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A Ayala

Publications and source records attributed to A Ayala.

At least 217 records · Page 12Linked to original sources
PubMed1991

The complex pattern of cytokines in sepsis. Association between prostaglandins, cachectin, and interleukins.

Although the cytokines tumor necrosis factor (TNF), interleukin-1 (IL-1), and interleukin-6 (IL-6) are important mediators of hemodynamic, metabolic, and immunologic alterations in the host during sepsis, it is not known whether there is any association between the release of these cytokines and prostanoids during sepsis. Sepsis induced by cecal ligation and puncture in rats led to a persistent elevation (p less than 0.05) of plasma TNF until 10 hours, steadily increasing (p less than 0.05) IL-1 plasma levels, and enhanced (p less than 0.05) IL-6 plasma levels at all time points compared to the sham group. Prostaglandin E2 plasma levels were elevated (p less than 0.05) at 5 hours (153 +/- 29 pg/mL; control: 47 +/- 11 pg/mL) and 10 hours (96 +/- 16 pg/mL; control: 21 +/- 5 pg/mL). Prostaglandin E2 production by splenic macrophages (sM phi) from septic animals was increased (p less than 0.05) at 5 hours (9.1 +/- 2.2 ng/mL) and 10 hours (5.6 +/- 1.5 ng/mL) compared to controls (3.3 +/- 0.3 ng/mL at 5 hours; 1.3 +/- 1.3 ng/mL at 10 hours). Incubation of sM phi from septic animals with ibuprofen enhanced (p less than 0.05) IL-1 and TNF synthesis, while IL-6 production was reduced (p less than 0.05). These results indicate that the alterations in prostanoid release and elevated plasma prostanoids may regulate the release and consequently the circulating levels of cytokines during sepsis.

Animals↗
PubMed1991

Adequate crystalloid resuscitation restores but fails to maintain the active hepatocellular function following hemorrhagic shock.

Studies have shown that active hepatocellular function is depressed early after trauma-hemorrhage and persists despite resuscitation with two or three times (x) the volume of maximum bleedout (MB) with lactated Ringer's solution (LR). However, it is not known if a larger volume of fluid resuscitation corrects this dysfunction. To study this, rats were bled to and maintained at a mean arterial pressure of 40 mm Hg until 40% of the MB volume was returned in the form of LR, and then resuscitated with 4x or 5x the volume of MB with LR. Three doses of indocyanine green (ICG) were given intravenously and [ICG] measured in vivo using an in-vivo hemoreflectometer. The initial velocity of the clearance of ICG was calculated. Maximal velocity of the clearance (Vmax: the number of functional ICG receptors) and kinetic constant (Km: the efficiency of the active transport) were determined from the Lineweaver-Burk plot. Vmax decreased during hemorrhage, was restored to control levels at 0-4 hours after resuscitation, but decreased at 4-8 hours after resuscitation despite restoration of cardiac output following resuscitation with 5x LR. This could be the result of increased TNF release. The Km also decreased during hemorrhage, but increased at 0-1.5 hours and remained at control levels even 4-8 hours after resuscitation. Thus the failure of Vmax to remain at control levels following adequate fluid resuscitation may form the basis of cellular dysfunction and multiple organ failure after severe hemorrhagic shock.

Adenine Nucleotides↗
PubMed1991

Eicosanoids regulate tumor necrosis factor synthesis after hemorrhage in vitro and in vivo.

The aim of this investigation was to determine whether PGE2 regulates TNF release in vitro and in vivo following hemorrhage. To study this, C3H/HeN mice were bled to a mean blood pressure (BP) of 35 mm Hg, maintained for 60 minutes, and then resuscitated. For in vitro studies, peritoneal (pM phi) and splenic (sM phi) macrophages obtained at 2 hours and 24 hours after hemorrhage were stimulated with LPS for 24 or 48 hours with or without ibuprofen (IBU). For in vivo studies, M phi were harvested 24 hours following hemorrhage with and without IBU treatment and stimulated with LPS for 48 hours. The decreased TNF release by pM phi but not sM phi from hemorrhaged mice was restored by IBU in vitro. IBU treatment in vivo significantly enhanced TNF release by pM phi compared with untreated hemorrhaged animals, while TNF release by sM phi was only slightly increased. These data indicate a major role of PGE2 in the regulation of TNF release by pM phi following hemorrhage.

Animals↗
PubMed1991

Differential alterations in plasma IL-6 and TNF levels after trauma and hemorrhage.

Tumor necrosis factor (TNF) and interleukin 6 (IL-6) are purported to be important mediators of inflammatory responses. It is not known whether the plasma levels of these cytokines are altered after trauma and hemorrhage. Our objectives were to determine whether there is any elevation of plasma TNF or IL-6 after trauma and hemorrhage and to what extent these changes are due to tissue trauma vs. simple hemorrhage. Trauma was induced in Sprague-Dawley rats under light ether anesthesia by performing a 5-cm midline laparotomy. On closure, animals were catheterized, awakened, hemorrhaged to a mean blood pressure of 40 mmHg, and maintained at that pressure until 40% of maximum shed blood volume was returned in the form of Ringer lactate (RL). Animals were then resuscitated with RL equivalent to four times shed blood volume. Blood samples (0.5 ml) were taken before inducing hemorrhage, at maximal bleed out (45 min), and at 4 and 6 h posthemorrhage to obtain plasma. IL-6 and TNF levels were measured using cytokine-dependent cellular assays. TNF levels were significantly elevated at 45 min into hemorrhage and remained so up to 4 h after hemorrhage. IL-6 levels were also elevated 45 min into hemorrhage and remained so up to 6 h posthemorrhage. IL-6, unlike TNF, was already significantly increased after midline laparotomy and before initiation of hemorrhage compared with unmanipulated animals. Thus induction of IL-6 by trauma may be partially independent of those mechanisms in hemorrhage that are involved in the release of TNF.

Animals↗
PubMed1991

Association between decreased splenic ATP levels and immunodepression: amelioration with ATP-MgCl2.

Although it is known that decreased ATP levels in liver and kidney contribute to organ dysfunction after shock, it remains unknown whether there is any association between decreased splenocyte ATP levels and splenic immune functions. Moreover, although studies have shown that ATP-MgCl2 treatment after shock improves hepatic and renal ATP levels and organ function, it remains unknown whether splenocyte ATP levels and immune functions are similarly affected by this agent. To study this, C3H/HeN mice were bled to a mean blood pressure of 35 mmHg, maintained at that pressure for 60 min, resuscitated with shed blood and Ringer lactate, and treated with ATP-MgCl2 (80 mumol/kg) or vehicle (saline). Splenocytes (SPL) were harvested at various intervals after hemorrhage, ATP levels were assessed by 31P nuclear magnetic resonance spectrometry, and functions were determined by measuring proliferative capacity and interleukin (IL)-2, and IL-3 synthesis. Hemorrhage depleted SPL ATP levels to 1.7 +/- 0.8% of control levels. However, there was a significant increase in ATP levels of ATP-MgCl2-treated mice (77 +/- 11%, P less than 0.05) compared with vehicle-treated animals (13 +/- 4.1%) at 1 h after resuscitation. SPL ATP levels returned to control by 2 h after resuscitation in the ATP-MgCl2 group, whereas ATP levels of the vehicle-treated mice remained significantly depressed (P less than 0.05) for up to 12 h after resuscitation. At 1 h after resuscitation, SPL proliferative capacity and IL-2 and IL-3 synthesis were all profoundly depressed in the vehicle-treated group (P less than 0.05 vs. control).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1991

Anti-TNF monoclonal antibodies prevent haemorrhage-induced suppression of Kupffer cell antigen presentation and MHC class II antigen expression.

Kupffer cells (KC), by virtue of their ability to present antigen (AP) and express major histocompatibility complex (MHC) class II antigen (Ia), play a pivotal role in the host defence system against invading micro-organisms. Although haemorrhagic shock depresses the above KC functions, it is not known whether increased KC tumour necrosis factor (TNF) production and elevated TNF plasma levels following haemorrhage are responsible for it. To study this, C3H/HeN mice were pretreated intraperitoneally with either anti-murine TNF antibody (anti-TNF Ab) or saline. Twenty hours later mice were bled and maintained at a mean blood pressure of 35 mmHg for 60 min followed by adequate fluid resuscitation. Two and 24 hr later, plasma was collected and KC were isolated. AP was measured by co-culturing KC with the D10.G4.1 Th cell clone. Ia expression was determined by direct immunofluorescence. Interleukin (IL)-1, IL-6 and TNF levels in KC supernatants and plasma were measured with bioassays or ELISA. Haemorrhage increased circulating TNF levels by 215% at 2 hr and by 76% at 24 hr (P less than 0.05), which was prevented by pretreatment with anti-TNF Ab. Haemorrhage-induced increase of circulating IL-6 was abolished (P less than 0.05) at 2 hr but not at 24 hr in the anti-TNF Ab group. The suppression of KC AP (P less than 0.05) and Ia expression (P less than 0.05) due to haemorrhage was attenuated (P less than 0.05) in anti-TNF Ab-treated mice at 2 and 24 hr and KC IL-1 and TNF synthesis was further (P less than 0.01) increased. These results indicate that TNF plays a critical role in the initiation and regulation of KC AP, Ia expression, and cytokine production following haemorrhage.

Animals↗
PubMed1991

Insights into the mechanisms of defective antigen presentation after hemorrhage.

Although hemorrhage depresses macrophage antigen presentation (AP), a critical component in eliciting an antigen-specific immune response, it is not known which particular step in macrophage AP (i.e., uptake, ingestion, catabolism, or presentation of degraded antigens to T cells) is defective. To study this, C3H/HeN mice were bled to an arterial mean blood pressure of 35 mm Hg, maintained for 60 minutes, and then adequately resuscitated. Peritoneal and splenic macrophage cultures were prepared 2 and 24 hours after hemorrhage. Macrophage AP capacity was measured by coculturing macrophages with the T-helper cell clone D10.G4.1. To gain information about macrophage ability to digest the specific antigen conalbumin, lysosomal activity was bypassed by use of chemically denatured conalbumin peptides. To study macrophage ability to present conalbumin peptides, macrophages were fixed and D10.G4.1 proliferation in response to fragmented conalbumin was determined. AP of native conalbumin by peritoneal macrophages and splenic macrophages was depressed (p less than 0.05) by 50% (peritoneal macrophages) and 55% (splenic macrophages) 2 hours and 57% (peritoneal macrophages) and 35% (splenic macrophages) 24 hours after hemorrhage. In contrast, presentation of conalbumin peptides was only slightly decreased. In addition, the ability of fixed peritoneal macrophages and splenic macrophages to present conalbumin peptides was similar in hemorrhaged and sham mice. Because bypassing of macrophage lysosomal activity with degraded native antigens prevented the suppression of AP, the results suggest that hemorrhage-induced suppression of AP is not caused by a reduced macrophage capacity to present antigenic peptides but by decreased antigen catabolism by macrophages.

Animals↗
PubMed1991

Intraarterial cisplatin in the management of stage IIB osteosarcoma in the pediatric and adolescent age group.

Sixty patients with extremity osteosarcoma were treated with intraarterial cisplatin. This was followed by surgical resection (amputation or limb salvage) and postoperative adjuvant chemotherapy utilizing two different protocols. Seventy-five percent of patients achieved an initial response. Overall disease-free survival was 58%. The number of patients treated with limb-salvage surgery gradually increased to the extent that 80% of newly-registered patients achieved a response and were subjected to limb salvage. Disease-free survival was 48% in amputation and 68% in limb salvage. The only factors found to have prognostic significance in determining disease-free survival were extent of tumor destruction induced by preoperative chemotherapy and tumor size.

Adolescent↗
PubMed1991

Adjuvant chemotherapy of high-grade osteosarcoma of the extremity. Updated results of the Multi-Institutional Osteosarcoma Study.

The Multi-Institutional Osteosarcoma Study (MIOS) was designed to determine whether intensive multiagent adjuvant chemotherapy improves the outcome of patients with nonmetastatic high-grade osteosarcoma of the extremity as compared with concurrent controls. After definitive surgery of the primary tumor, patients were randomly assigned to immediate adjuvant chemotherapy or to observation without adjuvant treatment. Updated results of this trial indicate that the projected six-year event-free survival for the control group is 11% compared to 61% for the chemotherapy group (p less than 0.001). Similar results were observed in patients who declined randomization but who were followed according to the treatment arms of the protocol. When randomized and nonrandomized patients are pooled according to assigned treatment, a survival advantage favoring those patients treated with immediate adjuvant chemotherapy is apparent. An analysis of prognostic factors among patients receiving immediate adjuvant chemotherapy reveals that elevation of the serum lactic dehydrogenase at diagnosis is the factor most predictive of adverse outcome. Location of the primary site in the tibia confers a favorable prognosis. The authors conclude that the natural history of high-grade osteosarcoma of the extremity has not changed over the past two decades. The administration of immediate adjuvant chemotherapy has a significant favorable impact on event-free survival and should be recommended for all such patients.

Adult↗
PubMed1990

Possible involvement of NADPH requirement in regulation of glucose-6-phosphate and 6-phosphogluconate dehydrogenase levels in rat liver.

Previous studies examining regulation of synthesis of Glucose-6-Phosphate and 6-Phosphogluconate dehydrogenase in rat liver have focussed on the induction of these enzymes by different diets and some hormones. However, the precise mechanism regulating increases in the activities of these enzymes is unknown and the factors involved remain unidentified. Considering that many of these metabolic conditions occur simultaneously with the increase of some NADPH consuming pathway, in particular fatty acid synthesis, we suggest that the activities of Glucose-6-Phosphate and 6-Phosphogluconate dehydrogenase could be regulated through a mechanism involving changes in the NADPH requirement. Here, we have studied the effect of changes in the flux through different NADPH consuming pathways on the NADPH/NADP ratio and on Glucose-6-Phosphate and 6-Phosphogluconate levels. The results show that: i) an increase in consumption of NADPH, caused by activation of fatty acid synthesis or the detoxification system which consumes NADPH, is paralleled by an increase in levels of these enzymes; ii) when increase in consumption of NADPH is prevented, Glucose-6-Phosphate and 6-Phosphogluconate dehydrogenase levels do not change.

Animals↗
PubMed1990

Enhanced susceptibility to sepsis after simple hemorrhage. Depression of Fc and C3b receptor-mediated phagocytosis.

To determine whether phagocytosis mediated by Fc receptors and/or receptors for the third component of complement (C3b) are altered after hemorrhage, C3H/HeN mice were subjected to nonlethal hemorrhage and then adequately resuscitated. Twelve hours after the hemorrhagic episode, a significant decrease in both Fc (-55.2%) and C3b (-46.6%) receptor-positive peritoneal macrophages was observed compared with controls. At 24 hours the extent of the depression, while still marked, was only -22.5% and -17.4% for Fc and C3b receptors, respectively. By day 3 after hemorrhage, no differences could be observed for either of these receptors. The capacity of macrophages from mice after hemorrhage to elaborate interleukin 1 or tumor necrosis factor-alpha showed no increase over that of the sham controls, and serum levels of endotoxin were not elevated 2 or 24 hours after hemorrhage. Moreover, endotoxin-tolerant C3H/HeJ mice also exhibited depression of both receptors after hemorrhage. Thus, the inability of the host macrophages to clear opsonized infectious agents after hemorrhage may be due in part to the loss of Fc and C3b receptors on macrophages.

Animals↗
PubMed1990

Decreased Fc receptor expression on macrophages following simple hemorrhage as observed by scanning immunoelectron microscopy.

Although it is known that macrophage (M phi) functions such as phagocytosis and antigen presentation are depressed following hemorrhage and resuscitation, the mechanism remains unknown. The aim of this study was to determine, using scanning immunoelectron microscopic techniques, whether there is any alteration in the Fc receptors on the M phi after hemorrhage. To study this, male C3H/HeN mice were bled to a mean blood pressure (BP) of 35 mm Hg and maintained at that pressure for 1 hr, then resuscitated with their own blood and adequate fluids. Twenty-four hrs later, Kupffer cells from livers and splenic adherent cells were isolated, incubated for 16 hr, and then exposed to polysterene beads conjugated with antimouse IgG that specifically binds to Fc receptors. The cells were then prepared for observation by scanning electron microscopy. At least 100 cells from each animal were examined. The number of Kupffer cells from posthemorrhage mice that exhibited specific receptor labeling was significantly decreased (41.0 +/- 2.6, P less than 0.05) compared with control (64.2 +/- 7.5). The number of splenic adherent cells from posthemorrhage mice exhibiting specific receptor labeling was also significantly decreased (35.7 +/- 2.5, P less than 0.01) compared with control (61.2 +/- 3.9). The internalization of markers was also seen in some cells. The cause of the decrease in receptor labeling following hemorrhage may be the loss, inactivation, and/or internalization of receptors. Thus the decreased number of functional macrophages may contribute to the depression of antigen presentation and to the enhanced susceptibility to sepsis following hemorrhage.

Animals↗
PubMed1990

Hemorrhage induces an increase in serum TNF which is not associated with elevated levels of endotoxin.

Although tumor necrosis factor (TNF) and interleukin 6 (IL 6) are purported to be important mediators of inflammatory responses following trauma, it is not known if the serum levels of these cytokines are altered by simple hemorrhage. The objective of this study therefore was to determine whether or not: 1) there is any elevation of TNF or IL 6, and 2) if endotoxin, an important upregulator of these cytokines, is also increased following hemorrhage. To study this, C3H/HeN mice were bled to, and maintained at a mean blood pressure of 35 mmHg for 60 min, and then resuscitated with their own shed blood and adequate fluid. Mice were sacrificed at 30 min into hemorrhage and at 2, 4 or 24 hr post-hemorrhage to obtain serum samples. IL 6 and TNF levels were measured using cytokine dependent cellular assays. Using a quantitative Limulus amebocyte lysate assay, endotoxin levels were determined. TNF levels were significantly elevated at 30 min into hemorrhage, remaining so at 2 hr after resuscitation, but absent by 4 hr. Although there was a trend toward elevated IL 6 levels at 2 hr following hemorrhage, which was sustained up to 24 hr, the values were not significantly different from sham controls. When compared to controls, no marked increase in endotoxin was seen at any time point during or following hemorrhage. These results indicate that hemorrhage, in the absence of significant tissue trauma, causes enhanced TNF release which is not the result of increased endotoxin.

Animals↗
PubMed1990

Regulation of Trypanosoma cruzi infectivity by alpha- and beta-adrenergic agonists: desensitization produced by prolonged treatments or increasing agonist concentrations.

We previously reported that blood forms of Trypanosoma cruzi express alpha- and beta-adrenergic receptors and that binding of specific agonists to these receptors modifies the infective capacity of the parasite in vitro. The present study has revealed that the inhibitory effect of the beta-adrenergic agonist L-isoproterenol and the stimulatory effect of the alpha-adrenergic agonist L-phenylephrine are not produced when the parasite is subjected to prolonged exposure to otherwise effective doses of these agonists or when supraoptimal doses of these agonists are used. We refer to these phenomena as 'desensitization' because of their analogy with vertebrate cells becoming desensitized by prolonged exposure to, or relatively high concentrations of, adrenergic agonists. At a constant agonist concentration, T. cruzi desensitization was time-dependent and, when the time of parasite treatment with the agonists was not changed, the higher concentrations of the agonist tested were the most effective in producing desensitization. The reduced infectivity resulting from treatment with optimal doses of L-isoproterenol was accompanied by elevated levels of cyclic adenosine monophosphate (cAMP) which were not detectable when L-isoproterenol concentrations producing desensitization were used. This finding implicated cAMP as a likely second signal in the inhibitory mechanisms of this agonist. No significant change in cAMP was detectable in parasites treated with L-phenylephrine, leaving open the question about how optimal doses of this alpha-adrenergic agonist enhance T. cruzi infectivity. Parasite responsiveness to alpha- and beta-adrenergic agonists as well as the desensitization effects define a system which regulates infectivity and could be modified at the host tissue level by naturally occurring agonists.

Animals↗
PubMed1990

Pediatric osteosarcoma: therapeutic strategies, results, and prognostic factors derived from a 10-year experience.

Ninety-eight pediatric patients were treated with three separate protocols (Treatment and investigation of Osteosarcoma [TIOS] I, II, and III) and 47 developed recurrent disease (metastases and/or local recurrence). Actuarial overall disease-free survival (hereafter designated survival) was 43%. Over 90% of the patients were treated initially with preoperative intraarterial cisplatin (CDP). Postoperative chemotherapeutic regimens comprised high-dose methotrexate with leucovorin rescue (MTX-CF), Adriamycin [( ADR] doxorubicin; Adria Laboratories, Columbus, OH), and cyclophosphamide. Primary definitive treatment comprised amputation or limb salvage (TIOS I and TIOS III). Patients treated with preoperative CDP and surgery (TIOS I and III) had a 62% survival. Patients in TIOS II refused surgical extirpation; they were treated exclusively with chemotherapy and had a 23% survival. Survival in patients treated with amputation was 55% and limb salvage 58%. Prognostic factors considered significant in relation to development of pulmonary metastases comprised tumor burden (P = .04) and the percentage of tumor necrosis induced by preoperative chemotherapy (P = .01). Histopathologic subtype was marginally significant: chondroblastic was more favorable as opposed to osteoblastic (P = .05). These findings are compared with results and prognostic factors published in the literature.

Child↗
PubMed1990

Defective macrophage antigen presentation following haemorrhage is associated with the loss of MHC class II (Ia) antigens.

Although recent studies indicate that severe and prolonged haemorrhage, despite adequate fluid resuscitation, induces profound depression of cell-mediated immunity, the mechanism of this remains unknown. Since macrophages (M phi) play a key role in the development of a competent immune response by the presentation of antigens, the study investigated (i) whether the capacity of the M phi to present antigen is altered even following mild hypotension, and (ii) what effects do different degrees of hypotension have on the M phi-mediated processes associated with antigen presentation (i.e. the expression Ia antigen, membrane-associated IL-1 or the secretion of IL-1). The results indicate that a minimal drop in blood pressure to approximately 50 mmHg (1 hr duration) was sufficient to depress M phi antigen presentation (AP). Similarly, even a transient hypotensive episode of 15 min duration at 35 mmHg was sufficient to produce a pronounced decline in AP. Decreased AP was observed as early as 12 hr after the haemorrhagic episode (35 mmHg; 1 hr) and remained detectable for at least 120 hr thereafter. The reductions in AP capacities were qualitatively similar in both peritoneal and splenic populations, and were not attributable to surgical stress, heparinization or ether anaesthesia. Determination of IL-1 production, as well as membrane-bound IL-1 levels, in these cell populations showed no significant difference from controls. However, a significant decrease was observed in the percentage of Ia antigen (MHC class II)-positive M phi, suggesting that reduced AP following haemorrhage may be related to the inability of these cells to express Ia.

Animals↗