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Biomedical subjects

T R Billiar

Publications and source records attributed to T R Billiar.

At least 73 records · Page 4Linked to original sources
PubMed2000

Distinct effects of systemic infusion of G-CSF vs. IL-6 on lung and liver inflammation and injury in hemorrhagic shock.

Production of pro-inflammatory cytokines, such as granulocyte colony-stimulating factor (G-CSF) and interleukin-6 (IL-6) occurs at multiple tissue sites in hemorrhagic shock (HS), resulting in elevated circulating plasma levels. The current study was designed to test the hypothesis that circulating G-CSF and IL-6 contribute to polymorphonuclear neutrophilic granulocyte (PMN)-mediated inflammation and organ injury in HS. Sprague-Dawley rats were subjected to decompensated HS (mean arterial blood pressure = 40 mm Hg for 2.5 h), followed by resuscitation with lactated Ringer's solution with or without G-CSF (3 microg/kg) or IL-6 (3 microg/kg). Animals were killed 4 h after resuscitation, and their lungs and livers were assessed quantitatively for PMN infiltration, organ injury, and activation of NF-kappaB and signal transducer and activator or transcription (STAT) 3. Infusion of G-CSF during resuscitation increased PMN infiltration into the lungs by 2.4-fold (P < 0.01) compared with animals resuscitated with lactated Ringer's solution alone. Increased PMN infiltration was accompanied by interstitial edema and pneumocyte swelling, resulting in a 42% increase in lung alveolar wall cross-sectional surface area (P < 0.01) and a 3.7-fold increase in Stat3 activity (P < 0.01). G-CSF infusion did not affect PMN infiltration into the liver and was accompanied by a 68% decrease in focal hepatocellular necrosis (P < 0.01). Infusion of IL-6, in contrast, dramatically decreased inflammation and injury in both the lung and liver; the anti-inflammatory effects of IL-6 may be mediated, in part, by down-modulation of nuclear factor (NF)-kappaB activity. Thus, circulating G-CSF and IL-6 have opposing effects on PMN recruitment and injury in the lung in HS while both protect against hepatic necrosis. The beneficial effect of these cytokines on liver injury in HS appears to be independent of PMN recruitment.

Animals↗
PubMed2000

Hepatocyte toll-like receptor 2 expression in vivo and in vitro: role of cytokines in induction of rat TLR2 gene expression by lipopolysaccharide.

We and others have demonstrated previously that cytokines, including interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNFalpha), regulate LPS recognition proteins such as CD14 in the liver and on hepatocytes. Based on recent findings that the mammalian homologue of Drosophila Toll participates in LPS signaling, we examined the regulation of Toll-Like Receptor (TLR) gene expression by cytokines in vitro and its distribution in vivo with a focus on the liver as a site of host-microbe interaction. Our results show that IL-1beta and/or TNFalpha participate in the upregulation of TLR2 mRNA levels in hepatocytes. Rats treated concurrently with LPS and antagonists of the IL-1 or TNFalpha receptor demonstrated significantly reduced LPS-induced hepatic expression of TLR2 compared to animals treated with LPS alone. The increase in hepatic TLR2 mRNA expression was associated with enhanced transcription as determined by nuclear run-on analysis. LPS treatment in vivo caused a marked TLR2 mRNA up-regulation in all of the tissues examined, with liver showing the highest expression. The high level of TLR2 expression in the liver may have important implications for pathogen-host interactions or microbial signaling.

Animals↗
PubMed2000

Endovascular repair of an aortoduodenal fistula.

PURPOSE: To demonstrate the utility of endovascular stent-graft repair for the management of an unusual aortoduodenal fistula. METHODS AND RESULTS: A 23-year-old man with an aortoduodenal fistula secondary to tumor necrosis was treated with a Corvita endoluminal stent-graft after several failed surgical attempts to repair the defect. At 2-year follow-up, the patient was clinically and radiographically devoid of any evidence of occult stent-graft infection. CONCLUSIONS: This case illustrates the usefulness of endovascular repair for the treatment of a primary aortoduodenal fistula. Endovascular repair should be included in the armamentarium for the management of difficult aortoduodenal fistulas.

Adult↗
PubMed1999

Molecular and functional contractile sequelae of rat intestinal ischemia/reperfusion injury.

BACKGROUND: Pathophysiological states that produce intestinal ischemia/reperfusion injury (I/R) initiate an inflammatory cascade and cause ileus. The aims of this study were to investigate the local cellular responses and molecular mechanisms, which contribute to intestinal dysmotility after selective intestinal I/R injury. METHODS: ACI rats were subjected to 75 min SMA clamp-induced ischemia followed by reperfusion and were killed at 0 min, 30 min, and 24 hr. Whole mounts of the jejunum were used to immunohistochemically quantify alterations in leukocytes, and circular muscle strips were used to assess organ bath muscle function. Muscularis and mucosa extracts were isolated from the intestine and used for reverse transcription assisted polymerase chain reaction mRNA measurements of granulocyte-colony stimulating factor and interleukin-6, and for determination of nuclear factor kappa B and Stat3 activation. RESULTS: Intestinal I/R injury resulted in the significant recruitment of neutrophils and monocytes into the intestinal muscularis and a functional suppression in jejunal circular muscle contractions. These I/R injury induced cellular responses were preceded by the molecular activation of nuclear factor kappa B, up-regulation of granulocyte colony-stimulating factor and interleukin-6 mRNA and phosphorylation of the downstream signaling and transcription factor Stat3. CONCLUSIONS: I/R injury evokes a molecular and cellular inflammatory response within the intestinal muscularis that is associated with a subsequent decrease in intestinal motility.

Animals↗
PubMed1999

Nitric oxide protects PC12 cells from serum deprivation-induced apoptosis by cGMP-dependent inhibition of caspase signaling.

Although nitric oxide (NO) induces neuronal cell death under some conditions, it also can prevent apoptosis resulting from growth factor withdrawal. We investigated the molecular mechanism by which NO protects undifferentiated and differentiated PC12 cells from trophic factor deprivation-induced apoptosis. PC12 cells underwent apoptotic death in association with increased caspase-3-like activity, DNA fragmentation, poly(ADP-ribose) polymerase (PARP) cleavage, and cytochrome c release after 24 hr of serum withdrawal. The apoptosis of PC12 cells was inhibited by the addition of NO-generating donor S-nitroso-N-acetylpenicillamine (SNAP) (5-100 microM) and the specific caspase-3-like protease inhibitor Ac-Asp-Glu-Val-Asp-aldehyde (Ac-DEVD-cho) but not the YVADase (or caspase-1-like protease) inhibitor N-acetyl-Tyr-Val-Ala-Asp-aldehyde (Ac-YVAD-cho). SNAP and Ac-DEVD-cho prevented the increase in DEVDase (caspase-3-like protease) activity. The SNAP-mediated suppression of DEVDase activity was only minimally reversed by the incubation of cell lysate with dithiothreitol, indicating that NO did not S-nitrosylate caspase-3-like proteases in PC12 cells. Western blot analysis showed that NO inhibited the proteolytic activation of caspase-3. The cGMP analog 8-bromo-cGMP (8-Br-cGMP) blocked apoptotic cell death, caspase-3 activity and activation, and cytochrome c release. The soluble guanylyl cyclase inhibitor 1-H-oxodiazol-[1,2,4]-[4,3-a] quinoxaline-1-one (CODQ) significantly attenuated NO-mediated, but not 8-Br-cGMP-dependent, inhibition of apoptotic cell death, PARP cleavage, cytochrome c release, and DEVDase activity. Furthermore, the protein kinase G inhibitor KT5823 reversed both SNAP- and 8-Br-cGMP-mediated anti-apoptotic events. All these apoptotic phenomena were also suppressed by NO production through neuronal NO synthase gene transfer into PC12 cells. Furthermore, similar findings were observed in differentiated PC12 cells stimulated to undergo apoptosis by NO donors and NGF deprivation. These findings indicate that NO protects against PC12 cell death by inhibiting the activation of caspase proteases through cGMP production and activation of protein kinase G.

Animals↗
PubMed1999

Nitric-oxide production by murine mammary adenocarcinoma cells promotes tumor-cell invasiveness.

The role of nitric oxide (NO) in tumor biology remains controversial and poorly understood. While a few reports indicate that the presence of NO in tumor cells or their micro-environment is detrimental for tumor-cell survival, and consequently their metastatic ability, a large body of data suggests that NO promotes tumor progression. The purpose of this study was to identify the source of NO in the spontaneously metastasizing C3-L5 murine mammary-adenocarcinoma model, the role of tumor-derived NO in tumor-cell invasiveness, and the mechanisms underlying the invasion-stimulating effects of tumor-derived NO. The source of NO was established by immunocytochemical localization of NO synthase (NOS) enzymes in C3-L5 cells in vitro and transplanted tumors in vivo. An in vitro transwell Matrigel invasion assay was used to test the invasiveness of C3-L5 cells in the presence or the absence of NO blocking agents or iNOS inducers (IFN-gamma and LPS). The mechanisms underlying the invasion-stimulating effects of tumor-derived NO were examined by measuring mRNA expression of matrix metalloproteinases (MMP)-2 and -9, and tissue inhibitors of metalloproteinases (TIMP) 1, 2 and 3 in C3-L5 cells in various experimental conditions. Results showed that C3-L5 cells expressed high level of eNOS protein in vitro, and in vivo, both in primary and in metastatic tumors. C3-L5 cells also expressed iNOS mRNA and protein when cultured in the presence of IFN-gamma and LPS. Constitutively produced NO promoted tumor-cell invasiveness in vitro by down-regulating TIMP 2 and TIMP 3. In addition, there was up-regulation of MMP-2, when extra NO was induced by IFN-gamma and LPS. In conclusion, NO produced by C3-L5 cells promoted tumor-cell invasiveness by altering the balance between MMP-2 and its inhibitors TIMP-2 and 3. Thus, our earlier observations of anti-tumor and anti-metastatic effects of NO inhibitors in vivo in this tumor model can be explained, at least in part, by reduced tumor-cell invasiveness.

Adenocarcinoma↗
PubMed1999

Nitric oxide suppresses apoptosis via interrupting caspase activation and mitochondrial dysfunction in cultured hepatocytes.

Nitric oxide (NO) is a potent inhibitor of apoptosis in many cell types, including hepatocytes. We and others have described NO-dependent decreases in caspase activity in cells undergoing apoptosis. However, previous work has not determined whether NO disrupts the proteolytic processing and thus the activation of pro-caspases. Here we report that NO suppresses proteolytic processing and activation of multiple pro-caspases in intact cells, including caspase-3 and caspase-8. We found that both exogenous NO as well as endogenously produced NO via adenoviral inducible NO synthase gene transfer protected hepatocytes from tumor necrosid factor (TNF) alpha plus actinomycin D (TNFalpha/ActD)-induced apoptosis. Affinity labeling with biotin-VAD-fmk of all active caspase species in TNFalpha-mediated apoptosis identified four newly labeled spots (activated caspases) present exclusively in TNFalpha/ActD-treated cells. Both NO and the caspase inhibitor, Ac-DEVD-CHO, prevented the appearance of the four newly labeled spots or active caspases. Immunoanalysis of affinity labeled caspases demonstrated that caspase-3 was the major effector caspase. Western blot analysis also identified the activation of caspase-8 in the TNFalpha/ActD-treated cells, and the activation was suppressed by NO. Furthermore, NO inhibited several other events associated with caspase activation in cells, including release of cytochrome c from mitochondria, decrease in mitochondrial transmembrane potential, and cleavage of poly(ADP-ribose) polymerase in TNFalpha/ActD-treated cells. These findings indicate the involvement of multiple caspases in TNFalpha-mediated apoptosis in hepatocytes and establish the capacity of NO to inhibit not only active caspases but also caspase activation.

Animals↗
PubMed1999

A caspase-9 variant missing the catalytic site is an endogenous inhibitor of apoptosis.

It is likely that endogenous inhibitors of the apical caspases such as caspase-9 exist to prevent undesirable activation of caspase cascades. A naturally occurring variant of caspase-9 named caspase-9S was cloned from human liver. Caspase-9S is missing most of the large subunit of caspase-9, including the catalytic site, but has the intact prodomain and small subunit. Caspase-9S did not show apoptotic activity in transfection analysis. Overexpression of caspase-9S inhibited apoptosis induced by caspase-9, indicating that caspase-9S is an endogenous dominant-negative of caspase-9. Moreover, caspase-9S inhibited apoptosis induced by tumor necrosis factor(TNF)-alpha, TNF factor-related apoptosis-inducing ligand (TRAIL), Bax, or Fas-associated death domain-containing protein (FADD) as well as the combination of Apaf-1 and caspase-9. In vitro binding assays demonstrated that caspase-9S binds to Apaf-1 and blocks the binding of caspase-9 to Apaf-1. Coexpression of caspase-9 and caspase-9S mRNA was identified in various cell lines. Thus, caspase-9S acts as a dominant-negative inhibitor of caspase-9 activation, at least in part, by blocking Apaf-1-caspase-9 interaction.

Amino Acid Sequence↗
PubMed1999

Hemorrhagic shock results in intestinal muscularis intercellular adhesion molecule (ICAM-1) expression, neutrophil infiltration, and smooth muscle dysfunction.

Intestinal stasis followed by mucosal barrier breakdown and the generation of locally produced cytokines has been proposed as the cause of systemic infection and multiple organ failure following hemorrhagic shock. The aim of this study was to investigate the underlying mechanisms of impaired intestinal muscle function leading to ileus following hemorrhagic shock. Rats were subjected to severe hemorrhagic shock (mean arterial pressure 40 mm Hg) followed by resuscitation and were killed early at 4 h or late at 24 h. Other groups consisted of control and sham animals. Intercellular adhesion molecule (ICAM-1) mRNA levels were significantly elevated in the muscularis but not in the mucosa using the semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR). There was a marked infiltration of neutrophils into the muscularis early and late after shock. Furthermore, smooth muscle contractility in response to bethanechol was significantly decreased, being more pronounced in the early group. Immunohistochemistry revealed signal for ICAM-1 in the muscularis microvasculature and on infiltrating cells. These results suggest that the expression of ICAM-1 within the muscularis vasculature after hemorrhagic shock promotes the local recruitment of leukocytes and that this inflammatory response is accompanied by a subsequent impairment of intestinal contractility.

Animals↗
PubMed1999

Rapid and simultaneous activation of Stat3 and production of interleukin 6 in resuscitated hemorrhagic shock.

The inflammatory response of the liver to hemorrhagic shock includes the production of acute phase proteins and a variety of mediators, such as the cytokine interleukin (IL)-6. The transcription of acute phase protein genes in hepatocytes has been shown to be activated by Stat3, one of six distinct signal transducers and activators of transcription (STAT) proteins. IL-6 signals through activation of Stat3. In this study, we examined whether or not Stat3 was activated and IL-6 mRNA produced in the liver of rats subjected to hemorrhagic shock and whether or not both phases of shock, the ischemic and the resuscitation phases, were required. We report here that Stat3 activation and increased IL-6 expression required resuscitation and displayed identical kinetics following resuscitation, suggesting that liver production of IL-6 was responsible for liver Stat3 activation in hemorrhagic shock.

Analysis of Variance↗
PubMed1999

The anti-apoptotic actions of nitric oxide in hepatocytes.

Nitric oxide (NO) has anti-apoptotic actions in hepatocytes in vitro and in vivo. The protection is mediated via the S-nitrosylation of procaspases as well as the active caspase enzymes. NO stimulation of the cGMP/protein kinase G pathway also appears to contribute to the protective effect of NO. Here we review the evidence for the direct inhibition of NO with the apoptotic signaling pathways in hepatocytes.

Animals↗
PubMed1999

Role of inducible nitric oxide synthase in transplant arteriosclerosis.

1. Transplant arteriosclerosis is a major obstacle to long-term allograft survival. Nitric oxide (NO) has been implicated as a mediator in the development of this disease. 2. We and others have shown that inducible nitric oxide synthase (iNOS) is up-regulated in allografts with transplant arteriosclerosis. Despite the acute cytotoxic effects produced by high levels of NO, a chronic increase in NO availability is protective against neointimal hyperplasia, mainly by suppressing the inflammatory cell recruitment and neointimal smooth muscle cell accumulation. 3. Currently, we have the technology to directly transfer the iNOS gene to allografts. We have demonstrated that this exciting strategy is feasible and therapeutic and may improve the long-term survival and function of allografts. Future challenges include optimizing the methods and the vectors of gene delivery.

Animals↗
PubMed1999

Surgically induced leukocytic infiltrates within the rat intestinal muscularis mediate postoperative ileus.

BACKGROUND & AIMS: Postoperative ileus is a poorly understood and common problem. We previously demonstrated an association between a suppression in jejunal circular muscle activity and a massive extravasation of leukocytes into the muscularis after surgical manipulation of the small bowel. This study was pursued to establish a direct causal link between these events. METHODS: Reverse-transcription polymerase chain reaction and immunohistochemistry were used to detect and localize expression of adhesion molecules: P-selectin, intercellular adhesion molecule 1 (ICAM-1), and lymphocyte function-associated antigen 1 (LFA-1). Leukocyte infiltration and in vitro jejunal circular muscle function were quantified in controls and manipulated animals with and without antibody treatment (1A29, WT.1, and WT.3). RESULTS: Surgical manipulation caused a significant up-regulation within the muscularis of ICAM-1 and P-selectin messenger RNA. ICAM-1 and P-selectin protein expression was increased within the muscularis microvasculature, and ICAM-1 and LFA-1 were expressed on infiltrating cells. Administration of adhesion molecule antibodies prevented the recruitment of monocytes and neutrophils into the muscularis and also averted jejunal circular muscle dysfunction. CONCLUSIONS: The data demonstrate that adhesion molecule antibodies prevent surgically induced suppression of intestinal muscle contractions and therefore suggests that late postoperative ileus is mediated through a leukocytic inflammatory response within the intestinal muscularis externa.

Animals↗
PubMed1999

Trauma center maturation: quantification of process and outcome.

BACKGROUND AND OBJECTIVE: The regional trauma system with the trauma center as its center is a model for health care networks. However, trauma center maturation has not been defined in the literature. The authors' hypothesis was that maturation of the trauma center would affect quantitatively both process and patient outcome. MATERIALS AND METHODS: A total of 15,303 trauma patients were admitted from 1987 to 1995. Annual admissions increased from 813 to 2669. Resources were generated as patient volume increased. Time to the operating room, length of stay, and complications were determined. TRISS methodology was used to calculate z scores and w values to compare actual with predicted mortality rates. RESULTS: Time to the operating room for laparotomy decreased from 62+/-73 to 35+/-47 minutes, from 32+/-32 to 20+/-17 minutes in hypotensive patients, and for craniotomy decreased from 88+/-54 to 67+/-49 minutes. The incidence of infectious, airway, neurologic, orthopedic, respiratory, gastrointestinal, and procedure-related complications declined significantly. Z scores and w values increased for penetrating and blunt injuries. Deaths for patients with ISS >15 declined significantly. Hospital length of stay decreased for all ranges of injury severity. CONCLUSIONS: As the trauma center matured, the process of delivering patient care became more efficient. The result was improved survival, fewer complications, and a shorter length of stay.

Efficiency, Organizational↗
PubMed1999

Neutrophil accumulation and damage to the gastric mucosa in resuscitated hemorrhagic shock is independent of inducible nitric oxide synthase.

Polymorphonuclear leukocytes (PMN) and inducible nitric oxide synthase (iNOS) appear to play important roles in the liver and in lung injury induced by hemorrhagic shock. Their precise roles in hemorrhagic shock-induced acute gastric mucosal lesions (AGML), however, are still poorly understood. In this study, we investigated the effect of neutropenia on hemorrhagic shock-induced AGML. We also examined the roles of iNOS in PMN infiltration into the mucosa and AGML during hemorrhagic shock by using L-N6-(1-iminoethyl)-lysine, a potent inhibitor of iNOS, and by reverse transcriptase polymerase chain reaction. Remarkable gastric mucosal damage occurs after hemorrhagic shock. PMN depletion caused by Vinblastine pretreatment significantly attenuates this AGML. Although low-dose L-N6-(1-iminoethyl)-lysine (50 microg/kg, iNOS inhibition) has no effect on AGML, high-dose L-N6-(1-iminoethyl)-lysine (250 microg/kg, iNOS + endothelial NOS inhibition) significantly exacerbates AGML without increasing PMN infiltration into the mucosa. The mRNA expression of iNOS in the stomach during hemorrhagic shock cannot be detected by reverse transcriptase polymerase chain reaction. We conclude that PMN play a pivotal role in hemorrhagic shock-induced AGML, iNOS does not regulate PMN infiltration into the mucosa, and endothelial NOS provides important protection against AGML during hemorrhagic shock.

Animals↗