclosporine for treating fibrotic lung disease, but the underlying mechanism remains elusive. We hypothesized that cyclosporine exerts direct effects against fibrogenesis of lung myofibroblasts, and aimed to elucidate the mechanism of this anti-fibrotic effect through gene-expression profiling using DNA microarray analysis. We found that cyclosporine suppressed the expression of alpha-smooth muscle actin and collagen type I in myofibroblasts that had been differentiated from a fetal human lung fibroblast cell line by induction with transforming growth factor (TGF)-β. Furthermore, microarray analysis revealed that cyclosporine down-regulated 57 genes whose expression levels were increased by TGF-β, and up-regulated 73 genes, whose expression was decreased by TGF-β. Classifying these 57 down-regulated and 73 up-regulated genes with the Database for Annotation, Visualization and Integrated Discovery (DAVID) web tool, we have identified the involvement of several functional categories, including innate immunity, cytokine interaction, growth factor, and cancer pathway. Of the identified genes, we selected three fibrosis-related genes, insulin-like growth factor binding protein 2 (IGFBP2), inhibitor of DNA binding 1 (ID1) and peroxisome proliferator-activated receptor gamma (PPARG), and validated their expression patterns by quantitative reverse transcription-polymerase chain reaction. Cyclosporine treatment decreased the expression levels of IGFBP2 and ID1, but increased PPARG expression. These results suggest that cyclosporine is a potent anti-fibrotic agent acting on myofibroblasts. Therefore, cyclosporine shows potential as a novel remedy for fibrotic lung disease.

Zyxin modulates the transmigration of Haemophilus influenzae to the central nervous system

The mechanism by which Haemophilus influenzae causes meningitis is unclear. Previously, we established murine meningitis by intranasal instillation of H. influenzae as a cell-bound organism (CBO). In this study, we aimed to identify the molecules associated with inhibiting the transmigration of cells across the blood-brain barrier (BBB). Two-dimensional difference gel electrophoresis and protein identification by mass spectrometry were used for proteomic analysis. Analysis of the membranous extract from a tumor necrosis factor (TNF)-α-treated human brain microvascular endothelial cell (HBMEC) monolayer revealed 41 differentially expressed proteins. Zyxin, which is thought to be essential for tight cell-to-cell junctions, decreased 1.8-fold in TNF-α-treated HBMECs. In addition, zyxin transcript levels decreased 1.5-fold in cells derived from TNF-α-treated HBMECs. Intranasal instillation of CBOs in zyxin-deficient mice resulted in a significant higher mortality rate than in wild-type mice. Transmigration of CBOs across a HBMEC monolayer pretreated with TNF-α (1 ng/mL), interleukin (IL)-1β (10 ng/mL), or lipopolysaccharide (LPS; 10 ng/mL) was assayed by counting CBOs that migrated from an upper chamber into a lower chamber. HBMEC pretreated with TNF-α exhibited significantly greater migration (P<0.01) than did control cells or cells treated with IL-1β or LPS. Our findings highlight that zyxin is an important protein protecting the tight junction of the BBB against cell transmigration across the BBB. Finally, TNF-α produced in respiratory infection when the primary infection reached the BBB caused decreased zyxin levels in BBB cell membranes. Furthermore, H. influenzae reaching the BBB as CBOs could transmigrate into cerebrospinal fluid across the zyxin-decreased BBB.

ACTH expression in synovium of patients with rheumatoid arthritis and Lewis rats with adjuvant arthritis

Abstract Adrenocorticotropic hormone (ACTH) and another pro-opiomelanocortin-derived neuropeptide, β-endorphin (β-End), are stimulated by corticotropin-releasing hormone (CRH) at the anterior pituitary. CRH and β-End have predominantly proinflammatory effects in peripheral inflammatory sites. We have supposed that inflammatory stimuli develop ACTH as well as β-End. In this study, we investigated the expression of ACTH in inflamed synovial tissue from patients with rheumatoid arthritis (RA) and osteoarthritis (OA), and at inflammatory joints with adjuvant-induced arthritis (AA) in female Lewis (LEW/N) rats. The expression of ACTH immunostaining was significantly greater in synovium of RA patients than in that of OA patients (P < 0.0001), and correlated with the extent of inflammatory mononuclear cell infiltration. Extensive and intense intracellular ACTH immunostaining, which correlated with the advance in arthritis score, was observed in the synovial lining layer, inflammatory mononuclear cells, and fibroblast-like cells of synovium and chondrocytes in LEW/N rats with AA. In addition, we performed double immunostaining of the same sections from arthritic joints in rats with anti-ACTH and anti-CRH antibodies. ACTH and CRH colocalized in inflammatory mononuclear cells and fibroblast-like cells. ACTH may play a role in the pathogenesis of RA as well as CRH.

Selection of autophagy or apoptosis in cells exposed to ER-stress depends on ATF4 expression pattern with or without CHOP expression

Cells exposed to ER-stress undergo the Unfolded Protein Response (UPR) to avoid apoptosis, but may also activate autophagy. However, the signal for selection of one of these two protective responses is unknown. To clarify the key switch between autophagy and apoptosis, we examined the correlation of UPR-related signals with autophagy and/or apoptosis inductions in HepG2 cells exposed to three ER-stress inducers (NaF, tunicamycin, and thapsigargin) with time, including the effect of small interfering RNA on the cell responses. Thapsigargin-induced ER-stress caused only apoptosis after ∼2 hr with Ire1 phosphorylation, and Grp78, ATF4, and CHOP expressions. On the other hand, NaF- and tunicamycin-induced ER-stress caused only autophagy in the early stage by ∼8 hr with ATF4 expression and without CHOP expression. ATF4-siRNA completely inhibited the autophagy induced by NaF or tunicamycin with suppressed ATF4 protein and mRNA expressions, and also inhibited apoptosis by thapsigargin with suppression of both ATF4 and CHOP. CHOP-siRNA had no effect on autophagy activation by NaF and tunicamycin. On the other hand, CHOP-siRNA activated autophagy in thapsigargin-induced ER-stress with significant ATF4 expression, and suppressed apoptosis with CHOP suppression. These results showed that ATF4 is the key signal for autophagy induced by ER-stress, and that autophagy is switched to apoptosis by subsequent CHOP upregulation, suggesting that the changeover switch between autophagy and apoptosis is located between ATF4 to CHOP in the PERK pathway.

A vasodilating β1 blocker celiprolol inhibits muscular release of uric acid precursor in patients with essential hypertension

Although nonvasodilating β1 blockers increase the levels of uric acid in serum, it is not known whether vasodilating β1 blockers have a similar effect. In the present study, we evaluated the effect of celiprolol on the release of hypoxanthine, a uric acid precursor, from muscles after an exercise. We used the semi-ischemic forearm test to examine the release of lactate (ΔLAC), ammonia (ΔAmm), and hypoxanthine (ΔHX) before and 4, 10, and 60 min after an exercise in 18 hypertensive patients as well as 4 normotensive subjects. Before celiprolol treatment, all the levels of ΔHX and ΔAmm, and ΔLAC were increased by semi-ischemic exercise in hypertensive patients, and the increases were remarkably larger than those in normotensive subjects. Celiprolol decreased both systolic and diastolic pressure. It also decreased the levels of ΔHX and ΔAmm without changes in ΔLAC after an exercise. These findings also were confirmed by summation of each metabolite (ΣΔMetabolites). Celiprolol caused a marginal decrease of serum uric acid, but the difference was not statistically significant. On the other hand, nonvasodilating β1 blockers did not suppress the levels of ΔHX and ΔAmm, whereas they significantly increased ΔLAC after an exercise. Celiprolol improved energy metabolism in skeletal muscles. It suppressed HX production and consequently did not adversely affect serum uric acid levels.

Sar1 translocation onto the ER-membrane for vesicle budding has different pathways for promotion and suppression of ER-to-Golgi transport mediated through H89-sensitive kinase and ER-resident G protein

ER-to-Golgi protein transport involves transport vesicles of which formation is initiated by assembly of Sar1. The assembly of Sar1 is suppressed by protein kinase inhibitor H89, suggesting that ER-to-Golgi transport is regulated progressively by H89 sensitive kinase. ER-resident G(i2) protein suppresses vesicle formation with inhibition of Sar1 assembly. This study examined whether these promotion and suppression of vesicle transport share the same signal pathway, by examining the effects of G(i/o) protein activator mastoparan 7 (Mp-7) and H89 on Sar1 and Sec23 recruitment onto microsomes. In a cell-free system for Sar1 translocation assay, GTPγS addition induced the translocation of Sar1 onto microsomes. Mp-7 and H89 decreased the Sar1 translocation. Double treatment of Mp-7 and H89 strongly decreased Sar1 translocation. In single and double treatments, however, G(i/o) protein inactivator pertussis toxin (IAP) partially restored the suppressive effect of Mp-7, but had not any effect on H89-induced effect. Then, the assembly of Sec23 onto the microsome was also increased by the addition of GTPγS. Sec23 translocation was decreased by Mp-7 and/or H89 treatment and recovered by IAP pretreatment except for H89 single treatment, similarly to Sar1 translocation in each treatment. Inhibitory effects of H89 and Mp-7on ER-to-Golgi vesicle transport by H89 or Mp-7 were also confirmed in a cell culture system by BFA-dispersion and BFA-reconstruction experiments. These findings indicate that promotion and suppression of ER-to-Golgi vesicle transport are modulated through separate signal pathways.

ER-resident Gi2 protein controls sar1 translocation onto the ER during budding of transport vesicles

In our previous study, fluoride ([AlF(4) ](-) ) disturbed ER-to-Golgi transport through the activation of ER-resident heterotrimeric G protein (ER-G protein). Therefore, ER-G protein may be implicated in ER-to-Golgi transport at the early stage prior to coat protein assembly. Sar1 translocation onto the endoplasmic reticulum (ER) membrane is suppressed by non-selective protein kinase inhibitor H89, suggesting the participation of H89-sensitive kinase in this process. To investigate the involvement of ER-G protein in ER-to-Golgi transport, the effect of G(i) protein activator (mastoparan 7) was examined on Sar1 translocation onto the ER in a cell-free system consisting of microsome membrane and cytosol. Sar1 translocation onto the microsome membrane was induced by addition of GTPγS in the cell-free system. Translocation of Sar1 by GTPγS was suppressed significantly by both H89 and mastoparan 7. Mastoparan 7 suppressed the translocation of Sar1 onto the microsome membrane with dosage dependency, but mastoparan 17, the inactive analog of mastoparan 7, had no effect on Sar1 translocation. The suppressive effect of mastoparan 7 was recovered by treatment with pertussis toxin (IAP). Moreover, G(i2) protein was detected on the microsome membrane by western blotting for heterotrimeric G(i) proteins. These results indicate that ER-G(i2) protein modulated Sar1 translocation onto the ER, suggesting that ER-resident G(i2) protein is an important negative regulator of vesicular transport at the early stage of vesicle formation before coat protein assembly on the ER.

Quantitative evaluation of cryptococcal pathogenesis and antifungal drugs using a silkworm infection model with Cryptococcus neoformans

AIMS

To develop an in vivo system that could quantitatively evaluate the therapeutic effects of antifungal drugs using a silkworm infection model with Cryptococcus neoformans.

METHODS AND RESULTS

Silkworms reared at 37°C died after an injection of viable serotype A C. neoformans fungus into the haemolymph. The serotype A C. neoformans, which is known to have higher mammal pathogenicity than the serotype D, was also more virulent against the silkworm. Furthermore, the deletion mutants of genes gpa1, pka1 and cna1, which are genes known to be necessary for the pathogenesis in mammals, showed an increase in the number of fungal cells necessary to kill half of the silkworm population (LD(50) value). Antifungal drugs, amphotericin B, flucytosine, fluconazole and ketoconazole, showed therapeutic effects in silkworms infected with C. neoformans. However, amphotericin B was not therapeutically effective when injected into the silkworm intestine, comparable to the fact that amphotericin B is not absorbed by the intestine in mammals.

CONCLUSIONS

The silkworm-C. neoformans infection model is useful for evaluating the therapeutic effects of antifungal drugs.

SIGNIFICANCE AND IMPACT OF THE STUDY

The silkworm infection model has various advantages for screening antifungal drug candidates. We can also elucidate the cryptococcal pathogenesis and evaluate the in vivo pharmacokinetics and toxicity of each drug.

The pH Dependent Uptake of Enoxacin by Rat Intestinal Brush-border Membrane Vesicles

The mechanism of the intestinal transport of enoxacin, an orally active fluoroquinolone antibiotic, has been investigated using brush-border membrane vesicles isolated from rat small intestine. The initial rate and time-course of enoxacin uptake were considerably dependent upon the medium pH (pH 5·5 &gt; pH 7·5) and upon the percent ionization of the carboxyl group (pKa 6·2, anionic charge), namely, the degree of uptake of cationic form was higher than that of the zwitterionic form. There was evidence of transport into the intravesicular space as shown by the effect of extravesicular medium osmolarity on enoxacin uptake at steady state (30 min). This transport across the brush-border membrane was stimulated by the valinomycin-induced K+-diffusion potential (interior negative) and an outward H+-diffusion potential. Furthermore, changing the pH of the medium from 5·5 to 7·5 significantly decreased the effect of valinomycin-induced K+-diffusion potential on the enoxacin uptake. These results suggest that the uptake behaviour of the cationic form of enoxacin plays an important role in the intestinal absorption process of enoxacin.

Chemical Structure of Native Oxide Grown on Hydrogenterminated Silicon Surfaces

Chemical bonding features and suboxide compositions in native oxide grown on chemically-cleaned hydrogen-terminated Si(100) surfaces stored in pure water have been studied by using surface sensitive infrared spectroscopy and x-ray photoelectron spectroscopy. The LO phonon peak for the native oxide is located at 1210cm−1, which is shifted to a significantly lower wavenumber side than the ultrathin thermal oxide peak at 1250cm−1. This is because an appreciable amount of SiHx bonds are incorporated in the native oxide/Si interface and such hydrogen termination in the network dramatically reduces strained bonds in the interface. Very weak Si2+ suboxide signal from the oxide grown in pure water is also explained by the incorporated SiHx bonds which interrupt the Si2+ suboxide formation in the interface.

Cleaning and Oxidation of Heavily Doped Si Surfaces

HF-treated Si surfaces and the oxidation kinetics in pure water or in clean room air have systematically been studied by x-ray photoelectron spectroscopy (XPS). The oxidation of heavily-doped n-type Si appears to proceed parallel to the surface, resulting in the layer-by-layer oxidation. The oxide growth rate in pure water for heavily-doped n-type Si is significantly higher than that of heavily-doped ptype Si. This is explained by the electron tunneling from the Si conduction band to adsorbed O2 molecules to form the O2 state. O2 ions easily decompose and induce a surface electric field, enhancing the oxidation rate. The growth rate of native oxide on heavily-doped n-type Si is less sensitive to the crystallographic orientations than the case of lightly doped Si where the steric hindrance against oxygen molecules significantly lowers the oxidation rate of the (110) and (111) surfaces. We suggest that the decomposed oxygen can penetrate into Si without steric hindrance. It is also found that the oxidation of heavily-doped n-type Si in pure water is effectively suppressed by adding a small amount (10 ∼ 3600 ppm) of HCI.

Layer-by-Layer Oxidation of Silicon

Growth kinetics of native oxide on HF-treated Si surfaces terminated with Si-H bonds has been studied by angle-resolved x-ray photoelectron spectroscopy. The oxide growth rate in pure water for an n+ Si(100) surface is significantly high compared to that of p+, and the n or p type Si oxidation rate is in between. This is explained by the formation of ions through electron transfer from Si to adsorbed O2 molecules and the resulting enhancement of the oxidation rate. The oxide growth on Si(100) is faster than (110) and (111) as interpreted in terms of the steric hindrance for molecular oxygen adsorption on the hydrogen terminated silicon 1×1 surface structures.

Shape Memory Behavior of Ti-Ni Thin Films Annealed at Various Temperatures

Ti-Ni thin films with three different types of compositions, titanium-rich Ti-Ni, near equiatomic TiNi and nickel-rich Ti-Ni were prepared by sputtering. The sputter-deposited films were annealed at various temperatures between 773 and 973K in order to crystallize. After the heat treatment, the shape memory behavior was examined with a thermomechanical tester. The shape memory behavior of the near equiatomic composition films was not affected by the heat treatment. On the other hand, the shape memory behavior of the other composition films strongly depended on the annealing temperature. As the annealing temperature increases, the martensitic and reverse martensitic transformation temperatures of the nickel-rich films decreased and those of the titanium-rich films increased. These opposite behaviors of the transformation temperatures can be explained by the opposite dependence of the precipitation of the second phase on the annealing temperature. All the nickel-rich films exhibited good shape memory effect over a wide range of stress, while all the titanium-rich films exhibited a small plastic strain only in the stress range where the shape changes associated with both the R-phase and the martensitic transformations were observed.

Self-Assembling Formation of Silicon Quantum Dots by Low Pressure Chemical Vapor Deposition

The growth of Si dots on thermally-grown SiO2/c-Si from a thermal decomposition of pure silane has been systematically studied in the temperature range from 500 to 650°C. It has been suggested mat the Si dot height and dot diameter on as-grown SiO2 are rate-limited by the cohesive action of adsorbed precursors and the thermal decomposition of silane on Si nucleation sites, respectively. The nucleation site on as-grown SiO2 is likely to be generated by the thermal dissociation of surface Si-O bonds. It has been also found that in Si dot formation on OH-terminated SiO2 surface the nucleation density is dramatically enhanced and consequently the dot size and its distribution become small. This implies that surface OH bonds can provide the nucleation sites.

Structural Characterization of Porous Silicon Fabricated by Electrochemical and Chemical Dissolution of Si Wafers

The structure of porous silicon exhibiting efficient visible photoluminescence has been characterized by using Fourier transformed infrared absorption, Raman scattering and x-ray diffraction. It is shown that the lattice spacing in the porous Si layer expands by about 0.3% in the direction perpendicular to the surface and also a partially disordered structure is existing. Electron beam irradiation causes desorption of hydrogen and fluorine bonds which terminate the surface, resulting in the quenching of the visible luminescence. The chemical etching of such layer has led to complete recovery of the luminescence intensity as well as the hydrogen and fluorine bonds termination.

Development of an enzyme-linked immunosorbent assay for measurement of rat pulmonary surfactant protein D using monoclonal antibodies

Surfactant protein D (SP-D) has been used as a biomarker of lung inflammation. In rat, several types of enzyme-linked immunosorbent assay (ELISA) using polyclonal antibodies have been reported. The purpose of this study was the development of a sensitive ELISA for rat SP-D using monoclonal antibodies. The authors developed a sandwich ELISA using monoclonal antibodies that were obtained by immunizing with purified rat SP-D. The ELISA was evaluated by performance tests. Furthermore, concentrations of serum SP-D were measured in normal control and bleomycin-treated rats. The working range of ELISA was between 0.47 and 30 ng/mL. Different concentrations of added SP-D were recovered, between 94.1% and 102.8%. Serum SP-D levels of bleomycin-treated rats were significantly higher than those of normal rats. In conclusion, this newly developed ELISA for rat SP-D using monoclonal antibodies is applicable for research on the mechanism and therapy of lung injury.

H89 sensitive kinase regulates the translocation of Sar1 onto the ER membrane through phosphorylation of ER-coupled β-tubulin

ER-to-Golgi protein transport is carried out by transport vesicles which are formed at the ER-exit sites with recruitment of cytoplasmic coat proteins. Vesicle formation is initiated by assembly of the small G protein (Sar1) onto the ER membrane. Sar1 assembly onto the ER membrane is suppressed by protein kinase inhibitor H89, suggesting participation of H89-sensitive kinase in this process. The present study identified an effector of H89-sensitive kinase by LC-MS PMF analysis combined with 1D- and 2D-PAGE autoradiography, and examined the changes on the effector and Sar1 translocation induced by H89. H89 significantly suppressed the phosphorylation of 55 kDa protein with dosage dependency, and phosphorylation of 55 kDa, pI 5.5 protein spot in 2-D-autoradiography was drastically diminished by H89. LC-MS PMF analysis showed that the protein spot was β-tubulin. H89 significantly suppressed Sar1 translocation onto the ER. These findings indicate that β-tubulin is one of downstream effectors of H89-sensitive kinase, and that suppression of ER-coupled β-tubulin phosphorylation decreases Sar1 translocation onto the ER, suggesting that phosphorylation of β-tubulin regulates Sar1 translocation.

First-principles study of blue silicate phosphors

First-principles calculations were performed to investigate the optical property of blue silicate phosphor, CMS:Eu. The optical absorption property is discussed based on electronic band structure and density of states. Our calculation results indicate that hybridization of the wavefunction plays an important role for nonradiative migration of electrons and holes. The calculated optical absorption spectrum could reproduce the optical features of the experimental excitation spectrum. It is also demonstrated that a practical approach using computational materials screening is effective in phosphor materials development.

Involvement of endotoxin in the mortality of mice with gut-derived sepsis due to methicillin-resistant Staphylococcus aureus

MRSA causes a wide diversity of diseases, ranging from benign skin infections to life-threatening diseases, such as sepsis. However, there have been few reports of the pathophysiology and mechanisms of sepsis resulting from the gut-derived origin of MRSA. Therefore, we established a murine model of gut-derived sepsis with MRSA and factors of MRSA sepsis that cause deterioration. We separated mice into four groups according to antibiotic treatment as follows: (i) ABPC 40 mg/kg; (ii) CAZ 80 mg/kg; (iii) CAZ 80 mg/kg + endotoxin 10 microg/mouse; and (iv) saline-treated control groups. Gut-derived sepsis was induced by i.p. injection of cyclophosphamide after colonization of MRSA strain 334 in the intestine. After the induction of sepsis, significantly more CAZ-treated mice survived compared with ABPC-treated and control groups. MRSA were detected in the blood and liver among all groups. Endotoxin levels were significantly lower in the CAZ-treated group compared to other groups. Inflammatory cytokine levels in the serum were lower in the CAZ-treated group compared to other groups. Fecal culture showed a lower level of colonization of E. coli in the CAZ-treated group compared to other groups. In conclusion, we found that CAZ-treatment ameliorates infection and suppresses endotoxin level by the elimination of E. coli from the intestinal tract of mice. However, giving endotoxin in the CAZ-treated group increased mortality to almost the same level as in the ABPC-treated group. These results suggest endotoxin released from resident E. coli in the intestine is involved in clinical deterioration resulting from gut-derived MRSA sepsis.

Interleukin-1 deficiency in combination with macrophage depletion increases susceptibility to Pseudomonas aeruginosa bacteremia

We evaluated the role of IL-1 during Pseudomonas aeruginosa bacteremia by intravenously injecting P. aeruginosa strain D4 into IL-1-deficient and WT mice. The two strains showed equivalent mortality rates. However, when the mice were pretreated with cyclophosphamide, bacteremia-induced mortality was significantly greater in the IL-1-deficient mice than in the WT mice (P < 0.01). We then investigated the role of neutrophils and macrophages in protecting IL-1-deficient mice from bacteremia by administering anti-Gr-1 antibody or liposomes containing dichloromethylene diphosphonate, respectively. After P. aeruginosa inoculation survival was significantly lower in the macrophage-depleted IL-1-deficient mice than in the WT mice. In contrast, neutrophil depletion did not have this effect. Compared to the macrophage-depleted WT mice, the macrophage-depleted IL-1-deficient bacteremic mice had higher bacterial counts in various organs 48 and 72 hr post-infection. They also had lower TNF-alpha, IL-6, and INF-gamma concentrations in their livers during the early phase of sepsis. Thus, IL-1 deficiency becomes disadvantageous during P. aeruginosa bacteremia when it is accompanied by immunosuppression, particularly when macrophage functions are seriously impaired.