Liver hyperthermia and oxidative stress: role of iron and aldehyde production.

Hyperthermia has been used to treat cancer in the liver. However, significant hepatotoxicity occurs at a therapeutic temperature of 42-43 degrees C. We have proposed that heat toxicity is the result of oxidative stress from superoxide generation with resultant lipid peroxidation. Further, iron release from liver iron stores (ferritin) appears to play a central role in hyperthermic toxicity. In this study, rat livers were perfused in situ at 37 or 42.5 degrees C with and without deferoxamine for 1 h with an asanguinous perfusate. Oxidative stress was assessed by the efflux of glutathione (GSH) into the perfusage. Prior studies by Skibba et al. (1989a, 1991) showed that perfusage equivalents of GSH were primarily present as oxidized glutathione (GSSG). Lipid peroxidation was assessed by the measurement of aldehydes appearing in the perfusate and formation of hydrocarbon gases (ethane and pentane) in the perfusion chamber head space. Liver injury was assessed by the leakage of cytosolic enzymes, AST and LDH, into the perfusate. Livers perfused at 42.5 degrees C showed significant rises (p < 0.05) in AST and LDH after 60 min of perfusion but perfusion at 42.5 degrees C with deferoxamine added, was not significantly different from perfusion at 37 degrees C. Perfusion at 42.5 degrees C caused an increase in GSH into the perfusate at a level significantly (p < 0.05) greater than at 37 degrees C. GSH levels in the liver after 60 min of perfusion decreased from 4.82 +/- 0.76 microM/gm at 37 degrees C to 1.48 +/- 0.54 microM/gm at 42.5 degrees C (p < 0.05) but only fell to 3.42 +/- 1.23 microM/gm at 42.5 degrees C with deferoxamine added. Efflux of iron into the perfusate increase significantly with time and temperature. Low molecular weight chelated iron within the liver after perfusion increased from 5.88 +/- 1.46 nM/gm at 37 degrees C to 25.8 nM/gm at 42.5 degrees C (p < 0.05). Perfusate total aldehyde levels increased from 0.085 +/- 0.056 to 0.32 +/- 0.09 microM/ml after 60 min at 37 degrees C and 0.87 +/- 0.45 to 2.01 +/- 0.90 microM/ml at 42.5 degrees C (n = 8). There was a significant decrease in total aldehyde levels at 42.5 degrees C with the addition of deferoxamine to the perfusate, 0.36 +/- 0.14 to 0.86 +/- 0.27 microM/ml, when compared to 42.5 degrees C levels (p < 0.05). Levels of ethane and pentane in the perfusion chamber head space showed no significant changes with time or temperature of perfusion. The data suggest that lipid peroxidation may play a causal role in hyperthermia induced liver toxicity and that iron plays a major role in this injury. Failure of hydrocarbon analysis to support this conclusion appears related to the use of membrane oxygenators.

Genetic alterations of microsatellites on chromosome 18 in human breast carcinoma.

Allelic alterations of chromosome 18 microsatellites were determined using normal and tumor DNA pairs from 29 patients with infiltrating ductal carcinoma of the breast. Loss of heterozygosity was detected in 62% (18 of 29 patients) of the tumors at one or more of these microsatellites. Eight of the 18 patients exhibited deletions in the region at 18q21.1. This chromosomal band is known to contain a tumor suppressor gene (DCC) whose expression is frequently inactivated in several types of cancer. Ten other patients had deletions in regions not included in the DCC locus. Five of these patients revealed a common deletion at the D18S50 locus (18q23), and the other five patients had deletions in various other regions of the chromosome. No apparent correlation between loss of heterozygosity of chromosome 18 microsatellites and the clinical stage was found in this series. The results indicate that, in addition to the DCC locus, the 18q23 region is likely to contain a second tumor suppressor gene relevant to breast carcinogenesis. Four percent of all microsatellites tested in these patients showed allelic differences in the sizes of repeat units between tumor and the corresponding constitutional DNAs. The pattern of allele instability observed in breast carcinoma differed from that originally reported in a hereditary type of colorectal carcinoma. The observation suggests that this phenomenon is not a mechanism specific to neoplastic processes in breast carcinoma.

Total pelvic exenteration. A 50-year experience at the Ellis Fischel Cancer Center.

OBJECTIVE: To review a 50-year experience with total pelvic exenteration for treatment of advanced pelvic cancer. DESIGN: Retrospective study with 100% follow-up. SETTING: Cancer hospital. PATIENTS: Two hundred thirty-two patients referred for treatment of advanced pelvic cancer who underwent total pelvic exenteration. MAIN OUTCOME MEASURES: Rates of operative mortality, complications, recurrence, and 5-year survival. RESULTS: The morbidity rate was 45%. The operative death rate was 14% during the 50-year period, but decreased from 16.8% in the first three decades to 10% thereafter. Eighty-nine patients (38%) had recurrences. The overall 5-year survival rate was 42%. CONCLUSIONS: Operative mortality and morbidity have declined over 50 years, largely because of proper patient selection, increasing experience, and advances in perioperative care. Exenteration has a major role in the treatment of advanced pelvic cancer.

Involvement of xanthine oxidase in oxidative stress and iron release during hyperthermic rat liver perfusion.

The hepatotoxic effects of hyperthermia have been proposed to be related to lipid peroxidation as a consequence of oxidative stress. This can result from exposure of the cell to "radical oxygen" species such as the superoxide and hydrogen peroxide generated by the activity of the oxidase form (type O) of xanthine oxidase (XO), which is converted to that form by perfusion of the liver at hyperthermic temperatures. These radical species are not reactive enough in themselves to cause cell damage but require the presence of a catalyst such as low molecular weight chelated iron. In these studies, ferritin was shown to be a source of iron for the oxidative stress of hyperthermia. (a) Iron was released from ferritin in vitro by the activity of rat liver XO. The rate of iron release from ferritin in this incubation system was a function of the amount of type O XO present and the temperature. Inclusion of allopurinol or superoxide dismutase in the incubation resulted in significantly lower rates of iron release. (b) Livers from Sprague-Dawley rats were perfused at 42.5 degrees and 37 degrees C for 1 h. During the recirculating perfusion, loss of iron from the liver into the perfusate was significantly greater (P less than 0.05) at 42.5 degrees C than at 37 degrees C. Also, there was a pronounced increase in the lactate dehydrogenase and aspartate aminotransferase enzymes in the perfusate during perfusion at 42.5 degrees C. Furthermore, intrahepatic levels of low molecular weight chelated iron were significantly (P less than 0.05) increased following perfusion at 42.5 degrees C. All these responses were abrogated by the inclusion of allopurinol in the perfusate. (c) Oxidative stress, assessed by the efflux of glutathione and oxided glutathione from the liver at 42.5 degrees and 37 degrees C, was significantly (P less than 0.05) increased at the hyperthermic temperature. This oxidative stress was inhibited by iron chelation and allopurinol. These results demonstrate that there is a causal relationship between the generation of superoxide by type O XO produced by hyperthermic perfusion and mobilization of iron from ferritin to form a pool of low molecular weight chelated iron. This iron pool in combination with active oxygen species leads to oxidative stress and lipid peroxidation.

Oxidative stress as a precursor to the irreversible hepatocellular injury caused by hyperthermia.

Heat-induced hepatotoxicity accompanying hyperthermic liver perfusion was studied in the isolated, haemoglobin-free perfused rat liver. Trypan blue uptake, a sensitive indicator of cell death, was used to examine the relationship between the efflux of oxidized glutathione (oxidative stress), the appearance of cytosolic enzymes in the perfusate and cell death. Livers were perfused at 37, 42, 42.5 and 43 degrees C. The efflux of total glutathione (GSH) and oxidized glutathione (GSSG) increased with time and temperature. Differences between temperature groups were significant for both parameters for 37 versus 42, 42.5 and 43 degrees C (p less than 0.05). Temperature-related differences in GSH levels appeared at 15 min for 37 versus 42 degrees C and in GSSG levels at 30 min for 37 versus 42 and 42.5 degrees C. Biliary excretion of total GSH increased from 72 nmol at 37 degrees C to 144 nmol at 42 degrees C, 160 nmol at 42.5 degrees C and 124 nmol at 43 degrees C, which was significant for 37 versus 42 and 42.5 degrees C (p less than 0.05). The release of allantoin into the perfusate, a measure of purine catabolism and flux through xanthine oxidase, was increased at 42, 42.5 and 43 degrees C compared to 37 degrees C (p less than 0.05). Liver injury was assessed by measuring the release of asportate aminotransferase (AST) and lactate dehydrogenase (LDH) and uptake of trypan blue after perfusion at each temperature. There was a pronounced release of LDH and AST into the perfusate after 60 min of perfusion at 42, 42.5 and 43 degrees C, the levels of which were significantly different from the 37 degrees C mean level. There was no uptake of trypan blue after 60 min perfusion at 37 degrees C. Perfusion at 42, 42.5 and 43 degrees C resulted in the uptake of trypan blue in the pericentral areas, but the dye uptake was significant (p less than 0.05) compared to 37 degrees C at 42.5 and 43 degrees C only. These data show that heat-induced pericentral cell death is minimal after 60 min at 42-43 degrees C, and that the biochemical process which occurred during this period suggest 'oxidative stress' as a causative factor in hyperthermic hepatotoxicity. In addition, this liver toxicity is probably related to xanthine oxidase activity or the depletion of GSH as the initiating event which leads to lipid peroxidation and cellular damage.

Lipid peroxidation caused by hyperthermic perfusion of rat liver.

The data presented support the premise that hyperthermia-induced hepatocellular injury is the end result of lipid peroxidation. Evidence for lipid peroxidation is the formation of diene conjugates and the decrease in microsomal P450 and glucose-6-phosphatase activity during hyperthermic liver perfusion.

Hyperthermic liver toxicity: a role for oxidative stress.

Rat livers were perfused at 37 degrees C, 41 degrees C, 42 degrees C, 42.5 degrees C, and 43 degrees C for 2 hr. Among perfusate constituents analyzed were urea, total amino acids, N-acetyl-beta-glucosaminidase (NAG), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), malonaldehyde (MDA), glutathione (GSH), oxidized glutathione (GSSG), allantoin, potassium, phosphate, and glucose. After perfusion, livers were homogenized and analyzed for xanthine oxidase (XO) activity, GSH content, and lysosomal lability. Perfusate AST, LDH, NAG, potassium, glucose, and phosphate increased significantly with time, and there were significant differences in the final values between 37 degrees C and 42 degrees C, 42.5 degrees C and 43 degrees C (P less than .05). GSH levels increased significantly at all temperatures after 90 and 120 min, whereas GSSG levels differed significantly at 60, 90, and 120 min for 37 degrees C vs. 42 degrees C, 42.5 degrees C, and 43 degrees C (P less than .05). Mean MDA levels at 37 degrees C differed from those at 41 degrees C and 43 degrees C (P less than .05) at each temperature. Allantoin levels increased significantly with time of perfusion; mean levels at 37 degrees C were significantly different from mean levels at each temperature at 60, 90, and 120 min. GSH liver tissue levels decreased with perfusion at hyperthermic temperatures; mean values at 41 degrees C, 42 degrees C, and 42.5 degrees C, and 43 degrees C differed from 37 degrees C mean values (P less than .01). Type O XO increased after 120 min perfusion from 6.4% +/- 2.0% at 37 degrees C to 55% +/- 30%, 43% +/- 27%, and 63% +/- 29% at 42 degrees C, 42.5 degrees C, and 43 degrees C, respectively. Lysosomal lability increased after perfusion at 42.5 degrees C. There was a significant increase in nonsedimentable NAG activity at 42.5 degrees C (P less than .05). These data support the premise that hyperthermic toxicity to the liver may be a consequence of oxidative stress brought about by enhanced adenosine triphosphate (ATP) consumption and conversion of XO to type O. Such conversion results in superoxide formation and subsequent depletion of cellular GSH, labilization of the lysosomes, and plasma membrane damage.

Effects of hyperthermia on xanthine oxidase activity and glutathione levels in the perfused rat liver.

The hepatotoxic effects of hyperthermic liver perfusion were investigated in male Fischer 344 rat livers. Perfusions were carried out at 37, 41, 42, 42.5, and 43 degrees C for 2 hr. During the 2 hr, the perfusate was analyzed for activity of aspartate aminotransferase (AST), lactate dehydrogenase (LDH), N-acetyl-beta-glucosaminidase (NAG), and glutathione (GSH), oxidized glutathione (GSSG), allantoin, and potassium. After perfusion, each liver was homogenized and analyzed for total xanthine oxidase (XO) activity, percentage type-D and type-O XO, and total GSH content. Perfusate AST, LDH, NAG, and potassium levels were increased significantly with time and were significantly different in all hyperthermic perfusions from the 37 degrees C perfusion values by the end of the perfusion. Perfusate GSH + GSSG levels were increased significantly in all hyperthermic perfusions after 60 min. Liver GSH levels were significantly lowered following perfusion at hyperthermic temperatures. There was a temperature-dependent increase in the percentage of XO in the type-O form following perfusion at hyperthermic temperatures, which was strongly and positively correlated with the loss of hepatic GSH. These data support the hypothesis that hyperthermic toxicity to the liver is the result of oxidative stress brought about by conversion of XO to the type-O form.

Hyperthermic liver perfusion and release of lysosomal enzymes.

Perfused rat liver was used to study the relationship between the hepatotoxic effects of hyperthermia and the effects of heat on lysosomes. Livers from fed rats were perfused for 180 min at 37-43 degrees C. Release of lysosomal enzymes into the perfusate during perfusion and lysosomal fragility at the end of perfusion were determined. Lysosomes were then incubated in vitro at 37-45 degrees C with xanthine and xanthine oxidase to generate superoxide in order to study lipid peroxidation as a potential causative factor in heat-induced lysosomal lability. Perfusate lysosomal enzymes p-nitrophenyl phosphatase and beta-glucuronidase increased significantly (P less than 0.05) at 42 and 43 degrees C over enzyme levels at 37 degrees C. Significant differences were not observed until after 120 min. Lysosomal fragility was found to be significantly increased (P less than 0.05) after perfusion at 42 and 43 degrees C when measuring p-nitrophenyl phosphatase, but not when measuring beta-glucuronidase activity. Xanthine oxidase acting on xanthine caused labilization of the lysosomes at all temperatures studied when compared to a control at each temperature. There was a temperature effect with an increase in release of p-nitrophenyl phosphatase and beta-glucuronidase from control lysosomes which became significant (P less than 0.05) at 43 degrees C on comparison to 37 degrees C. There were no significant increases in lysosomal lability with temperature in the presence of xanthine and xanthine oxidase. Lastly, salicylic acid peroxidation was used as a measure of superoxide formation from the action of xanthine oxidase with increasing temperature.(ABSTRACT TRUNCATED AT 250 WORDS)

Tumoricidal effects and patient survival after hyperthermic liver perfusion.

Hyperthermic liver perfusion for four hours at 42.0 degrees C to 42.5 degrees C was used as the sole modality of therapy for cancer confined to the liver in eight patients. Two patients had melanoma, one had cholangiolar carcinoma of the liver, and five had liver metastases from colorectal carcinoma. Two postoperative deaths occurred, both in patients with colorectal carcinoma metastases. Response was indicated by computed tomographic and/or liver biopsy or autopsy findings of tumor necrosis. There were five responders to hyperthermic liver perfusion among the six survivors. Hyperthermic liver perfusion was an effective tumoricidal agent for hepatic metastases from colorectal cancer; ie, tumor necrosis occurred in all five patients, as well as in the two who died, as shown by autopsy findings. Conversion to a disease-free state with hyperthermic perfusion may be possible with other treatment modalities used in combination or sequence.

Nitrogen metabolism and lipid peroxidation during hyperthermic perfusion of human livers with cancer.

Isolation-perfusion was used as a means of heating human livers with cancer. Perfusion was at 42-42.5 degrees C for 4 h. Perfusate constituents were analyzed in an attempt to identify factors contributing to the hepatotoxic effects of hyperthermia. During perfusion the perfusate constituents analyzed were: urea; total amino acids; uric acid; malonaldehyde; and lysosomal enzymes. Hepatic ammonia for urea synthesis is derived from degradation of amino acids, amines, and nucleic acids. An increase in proteolysis was reflected in the increase in urea from 0.6 +/- 0.2 mM to 1.9 +/- 8 mM and total amino acids from 1.0 +/- 0.6 mM to 4.4 +/- 1.7 mM during the 4 h of perfusion at 42-42.5 degrees C. An increase in purine catabolism occurred as evidenced by an increase in perfusate uric acid from 1.7 +/- 1.0 mg/100 ml to 6.1 +/- 2.7 mg/100 ml. Free oxygen radicals, which can lead to lipid peroxidation, are generated by the action of xanthine oxidase on xanthine. Lipid peroxidation occurring during perfusion was assessed by an increase in malonaldehyde from 2.3 +/- 1.3 microM to 10.4 +/- 10.0 microM. An increase in acid phosphatase in the perfusate from 38 +/- 15 units/liter to 78 +/- 45 units/liter occurred, suggesting labilization of lysosomes, perhaps through lipid peroxidation. Proteolysis and lipid peroxidation are suggested to be two interrelated factors contributing to heat toxicity in the perfused human liver with cancer.

Alterations in biochemical functions during hyperthermic isolation-perfusion of the human liver.

Hyperthermia (42-42.5 degrees) was applied to the liver of eight patients with cancer in the liver by a technique of isolation-perfusion. Hepatic functional integrity was assessed during perfusion through measurement of multiple perfusate constituents. Data from seven perfusions were available for analysis. During perfusion there was an increase in perfusate lactate, pyruvate, glucose, urea, potassium, alkaline phosphatase, SGOT, and LDH. All increases in these constituents were significant (P less than 0.05) except for potassium. Lactate accumulated throughout the perfusion from an initial level of 3.8 +/- 1.0 mM to 7.6 +/- 3.5 mM at 4 hr. Pyruvate increased over the first 3 hr of perfusion from 0.14 +/- 0.06 mM to 0.80 +/- 0.37 mM before declining to 0.54 +/- 0.24 mM at 4 hr. The L/P (lactate/pyruvate) ratio decreased during perfusion to less than 10 in the first 2 hr, but rose to within normal limits by the end of perfusion. The decreases in L/P ratios were significant (P less than 0.05). Initially there was a rapid rise in perfusate glucose concentrations from 4.5 +/- 0.8 mM to 20.7 +/- 5.4 mM at 2 hr with nonsignificant changes thereafter. Urea levels increased from 0.64 +/- 0.22 mM to 1.92 +/- 0.76 mM. Perfusate potassium increased from the initial level of 7.0 +/- 1.0 mM during perfusion to 8.3 +/- 1.7 mM at 2 hr before declining. SGOT, LDH, and alkaline phosphatase increased during perfusion from 21 +/- 15, 142 +/- 48, and 16 +/- 6 to 176 +/- 22, 472 +/- 53 and 52 +/- 42, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Interrelationships and metabolic effects of fatty acids in the perfused rat liver at hyperthermic temperatures.

Livers of fasted rats were perfused for 70 min at 37 degrees-43 degrees C in the presence or absence of acetate, octanoate or palmitate. Hepatic biosynthetic capacity was assessed by measuring rates of gluconeogenesis, ureogenesis, ketogenesis and O2 consumption. In the presence of each fatty acid, gluconeogenesis, ureogenesis and oxygen consumption were maintained at 37 degrees and 42 degrees C. At 43 degrees, the rate of glucose formation decreased markedly and rates of ureogenesis and oxygen consumption were distinctly lower. As the temperature was increased from 37 degrees to 43 degrees C without fatty acids, i.e. albumin only, there was a progressive decrease in the rate of gluconeogenesis while the ratio of net C3 utilized to glucose formed, increased successively. The values of this ratio in the presence of palmitate or octanoate at 43 degrees were smaller than those for albumin or acetate, but higher than the figure of 2 for complete conversion of C3 units to glucose. Although fatty acid was added in equimolar amounts of C2 units, total ketone formation was influenced significantly by chain length. Hepatic ketogenesis was similar at 37 degrees with albumin, palmitate, or acetate, but was stimulated significantly by octanoate at 37 degrees and 42 degrees C. At 42 degrees, ketone formation increased in the presence of palmitate. At 43 degrees C, ketogenesis with palmitate or octanoate decreased, while that with acetate or albumin was maintained at the same lower rates. The ratio of 3-hydroxybutyrate to acetoacetate in the perfusate was increased with palmitate at the end of perfusion at 37 degrees and 42 degrees C or octanoate at 42 degrees and 43 degrees C. Thus, long (palmitate)- and medium (octanoate)- but not short (acetate)-chain fatty acids enhance not only beta-oxidation, but influence the redox state of hepatic mitochondria with an increase in the state of reduction of the pyridine nucleotides. Such a shift in the redox state would be operable in the perfused liver even at 43 degrees C and may be responsible for improved conversion of lactate to glucose when medium- or long-chain fatty acids are present at hyperthermic temperatures.

Canine liver isolation-perfusion at normo- and hyperthermic temperatures with perfluorochemical emulsion (Fluosol-43).

A perfluorocarbon emulsion, Fluosol-43, was used as a blood substitute for oxygen transport during isolation-perfusion of the dog liver at 37 and 43 degrees C. Preservation of hepatic functional integrity was assessed through analysis of perfusate constituents and animal survival after perfusion. Flow to the liver during perfusion was greater than 1 ml/min/g with one-third of total flow provided through the hepatic artery and two-thirds through the protal vein. Perfusion duration was 3 h. The pO2 gradient across th liver indicated that oxygen was consumed during perfusion at both temperatures. The expected rise in pCO2 and decrease in pH of the outflow perfusate is consistent with active aerobic metabolism. Perfusate chemistries lactate, pyruvate, glucose, urea, total alpha-amino acids, ketone bodies and SGPT demonstrated that hepatic functional integrity was maintained during perfusion. Significant differences (p less than 0.05) between temperatures occurred in the perfusate levels of lactate, pyruvate, L/P ratios, glucose and total alpha-amino acids. Animal survival after a 3-hour perfusion was 3/4 at 37 degrees C, and 2/5 at 43 degrees C. After perfusion, SGPT levels were significantly higher in dogs subjected to perfusion at 43 degrees C. The success of these experiments demonstrates that perfusion of the liver with Fluosol-43 was not in itself hepatotoxic, and that Fluosol-43 may allow perfusion of the liver at 43 degrees C with only wild toxicity.

A technique for isolated hyperthermic liver perfusion.

Hyperthermia, either alone or combined with chemotherapy, has been shown to be effective in treating cancer. Because some investigators believe that regional hyperthermia may be more effective than whole body hyperthermia, we developed a technique to heat only the liver to 42-43 degrees for 4 hr. The procedure was adapted from a previously described animal model and was performed in four humans. Vascular isolation of the liver was accomplished by cannulating the hepatic artery, the portal vein, and the inferior vena cava followed by occluding the suprahepatic vena cava and the liver was then perfused with blood and nutrients from an oxygenated reservoir. Preliminary results show radiologic and histologic evidence of tumor necrosis or cessation of tumor growth in three of the patients. We believe this technique is safe enough for clinical experimental use and deserves further investigation.

Azathioprine induction of lymphomas and squamous cell carcinomas in rats.

The carcinogenicity of azathioprine was evaluated in weaning female noninbred Sprague-Dawley rats by feeding it in the diet. Due to toxicity, the dose had to be changed during the course of the experiments and ranged from 0.015 to 0.04% of the diet by weight. In the first experiment, the estimated maximal cumulative consumption of azathioprine was 1.5 g/rat. Of the 14 rats evaluated, six developed thymic lymphomas, and four developed squamous cell carcinomas of the ear duct. When the experiment was repeated with a slightly lower daily consumption but with a cumulative total dose of 2.2 g/rat, there were seven of 19 rats with thymic lymphoma and two rats with ear duct carcinoma. These data support the hypothesis that azathioprine is a carcinogen.