Decreasing incidence of cancer after liver transplantation-A Nordic population-based study over 3 decades.

Cancer remains one of the most serious long-term complications after liver transplantation (LT). Data for all adult LT patients between 1982 and 2013 were extracted from the Nordic Liver Transplant Registry. Through linkage with respective national cancer-registry data, we calculated standardized incidence ratios (SIRs) based on country, sex, calendar time, and age-specific incidence rates. Altogether 461 cancers were observed in 424 individuals of the 4246 LT patients during a mean 6.6-year follow-up. The overall SIR was 2.22 (95% confidence interval [CI], 2.02-2.43). SIRs were especially increased for colorectal cancer in recipients with primary sclerosing cholangitis (4.04) and for lung cancer in recipients with alcoholic liver disease (4.96). A decrease in the SIR for cancers occurring within 10 years post-LT was observed from the 1980s: 4.53 (95%CI, 2.47-7.60), the 1990s: 3.17 (95%CI, 2.70-3.71), to the 2000s: 1.76 (95%CI, 1.51-2.05). This was observed across age- and indication-groups. The sequential decrease for the SIR of non-Hodgkin lymphoma was 25.0-12.9-7.53, and for nonmelanoma skin cancer 80.0-29.7-10.4. Cancer risk after LT was found to be decreasing over time, especially for those cancers that are strongly associated with immunosuppression. Whether immunosuppression minimization contributed to this decrease merits further study.

Asymptomatic De Novo Inflammatory Bowel Disease Late After Liver Transplantation for Primary Sclerosing Cholangitis: A Case Report.

Guidelines recommend colonoscopy screening for possible asymptomatic inflammatory bowel disease (IBD) in all patients diagnosed with primary sclerosing cholangitis (PSC). PSC-IBD warrants regular dysplasia-surveillance colonoscopy. However, no consensus exists regarding follow-up colonoscopy in PSC patients without IBD who remain asymptomatic. We describe a 43-year-old female who had undergone liver transplantation (LT) due to advanced PSC. Previous colonoscopies had been normal. The post-transplantation course was uneventful, with no rejections and signs of PSC recurrence. Immunosuppression was by tacrolimus monotherapy. She was asymptomatic with normal inflammation markers. A protocol colonoscopy, performed as general dysplasia surveillance 8 years post-transplantation, revealed mucopurulent-covered small superficial ulcerations and erythema diffusely distributed from the cecal to sigmoid colon with intervening normal mucosa and rectal sparing. Histologic examination showed patchy chronic colitis with crypt architectural distortion and mild-moderate inflammation activity. Infection samples were negative. Findings complied with de novo IBD, type unclassified. In conclusion, the link between PSC and clinically silent IBD may manifest after the PSC diagnosis and even several years after LT. Given the increased colorectal cancer risk associated with PSC, IBD, and LT, repeat colonoscopy might be warranted in PSC patients without IBD at initial assessment, and also after LT.

Transmission of LDLR mutation from donor through liver transplantation resulting in hypercholesterolemia in the recipient.

Donor-transmitted disease in organ transplantation is uncommon, but possible. The LDL receptor (LDLR), a key regulator of lipoprotein metabolism, is abundant in the liver. Mutations in the LDLR gene, leading to reduced LDLR activity, are the main cause for familial hypercholesterolemia (FH). The estimated prevalence of FH is 1/200-1/500 in the population indicating that there are 14-34 million individuals with FH worldwide. We describe a patient who developed severe hypercholesterolemia after liver transplantation (LT). The 42-year-old female, who was transplanted because of hepatic epithelioid hemangioendothelioma with normal liver function, exhibited an increase in plasma total cholesterol from 5.6 mmol/L (217 mg/dL) pretransplant to 11.7 mmol/L (452 mg/dL) at 6 months posttransplant. The respective increase in LDL cholesterol was from 3.30 (128 mg/dL) to 8.99 mmol/L (348 mg/dL). At 1 year, total and LDL cholesterol levels were 11.0 (425 mg/dL) and 7.81 (302 mg/dL), respectively. Sequencing of the coding region of LDLR from a liver graft biopsy revealed a splicing heterozygous mutation of LDLR, whereas no FH-related mutation was found in DNA extracted from the patient's blood white cells. This confirmed the first reported case of a patient receiving a mutation in LDLR through LT. The case shows that a donor-transmitted disorder should not be overlooked as a possible cause for severe hypercholesterolemia.

Long-term renal function deteriorates at a similar rate among liver transplant patients with preserved renal function at 1 year and in the general population: is chronic calcineurin inhibitor nephrotoxicity overrated?

BACKGROUND: Chronic calcineurin inhibitor (CNI) nephrotoxicity is associated with histologic kidney lesions, but the contribution of maintenance-dose CNI use to the decline over time in glomerular filtration rate (GFR) post liver transplantation (OLT) remains unclear. METHODS: We studied annual changes in estimated GFR >1 year posttransplant among 105 CNI-treated adult OLT patients with a GFR of 60-100 mL/min at 1 year during a mean follow-up of 7 years (20 years in 20 patients). RESULTS: The annual GFR decline >1 year posttransplant was 0.2 mL/min per year (SD 3.8). This decline rate was unaffected by the decade of OLT, follow-up period, or GFR at 1 year, and showed no correlation with CNI blood levels. Of the 13 (12%) patients with a GFR deterioration >3 mL/min per year, 77% presented with hypertension, diabetes, and/or dyslipidemia. The decline in GFR >1 year post-OLT did not exceed the decline of 0.5-0.8 mL/min per year reported in the general population. Declines faster than 3 mL/min per year, which occurred no more frequently among patients than in the general population, seemed attributable to coexistent vascular risk factors. CONCLUSIONS: Among OLT patients with preserved renal function at 1 year posttransplant, our findings challenge the clinical impact of chronic progressive CNI nephrotoxicity and highlight the importance of a tight control of blood pressures, glucose and lipid levels, and other modifiable risk factors in order to preserve long-term renal function.

Increased infection risk postliver transplant without pretransplant dental treatment.

OBJECTIVE: Infections cause considerable morbidity after liver transplantation (LT). Acute liver failure is a rapidly progressing life-threatening condition where pretransplant dental evaluation is not always possible. We investigated how missing pretransplant dental treatment in acute or subacute liver failure correlates with post-transplant infectious complications. SUBJECTS AND METHODS: Medical and dental data came from hospital records and infection data from the Finnish LT registry. The follow-up was until February 2011. Of 51 patients (LT during 2000-2006), 16 had and 35 did not have dental treatment pretransplant. RESULTS: Univariate Cox regression analysis demonstrated a 2.46-fold (95% CI 1.06-5.69) infection risk among the patients omitted from dental treatment. After adjustment for either pretransplant factors alone or both pre- and post-transplant factors, the corresponding infection risk increased, respectively, to 8.17-fold (95% CI 2.19-30.6) and 8.54-fold (95% CI 1.82-40.1). This increased risk involved a variety of bacterial, viral, and fungal infections of various sources both < 6 and > 6 months after transplantation. CONCLUSION: High risk of infections was noticed in acute liver failure patients without pretransplant dental treatment, but a more severe medical condition might have influenced the results. We encourage eradication of dental infection foci whenever clinical condition allows.

Long-term results of liver transplantation.

Liver transplantation (LT) is an established therapy associated with a dramatic improvement in patients life expectancy. With improved early-term management, current 10-year patient survival rates in many indications exceed 70%. Life-long immunosuppressive therapy may, however, be accompanied by considerable longterm toxicity: most importantly, renal dysfunction, cardiovascular disease, and cancer, which, in addition to recurrence of the primary liver disease, emerge as key contributors to late mortality. Chronic kidney disease cumulatively affects up to 28% of patients by ten years after LT. Various factors can contribute to renal impairment, but perioperative acute kidney injury, calcineurin inhibitor toxicity, hypertension, and diabetes are considered most important. LT patients demonstrate 3-fold risk for cardiovascular events, which seems to result mostly from an excess of traditional risk factors, mainly hypertension and diabetes. The cumulative cancer incidence reaches 16-42% by 20 years after LT, and cancer rates are 2- to 4-fold higher among LT patients than among matched controls. Highest rates are for nonmelanoma skin cancer (3- to 70-fold) and lymphoma (8- to 29-fold). The liver graft usually displays uncomplicated function in the long term. Most common causes for chronic graft dysfunction include disease recurrence and biliary problems. LT generally restores patients quality of life to a level comparable with that of the general population, with only minor deficits in some areas. Thus, long-term survival after LT is impressive, and despite these long-term complications, patients quality of life remains comparable with that of the general population.

Infectious complications more than 1 year after liver transplantation: a 3-decade nationwide experience.

Because few reports have addressed infections late (≥1 year) after liver transplantation (LT), we evaluated the incidence, risk factors and pathogens involved. Infection data were from the Finnish LT registry, with starting date, type and relevant pathogens for 501 Finnish adult LT patients surviving ≥1 year post-transplant. Follow-up end points were end of study, death or retransplantation. Logistic regression to assess risk factors was adjusted for age, gender and follow-up time. With 3923 person-years of follow-up, overall infection incidence was 66/1000 person-years; 155 (31%) suffered 259 infections, and two-thirds experienced only one infection. Cholangitis (20%), pneumonia (19%) and sepsis (14%) were most common. The most frequent bacteria were Enterococcus spp. and Escherichia coli, and the most frequent viruses cytomegalovirus and varicella zoster virus. Fungal infections were rare (n = 7). With 13 fatal infections, 17% of all late deaths involved infection. Primary sclerosing cholangitis (PSC) and Roux-en-Y-type biliary anastomosis were associated with cholangitis; 18% of PSC patients suffered late cholangitis. Late acute rejection was associated with sepsis. Age, gender or cytomegalovirus did not significantly influence late infections. In conclusion, although infection risk under maintenance immunosuppression therapy is relatively low, particular vigilance regarding cholangitis, pneumonia and sepsis seems appropriate.

Identification by mass spectrometry of a new alpha-tubulin isotype expressed in human breast and lung carcinoma cell lines.

The extensive C-terminal molecular heterogeneity of alpha- and beta-tubulin is a consequence of multiple isotypes, the products of distinct genes, that undergo several posttranslational modifications. These include polyglutamylation and polyglycylation of both subunits, reversible tyrosination and removal of the penultimate glutamate from alpha-tubulin, and phosphorylation of the beta III isotype. A mass spectrometry-based method has been developed for the analysis of the C-terminal diversity of tubulin from human cell lines. Total cell extracts are resolved by SDS--PAGE and transferred to nitrocellulose, and the region of the blot corresponding to tubulin (approximately 50 kDa) was excised and digested with CNBr to release the highly divergent C-terminal tubulin fragments. The masses of the human alpha- and beta-tubulin CNBr-derived C-terminal peptides are all in the 1500--4000 Da mass range and can be analyzed directly by MALDI-TOF mass spectrometry in the negative ion mode without significant interference from other released peptides. In this study, the tubulin isotype diversity in MDA-MB-231, a human breast carcinoma cell line, and A549, a human non-small lung cancer cell line, is reported. The major tubulin isotypes present in both cell lines are k-alpha 1 and beta 1. Importantly, we report a previously unknown alpha isotype present at significant levels in both cell lines. Moreover, the degree of posttranslational modifications to all isotypes was limited. Glu-tubulin, in which the C-terminal tyrosine of alpha-tubulin is removed, was not detected. In contrast to mammalian neuronal tubulin which exhibits extensive polyglutamylation, only low-level monoglutamylation of the k-alpha 1 and beta 1 isotypes was observed in these two human cell lines.

Metastasis-associated mts1 (S100A4) protein in the developing and adult central nervous system.

We have found recently that white matter astrocytes in the spinal cord constitutively express immunoreactivity for Mts1 (S100A4) protein and that this expression is up-regulated ipsilaterally after sciatic nerve or dorsal root injury. Here, we have studied the expression pattern of Mts1 throughout the rat central nervous system (CNS). We found Mts1 immunoreactivity in myelinated tracts such as the olfactory tract, optic nerve, corpus callosum, internal capsule, fimbria, and spinal cord funiculi but not in cerebellar white matter. Mts1-immunoreactive (IR) cells were consistently astrocytic (glial fibrillary acidic protein positive). In addition to myelinated tracts, Mts1 immunoreactivity was also present in a few nonmyelinated or poorly myelinated areas, such as pituitary gland, olfactory bulb, and around the lateral ventricle. Based on location, three Mts1-IR astrocyte groups were distinguished: 1) astrocytes at the surfaces of the CNS, i.e., adjacent to the cerebrospinal fluid, organized perpendicularly to the bundles of axonal tracts; 2) astrocytes located in parallel to, and inserted between, axonal bundles; and 3) clusters of astrocytes around the lateral ventricle and in the olfactory bulb. We further analyzed the relationship between Mts1 immunoreactivity and the development of CNS fiber tracts by combining staining for Mts1 and myelin basic protein (MBP). Mts1 immunoreactivity appeared postnatally in recently myelinated areas. During the development of corpus callosum and the optic tract, Mts1 immunoreactivity was concentrated at the frontier of myelination. The developmental expression pattern suggests a role of Mts1-IR astrocytes in the maturation of myelinated fiber tracts. The preferential localization of Mts1 to the subpial region in the mature CNS suggests that Mts1 participates in astrocyte-mediated CNS-cerebrospinal fluid exchange.

Free malondialdehyde determination in rat brain tissue by capillary zone electrophoresis: evaluation of two protein removal procedures.

Two procedures for the determination of underivatised, free malondialdehyde in rat brain tissue have been evaluated. Both procedures are based on capillary zone electrophoresis (CZE) and UV detection at 267 nm and differ only with respect to the protein removal step, for which ultrafiltration or precipitation with acetonitrile have been employed. The total analytical processes include sample homogenisation, addition of antioxidant, protein removal, and separation and detection in the CZE system, and take less than 20 min. The CZE buffer consists of 10 mM borax and 0.5 mM CTAB at pH 9.3. The malondialdehyde peak reaches the detector about 3 min after injection as one of the very first peaks in the electropherogram. The limit of detection (3 S/N) is 0.2 microM, corresponding to 4 fmol for an injection volume of 20 nl. The method is fast, reproducible and has a large linear range, spanning 0-200 microM.

Determination of malondialdehyde in rat brain by capillary zone electrophoresis.

A method for determination of malondialdehyde with capillary electrophoresis using UV detection at 267 nm has been developed. The buffer system consisted of 10 mM borax and 0.5 mM CTAB at pH 9.3. Malondialdehyde migrated as the first peak in the electropherogram at 2.6 min. Limit of detection was 1.2 microM corresponding to 7.8 pg. Malondialdehyde was determined before and after stimulating lipid peroxidation with the addition of ferrous ammonium sulphate to homogenates of rat brain tissue. Proteins were precipitated by boiling and removed from the brain homogenates with centrifugation. No further pretreatment was made before injecting the homogenates on the CE system. Non-precipitated homogenates could also be analyzed, but this required washing of the capillary with 0.1 M NaOH before introduction of the next sample.

Gemfibrozil-induced decrease in serum ubiquinone and alpha- and gamma-tocopherol levels in men with combined hyperlipidaemia.

BACKGROUND: Low blood levels of antioxidants are associated with an increased risk of developing coronary artery disease. Lipophilic antioxidants are transported in lipoproteins, and hypolipidaemic therapy may therefore alter their blood concentrations. METHODS: The present randomized, placebo-controlled cross-over study of 21 men with combined hyperlipidaemia examines whether 10-12 weeks of gemfibrozil treatment affects the serum concentrations of the antioxidants ubiquinone-10 or alpha- or gamma-tocopherol. RESULTS: Gemfibrozil treatment lowered plasma triglycerides and both total and very low-density lipoprotein (VLDL)-cholesterol (P < 0.001 for all by ANOVA), whereas high-density lipoprotein (HDL)-cholesterol increased (P < 0.001). The median serum levels of ubiquinone-10 decreased from 1.30 mumol L-1 (interquartile range 0.87-1.71 mumol L-1) with placebo to 0.76 mumol L-1 (0.66-0.95) with gemfibrozil treatment (P < 0.001). Corresponding levels for alpha- and gamma-tocopherol were: 68.5 mumol L-1 (51.1-84.7) vs. 40.8 mumol L-1 (30.3-55.0) and 8.6 mumol L-1 (5.2-16.7) vs. 4.3 mumol L-1 (3.5-7.0) respectively (P < 0.001 for both). The decrease in serum antioxidants was also evident when standardized for total cholesterol (P < 0.05) or LDL-cholesterol (P < 0.001). Normolipaemic control subjects had significantly lower antioxidant levels than placebo-treated patients: ubiquinone 0.63 mumol L-1 (0.41-1.05), alpha-tocopherol 34.3 mumol L-1 (27.3-45.6) and gamma-tocopherol 3.2 mumol L-1 (2.5-4.2) (P < 0.001 for all). The association of antioxidants with lipoprotein lipids was further established by positive correlations between the levels of antioxidants and those of total cholesterol (r = 0.64, P < 0.001) or total triglycerides (r = 0.71, P < 0.001). CONCLUSION: Gemfibrozil treatment of men with combined hyperlipidaemia reduces serum antioxidant levels to the levels seen in healthy normolipidaemic men. The mechanisms and the relevance of this finding remain unclear and need to be addressed in further studies.

Trypanosoma cruzi infection in tumor necrosis factor receptor p55-deficient mice.

Tumor necrosis factor receptor p55 (TNFRp55) mediates host resistance to several pathogens by allowing microbicidal activities of phagocytes. In the studies reported here, TNFRp55-/- mice infected with the intracellular parasite Trypanosoma cruzi showed clearly higher parasitemia and cumulative mortality than wild-type (WT) controls did. However, gamma interferon (IFN-gamma)-activated macrophages from TNFRp55-/- mice produced control levels of nitric oxide and killed the parasite efficiently in vitro. Trypanocidal mechanisms of nonphagocytic cells (myocardial fibroblasts) from both TNFRp55-/- and WT mice were also activated by IFN-gamma in a dose-dependent way. However, IFN-gamma-activated TNFRp55-/- nonphagocytes showed less effective killing of T. cruzi than WT control nonphagocytes, even when interleukin 1beta (IL-1beta) was added as a costimulator. In vivo, T. cruzi-infected TNFRp55-/- mice and WT mice released similar levels of NO and showed similar levels of IFN-gamma mRNA and inducible nitric oxide synthase mRNA in their tissues. Instead, increased susceptibility to T. cruzi of TNFRp55-/- mice was associated with reduced levels of parasite-specific immunoglobulin G (IgG) (but not IgM) antibodies during infection, which is probably linked to abnormal B-cell differentiation in secondary lymphoid tissues of the mutant mice. Surprisingly, T. cruzi-infected TNFRp55-/- mice showed increased inflammatory and necrotic lesions in several tissues, especially in skeletal muscles, indicating that TNFRp55 plays an important role in controlling the inflammatory process. Accordingly, levels of Mn2+ superoxide dismutase mRNA, a TNF-induced enzyme which protects the cell from the toxic effects of superoxide, were lower in mutant than in WT infected mice.

Influence of dolichol on microsomal membrane functions.

Microsomal membranes from rat liver were extracted with n-pentane in order to remove the lipid products of the mevalonate pathway, dolichol, ubiquinone and cholesterol. Dolichol and cholesterol were subsequently reincorporated into these extracted membranes. Electron microscopic examination demonstrated that extraction did not alter the vesicular membrane structure of the microsomes. The extracted vesicles were permeable to uncharged molecules in the same manner as control microsomes but had an increased permeability for charged molecules. Enzyme denaturation was not observed. The contraction of extracted vesicles was greatly increased when the incubation medium was supplemented with non-penetrating compounds such as polyethylene glycol and was much greater than that of control microsomes. When extracted membranes were reconstituted with dolichol or cholesterol, the original lower degree of contraction was reestablished. The effects of dolichol reincorporation on a number of microsomal enzyme activities were investigated and some limited changes were observed. These results demonstrate that extraction of microsomes with n-pentane and subsequent reincorporation of dolichol is an effective approach for investigating the functions of this lipid. Dolichol and cholesterol both affect microsomal membrane fluidity, but only cholesterol modifies the activities of certain integral microsomal membrane enzymes to a larger extent.

Increases in tissue levels of ubiquinone in association with peroxisome proliferation.

Rats were treated with various peroxisome proliferators and concomitant changes in ubiquinone levels were monitored. In addition to clofibrate and di(2-ethylhexyl)phthalate, acetylsalicylic acid, 2-ethylhexanoic acid, thyroxine and dehydroepiandrosterone were used as proliferators. Administration of these compounds increased the contents of ubiquinone in liver and, to some extent, in kidney and muscle. No change in corresponding valued for heart or brain were observed. The treatments did not influence cholesterol levels, but increased the amounts of dolichol in the liver to various extents. Treatment of rats with the catalase inhibitor aminotriazole increased the ubiquinone levels in kidney, heart and muscle but not in liver. Comparison of peroxisomal fatty acid beta-oxidation with ubiquinone amounts in liver homogenates after treatment with a number of peroxisome proliferators demonstrated a direct correlation between these two parameters. Subcellular fractionation of liver after peroxisome proliferation revealed that the ubiquinone level was increased in mitochondria and lysosomes which are the main compartments for this lipid, but an increase was also observed in both peroxisomes and microsomes. The increase in hepatic ubiquinone after treatment with various types of proliferators was related to the decrease in blood cholesterol level. These results show that the volume of the peroxisomal compartment and the ubiquinone content in animal tissues are interrelated.

Age-dependent modifications in the metabolism of mevalonate pathway lipids in rat brain.

The levels and rates of biosynthesis of mevalonate pathway lipids in rat brain were investigated during development and aging. Between birth and 18 months of age there are only moderate decreases in the phospholipid and cholesterol contents but an increase in the levels of dolichyl-P and, particularly of dolichol. The amount of ubiquinone is unchanged. The rate of incorporation of [3H]leucine into protein decreases by 10% during the first year, while the incorporation of [3H]glycerol into phospholipids decreases by 20%. The high rates of [3H]mevalonate incorporation into cholesterol and dolichol after birth decreases rapidly. In contrast, the rate of incorporation into ubiquinone is constant. Squalene synthase activity decreases rapidly in the early postnatal period and at 18 months of age this activity is 10-fold lower than immediately after birth. cis-Prenyltransferase activity is also high during the first postnatal month and reaches a constant level at 4 months of age. Significantly, nonaprenyl 4-hydroxybenzoate transferase activity is high during the entire period investigated. The rate of lipid peroxidation does not change during aging. These results demonstrate that brain cholesterol and dolichol exhibit a low rate of turnover during aging, whereas ubiquinone is synthesized at a high rate and exhibits rapid turnover throughout the entire lifespan.

Uptake of dietary coenzyme Q supplement is limited in rats.

Coenzyme Q is an important mitochondrial redox component and the only endogenously produced lipid-soluble antioxidant. Its tissue concentration decreases with aging and in a number of diseases; dietary supplementation of this lipid would fulfill important functions by counteracting coenzyme Q depletion. To investigate possible uptake, rats were administered 12 mumol coenzyme Q10/100 g body wt once daily by gastric intubation. The appearance of coenzyme Q10 in various tissues and blood after 6 h, 4 d or 8 d was studied. The control group of rats received rapeseed-soybean oil (the vehicle in the experimental group). Lipids were extracted with petroleum ethermethanol, and the reduced and oxidized forms of coenzyme Q9 and Q10 were separated and quantified by reversed-phase HPLC. In the plasma, the total coenzyme Q concentration was doubled after 4 d of treatment. Coenzyme Q10 was also recovered in liver homogenates, where, as in the plasma, it was largely in the reduced form. Uptake into the spleen could be to a large extent accounted for by the blood content of this organ. No dietary coenzyme Q10 was recovered in the heart or kidney. The uptake in the whole body was 2-3% of the total dose. Coenzyme Q10 found in the liver was located mainly in the lysosomes. Dietary coenzyme Q10 did not influence the endogenous biosynthesis of coenzyme Q9. This is in contrast to dietary cholesterol, which down-regulates cholesterol biosynthesis. The dietary coenzyme Q10 level in the plasma decreased to approximately 50% after 4 d. These results suggest that dietary coenzyme Q10 may play a role primarily in the blood and that no appreciable uptake occurs into tissues.

Coenzymes Q9 and Q10 in skeletal and cardiac muscle in tumour-bearing exercising rats.

Physical exercise increases metabolic rate, and induces both adaptational biogenesis of mitochondria in skeletal muscle and an increase in antioxidant capacity. The onset of experimental anorexia and cachexia can be delayed by voluntary exercise. As skeletal muscle is the main target for cancer cachexia, we determined the levels of coenzymes Q9 and Q10 in skeletal muscle from tumour-bearing exercising rats, and compared them to those of sedentary tumour-bearers and controls. Both tumour-bearing groups had increased levels of coenzymes Q9 and Q10 in the anterior tibial muscle (P < 0.05 for exercised animals). In the soleus muscle, only the tumour-bearing exercising animals demonstrated an increase in the levels of both coenzymes (P < 0.05). In cardiac muscle, the presence of tumour and exercise reduced the levels of coenzymes below that of sedentary controls. Exercise counteracted the anaemia in the tumour-bearing host (P < 0.05). In conclusion, the increase in antioxidant capacity in skeletal muscle indicates a defence mechanism in the tumour-bearing hosts which is augmented by physical exercise.

Lipid peroxidation of microsomal and mitochondrial membranes extracted with n-pentane and reconstituted with ubiquinol, dolichol and cholesterol.

Microsomes and mitochondria prepared from rat liver were extracted with n-pentane, a procedure which does not denature enzyme proteins. Protein and phospholipid were not extracted, but 75-80% of the total dolichol, 80-100% of the ubiquinone and 85-95% of the cholesterol were removed from both organelles by this procedure. Enzymatic and non-enzymatic lipid peroxidation in microsomes and non-enzymatic peroxidation in mitochondria were strongly inhibited when ubiquinol was reinserted into n-pentane-extracted membranes. When reconstitution with dolichol was performed, lipid peroxidation was increased or unchanged, while cholesterol decreased this activity in a concentration-dependent manner. In reconstitution experiments ubiquinol and dolichol together were less inhibitory than ubiquinol alone, whereas cholesterol accentuated the inhibitory effect of ubiquinol. Reconstitution with dolichols of different lengths, dolichyl esters or with alpha-unsaturated polyprenols further demonstrated that dolichol is not an antioxidant. It appears that mevalonate pathway lipids influence lipid peroxidation in membranes by modifying the properties of the bilayer.

Effects of clofibrate, phthalates and probucol on ubiquinone levels.

Rats were exposed through their diet to clofibrate, di(2-ethylhexyl)phthalate or probucol for 6 weeks and the levels of ubiquinone (UQ), cholesterol and dolichol were monitored in liver, muscle, heart, brain and blood. The levels of UQ-9 and -10 were increased by clofibrate and, in particular by phthalate administration. With the latter agent this increase in liver was fourfold, in muscle was twofold and levels in the heart and blood increased by 20%, whereas there was no change in the brain. Probucol led to a moderate decrease in the level of UQ in liver, muscle and blood, but not in heart or brain. The extent of reduction of UQ was not modified by any of the treatments employed. Probucol did not have any effect on tissue or blood cholesterol levels, whereas clofibrate or phthalate elicited a variable response, including both increases and decreases depending on the tissue analyzed. Phthalate treatment increased the dolichol content to some extent in all tissues and in blood, but the level of this lipid was not modified upon clofibrate or probucol treatment. These results demonstrate that tissue and blood levels of UQ can be increased by exposure to appropriate chemical agents without elevating the concentration of cholesterol.