Biomedical subjects

G Bolgos

Publications and source records attributed to G Bolgos.

10 recordsLinked to original sources

PubMed1999

Immunopathologic responses to non-lethal sepsis.

Although sepsis causes significant morbidity and mortality, its basic pathology is still not well understood. We investigated the inflammatory and physiologic alterations of non-lethal sepsis using cecal ligation and puncture (CLP), a model that induces peritonitis due to mixed intestinal flora, reproducing the complex immunology of sepsis. Groups of mice were subjected to CLP (25G needle) or sham surgery, had minimitters implanted to continuously monitor temperature and activity, and were sacrificed daily for 6 days. There was significant hypothermia (6-13 hrs post-surgery), and decreases in activity (to day 4) and weight (to day 3) but no mortality in the CLP group. Blood analyses of the CLP-treated mice showed reduced hemoglobin, platelets, lymphocytes, monocytes, and neutrophils, compared to sham animals. Both groups had nearly equivalent neutrophil influx into the peritoneum. Plasma and peritoneal G-CSF, IL-6, as well as the murine chemokines KC and MIP2-alpha were significantly higher in the CLP-treated mice at day 1. Plasma and peritoneal TNF were low (<70 pg/mL). While there was elevated IL-1beta in the peritoneum of the CLP-treated mice, this cytokine was not detected in the plasma in either treatment group. Cytokines were not detected in the pulmonary airspace of the CLP-treated mice and PMNs were not recruited to this site. Our data shows altered immunopathology in non-lethal sepsis with significant blood and cytokine alterations. Since there was 100% survival, the inflammatory response was appropriate and probably even protective.

Animals↗

PubMed1999

Immunopathologic alterations in murine models of sepsis of increasing severity.

We investigated inflammatory and physiologic parameters in sepsis models of increasing lethality induced by cecal ligation and puncture (CLP). Mice received imipenem for antibiotic therapy, and groups were sacrificed at 2, 4, 8, 12, 16, 20, and 24 h after CLP. The severity of sepsis increased with needle puncture size (lethality with 18-gauge puncture [18G], 100%; 21G, 50%; 25G, 5%; sham treatment, 0%). While the temperature (at 12 h) and the activity and diurnal rhythm (at day 4) of the 25G-treated CLP group recovered to normal, the 21G and 18G treatment groups exhibited severe hypothermia along with decreased activities. A direct correlation was also observed between the severity of sepsis and cytokine (interleukin 1beta [IL-1beta], tumor necrosis factor [TNF], IL-6, and IL-10) concentrations in both the peritoneum and the plasma. There were substantially higher cytokine levels in the more severe CLP models than in the sham-treated one. Peritoneal and plasma TNF levels were always less than 40 pg/ml in all models. None of the cytokines in the septic mice peaked within the first hour, which is in contrast to the results of most endotoxin models. Chemokine (KC and macrophage inflammatory protein 2) profiles also correlated with the severity of sepsis. Except for the chemokines, levels of inflammatory mediators were always higher at the site of inflammation (peritoneum) than in the circulation. Our study demonstrated that sepsis of increasing severity induced increased cytokine levels both within the local environment (peritoneum) and systemically (plasma), which in turn correlated with morbidity and mortality.

Animals↗

PubMed1998

Antibiotic treatment influences outcome in murine sepsis: mediators of increased morbidity.

Different antibiotic treatments may affect the survival and physiological responses of Balb/c mice following cecal ligation and puncture (CLP). The broad spectrum imipenem (IMP) was compared with a triple antibiotic mixture of gentamicin, clindamycin, and ciprofloxacin (3AB). Control mice received injections of 5% dextrose (D5W). After CLP with a 25 gauge needle, Mini-Mitters were implanted to measure temperature and activity. Therapy began with 1 mL injections of antibiotics or D5W 2 h post-CLP and continued every 12 h for 3 days. Survival was higher in IMP mice than in 3AB or D5W mice. Starting with the injection 12 h after CLP, 3AB always induced a profound hypothermic response not observed with D5W or IMP. Nocturnal activity levels were higher in IMP mice compared with 3AB or D5W mice during the first night following CLP. To determine the cause of this hypothermic response and to further investigate the acute effects that antibiotic choice may have on murine physiology, the kinetic appearance of IL-1, IL-6, TNF, and KC as well as lipopolysaccharide (LPS), were measured in the plasma and peritoneum of mice sacrificed at 0, .5, and 1.5 h after antibiotic injection at 24 h post-CLP. Cytokine and LPS concentrations in 3AB mice were not significantly different at any of the three time points when compared with IMP or D5W mice. Our data demonstrate that antibiotic therapy consisting of 3AB produces greater morbidity and mortality compared with therapy consisting of IMP. However, the mechanism of these alterations is not due to elevated systemic levels of cytokines or LPS.

Animals↗

PubMed1995

Blockade of tumor necrosis factor reduces lipopolysaccharide lethality, but not the lethality of cecal ligation and puncture.

Inhibition of tumor necrosis factor (TNF) bioactivity has afforded protection in several animal models of sepsis. We examined whether inhibition of TNF could improve survival after lethal lipopolysaccharide (LPS) or cecal ligation and puncture (CLP) in CD-1 or BALB/c mice. Neutralizing rabbit anti-TNF antisera were evaluated in CD-1 mice by injecting the antisera 3 h before intravenous (i.v.) LPS (600 micrograms). Implantable radiotransmitters were used for continuous monitoring of temperature. No decrease in mortality was observed, and the anti-TNF failed to prevent the drop in temperature. In BALB/c mice injected with antisera before LPS (200 micrograms) mortality was reduced (dead/total: control sera, 14/14; anti-TNF, 4/12; p = .007 control sera vs. anti-TNF). CD-1 mice were pretreated with anti-TNF or control sera; CLP was performed followed by administration of antibiotics. Anti-TNF did not decrease pulmonary neutrophil sequestration, improve survival, or prevent the decrease in temperature observed as sepsis developed. CLP was performed in the BALB/c mice using antibiotics plus anti-TNF antisera, but no protection was observed. Our results demonstrate that anti-TNF treatment prevents LPS mortality only when using certain strains of mice and inhibition of TNF fails to reduce mortality in a more clinically relevant model of sepsis.

Animals↗

PubMed1993

Differential expression of tumor necrosis factor and interleukin-6 by peritoneal macrophages in vivo and in culture.

To investigate the differences in cytokine regulation in vitro as compared to in vivo, we examined the synthesis of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) by peritoneal macrophages in response to lipopolysaccharide (LPS). Mice (CBA/J) were primed with an intraperitoneal injection of complete Freund's adjuvant and after 2 weeks, peritoneal cells were harvested for culture or mice were injected intraperitoneally with LPS for in vivo studies. In ascites fluid, TNF-alpha peaked 1 hour after LPS and returned to baseline levels by 4 hours. In contrast, TNF-alpha in the media reached maximum at 7 hours. Expression of TNF-alpha messenger (m)RNA in vivo was rapid but transient, as levels peaked at 15 minutes and returned to baseline 1 hour after LPS. In contrast, TNF-alpha mRNA in vitro became maximal at 1 hour, but remained elevated to 5 hours after LPS. In vivo, IL-6 in ascites fluid peaked at 2 hours, whereas in vitro, IL-6 continued increasing to 24 hours. In vivo, IL-6 mRNA reached maximum at 30 minutes, but fell below baseline by 1.5 hours after LPS. In contrast, IL-6 mRNA in vitro was sustained at maximal expression between 5 to 9 hours after LPS. These results demonstrate that both TNF-alpha and IL-6 synthesis is more rapid in vivo than in vitro. The rapid kinetics of cytokine expression in vivo must considered when designing strategies to inhibit cytokine action in vivo.

Animals↗

PubMed1992

Anti-tumor necrosis factor antibody therapy fails to prevent lethality after cecal ligation and puncture or endotoxemia.

Cytokines have been studied intensively to delineate their role in the altered pathophysiology observed in septic shock. We studied the role of TNF in the lethality of two well characterized models of septic shock by inhibiting TNF's activity with a specific antibody. In the first model, sepsis was induced by cecal ligation and puncture (CLP), and in the second model sepsis was induced by either an i.p. or i.v. injection of LPS. After CLP, plasma endotoxin was detectable within 4 h and reached a peak at 8 h (136 +/- 109 ng/ml). TNF bioactivity peaked at 12 h (528 +/- 267 pg/ml) at a significantly higher level than sham-operated control mice (64 +/- 31 pg/ml). After i.p. LPS, TNF peaked much more quickly (90 min) compared with CLP and at a significantly higher level (107,900 +/- 25,000 pg/ml). Another cytokine studied in septic shock, IL-6, peaked at 12 h after CLP at 1011 +/- 431 pg/ml, and at 90 min after lethal LPS at 16,300 +/- 3,700 pg/ml. Mice were treated with an anti-TNF antibody that has been shown previously to inhibit in vivo TNF activity. Antibody treatment of mice subjected to CLP significantly reduced TNF bioactivity but did not reduce mortality or pulmonary neutrophilic infiltration. In the i.v. LPS model, anti-TNF antibody treatment concomitant with LPS injection reduced plasma TNF activity from 80,000 +/- 20,000 pg/ml to undetectable levels. However, anti-TNF treatment immediately before either i.v. or i.p. LPS did not reduce mortality. Additionally, when the antibody was administered 4 h before the lethal i.v. LPS, there was no reduction in lethality. These data show that in two separate models of septic shock blockade of TNF biologic activity will not prevent lethality.

Animals↗

PubMed1991

Measuring acute changes in adrenergic nerve activity of the heart in the living animal.

Changes in the function of the adrenergic neurons of the heart may be important indicators of the adaptations of an animal to physiologic stress and disease. Rates of loss of norepinephrine (NE) from the heart were considered to be proportional to NE secretion and to adrenergic function. In rat hearts, yohimbine induced almost identical increases in rates of loss of 3H-NE and of 125I-metaiodobenzylguanidine (MIBG), a functional analog of NE. Clonidine induced decreases in rates of loss of 3H-NE that were also mimicked by those of 125I-MIBG. In the dog heart, pharmacologically-induced increases and decreases in rates of loss of 123I-MIBG could be measured externally; these values were similar to those obtained for 125I-MIBG in the rat heart. Thus acute changes in the adrenergic neuron activity can be measured in the living heart. The method is applicable to man in determining the capacity of the adrenergic system to respond to provocative challenges.

3-Iodobenzylguanidine↗

PubMed1991

Scintigraphic portrayal of beta receptors in the heart.

Myocardial beta adrenergic receptors play important roles in physiology and disease, but the receptors have not before been portrayed. The beta antagonist, iodocyanopindolol (ICYP), was used to develop a scintigraphic method for depicting the receptors in the living heart. Labeled with 125I, ICYP bound firmly to beta receptors in the rat heart; the data conformed to a mathematical model. In vivo saturation kinetics indicated binding sites with two affinities. Inhibition of ICYP binding by beta antagonists of different potency and different selectivity for beta-1 and beta-2 receptors produced the expected pharmacologic effects. Inhibition by lipophilic and hydrophilic antagonists gave no evidence that ICYP was appreciably bound to internalized receptors. Fractional binding by tracer quantities of (-) ICYP and (+/-) ICYP demonstrated stereospecificity. Labeled with 123I, ICYP bound to the hearts of intact dogs so that scintigraphic tomographs depicted ventricular myocardium. Small doses of beta antagonists selectively reduced the binding of ICYP to lung enabling better visualization of the heart. Thus, 123I-ICYP appears to portray the beta receptors in the living heart, and the characteristics of binding permit the development of mathematical models and lay the basis for quantifying this receptor binding.

Animals↗

PubMed1990

Portrayal of adrenergic denervation in the presence of myocardial infarction: a feasibility study.

Myocardial infarction interrupts adrenergic neurons beyond the region of necrosis to give peri-infarct denervation. A method to define the regions of denervation would be a valuable aid in determining the role that loss of adrenergic neurons plays in myocardial infarction and particularly in causing arrhythmias. [123I] meta-iodobenzylguanidine (MIBG) was used to portray scintigraphically the intact neurons in dog hearts. Occlusion of the left circumflex (LCX) or the left anterior descending coronary artery (LAD) produced defects that appeared to be regularly larger in the [123I]MIBG images than in the [201T1]images of the same heart; the differences were considered to be the regions of denervation which were relatively larger after LCX than LAD infarcts. Ex vivo measurements of endogenous norepinephrine and residual [125I]MIBG concentrations gave confirmation of neuronal injury. A computer program to quantify the regions of denervation appeared imprecise, but gave some promise. Scintigraphy of [123I]MIBG offers a method to define patterns of denervation in the living animal and man.

3-Iodobenzylguanidine↗

PubMed1988

Scintigraphic detection of regional disruption of adrenergic neurons in the heart.

Experiments were designed to detect regional disruptions of adrenergic neurons in the hearts of living dogs. The neuron disruption was achieved by the application of phenol to the epicardium of the left ventricle. Evidence for denervation was the reduction in endogenous norepinephrine (NE) concentrations in the myocardium beneath the region of phenol treatment and toward the apex. Radiolabeled meta-iodobenzylguanidine (MIBG) acts as an analog of NE and as such is concentrated in adrenergic nerve terminals. Following phenol application, MIBG labeled with 125I was found, 20 hours after injection, to be distributed within myocardium in patterns comparable to those of NE. However, left stellectomy did not alter the distributions of NE or 125I-MIBG in the myocardium and apparently did not disrupt adrenergic innervation. MIBG labeled with 123I enabled scintigraphic images of heart neurons in the living dog 3 and 20 hours after injection; these images portrayed the regions of adrenergic neuron disruption caused by phenol treatment. Concentrations of thallium-201 depicted on scintigraphic image and of triphenyltetrazolium observed on in vitro staining demonstrated no myocardial injury. Thus scintigraphy with 123I-MIBG will display regional adrenergic denervations in the heart.

3-Iodobenzylguanidine↗