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Biomedical subjects

R F Guo

Publications and source records attributed to R F Guo.

17 recordsLinked to original sources
PubMed2004

Exogenous nitric oxide donor and related compounds protect against lung inflammatory response after hemorrhagic shock and resuscitation.

BACKGROUND: Resuscitation from hemorrhagic shock triggers an inflammatory response characterized by upregulation of cytokine and adhesion molecule expression, increased leukocyte activity, and accumulation of polymorphonuclear neutrophils in a variety of tissues. This study investigated the capability of an exogenous nitric oxide (NO) donor, sodium nitroprusside (NP); a NO substrate, L-arginine; and an inducible NO synthase inhibitor, L-N6-(1-iminoethyl)lysine (L-NIL) to reduce lung injury in an animal model of mixed controlled and uncontrolled hemorrhagic shock. METHODS: For this study, 72 Sprague-Dawley rats weighing 250 to 300 g were subjected to a model of uncontrolled hemorrhagic shock for 150 minutes. Six groups of animals were included in this study (12 per group): sham-saline, sham-NP, shock-saline, shock-NP, shock-L-arginine, and shock-L-N6-(1-iminoethyl)lysine. After the period of hemorrhagic shock, resuscitation of the groups was accomplished using normal saline (groups 1 and 3), NP (0.5 mg/kg) (groups 2 and 4), L-arginine (300 mg/kg) (group 5), or L-NIL (50 mg/kg) (group 6). The following indices were evaluated: fluid requirements for resuscitation, mean arterial pressure (MAP), arterial po2, pco2, and pH, lung wet-to-dry weight ratio, lung histology and cytokine (interleukin [IL]-1 alpha, IL-beta 1, tumor necrosis factor-beta [TNF beta], IL-3, IL-4, IL-5, IL-6, IL-10, TNF alpha, IL-2, interferon-gamma [IFN gamma]), and mRNA expression in the lung by a ribonuclease protection assay (RPA). RESULTS: Sodium nitroprusside significantly increased MAP and reduced fluid requirements during resuscitation after hemorrhage. There also was a significant improvement in lung function, as expressed by improvements in po2, pco2, and pH, and reduction of the wet-to-dry weight ratio. In addition, a significant reduction in acute lung injury was observed in the histologic studies. Furthermore, the expression of cytokines was reduced by NP treatment. The use of L-arginine and L-NIL offered similar protective results for the injured lung. CONCLUSIONS: These data suggest that limiting inducible NO synthase-generated NO availability with the exogenous NO donor, sodium nitroprusside, may reduce lung injury after severe hemorrhage, possibly, among other effects, by downregulating the expression of inflammatory cytokines. L-arginine and L-NIL also had a beneficial effect on lung function and structure.

Animals↗
PubMed2001

Role of IL-18 in acute lung inflammation.

We have examined the role of IL-18 after acute lung inflammation in rats caused by intrapulmonary deposition of IgG immune complexes. Constitutive IL-18 mRNA and protein expression (precursor form, 26 kDa) were found in normal rat lung, whereas in inflamed lungs, IL-18 mRNA was up-regulated; in bronchoalveolar (BAL) fluids, the 26-kDa protein form of IL-18 was increased at 2-4 h in inflamed lungs and remained elevated at 24 h, and the "mature" protein form of IL-18 (18 kDa) appeared in BAL fluids 1-8 h after onset of inflammation. ELISA studies confirmed induction of IL-18 in inflamed lungs (in lung homogenates and in BAL fluids). Prominent immunostaining for IL-18 was found in alveolar macrophages from inflamed lungs. When rat lung macrophages, fibroblasts, type II cells, and endothelial cells were cultured in vitro with LPS, only the first two produced IL-18. Intratracheal administration of rat recombinant IL-18 in the lung model caused significant increases in lung vascular permeability and in BAL content of neutrophils and in BAL content of TNF-alpha, IL-1beta, and cytokine-induced neutrophil chemoattractant, whereas intratracheal instillation of anti-IL-18 greatly reduced these changes and prevented increases in BAL content of IFN-gamma. Intratracheal administration of the natural antagonist of IL-18, IL-18 binding protein, resulted in suppressed lung vascular permeability and decreased BAL content of neutrophils, cytokines, and chemokines. These findings suggest that endogenous IL-18 functions as a proinflammatory cytokine in this model of acute lung inflammation, serving as an autocrine activator to bring about expression of other inflammatory mediators.

Acute Disease↗
PubMed2001

Regulatory effects of eotaxin on acute lung inflammatory injury.

Eotaxin, which is a major mediator for eosinophil recruitment into lung, has regulatory effects on neutrophil-dependent acute inflammatory injury triggered by intrapulmonary deposition of IgG immune complexes in rats. In this model, eotaxin mRNA and protein were up-regulated during the inflammatory response, resulting in eotaxin protein expression in alveolar macrophages and in alveolar epithelial cells. Ab-induced blockade of eotaxin in vivo caused enhanced NF-kappaB activation in lung, substantial increases in bronchoalveolar lavage levels of macrophage inflammatory protein (MIP)-2 and cytokine-induced neutrophil chemoattractant (CINC), and increased MIP-2 and CINC mRNA expression in alveolar macrophages. In contrast, TNF-alpha levels were unaffected, and IL-10 levels fell. Under these experimental conditions, lung neutrophil accumulation was significantly increased, and vascular injury, as reflected by extravascular leak of (125)I-albumin, was enhanced. Conversely, when recombinant eotaxin was administered in the same inflammatory model of lung injury, bronchoalveolar lavage levels of MIP-2 were reduced, as was neutrophil accumulation and the intensity of lung injury. In vitro stimulation of rat alveolar macrophages with IgG immune complexes greatly increased expression of mRNA and protein for MIP-2, CINC, MIP-1alpha, MIP-1beta, TNF-alpha, and IL-1beta. In the copresence of eotaxin, the increased levels of MIP-2 and CINC mRNAs were markedly diminished, whereas MIP-1alpha, MIP-1beta, TNF-alpha, and IL-1beta expression of mRNA and protein was not affected. These data suggest that endogenous eotaxin, which is expressed during the acute lung inflammatory response, plays a regulatory role in neutrophil recruitment into lung and the ensuing inflammatory damage.

Acute Disease↗
PubMed2001

Protective effects of anti-C5a peptide antibodies in experimental sepsis.

We evaluated antibodies to different peptide regions of rat C5a in the sepsis model of cecal ligation and puncture (CLP) for their protective effects in rats. Rabbit polyclonal antibodies were developed to the following peptide regions of rat C5a: amino-terminal region (A), residues 1-16; middle region (M), residues 17-36; and the carboxyl-terminal region (C), residues 58-77. With rat neutrophils, the chemotactic activity of rat C5a was significantly inhibited by antibodies with the following rank order: anti-C > anti-M >> anti-A. In vivo, antibodies to the M and C (but not A) regions of C5a were protective in experimental sepsis, as determined by survival over a 10-day period, in a dose-dependent manner. The relative protective efficacies of anti-C5a preparations (in descending order of efficacy) were anti-C > anti-M >> anti-A. In CLP rats, a delay in infusion of antibodies, which were injected at 6 or 12 h after CLP, still resulted in significant improvement in survival rates. These in vivo and in vitro data suggest that there are optimal targets on C5a for blockade during sepsis and that delayed infusion of anti-C5a antibody until after onset of clinical evidence of sepsis still provides protective effects.

Animals↗
PubMed2001

Role of C5a in multiorgan failure during sepsis.

In humans with sepsis, the onset of multiorgan failure (MOF), especially involving liver, lungs, and kidneys, is a well known complication that is associated with a high mortality rate. Our previous studies with the cecal ligation/puncture (CLP) model of sepsis in rats have revealed a C5a-induced defect in the respiratory burst of neutrophils. In the current CLP studies, MOF occurred during the first 48 h with development of liver dysfunction and pulmonary dysfunction (falling arterial partial pressure of O(2), rising partial pressure of CO(2)). In this model an early respiratory alkalosis developed, followed by a metabolic acidosis with increased levels of blood lactate. During these events, blood neutrophils lost their chemotactic responsiveness both to C5a and to the bacterial chemotaxin, fMLP. Neutrophil dysfunction was associated with virtually complete loss in binding of C5a, but binding of fMLP remained normal. If CLP animals were treated with anti-C5a, indicators of MOF and lactate acidosis were greatly attenuated. Under the same conditions, C5a binding to blood neutrophils remained intact; in tandem, in vitro chemotactic responses to C5a and fMLP were retained. These data suggest that, in the CLP model of sepsis, treatment with anti-C5a prevents development of MOF and the accompanying onset of blood neutrophil dysfunction. This may explain the protective effects of anti-C5a in the CLP model of sepsis.

Acidosis↗
PubMed2000

Molecular cloning and characterization of DEFCAP-L and -S, two isoforms of a novel member of the mammalian Ced-4 family of apoptosis proteins.

We report the deduced amino acid sequences of two alternately spliced isoforms, designated DEFCAP-L and -S, that differ in 44 amino acids and encode a novel member of the mammalian Ced-4 family of apoptosis proteins. Similar to the other mammalian Ced-4 proteins (Apaf-1 and Nod1), DEFCAP contains a caspase recruitment domain (CARD) and a putative nucleotide binding domain, signified by a consensus Walker's A box (P-loop) and B box (Mg(2+)-binding site). Like Nod1, but different from Apaf-1, DEFCAP contains a putative regulatory domain containing multiple leucine-rich repeats (LRR). However, a distinguishing feature of the primary sequence of DEFCAP is that DEFCAP contains at its NH(2) terminus a pyrin-like motif and a proline-rich sequence, possibly involved in protein-protein interactions with Src homology domain 3-containing proteins. By using in vitro coimmunoprecipitation experiments, both long and short isoforms were capable of strongly interacting with caspase-2 and exhibited a weaker interaction with caspase-9. Transient overexpression of full-length DEFCAP-L, but not DEFCAP-S, in breast adenocarcinoma cells MCF7 resulted in significant levels of apoptosis. In vitro death assays with transient overexpression of deletion constructs of both isoforms using beta-galactosidase as a reporter gene in MCF7 cells suggest the following: 1) the nucleotide binding domain may act as a negative regulator of the killing activity of DEFCAP; 2) the LRR/CARD represents a putative constitutively active inducer of apoptosis; 3) the killing activity of LRR/CARD is inhibitable by benzyloxycarbonyl-Val-Ala-Asp (OMe)-fluoromethyl ketone and to a lesser extent by Asp-Glu-Val-Asp (OMe)-fluoromethyl ketone; and 4) the CARD is critical for killing activity of DEFCAP. These results suggest that DEFCAP is a novel member of the mammalian Ced-4 family of proteins capable of inducing apoptosis, and understanding its regulation may elucidate the complex nature of the mammalian apoptosis-promoting machinery.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Role of CC chemokines (macrophage inflammatory protein-1 beta, monocyte chemoattractant protein-1, RANTES) in acute lung injury in rats.

The role of the CC chemokines, macrophage inflammatory protein-1 beta (MIP-1 beta), monocyte chemotactic peptide-1 (MCP-1), and RANTES, in acute lung inflammatory injury induced by intrapulmonary deposition of IgG immune complexes injury in rats was determined. Rat MIP-1 beta, MCP-1, and RANTES were cloned, the proteins were expressed, and neutralizing Abs were developed. mRNA and protein expression for MIP-1 beta and MCP-1 were up-regulated during the inflammatory response, while mRNA and protein expression for RANTES were constitutive and unchanged during the inflammatory response. Treatment of rats with anti-MIP-1 beta Ab significantly decreased vascular permeability by 37% (p = 0.012), reduced neutrophil recruitment into lung by 65% (p = 0.047), and suppressed levels of TNF-alpha in bronchoalveolar lavage fluids by 61% (p = 0.008). Treatment of rats with anti-rat MCP-1 or anti-rat RANTES had no effect on the development of lung injury. In animals pretreated intratracheally with blocking Abs to MCP-1, RANTES, or MIP-1 beta, significant reductions in the bronchoalveolar lavage content of these chemokines occurred, suggesting that these Abs had reached their targets. Conversely, exogenously MIP-1 beta, but not RANTES or MCP-1, caused enhancement of the lung vascular leak. These data indicate that MIP-1 beta, but not MCP-1 or RANTES, plays an important role in intrapulmonary recruitment of neutrophils and development of lung injury in the model employed. The findings suggest that in chemokine-dependent inflammatory responses in lung CC chemokines do not necessarily demonstrate redundant function.

Acute Disease↗
PubMed2000

Role of RANTES in experimental cardiac allograft rejection.

The host response to alloantigen results in upregulation of Class II MHC antigens and associated cytokine production (especially IL-2 and interferon-gamma (IFN-gamma)) as well as lymphocytic infiltration and cellular activation which leads to graft damage/destruction. RANTES (Regulated upon Activation, Normal T-cell Expressed and presumably Secreted) is a member of the beta subfamily (CC) of chemokines and has been shown to function as a lymphocyte chemoattractant. We now describe the requirement for RANTES in cardiac heterotopic allograft (brown Norway into Lewis rats) rejection in rats. By Northern blot analysis, mRNA could be detected in allografts at 6 and 8 days post-transplantation but not in isogenic (Lewis) grafts. RANTES protein could be demonstrated by Western blot analysis in homogenates from allografts at day 8 but not at day 0 and could not be identified in isogenic cardiac transplants. By immunostaining, RANTES protein was present in mononuclear cells of allografts at day 6 but was absent in the isogenic transplants. When rats were treated with anti-RANTES serum, there was a significant delay in rejection time (cessation of beating) of the allografts. These data demonstrate that expression of RANTES in rat cardiac allografts is linked to the rejection phenomenon.

Amino Acid Sequence↗
PubMed2000

Anti-inflammatory effects of mutant forms of secretory leukocyte protease inhibitor.

The secretory leukocyte protease inhibitor (SLPI) is found in a variety of secreted fluids in mammals and is a known inhibitor of serine proteases. Wild-type (WT) SLPI has recently been shown to block nuclear factor kappaB (NF-kappaB) activation in rat lungs and to interfere with the ensuing inflammatory response and recruitment of neutrophils after an intrapulmonary deposition of IgG immune complexes. In this study, WT SLPI and SLPI mutants with various degrees of protease-inhibitory capacity (for trypsin, chymotrypsin, and elastase) were evaluated for their ability to suppress the lung-vascular leak, neutrophil accumulation, and NF-kappaB activation in the lung inflammatory model. The SLPI mutant with Gly(72) (replacing Leu(72) ) lost its ability to block in vivo activation of NF-kappaB, as well as its ability to suppress the lung vascular leak and neutrophil recruitment. The Phe(72) and Gly(20) mutants were as effective as the WT SLPI in suppressing NF-kappaB activation and neutrophil recruitment. The Lys(72) mutant had the most suppressive effects of the lung vascular leak and for neutrophil recruitment into the lung. The in vivo suppressive effects of SLPI mutants on lung vascular permeability, neutrophil recruitment, and NF-kappaB activation appear to be most closely related to their trypsin-inhibiting activity. These data suggest that the suppressive effects of SLPI on the intrapulmonary activation of NF-kappaB and neutrophil recruitment into the lung may be linked to their antiprotease activity, directed, perhaps, at the intracellular proteases.

Acute Disease↗
PubMed2000

Protective effects of anti-C5a in sepsis-induced thymocyte apoptosis.

Multiorgan apoptosis occurs during sepsis. Following cecal ligation and puncture (CLP) in rats, thymocytes underwent apoptosis in a time-dependent manner. C5a blockade dramatically reduced thymocyte apoptosis as measured by thymic weight, binding of annexin V to thymocytes, and laddering of thymocyte DNA. When C5a was generated in vivo by infusion of purified cobra venom factor (CVF), thymocyte apoptosis was significantly increased. Similar results were found when CVF was injected in vivo during the early stages of CLP. In animals 12 hours after induction of CLP, there was an increase in the activities of caspase-3, -6, and -9, but not caspase-1 and -8. Cytosolic cytochrome c levels increased by twofold, whereas mitochondrial levels showed a 50% decrease. Western blot analysis revealed that the content of Bcl-X(L) (but not of Bcl-2, BAX, Bad, and Bim) significantly decreased in thymocytes after CLP. C5a blockade in the sepsis model almost completely inhibited caspase-3, -6, and -9 activation, significantly preserved cytochrome c in the mitochondrial fraction, and restored Bcl-X(L) expression. These data suggest that systemic activation of complement induces C5a-dependent apoptosis of thymocytes and that the blockade of C5a during sepsis rescues thymocytes from apoptosis.

Animals↗
PubMed1999

Molecular cloning and characterization of a novel human CC chemokine, SCYA26.

By searching the Expressed Sequence Tag database, a full-length cDNA for a novel human CC chemokine was cloned. This cDNA encoded a 94-amino-acid protein with a putative signal peptide of 26 amino acids. The deduced mature protein had the four conserved cysteine residues characteristic of CC chemokines and showed 44% identity with MIP-1beta and 40% identity with MIP-1alpha, RANTES, and MCP-4. mRNA for this chemokine was expressed constitutively in human heart and liver and with lesser but detectable levels in skeletal muscle, kidney, and small intestine. To investigate its biological activity, the protein was expressed in mammalian cells and purified by affinity chromatography. The recombinant protein demonstrated chemotactic activity in vitro for T cells and monocytes but not for neutrophils. The gene was mapped to chromosome 7q11.2 by fluorescence in situ hybridization. Based on its structural identity with other CC chemokines and the chemotactic activity and chromosomal location of this chemokine, we designate this chemokine small inducible cytokine subfamily A, member 26 (SCYA26). This gene symbol has been approved by the HUGO Gene Nomenclature Committee.

Amino Acid Sequence↗
PubMed1999

Eotaxin expression in Sephadex-induced lung injury in rats.

The CC chemokine eotaxin is a potent and specific eosinophil chemoattractant. Eosinophil-dependent tissue injury has been shown to contribute to airway inflammation such as that in asthma. In the present study, We investigated eotaxin expression in a rat model of pulmonary inflammation (featuring accumulation of eosinophils) induced by intratracheal instillation of cross-linked dextran beads (Sephadex G200). Intratracheal instillation of 5 mg/kg Sephadex caused a time-dependent eosinophil infiltration into the lung, reaching a peak at 24 hours. Eotaxin mRNA in the lung paralleled the eosinophil influx. Eotaxin protein in bronchoalveolar (BAL) fluids and lung homogenates was shown by Western blot and immunostaining to be maximally expressed by 24 hours. Sephadex-induced lung injury, as measured by (125)I-labeled albumin leakage from the pulmonary vasculature, developed in a time-dependent manner. Intravenous injection of blocking antibody to eotaxin significantly decreased eosinophil infiltration and lung permeability. These data suggest that, in the Sephadex model of lung inflammation, eotaxin up-regulation mediates intrapulmonary accumulation of eosinophils and the development of lung injury.

Animals↗
PubMed1998

The promoting effect of tumour necrosis factor alpha in radiation-induced cell transformation.

The ability of tumour necrosis factor alpha (TNF-alpha), a potent endogenous inflammatory agent, to promote malignant transformation of Syrian hamster embryo cells (SHE) initiated by a 0.5-Gy dose of alpha-particles was investigated. Opsonized zymosan particles, which were phagocytosed by a human macrophage-like cell line, triggered TNF-alpha production from U937 cells. This cell supernatant could significantly increase the transformation frequency (TF) of primary SHE cells previously irradiated by a 0.5-Gy dose of alpha-particles. The TF decreased significantly if monoclonal antibody against TNF-alpha was added to the supernatant. Similarly, recombinant human TNF-alpha (rhTNF-alpha) increased the TF of alpha-irradiated primary SHE cells to an even greater extent. Addition of TNF-alpha to subcultures of irradiated SHE cells permitted the continuous propagation of these primary cells. In contrast, both TNF-alpha-treated control and alpha-irradiated cells without subsequent TNF-alpha treatment senesced after 7-15 passages. Irradiated SHE cells treated continuously with TNF-alpha could be subcultured over 40 passages and produced fibrosarcomas upon inoculation into nude mice. Our results provide the first evidence that TNF-alpha released by activated macrophages may contribute to the process of malignant transformation initiated by low-dose alpha-particles.

Animals↗
PubMed1988

Wounding effects of small fragments of different shapes at different velocities on soft tissues of dogs.

The wounding effects of small fragments of the same weight (0.44 gm) but different shapes and at different impact velocities (708-1,560 m/s) on the soft tissues of the hind legs of 156 dogs were studied. The experiments showed that velocity was the major factor in causing wounds. For fragments of the same shape, the energy transmission, volume of wound cavity, sectional areas at entrance and exit, and amount of tissue that had to be excised increased rapidly with increasing velocity. In particular, as the velocity reached about 1,500 m/s, a shallow and wide wound tract was liable to occur, peripheral tissue lesion was relatively apparent, even extended to the whole leg, and the rate of occurrence of bone fracture was high. The wounding effect of the shape of the fragment closely related to its sectional specific weight (W) and drag coefficient (CD). Given the weight of the projectile and the density and thickness of the tissue, the energy transmission (delta E) was directly proportional to the square of the velocity and to the drag coefficient, and inversely proportional to the sectional specific weight of the fragment. Therefore, under certain conditions, reducing the sectional specific weight often increased the drag coefficient, in favour of causing a wound. In this experiment, the extent of wounds caused by the triangular, the square, and the cylindrical, and the spherical fragments decreased in that order, in agreement with their values of sectional specific weight and drag coefficient.

Animals↗
PubMedDate not supplied

The attenuation of hemorrhage-induced liver injury by exogenous nitric oxide, L-arginine, and inhibition of inducible nitric oxide synthase.

We investigated the role of nitric oxide (NO) in its ability to reduce liver injury in an animal model of hemorrhagic shock (HS). Ninety-six Sprague-Dawley rats weighing 250 to 300 g were divided in 6 groups (n = 16 per group) that included treatment at the beginning of resuscitation with normal saline (groups 1, 3) sodium nitroprusside (NP) (0.5 mg/kg) (groups 2, 4) L-arginine (300 mg/kg) (group 5), and L-N6-(1-iminoethyl) lysine (L-NIL, 40 mg/kg) (group 6). The experimental model of HS consisted of the withdrawal of 3 mL blood per 100 g in a 15-min period, tail amputation (75%), and drug administration at 30 min. This was followed by fluid resuscitation (FR) with lactated Ringer's (LR) solution to reach a mean arterial pressure (MAP) of 40 mm Hg, then a hospital phase of 60 min with hemostasis and FR with LR solution to reach a MAP of 70 mm Hg with a 3-day observation phase. NP, L-Arginine, and L-NIL significantly reduced fluid requirements for resuscitation (p =.0001) as well as significantly increased MAP after resuscitation from hemorrhage. We also observed an improved statistically significant difference (p =.001) in tests demonstrating less hepatic injury and histology damage. The mRNA expression of cytokines in the liver (interleukin [IL]-1alpha, IL-beta1, tumor necrosis factor [TNF]beta, IL-3, IL-4, IL-5, IL-6, IL-10, TNFalpha, IL-2, interferon [IFN]gamma) was reduced by NP treatment, L-arginine, and L-NIL. These data suggest that excess NO mediates hemorrhage-induced liver injury and that the suppression of inducible nitric oxide synthase (iNOS)-generated NO bioavailability with the NO donor sodium nitroprusside may reduce the pathophysiologic consequences of severe hemorrhage. This effect could be possibly related to the scavenging of to superoxide radicals (O2-) or the blockade of the deleterious effects of TNF and other inflammatory cytokines. The protective action noted with L-arginine cannot be fully explained within the context of this article, although it could be most likely associated with the supplementation of eNOS-generated NO.

Animals↗