Biomedical subjects

A Ayala

Publications and source records attributed to A Ayala.

At least 181 records · Page 10Linked to original sources

PubMed1993

Protective effect of deprenyl against 1-methyl-4-phenylpyridinium neurotoxicity in rat striatum.

Rats were treated with deprenyl for 3 weeks. Afterwards, slices of the corpus striatum were incubated with 1-methyl-4-phenylpyridinium ion (MPP+). Concentrations of dopamine and its metabolite concentrations were assayed. The effect of MPP+ in animals treated with deprenyl was smaller than in controls, indicating that deprenyl protects against MPP+. We also measured superoxide dismutase (SOD) and catalase activities and carbonyl group content of the proteins. Both activities increased in deprenyl-treated rats, and the amount of carbonyl groups was unchanged. These results suggest that the protective effect of deprenyl is independent of the monoamine oxidase-B inhibitor and of the induction of SOD and catalase activities.

1-Methyl-4-phenylpyridinium↗

PubMed1993

Modulation of macrophage membrane phospholipids by n-3 polyunsaturated fatty acids increases interleukin 1 release and prevents suppression of cellular immunity following hemorrhagic shock.

Studies have suggested that the significant suppression of cellular immunity following hemorrhage may be due to an increased release of prostaglandin E2 (PGE2) by macrophages. Since diets high in n-3 polyunsaturated fatty acids decrease PGE2 synthesis, we assessed whether hemorrhage-induced immunosuppression could be prevented by dietary manipulation. C3H/HeN mice were fed for 3 weeks with fat sources derived from corn oil, safflower oil, or fish oil, then bled to a mean blood pressure of 35 mm Hg maintained for 60 minutes. Following this, the animals were adequately resuscitated with fluids and killed 24 hours later. In the corn oil and safflower oil groups, hemorrhage resulted in a significant increase in PGE2 release by peritoneal macrophages, a marked suppression of peritoneal macrophage antigen presentation capacity, interleukin 1 release, splenocyte proliferation, and interleukin 2 secretion compared with shams. However, feeding mice with fish oil for 3 weeks prior to hemorrhage prevented the rise in PGE2 release and maintained normal macrophage and splenocyte functions following hemorrhage. Thus, the elevated release of PGE2 by peritoneal macrophages plays a pivotal role in hemorrhage-induced immunosuppression. Moreover, diets high in n-3 polyunsaturated fatty acids may offer a new therapeutic approach for preventing posthemorrhage immunosuppression and increased mortality from sepsis.

Animals↗

PubMed1993

Role of interleukin 6 and transforming growth factor-beta in the induction of depressed splenocyte responses following sepsis.

We examined whether (1) there is an association between elevated circulating levels of transforming growth factor-beta (TGF-beta) and splenocyte dysfunction during sepsis, and (2) administration of monoclonal antibodies to interleukin 6 (an inducer of TGF-beta release) or TGF-beta could ablate these changes. Blood and splenocytes were obtained from C3H/HeN mice at 1, 4, or 24 hours following cecal ligation and puncture or sham operation. Only at 24 hours after cecal ligation and puncture was there an association between elevated blood TGF-beta value and depressed splenocyte interleukin 2 release. Administration of monoclonal antibodies against interleukin 6, but not against TGF-beta (intraperitoneally immediately following cecal ligation and puncture), significantly decreased the blood levels of TGF-beta at 24 hours following cecal ligation and puncture and improved splenocyte interleukin 2 release. Thus, the judicious use of monoclonal antibodies against interleukin 6 may block the subsequent elevation of TGF-beta, thereby attenuating host immunosuppression during sepsis.

Animals↗

PubMed1993

Insights into the mechanism by which interferon-gamma improves macrophage function following hemorrhage and resuscitation.

Recent studies indicate that depressed macrophage (M phi) immune responses following hemorrhage can be restored by the administration of interferon (IFN)-gamma as an adjuvant to resuscitation. However, the mechanism of these effects remains unknown. An important component of the process of M phi activation in response to pathogens is the mobilization of intracellular calcium ([Ca2+]i). Since hemorrhage alters the M phi signal transduction system, the aim of this study, therefore, was to determine whether administration of IFN-gamma after hemorrhage restores this mode of macrophage signal transduction. To assess this, C3H/HeN mice were bled to and maintained at a mean blood pressure of 35 mm Hg for 1 hr and then adequately resuscitated. Mice then received either 40,000 units IFN-gamma/kg body wt or saline vehicle and were killed 2 hr posthemorrhage to obtain splenic M phi. These M phi were loaded with Fluo-3 AM (fluorescent [Ca+2]i probe) and their capacity to mobilize [Ca+2]i in response to stimulation with f-met-leu-phe (FMLP; bacterial peptide) was assessed on a laser cytometer. The results indicated that IFN-gamma restored the capacity of splenic M phi to mobilize [Ca+2]i in response to FMLP. Moreover, the results demonstrated that hemorrhage produced a marked increase in resting cAMP levels in these cells that were lowered to sham levels by the administration of IFN-gamma. Thus, it appears that IFN-gamma acts to restore M phi signal transductional capacity, thereby improving M phi-mediated immune functions following hemorrhage and resuscitation.

Animals↗

PubMed1993

Mechanism of increased susceptibility to infection following hemorrhage.

Although hemorrhage is known to cause increased susceptibility to infection, the precise mechanism remains unknown. Regional hypoxia due to reduced blood flow following hemorrhage appears to be a primary mediator that initiates the cascade of events leading to immunodepression and increased susceptibility to infection. This was evident from depression of lymphocyte functions, production of various lymphokines, macrophage expression of receptors involved in opsonin-mediated phagocytosis, and antigen presentation function of peritoneal, splenic, and Kupffer cells following hemorrhage. The depression in various immune functions is apparent immediately after hemorrhage and persists for a prolonged period of time, despite volume resuscitation. Furthermore, it appears that the increased release of systemic mediators, such as interleukin-1 (IL-1), IL-6, tumor necrosis factor, transforming growth factor type beta, and prostaglandin E2 is associated with marked depression in immune responses and increased susceptibility to infection following hemorrhage.

Bacterial Infections↗

PubMed1993

Mechanism of diltiazem's immunomodulatory effects after hemorrhage and resuscitation.

Although diltiazem improves immune responses after hemorrhage and resuscitation, its mechanism remains unknown. To study this, C3H/HeN mice were bled to a mean blood pressure of 35 mmHg, maintained at that level for 1 h, and then adequately resuscitated and treated with diltiazem (400 micrograms/kg body wt) or saline (vehicle). One hour after hemorrhage and resuscitation, splenic microvascular blood flow was determined by laser Doppler flowmetry. Splenocytes were also harvested and ATP levels and cytoplasmic free Ca2+ concentration ([Ca2+]i) were determined by 31P nuclear magnetic resonance and fluo 3 flow cytometry, respectively. Splenocyte functions were determined by measuring interleukin (IL)-1, IL-2, IL-3, IL-6, and tumor necrosis factor concentrations in concanavalin A-stimulated supernatant with cytokine-specific cellular assays. Hemorrhage and resuscitation caused a significant decrease in the splenocyte's ability to release cytokines, which was correlated with significant reductions in splenocyte ATP levels and splenic microvascular blood flow as well as a significant increase in splenocyte [Ca2+]i. Diltiazem significantly decreased splenocyte [Ca2+]i while improving splenocyte ATP levels, cytokine production, and splenic microvascular blood flow. Nitroglycerin (71 micrograms/kg body wt) administration improved splenic microvascular blood flow to diltiazem-treated levels but failed to concomitantly improve splenocyte ATP levels or cytokine production. Thus diltiazem's immunoprotective effects appear to be the result of decreased Ca(2+)-induced splenocyte injury.

Adenosine Triphosphate↗

PubMed1993

Tumor necrosis factor-alpha produces hepatocellular dysfunction despite normal cardiac output and hepatic microcirculation.

Although plasma levels of tumor necrosis factor (TNF) are elevated and hepatocellular dysfunction occurs even in the early hyperdynamic stage of sepsis, the precise mechanism responsible for this dysfunction remains unknown. Although TNF at high doses produces circulatory failure, it is not known whether the dose of TNF that does not adversely affect hemodynamics alters hepatocellular function. To study this, recombinant murine TNF-alpha was infused intravenously (0.05 or 0.25 mg/kg) over 30 min in normal rats. At 1 and 4 h after infusion of TNF-alpha or an equivalent volume of saline, hepatocellular function [i.e., maximum velocity (Vmax) and Michaelis constant (Km)] was assessed using in vivo indocyanine green clearance without blood sampling. Additional parameters measured were as follows: cardiac output by dye dilution, hepatic microcirculation by laser Doppler flowmetry and colloidal carbon infusion, plasma TNF and interleukin-6 (IL-6) by cytokine-dependent cellular assays, and plasma glucose enzymatically. The results indicate that although infusion of 0.05 mg/kg TNF-alpha did not affect Vmax and Km, its infusion at 0.25 mg/kg produced a significant depression of hepatocellular function and markedly increased the synthesis and/or release of IL-6. TNF-alpha-induced hepatocellular dysfunction was not associated with any significant changes in hepatic microcirculation, plasma glucose, cardiac output, and other measured hemodynamic parameters. Thus hepatocellular dysfunction observed after TNF infusion may be due to the direct effect of this cytokine alone or in combination with IL-6.

Alanine Transaminase↗

PubMed1993

A model of pulmonary atelectasis in rats: activation of alveolar macrophage and cytokine release.

Although atelectasis frequently occurs after surgery and trauma, and such patients have elevated body temperatures, the mechanism of temperature elevation secondary to atelectasis is unknown. Moreover, a small animal model has not been available to study the pathophysiology of pulmonary atelectasis. The purpose of this study, therefore, was to develop a model of pulmonary atelectasis in rats. Because interleukin-1 (IL-1) and tumor necrosis factor (TNF), both potent pyrogens, are produced by macrophages during infection and inflammation, our aim was also to determine whether alveolar macrophages produce IL-1 or TNF in response to atelectasis. Whole-lung atelectasis was produced in rats by ligating the left main stem bronchus while maintaining ventilation of the right lung. After a 1-h period of atelectasis, alveolar macrophages were harvested from the right and left lungs and incubated for 24 h, and the supernatants were assayed for IL-1 and TNF. Both IL-1 and TNF levels of macrophage cultures from the atelectatic lung were significantly increased compared with the control lung. These results suggest that increased IL-1 or TNF production by alveolar macrophages may be responsible for fever caused by atelectasis.

Animals↗

PubMed1993

Chemically induced hypotension increases PGE2 release and depresses macrophage antigen presentation.

Hemorrhagic shock causes severe depression of macrophage functions and is associated with increased susceptibility to sepsis. Because hemorrhagic shock and resuscitation encompasses several pathophysiological conditions, such as hypotension, low-flow conditions, hypoxia, and reperfusion injury, it remains unknown whether severe hypotension in the absence of blood loss has any adverse effects on macrophage functions. To study this, systemic arterial hypotension was induced in C3H/HeN mice for 15 min by intravenous infusion of sodium nitroprusside or ATP-MgCl2. Peritoneal macrophages (PM) was harvested 20 h later with lavage. Antigen presentation was measured by coculturing PM with the D10.G4.1 Th cell clone. Tumor necrosis factor (TNF), interleukin (IL)-6, IL-1, and prostaglandin (PG) E2 levels in supernatants of PM stimulated with lipopolysaccharide were measured with bioassays or radioimmunoassay. Systemic arterial hypotension resulted in a significant decrease of PM capacity to present antigen. Although the release of TNF, IL-6, and IL-1 by PM was unaltered after hypotension, PGE2 release by PM was significantly elevated compared with the control group. These data indicate that chemically induced systemic arterial hypotension without blood loss leads to a depression of antigen presentation, which may be caused by elevated release of the immunosuppressive eicosanoid PGE2.

Adenosine Triphosphate↗

PubMed1993

Chloroquine inhibits macrophage tumour necrosis factor-alpha mRNA transcription.

Although chloroquine administration in vivo following haemorrhage in mice decreases tumour necrosis factor-alpha (TNF-alpha) release by macrophage (M phi), the mechanism remains unknown. To study this, peritoneal M phi (pM phi) from unmanipulated, sham-operated and post-haemorrhage mice were isolated, treated with 0.13 mg/ml chloroquine for 2 hr, and then stimulated with lipopolysaccharide (LPS) for 48 hr. Pretreatment of pM phi from various groups of mice with chloroquine resulted in 75-90% inhibition of TNF-alpha release, determined by bioassay. Total RNA was isolated from pM phi and murine M phi-derived cell lines (P388D1 and RAW 264.7), stimulated with LPS for 0.5 or 1 hr, respectively, and Northern blot analysis for TNF-alpha mRNA performed. Chloroquine inhibited TNF-alpha mRNA expression without interfering with mRNA stability, suggesting that this agent reduces M phi TNF-alpha release by disrupting TNF-alpha gene transcription.

Animals↗

PubMed1993

The release of transforming growth factor-beta following haemorrhage: its role as a mediator of host immunosuppression.

Haemorrhage in the absence of trauma is reported to induce a profound depression in cell-mediated immunity. Recent studies have drawn attention to the cytokine transforming growth factor-beta (TGF-beta) that, while important in wound healing, also has marked immunosuppressive effects. The aim of this study was to determine whether: (1) haemorrhage induces an increase in circulating TGF-beta and if this is associated with the loss of host immunoresponsiveness; and (2) administration of monoclonal antibody (mAb) to TGF-beta following haemorrhage ablates these changes. To determine this, C3H/HeN mice were bled to and maintained at a mean arterial pressure of 35 mmHg for 1 hr. This required removing approximately 50% of the circulating blood volume. Following this period of hypotension, the mice were adequately resuscitated. Blood samples obtained at 24 and 72 hr, but not at 2 hr, following haemorrhage showed a significant elevation in plasma TGF-beta levels when compared to shams. At 24 hr, the increase of TGF-beta in the plasma was associated with decreases in both concanavalin A (Con A)-induced splenocyte proliferation and splenic macrophage antigen presentation. Treating animals with neutralizing antibody (animals received 200 micrograms mAb against bovine TGF-beta 1,2,3/mouse intraarterially) not only reduced the levels of TGF-beta in the blood at 24 hr, but also restored splenocyte functions, such as Con A-induced proliferation, interleukin-2 (IL-2) release, and the capacity of splenic macrophages to present antigen. However, elevated levels of prostaglandin E2 (PGE2) seen in plasma during haemorrhage were only partially depressed by the antibody treatment. These results indicate that the release of TGF-beta contributes to the protracted (> or = 24 hr) suppression of cell-mediated immunity following haemorrhage.

Animals↗

PubMed1992

Chloroquine attenuates hemorrhagic shock-induced immunosuppression and decreases susceptibility to sepsis.

Hemorrhagic shock causes a severe suppression of cellular immunity and an increased susceptibility to sepsis that may be due to increased release of prostaglandin E2 by macrophages. Since chloroquine inhibits the secretion of prostaglandin E2 by macrophages in vitro, the effects of chloroquine administration in vivo following hemorrhagic shock on macrophage prostaglandin E2 secretion and on depressed cellular immunity were examined. Inbred C3H/HeN male mice, aged 6 to 8 weeks, were bled to a mean blood pressure of 35 mm Hg, which was maintained for 60 minutes, and adequately, resuscitated. Mice then received intramuscular injections of either saline (vehicle) or chloroquine (10 mg/kg of body weight). Prostaglandin E2 in macrophage supernatants (radioimmunoassay) concanavalin A-dependent splenocyte proliferation, and interleukin 2 in splenocyte supernatants (CTLL 20 interleukin 2-dependent proliferation) were determined 2 or 24 hours later. Hemorrhage caused a significant decrease of splenocyte proliferation (47%) and interleukin 2 release (49%) at 24 hours, while prostaglandin E2 secretion from macrophages was elevated at 2 hours. Chloroquine treatment attenuated depression of splenocyte functions and reduced prostaglandin E2 release. Furthermore, chloroquine treatment decreased the mortality of septic mice after hemorrhage to levels comparable with those of sham-operated mice. Thus, chloroquine may be a useful adjunct in the clinical setting for the treatment of shock-induced immunodepression and increased susceptibility to sepsis following hemorrhage.

Animals↗

PubMed1992

Does endotoxin tolerance prevent the release of inflammatory monokines (interleukin 1, interleukin 6, or tumor necrosis factor) during sepsis?

Mice were subjected to sepsis by cecal ligation and puncture to determine whether macrophages from endotoxin-tolerant C3H/HeJ mice are also activated systemically to release inflammatory monokines associated with septic mortality. Blood levels of both tumor necrosis factor and interleukin 6 were significantly elevated during the first 1 to 4 hours of sepsis as compared with sham controls. Peritoneal macrophages from septic mice exhibited a marked spontaneous release of interleukin 1, interleukin 6, and tumor necrosis factor at 1 hour. However, the addition of endotoxin to macrophage cultures taken from septic mice had no further stimulatory effect. Sham controls alternatively showed no significant innate monokine release, but their macrophages did release increased monokine numbers in response to endotoxin. These results indicate that the spontaneous macrophage release of these monokines is comparable with that previously observed in endotoxin-sensitive mice, suggesting a common mechanism by which macrophages are primed by traumatic injury by an agent other than endotoxin to release monokines during sepsis. Thus, the administration of agents that decrease or prevent the deleterious effects of systemic inflammatory mediators during sepsis could be useful adjuvants in those clinical situations where the bacterial origin is unknown.

Animals↗

PubMed1992

Ibuprofen restores cellular immunity and decreases susceptibility to sepsis following hemorrhage.

Although hemorrhage depresses splenocyte (SPL) functions and increases susceptibility to sepsis, it is not known whether increased tumor necrosis factor (TNF) or prostaglandin (PG) production are responsible for it. To study this, mice (C3H/HeN) were bled to a mean blood pressure of 35 mm Hg, maintained at that pressure for 60 min, resuscitated, and treated with ibuprofen (1.0 mg/kg body weight) or vehicle (saline). Hemorrhage reduced (P less than 0.05) SPL proliferation by 60%, SPL release of interleukin-2 (IL-2) by 47%, interferon-gamma (IFN-gamma) by 67%, TNF by 54%, and interleukin-6 (IL-6) by 46% compared to sham. In addition, splenic macrophage (sM phi) release of interleukin-1 (IL-1) and TNF was decreased by 58 and 67% (P less than 0.05), respectively. However, ibuprofen treatment increased (P less than 0.05) SPL proliferation, lymphokine (IL-2, IFN-gamma, and IL-6) synthesis, and IL-1 release by sM phi compared to hemorrhage alone. Furthermore, ibuprofen enhanced the release of TNF by SPL (+175%, P less than 0.05) and sM phi (+68%) compared to the vehicle group. Ibuprofen also decreased (P = 0.011) the susceptibility to sepsis following hemorrhage. These results indicate that PGs are involved in hemorrhage-induced suppression of cellular immunity and in the increased mortality of such animals following a septic challenge.

Animals↗

PubMed1992

Mechanism of the beneficial effects of ATP-MgCl2 following trauma-hemorrhage and resuscitation: downregulation of inflammatory cytokine (TNF, IL-6) release.

Although ATP-MgCl2 improves hepatocellular function in a nonheparinized model of trauma-hemorrhage and crystalloid resuscitation, it remains unknown whether the beneficial effects of this agent are due to downregulation of the release of the inflammatory cytokines, tumor necrosis factor (TNF), and interleukin-6 (IL-6) under those conditions. To study this, rats underwent a 5-cm laparotomy (i.e., trauma induced) and were bled to and maintained at a mean arterial pressure of 40 mm Hg until 40% of maximum bleedout volume was returned in the form of Ringer's lactate (RL). The animals were then resuscitated with four times the volume of shed blood with RL over 60 min. ATP-MgCl2 (50 mumoles/kg body weight each) or an equivalent volume of normal saline was infused intravenously for 95 min. This infusion was started during the last 15 min of RL resuscitation. Plasma levels of TNF and IL-6 were measured at 1.5 hr after the completion of resuscitation by cytokine-dependent cellular assays. Hepatic blood flow was determined by in vivo indocyanine green clearance (corrected by hepatic extraction ratio for indocyanine green), radioactive microspheres, and [3H]-galactose clearance techniques. The results indicate that the levels of circulating TNF and IL-6 increased significantly in the hemorrhaged-resuscitated animals. ATP-MgCl2 treatment, however, markedly decreased the synthesis and/or release of these cytokines to levels similar to the sham group. The markedly decreased hepatic blood flow (as determined by three different methods) and hepatic extraction ratio for indocyanine green were also restored by ATP-MgCl2 treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗

PubMed1992

Sepsis induces an early increased spontaneous release of hepatocellular stimulatory factor (interleukin-6) by Kupffer cells in both endotoxin tolerant and intolerant mice.

Previous studies have shown that hepatocellular function is significantly depressed early during sepsis and that this is associated with a marked increase in the circulating levels of the hepatocellular stimulatory factor (IL-6). It remains unknown, however, whether or not Kupffer cells (KC) are activated during sepsis and whether these cells are the major contributors to the increased circulating levels of this cytokine. The objectives of this study were, therefore, to determine whether or not during sepsis: (1) KC are stimulated in vivo to release IL-6, as compared to other cytokines; (2) KC differ from splenic macrophages (SM phi) in their ability to release cytokines; and (3) there is a difference in macrophage (M phi) cytokine release between endotoxin (ET)-tolerant (C3H/HeJ) and ET-intolerant (C3H/HeN) mice. To assess this, KC and SM phi were harvested at 1 or 24 hr from mice which had been subjected to polymicrobial sepsis by cecal ligation and puncture (CLP) or sham-operation. Following depletion of the nonadherent cells, KC and SM phi cultures were incubated for 24 hr in the presence or absence of 10 micrograms of ET/ml, and the levels of interleukin (IL)-1, IL-6, and TNF release were determined by bioassays. Sepsis induced an early (at 1 hr) in vivo stimulation of KC but not SM phi IL-6 release, irrespective of ET-tolerance/intolerance. However, the release of IL-1 or TNF was not markedly different for either CLP or sham KC.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Differential effects of hemorrhage on Kupffer cells: decreased antigen presentation despite increased inflammatory cytokine (IL-1, IL-6 and TNF) release.

Although studies indicate that simple hemorrhage induces profound depression of cell-mediated immunity and enhances the host's susceptibility to sepsis, the mechanism for this remains unknown. Since the Kupffer cells (KC) are positioned to have constant exposure to various immunomodulators and antigens released during hypotension, we have examined whether antigen presentation by KC, a critical component in eliciting an antigen specific immune response or those processes associated with it, are depressed following hemorrhage. C3H/HeN mice were bled to and maintained at a mean BP of 35 mmHg for 60 min, and then resuscitated with their own blood and adequate fluids. The mice were killed at varying periods of time after hemorrhage to obtain KC from the liver, and assessed for their capacity to present antigen to a sensitized clone Th/cell line (D10.G4.1). Hemorrhaged mice exhibited a marked decrease in antigen presenting capacity beginning as little as 2 h and lasting up to 3-5 days post-hemorrhage. The ability of KC to express mouse interleukin 1 (mIL-1) showed a significant decline at 2 h following hemorrhage, but this effect was not apparent at 24 h post-hemorrhage. In contrast, KC capacity to produce IL-1, IL-6 and tumour necrosis factor (TNF) (cytokines which can co-stimulate T cell antigen presentation) was markedly enhanced during the first 24 h following hemorrhage. A marked decrease was observed in both the mean of the average fluorescence per KC and the percent of Ia antigen-positive KC which persisted for at least 3 days after hemorrhage. The ability of ibuprofen (a cyclooxygenase blocker) to partially restore the antigen presenting capacity of KC from hemorrhaged mice in vitro indicates that prostaglandins are involved in this dysfunction. Thus, the depression of KC antigen presentation, as well as the enhanced capacity of these cells to release inflammatory mediators (TNF, IL-1, IL-6 and prostanoids) which may produce cell and organ dysfunction, could contribute to the host's enhanced susceptibility to sepsis following hemorrhage.

Animals↗

PubMed1992

Preoperative chemotherapy for osteosarcoma with intravenous adriamycin and intra-arterial cis-platinum.

Ninety-seven patients with primary osteosarcoma of the extremities, all age 16 or older, were treated with adriamycin, 90 mg/m2, continuous i.v. infusion over 96 h, followed by cis-platinum, 120-160 mg/m2 by intra-arterial infusion. The first 37 patients, treated from 1979-1982, had a 59% complete response rate and a 54% 5-year continuous disease free survival (CDFS). Patients with complete response had an 85% 5-year CDFS compared with 13% for patients with partial and poor response. Patients treated between 1983-1988 with an intensified regimen have a 68% complete response rate and a 69% 3-year CDFS. Those who did not achieve complete remission were switched to an alternating chemotherapy program emphasizing the use of high-dose methotrexate. Limb salvage has been accomplished in 59% of patients in the first group and 80% in patients of the second group. Preoperative chemotherapy allows informed decisions to be made in postoperative management which can influence overall cure rates. Long-term follow-up is essential before final interpretation of the data.

Bone Neoplasms↗