Biomedical subjects

B Giannias

Publications and source records attributed to B Giannias.

7 recordsLinked to original sources

PubMed2001

Hemorrhagic shock resuscitation with a low molecular weight starch reduces neutrophil-endothelial interactions and vessel leakage in vivo.

BACKGROUND: The polymorphonuclear neutrophil (PMN) has been implicated in the pathogenesis of endothelial cell (EC) damage and organ injury following hemorrhagic shock. Pentastarch (PTS), a low substituted medium molecular weight (MW) colloid, improves hemodynamics in hypovolemic shock and cardiac surgery. No data exist comparing the immunomodulation of PTS and Ringer's lactate (RL) on the activation of PMN in hemorrhagic shock in vivo. METHODS: Using an in vivo murine hemorrhagic shock model (blood withdrawal to maintain 50 mmHg x 45 min), circulating PMN were observed every 15 minutes using intravital microscopy on cremaster muscle. EC-PMN interactions (videorecorded and subsequently analyzed blindly), vessel leakage (live epifluorescence after injection of 50 mg/kg fluorescent albumin) and PMN expression of L-selectin (immunofluorescent monoclonal antibodies and flow cytometry) were evaluated in three resuscitation groups: PTS (7.14 mL/kg 10% pentastarch/0.9% NaCl + shed blood, n = 13), RL (RL [2 x shed blood volume] + shed blood, n = 13) and SHAM (0 hemorrhage, 0 resuscitation, n = 9). Significance was evaluated by ANOVA with Bonferroni correction. RESULTS: PMN rolling was significantly diminished in PTS and SHAM as compared to RL animals at all time points. Similar differences were found in PMN adherence to EC at most time points onwards from 15 minutes following resuscitation. In vivo vessel permeability was lowest in SHAM and PTS animals (mean 0.274 +/- 0.07 and 0.356 +/- 0.15, respectively, p > 0.05) and highest in RL animals (0.667 +/- 0.09, p < 0.001 vs PTS or SHAM). PMN L-selectin expression tended to be higher in the RL group than either SHAM and PTS groups. There were no flow-mechanics differences between groups (vessel diameter, mean red cell velocity, shear stress, shear rate). CONCLUSIONS: 10% pentastarch reduces RL-associated EC-PMN interactions and vessel leakage following hemorrhagic shock. These results support the use of low MW starches to resuscitate hemorrhagic shock, potentially reducing PMN-mediated tissue injury.

Animals↗

PubMed2000

Decreased systemic polymorphonuclear neutrophil (PMN) rolling without increased PMN adhesion in peritonitis at remote sites.

BACKGROUND: Previous in vitro studies have demonstrated that the host response to intra-abdominal infection produces increased generalized polymorphonuclear neutrophil (PMN) adherence to vascular endothelial cells (ECs), which may lead to subsequent endothelial damage, leaky capillaries, and organ dysfunction. There are scant data to demonstrate this enhanced systemic PMN adherence in vivo or the influence of PMN rolling on PMN endothelial adherence. HYPOTHESIS: Systemic PMN adherence in the animal with sepsis is increased. DESIGN: In vivo murine model of a 2-front infection using intravital microscopy of the cremasteric muscle to quantify PMN-EC adherence in a septic response. SETTING: Basic science laboratory and animal surgical facility. PATIENTS OR OTHER PARTICIPANTS: One hundred CD1 male mice. INTERVENTIONS: Animals underwent cecal ligation and puncture peritonitis, cremasteric muscle Escherichia coli infection, both infections, or neither (controls). Eighteen hours later, the mice underwent exteriorization of the cremasteric muscle under an intravital microscope for measurement of PMN-EC interactions. Blood was then drawn for calculation of circulating PMN counts. MAIN OUTCOME MEASURES: Adherence of PMNs, PMN rolling flux, PMN rolling velocity, and circulating PMN counts. RESULTS: Circulatory mechanics did not differ between the groups. Unlike static in vitro systems, we could not detect an increase in PMN adherence after peritonitis with this dynamic in vivo model. A local (cremasteric) infection was associated with marked PMN adherence. Peritonitis was associated with reduced PMN adherence at a local infection site as well as reduced rolling adhesion and PMN rolling velocity. CONCLUSIONS: The data suggest that intra-abdominal infection does not increase remote PMN adherence, and may actually result in reduction of systemic adherence via modulation of PMN rolling.

Abdominal Muscles↗

PubMed2000

Polymorphonuclear neutrophil (PMN) recruitment in a 2-front murine injury model: triage of PMNs to competing stimuli of recruitment.

BACKGROUND: Intensive care unit patients as a group have the highest rate of nosocomial infections, such as pneumonia, urinary tract infections, and wound infections. The triage of polymorphonuclear neutrophils (PMNs) during an acute inflammatory response was investigated to determine if the severity of injury or infection contributes to PMN delivery. METHODS: A murine cecal ligation and puncture-induced peritonitis model with polyvinyl sponge discs were used to collect the PMNs in the abdomen (primary site) and in the subcutaneous tissue of the dorsum (remote site). Eighty CD1 male mice--20 in each of 4 groups--were assigned to the following: cecal ligation and puncture (CLP), sham laparotomy with cecal manipulation (CM), polyvinyl sponge placement in the abdomen and back only (SP), and sponge placement in the back alone (CON [control]). After 24 hours, the sponges were harvested, and the PMNs were collected and counted on a hemocytometer. RESULTS: These data, reported as mean PMN cells x 10(5) +/- SEM, demonstrated that back sponges contained significantly fewer PMNs in the CLP group (3.29 +/- 1.1) than in the CM group (7.77 +/- 1.61, P = .04), the SP group (8.69 +/- 1.67, P = .01), and the CON group (11.04 +/- 1.91, P < .001). CONCLUSIONS: These results demonstrate that PMN delivery to sites of secondary injury are inversely correlated to the severity of the primary injury or peritonitis.

Animals↗

PubMed1998

Reduction in neutrophil cell surface expression of tumor necrosis factor receptors but not Fas after transmigration: implications for the regulation of neutrophil apoptosis.

OBJECTIVES: To test the hypothesis that loss of polymorphonuclear neutrophil tumor necrosis factor alpha (TNF-alpha) receptors during transmigration renders the exudate neutrophil refractory to TNF-alpha-mediated stimulation of apoptosis; and to investigate the surface expression of Fas on both circulating and exudate neutrophils. DESIGN: A prospective cohort study. SETTING: Surgical laboratory of a tertiary care hospital. PARTICIPANTS: Twenty-one healthy human volunteers. INTERVENTIONS: All subjects had circulating neutrophils and exudate neutrophils collected by venipuncture and skin window methods, respectively. MAIN OUTCOME MEASURES: Circulating and exudate neutrophils were incubated in culture medium (1.0x10(6) neutrophils per milliliter) alone or with TNF-alpha (100 ng/mL). Apoptosis was evaluated by flow cytometry (annexin V-fluorescein isothiocyanate and propidium iodide). Tumor necrosis factor alpha-phycoerythrin and anti-human Fas-fluorescein isothiocyanate were used to evaluate neutrophil TNF-alpha receptors and surface expression of Fas. RESULTS: Exudate neutrophils had a significant delay in apoptosis rates when compared with circulating neutrophils. The percentage of neutrophils expressing TNF-alpha receptors was significantly diminished after exudation (80%+/-15% vs 33%+/-9%; P<.001), as was the median channel number of TNF-alpha phycoerythrin fluorescence (8.1+/-1.6 vs 5.2+/-0.5; P=.001). However, the expression of Fas was unchanged after transmigration (percentage positive for Fas: 98.7%+/-0.7% vs 92.8%+/-3.4%, P=.89; Fas antibody-fluorescein isothiocyanate median channel fluorescence: 12.2+/-1.1 vs 13.1+/-1.2; P=.80). Exposure of exudate neutrophils to TNF-alpha failed to increase their rate of apoptosis. CONCLUSIONS: Exudate polymorphonuclear neutrophils are confirmed to have delayed apoptosis. Loss of TNF-alpha receptors during transmigration is necessary for neutrophil survival in the extravascular inflammatory milieu.

Apoptosis↗

PubMed1996

Expression of human neutrophil L-selectin during the systemic inflammatory response syndrome is partly mediated by tumor factor alpha.

BACKGROUND: Rolling of neutrophils on the vascular endothelium is a requisite step to transmigration to areas of infection or inflammation, and this is regulated in part by the neutrophil cell adhesion molecule L-selectin. OBJECTIVES: To compare L-selectin expression in patients with systemic inflammatory response syndrome (SIRS) and healthy age-matched control subjects and to determine whether tumor necrosis factor alpha modulates L-selectin expression on human neutrophils. SETTING: A tertiary care surgical intensive care unit at a university teaching hospital. SUBJECTS: Patients identified with SIRS (American College of Critical Care Physicians and Society of Critical Care Medicine criteria) were compared with healthy age-matched control subjects. Venous blood samples that were obtained from healthy laboratory control subjects were used to examine the time course of L-selectin expression. MAIN OUTCOME MEASURES: Neutrophil L-selectin expression was determined by flow cytometry in patients with SIRS and control subjects. Tumor necrosis factor alpha concentrations were determined in blood and exudative fluid from patients with SIRS. Neutrophil L-selectin expression was measured during a 45-minute time course in the presence of recombinant human tumor necrosis factor alpha and N-formyl-methionyl-leucyl-phenylalanine. RESULTS: Circulating neutrophils from patients with SIRS had significantly less L-selectin expression than did control subjects. Tumor necrosis factor alpha at concentrations similar to those found in exudative fluid caused a dose- and time-dependent decrease in neutrophil L-selectin expression. CONCLUSION: Tumor necrosis factor alpha may act as a paracrine modulator of site-specific neutrophil rolling, adhesion, and exudation via mechanisms that involve the down-regulation of L-selectin.

Age Factors↗

PubMed1994

Exudative neutrophils. Modulation of microbicidal function in the inflammatory microenvironment.

OBJECTIVE: To determine whether the inflammatory microenvironment primes neutrophils for increased microbicidal activity. DESIGN: In vitro studies of host defense were performed on surgical patients. SETTING: A tertiary care, university hospital. PATIENTS: A volunteer sample of hospitalized preoperative, noninfected surgical patients. INTERVENTION: Exudative neutrophils were collected from skin-blister chambers and functionally compared with circulating neutrophils. METHODS: Flow cytometry was used to evaluate directly neutrophil microbicidal activity (using fluoresceinated Candida albicans), formyl-methionyl-leucyl-phenylalanine (fMLP)-induced superoxide production (using 123 dihydrorhodamine), and surface expression of CD11b, CD16, and the fMLP receptor. In vitro tumor necrosis factor alpha was used to determine the possibility and extent of further priming in both circulating and exudative neutrophils. RESULTS: Exudative polymorphonuclear neutrophils have enhanced microbicidal activity, superoxide production, and expression of CD11b, CD16, and the fMLP receptor. Exogenous tumor necrosis factor was able to prime circulating neutrophils but did not further augment superoxide production in exudative neutrophils. CONCLUSION: The microbicidal activity of neutrophils is enhanced after exudation and is associated with neutrophil priming. The inability of exogenous tumor necrosis factor to further augment superoxide production after exudation suggests that this priming has been maximized.

Candida albicans↗

PubMed1990

Anergic patients before elective surgery have enhanced nonspecific host-defense capacity.

Albeit anergy in patients before surgery is associated with an increase in septic-related complications and mortality, it is not clear whether this is due to a downregulated nonspecific host defense or a specific cellular immune defect. We studied polymorphonuclear leukocyte neutrophil (PMN) function in 14 patients who were admitted for elective surgery and compared them with 5 healthy controls. At admission, patients were classified according to their delayed-type hypersensitivity skin test response into reactive or anergic groups. In vivo PMN delivery to skin windows, the plasma lactoferrin level, serum and skin window fluid chemoattractant activity, and in vitro superoxide production were measured. Compared with reactive patients, anergic patients showed an increased cell delivery (8.7 x 10(6) PMNs per well vs 1.6 x 10(6) PMNs per well), an increased plasma lactoferrin level (4.4 +/- 1.5 mg/L vs 3.1 +/- 0.8 mg/L), an increased chemoattractant capacity of serum and skin window fluid (38 +/- 21 cells per high-power field vs 16.8 +/- 7.2 cells per high-power field), and an increased superoxide production. We concluded that nonspecific host defense, as reflected by PMNs, is enhanced in anergic patients before surgery and may not explain the increased susceptibility to infection.

Adult↗