Sister chromatid exchange and chromosome abnormalities in uremic patients

The role of DNA damage as a therapeutic target in autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is the most common monogenic kidney disease and is caused by heterozygous germ-line mutations in either PKD1 (85%) or PKD2 (15%). It is characterised by the formation of numerous fluid-filled renal cysts and leads to adult-onset kidney failure in ~50% of patients by 60 years. Kidney cysts in ADPKD are focal and sporadic, arising from the clonal proliferation of collecting-duct principal cells, but in only 1-2% of nephrons for reasons that are not clear. Previous studies have demonstrated that further postnatal reductions in PKD1 (or PKD2) dose are required for kidney cyst formation, but the exact triggering factors are not clear. A growing body of evidence suggests that DNA damage, and activation of the DNA damage response pathway, are altered in ciliopathies. The aims of this review are to: (i) analyse the evidence linking DNA damage and renal cyst formation in ADPKD; (ii) evaluate the advantages and disadvantages of biomarkers to assess DNA damage in ADPKD and finally, (iii) evaluate the potential effects of current clinical treatments on modifying DNA damage in ADPKD. These studies will address the significance of DNA damage and may lead to a new therapeutic approach in ADPKD.

Oral status, quality of life, and anxiety and depression in hemodialysis patients and the effect of the duration of treatment by dialysis on these variables

This study aimed is to evaluate the oral health status, quality of life, anxiety and depression among hemodialysis patients and to analyze the effect of the duration of dialysis on these variables. 120 patients on hemodialysis and 120 control subjects underwent oral examination, periodontal evaluation, xerostomia study using a Visual Analogue Scale (VAS), sialometry evaluation; quality of life (QOL) using the OHIP-14 questionnaire and anxiety/depression. Bleeding index, CPTIN, clinical attachment level, and probing depth were significantly higher in the hemodialysis group than the control group (p < 0.001). VAS scores were higher in patients on hemodialysis with significant differences in 6 of the 8 domains (p ≤ 0.05). Unstimulated whole saliva was significantly lower in hemodialysis patients than control subjects (p < 0.001). OHIP-14 scores showed significantly poorer QOL in patients on hemodialysis than control subjects (p = 0.042). Hemodialysis patients presented greater depression and anxiety than control (p < 0.001). Periodontal health was worse among the patients who had been in treatment >10 years, xerostomia and sialorrea was worse in patients treated for 5-9.9, and >10 years, QOL was worse in patients who had spent <1 year; depression and anxiety was greater among those treated for 1-2.9 years. In conclusion, Oral health, QOL, anxiety and depression are worse in patients on hemodialysis, and oral health deteriorates as the time spent in dialysis lengthens, but patients in treatment for <3 years presented the poorest QOL and the greatest anxiety and depression.

DNA Damage in Chronic Kidney Disease: Evaluation of Clinical Biomarkers

Patients with chronic kidney disease (CKD) exhibit an increased cancer risk compared to a healthy control population. To be able to estimate the cancer risk of the patients and to assess the impact of interventional therapies thereon, it is of particular interest to measure the patients' burden of genomic damage. Chromosomal abnormalities, reduced DNA repair, and DNA lesions were found indeed in cells of patients with CKD. Biomarkers for DNA damage measurable in easily accessible cells like peripheral blood lymphocytes are chromosomal aberrations, structural DNA lesions, and oxidatively modified DNA bases. In this review the most common methods quantifying the three parameters mentioned above, the cytokinesis-block micronucleus assay, the comet assay, and the quantification of 8-oxo-7,8-dihydro-2′-deoxyguanosine, are evaluated concerning the feasibility of the analysis and regarding the marker's potential to predict clinical outcomes.

Oxidative stress and nucleic acid oxidation in patients with chronic kidney disease

Patients with chronic kidney disease (CKD) have high cardiovascular mortality and morbidity and a high risk for developing malignancy. Excessive oxidative stress is thought to play a major role in elevating these risks by increasing oxidative nucleic acid damage. Oxidative stress results from an imbalance between reactive oxygen/nitrogen species (RONS) production and antioxidant defense mechanisms and can cause vascular and tissue injuries as well as nucleic acid damage in CKD patients. The increased production of RONS, impaired nonenzymatic or enzymatic antioxidant defense mechanisms, and other risk factors including gene polymorphisms, uremic toxins (indoxyl sulfate), deficiency of arylesterase/paraoxonase, hyperhomocysteinemia, dialysis-associated membrane bioincompatibility, and endotoxin in patients with CKD can inhibit normal cell function by damaging cell lipids, arachidonic acid derivatives, carbohydrates, proteins, amino acids, and nucleic acids. Several clinical biomarkers and techniques have been used to detect the antioxidant status and oxidative stress/oxidative nucleic acid damage associated with long-term complications such as inflammation, atherosclerosis, amyloidosis, and malignancy in CKD patients. Antioxidant therapies have been studied to reduce the oxidative stress and nucleic acid oxidation in patients with CKD, including alpha-tocopherol, N-acetylcysteine, ascorbic acid, glutathione, folic acid, bardoxolone methyl, angiotensin-converting enzyme inhibitor, and providing better dialysis strategies. This paper provides an overview of radical production, antioxidant defence, pathogenesis and biomarkers of oxidative stress in patients with CKD, and possible antioxidant therapies.

Base excision repair capacity in chronic renal failure patients undergoing hemodialysis treatment

The aim of this study was to determine if the differences observed in the levels of DNA damage in a group of patients suffering from chronic renal failure are due to differences in the repair capability. DNA damage was initially measured with the comet assay in 106 hemodialysis patients. A selected group of 21 patients representing high (ten patients) and low (11 patients) levels of DNA damage were obtained for determination of base excision repair capacity. This was measured in an in vitro assay where protein extracts from lymphocytes were incubated with a substrate of DNA containing 8-oxoguanine, and the rate of incision was measured with the comet assay. Patients with high levels of genomic damage showed, as an average, significantly lower repair capacity (12·73 ± 1·84) in comparison with patients with low levels of genomic damage (18·13 ± 1·13). Nevertheless, the correlation coefficient between repair ability and levels of genomic damage was found to be only close to the significance value (r:-0·423, p: 0·056). Although DNA damage was clearly related to time on hemodialysis, base excision repair capacity was not. This is one of the few studies providing information on the repair capacity of chronic renal failure patients undergoing hemodialysis. As a summary, our results would indicate that DNA damage levels are in part associated to the repair capacity of the patients, and this repair capacity is not associated with the duration of hemodialysis treatment.

Effect of immunosuppression for primary renal disease on the risk of cancer in subsequent renal transplantation: a population-based retrospective cohort study

BACKGROUND

To measure the risk of cancer in renal transplantation for recipients who had previously been treated with immunosuppressive agents for primary renal disease.

METHODS

A retrospective population-based cohort study of 5970 renal transplant recipients in Australia registered on the Australia and New Zealand Dialysis and Transplant Registry between 1982 and 1997 and followed until 2007. Data about the incidence of a range of cancer types from this Registry were compared with cancer incidence data for the general population matched for cancer type, year of incidence, age, and gender derived from national cancer records. Outcome measures for each cancer group with or without pretransplantation immunosuppression were cancer-specific standardized incidence ratios and a multivariate hazard ratio (HR) standardized to 1.

RESULTS

For those treated with pretransplantation immunosuppression, the risks for four cancer groups during renal transplantation were significantly increased: anogenital cancer (HR, 3.13; confidence interval [CI], 1.92-5.11; P<0.0001), non-Hodgkin's lymphoma (HR, 2.37; CI, 1.53-3.68; P=0.0001), breast cancer (HR, 2.52; CI, 1.13-5.61; P=0.024), and urinary tract cancer (excluding kidney) (HR, 1.84; CI, 1.13-3.01; P=0.015). However, the risks of cancer in the oral cavity and pharynx, kidney, thyroid, colon, leukemia, lung, melanoma, prostate, and stomach were not significantly increased.

CONCLUSIONS

Pretransplantation immunosuppression for primary renal disease increases the risks of four cancer types in renal transplantation while sparing the others. Patients in whom this treatment is being considered should be informed of these risks.

Genomic instability in chronic renal failure patients

Patients suffering chronic renal failure (CRF) exhibit a high incidence of cancer, as well as high levels of genetic damage. We hypothesized that these patients show genomic instability as measured by increased radiosensitivity to the induction of genetic damage. The background levels of genetic damage and the net genetic damage after in vitro irradiation with 0.5 Gy were analyzed using the micronucleus assay in peripheral blood lymphocytes of 174 CRF patients and 53 controls. The net radiation-induced genetic damage was significantly higher in CRF patients with respect to controls. Among CRF patients, the levels of genetic damage were higher in those with prior incidence of cancer than in those without cancer; in addition, those CRF patients undergoing hemodialysis presented with higher levels of genetic damage than those in the advanced Stages (4-5) of the pathology. A positive association was observed between basal and net micronucleus frequency among CFR patients. However, no association was found between net genetic damage and parameters linked to the different stages of the pathology, such as urine creatinine levels and glomerular filtration rate. Our results indicate that CRF patients show increased radiosensitivity and that the degree of radiosensitivity is associated with the progression of the pathological stage of the disease.

Increased risk of cancer in chronic dialysis patients: a population-based cohort study in Taiwan

BACKGROUND

An increased incidence of cancer in chronic dialysis patients has not been confirmed in the Chinese population. The aim of this population-based study was to examine the risk of various types of cancers in chronic dialysis patients in Taiwan.

METHODS

Data of 92 348 chronic dialysis patients extracted from the National Health Institutes Research Database during 1997-2008 were analyzed. Patients newly diagnosed with end-stage renal disease, free of cancer and receiving dialysis for >3 months were eligible for inclusion in the study.

RESULTS

After a mean follow-up of 4.4 years, a new cancer was diagnosed in 4328 chronic dialysis patients. The standardized incidence ratio (SIR) of chronic dialysis patients was 1.4 [95% confidence interval (CI): 1.3-1.4] and annual incidence of cancer was 1.1%. A trend of an increased SIR of cancer was observed in young patients and within the first year of dialysis. Bladder cancer carried the highest SIR (SIR: 8.2, 95% CI: 6.7-9.9) and had the highest frequency (21.2%). Importantly, the frequency (15.3%) of liver cancer was the second highest and the SIR (SIR: 1.4, 95% CI: 1.2-1.5) of liver cancer in chronic dialysis patients was higher than that of their healthy counterparts. Unexpectedly, chronic dialysis patients had a significantly reduced risk of developing lung cancer.

CONCLUSION

Increased risk of cancer in chronic dialysis patients is confirmed in the Taiwanese population and it is necessary to develop different strategies for cancer screening in chronic dialysis patients among different ethnicities.

AT1 receptor antagonist candesartan attenuates genomic damage in peripheral blood lymphocytes of patients on maintenance hemodialysis treatment

BACKGROUND

Angiotensin II (ANG II) and advanced glycation end products (AGEs) exert genotoxic effects in vitro which were prevented by the ANG II type 1 (AT1) receptor blocker, candesartan. In end-stage renal disease (ESRD) the incidence of genomic damage is increased. A stimulation of the renin-angiotensin system and accumulation of AGEs could be involved.

METHODS

We tested whether oral co-administration of candesartan modulates enhanced DNA damage in ESRD patients. Fifteen maintenance hemodialysis (MHD) patients with mild hypertension were treated with candesartan for 4.5 months. Fourteen MHD patients served as conventionally treated uremic controls. DNA damage was measured as micronucleus frequency (MNF) in peripheral blood lymphocytes and evaluated three times before candesartan therapy and afterwards every 6 weeks.

RESULTS

Compared to 14 healthy controls, MNF at baseline was significantly elevated in MHD patients. While in the conventionally treated MHD patients the enhanced DNA damage persisted, the co-administration of candesartan ameliorated the genomic damage significantly and independently of blood pressure changes.

CONCLUSION

Blockade of AT1 receptors with candesartan can reduce DNA damage in MHD patients. Long-term studies in larger patient groups are needed to investigate whether the improved genomic damage lowers atherosclerotic complications and cancer development.

Genetic damage in chronic renal failure patients is associated with the glomerular filtration rate index

Chronic renal failure (CRF) patients are considered to present genomic instability and, as a consequence, elevated levels of genetic damage. An open question is whether this damage is related to the stage of the pathology. To determine the background levels of genetic damage, a large population of 258 Caucasian adults (201 CRF patients and 57 controls) was analysed using the micronucleus (MN) assay. The frequency of MN in CRF patients was significantly higher than in controls and correlated with the progression of the disease, according to the glomerular filtration rate. In addition, a significant association was observed between genetic damage and serum creatinine levels. Genetic damage, measured as frequency of MN, increases when renal function decreases. The fact that an increased level of MN is already observed in patients' Stage 2 seems to indicate a genetic predisposition on these patients. Nevertheless, part of the observed damage can be attributed to the uraemic state itself.

Cancer in patients on chronic dialysis in Korea

The study of cancer in patients treated with dialysis in Korea has not been reported. The aim of this study was to investigate the incidence and mortality of cancer among patients on dialysis in Korea. The study subjects were 106 cancer patients (2.3%) out of 4,562 end-stage renal disease (ESRD) patients maintained on hemodialysis (HD) or peritoneal dialysis (PD) at Yonsei University Health System from 1996 to 2005. We excluded patients in whom the diagnosis of cancer preceded dialysis or those who received renal allograft or started dialysis after renal allograft. Seventy-three (69%) of our subjects were male and 33 (31%) were female. The mean age at the time of cancer diagnosis was 57.9+/-11.7 yr. The mean time from the start of dialysis to the diagnosis of cancer was 75.2+/-63.9 months. The most common cancer site was gastrointestinal tract (GIT) (51%) followed by urinary tract (20%), lung (8%), and thyroid (7%). Sixty nine percent of the total mortality was due to cancer. The mean time from diagnosis to death was 2.9+/-2.5 yr. In ESRD patients with cancer, there were no significant differences in mortality rates by dialysis modality. In ESRD patients, the most common cancer was GIT cancer followed by urinary tract cancer. Therefore, careful surveillance of these cancers in ESRD patients is highly recommended.

Benfotiamine reduces genomic damage in peripheral lymphocytes of hemodialysis patients

Hemodialysis patients have an elevated genomic damage in peripheral blood lymphocytes (PBLs) and an increased cancer incidence, possibly due to accumulation of uremic toxins like advanced glycation end products (AGEs). Because the vitamin B1 prodrug benfotiamine reduces AGE levels in experimental diabetes, and dialysis patients often suffer from vitamin B1 deficiency, we conducted two consecutive studies supplementing hemodialysis patients with benfotiamine. In both studies, genomic damage was measured as micronucleus frequency of PBLs before and at three time-points after initiation of benfotiamine supplementation. AGE-associated fluorescence in plasma, and in the second study additionally, the antioxidative capacity of plasma was analyzed. Benfotiamine significantly lowered the genomic damage of PBLs in hemodialysis patients of both studies independent of changes in plasma AGE levels. The second study gave a hint to the mechanism, as the antioxidative capacity of the plasma of the treated patients clearly increased, which might ameliorate the DNA damage.

Prevalence of 4977bp deletion in mitochondrial DNA from patients with chronic kidney disease receiving conservative treatment or hemodialysis in southern Brazil

BACKGROUND

Damage to mitochondrial DNA (mtDNA) has been described in patients with chronic kidney disease (CKD). The presence of mtDNA 4977bp deletion in many different tissues can serve as a marker of this damage. However, no attempt has been made to detect the presence of mtDNA 4977bp in blood cells of patients with CKD.

METHODS

Polymerase chain reaction techniques (PCR) were used to detect mtDNA 4977bp deletion in blood samples of 94 CKD patients.

RESULTS

The prevalence of 4977bp deletion in mtDNA was 73.1% (38/52) in patients with CKD undergoing hemodialysis, 57.1% (27/42) in patients with CKD receiving conservative treatment, and 27.8% (15/54) in control samples (p < 0.001). Higher prevalence of this mutation was not associated with patient age (p = 0.54) or time on hemodialysis (p = 0.70).

CONCLUSION

The higher prevalence of mtDNA 4977bp deletion in patients in this study indicates that the CKD can induce damage to mtDNA in blood cells and could be exacerbated by hemodialysis.

Identifying high risk groups and quantifying absolute risk of cancer after kidney transplantation: a cohort study of 15,183 recipients

Transplant recipients have increased cancer risk, but data on risk variation across different patient groups are sparse. Rates and standardized rate ratios (SRR) of cancer (all sites, excluding nonmelanocytic skin and lip cancer) compared to the general population were calculated, using Australia and New Zealand Dialysis and Transplant Registry data. Within the transplant population, risk factors were identified (hazard ratios: HR; 95% CI) and absolute risk estimated for recipient groups. A total of 1642 (10.8%) of 15 183 recipients developed cancer. Risk was inversely related to age (SRR 15-30 children, 2 if >65 years). Females aged 25-29 had rates equivalent to women aged 55-59 from the general population. Age trend for lymphoma, colorectal and breast risk was similar; melanoma showed less variability across ages, prostate showed no risk increase. Within the transplanted population, risk was affected by age differently for each sex (p = 0.007), elevated by prior malignancy (HR 1.40; 1.03-1.89), white race (HR 1.36; 1.12-1.89), but reduced by diabetic end-stage kidney disease (ESKD) (HR 0.67; 0.50-0.89). Cancer rates in kidney recipients are similar to nontransplanted people 20-30 years older, but absolute risk differs across patient groups. Men aged 45-54 surviving 10 years have cancer risks varying from 1 in 13 (non-white, no prior cancer, diabetic ESKD) to 1 in 5 (white, prior cancer, other ESKD).

Genomic damage in chronic renal failure--potential therapeutic interventions

In end-stage renal failure, genomic damage is enhanced. This has been shown both in the predialysis and dialysis phase by various biomarkers, such as micronuclei frequency and single cell gel electrophoresis in lymphocytes as well as with 8-hydroxy-2'-deoxyguanosine in leukocytes. There are also data about mitochondrial DNA deletions and chromosomal abnormalities. Genomic damage may be induced by a multitude of toxic factors and mutagens, in particular via enhanced generation of reactive oxygen species. In in vitro studies, incubation of tubular cells with various AGEs (carboxymethyllysine-BSA, AGE-BSA, and methylglyoxal-BSA) and angiotensin II resulted in a marked DNA damage. Coincubation with various antioxidants as well as the angiotensin II receptor blocker, candesartan, suppressed the toxic action. Moreover, an improved uremic state by daily hemodialysis ameliorated the genomic damage in lymphocytes, as compared to patients on conventional hemodialysis.

The association of circulating leptin level with peripheral DNA damage in hemodialysis subjects

OBJECTIVES

Hemodialysis subjects have been shown to have both elevated serum leptin and peripheral DNA damage level, and leptin has been suggested to induce apoptotic features. Thus, in the present study, we aimed at finding out if there is any relationship between serum leptin level and peripheral DNA damage in hemodialysis subjects.

DESIGN AND METHODS

Forty hemodialysis subjects and 21 controls were included in the present study. Serum leptin level and peripheral DNA damage were assayed in all subjects enrolled in the study. Comet assay was used in determining DNA damage in peripheral lymphocyte.

RESULTS

Both serum leptin level and peripheral DNA damage were significantly higher in hemodialysis subjects than control (P<0.05 and P<0.001, respectively). Female subjects had significantly higher serum leptin level than male subjects in both hemodialysis and control group (both P<0.05). Significant correlation was observed between serum leptin level, and gender and body fat mass in both hemodialysis (P<0.05, beta=-0.637 and P<0.05, beta=0.386, respectively) and control group (P<0.05, beta=-0.569 and P<0.05, beta=-0.460, respectively). In hemodialysis subjects, peripheral DNA damage was significantly correlated with serum leptin level (P<0.05, beta=0.508).

CONCLUSION

In end-stage renal disease subjects, elevated serum leptin level seems to be associated with peripheral DNA damage and thus, may, in part, have a role in the development of DNA damage associated disorders.

Chromosomal damage and atherosclerosis. A protective effect from simvastatin

In uremic patients, the frequency of sister chromatid exchanges appears markedly higher than in the general population. Statins are well known for their pleiotropic effects, which are independent of any reduction in cholesterol circulating levels. The aim of the present study was to determine the effects of exposure to escalating doses of simvastatin on the sister chromatid exchange rate in cultured lymphocytes in order to identify the influence of statin on genomic damage. Peripheral lymphocytic samples for culture were obtained from 25 healthy volunteers, 20 patients with documented carotid atherosclerosis and 30 atherosclerotic patients on maintenance regular acetate-free biofiltration. Hemodialyzed patients had a greater percentage of high frequency cells (50%) than healthy controls (3%) and a significantly higher average number of sister chromatid (9.82+/-2.1 vs. 4.65+/-2.18). The subgroup of hemodialyzed patients with high plaque score values was characterized by significantly greater values for both sister chromatid exchanges rate and high frequency cells percentage. Our findings demonstrate that there is an association between sister chromatid exchanges and high frequency cells rate and atherosclerosis in acetate-free biofiltration patients. In cultures with added simvastatin, high frequency cells percentages and mean sister chromatid exchanges levels were significantly lower than in cultures with an added vehicle alone, the reduction occurring in a dose-dependent fashion, above all in cultures from end stage renal disease patients. The findings, moreover, demonstrate new effects of simvastatin, which appeared to mitigate the expression of genomic damage in our model. However, it is not yet clear whether this effect is due to the prevention of genomic damage or to the potentiation of the DNA repair capacity. Statins may therefore have an anti-atherogenic action partly ascribable to their ability to provide protection against the development of atherosclerotic plaque.

Assessment of peripheral DNA damage by alkaline comet assay in maintenance hemodialysis subjects with hepatitis C infection

Despite the high prevalence of hepatitis C infection among hemodialysis subjects, there is no information concerning the DNA damage of hepatitis C (+) hemodialysis subjects. We aimed to find out if there is any additional effect of hepatitis C infection on peripheral DNA damage in maintenance hemodialysis subjects. Fifteen hepatitis C (+) and 22 hepatitis C (-) hemodialysis subjects, 21 hepatitis C subjects without renal disease, and 22 healthy controls were enrolled. Peripheral DNA damage was assayed using alkaline comet assay. Median DNA damage levels of the study groups were as follows: hepatitis C (+) maintenance hemodialysis subjects, 88 (0-232); hepatitis C (-) maintenance hemodialysis subjects, 58 (0-228); hepatitis C (+) subjects without renal disease, 112 (44-252); controls, 26 (0-72). DNA damage level was significantly higher among hepatitis C (+) subjects without renal disease than hepatitis C (-) maintenance hemodialysis subjects and healthy controls (both p<0.05/6). Both maintenance hemodialysis subjects with and without HCV infection had significantly higher DNA damage level than healthy controls (both p<0.05/6). DNA damage level was comparable between hepatitis C (+) subjects without renal disease and HCV (+) hemodialysis subjects, and between hemodialysis subjects with and without hepatitis C infection (all p>0.05/6). Linear regression analysis revealed that hepatitis C infection was the only independent factor in predicting the peripheral DNA damage (p<0.05, beta=0.395). Each one of end-stage renal disease and hepatitis C infection significantly increases DNA damage level. However, in hemodialysis subjects, hepatitis C infection does not cause significant additional increase in DNA damage level, and it may be partly due to protective effect of hemodialysis on hepatitis C infection.

Apolipoprotein and anticardiolipin antibodies in patients with renal amyloidosis

BACKGROUND

Thromboembolic events are seen more frequently in patients with chronic renal failure (CRF) and amyloidosis. The anticardiolipin antibody (ACA) that is important for thromboembolic events has never been studied.

METHODS

This study included 43 amyloidosis patients of different aetiologies; 28 with CRF as well as 20 patients who had CRF without amyloidosis. Thirty normal subjects were included as a control group. We determined the serum levels of ACA, apolipoprotein AI (ApoAl), ApoE and lipoprotein (a) (Lp(a)) in these groups.

RESULTS

Anticardiolipin antibody was found to be positive in 30.2% of patients with amyloidosis, this is in contrast to 3.3% in the control group (chi = 8.25, P < 0.005). We also showed that there was a statistically significant difference (chi = 5.03, P < 0.05) between the CRF patients with amyloidosis (31%) and the CRF patients without amyloidosis (5%). The average levels of serum ApoAI were shown to be significantly lower (P < 0.05) in CRF patients with amyloidosis in comparison with the amyloidosis patients who had normal renal functions (93.60 +/- 27.84 vs 119.8 +/- 36.26 mg/dL, P < 0.05). There was also significant a difference in ApoAI levels between CRF patients with and without amyloidosis (P < 0.001). The serum Lp (a) levels were significantly higher in CRF patients with amyloidosis when compared with the controls (41.2 +/- 22.39 vs 19.13 +/- 8.78 mg/dL, P < 0.001). The serum Lp (a) levels were also positively correlated with ACA (r = 0.211; P < 0.05).

CONCLUSION

In conclusion, ACA positivity is more common in all patients with amyloidosis as compared with CRF patients and normal controls. This study is the first to show the presence of high levels of ACA in patients with CRF, which is caused by secondary amyloidosis. Further studies are recommended to investigate the mechanism of this finding.

Mutations of mtDNA in renal cell tumours arising in end-stage renal disease

Toxic effects in the uraemic state or during maintenance dialysis have been suggested to be responsible for DNA damage and tumour development in end-stage renal disease (ESRD). This study therefore analysed the mitochondrial DNA alterations in six kidneys with ESRD and in nine renal cell tumours arising in these kidneys. Sequencing the entire 16 569 bp mitochondrial genome disclosed 94 sequence variations in normal and corresponding tumour tissues. Thirty-eight polymorphisms occurred in the D-loop region, 40 in the polypeptide coding regions, 12 in the rRNAs, and four in the tRNAs. Nine somatic nucleotide changes were found in seven of the nine tumours analysed; four of them were G to A transitions. Two of the G to A changes occurred in the D-loop region, one in the MTTA gene, and one in the MTND2 gene. An A to G substitution was seen in the control region at the mtTF1 binding site. A T to C transition also occurred also in the D-loop region. A T insertion was seen in MTRNR2 (16S rRNA). One C insertion in MTND4 and one A deletion in the polyA tract of the MTND5 gene resulted in frameshift mutations in two tumours. This study reveals a high mutational rate of the mitochondrial DNA in tumours, which may correspond to the increased level of reactive oxidative species in renal parenchymal cells in ESRD.

Biomarkers of DNA damage in patients with end-stage renal disease: mitochondrial DNA mutation in hair follicles

BACKGROUND

DNA damage was noted in patients with end-stage renal disease (ESRD). Mitochondrial DNA (mtDNA) mutations have been proposed as a genomic biomarker in the process of human ageing, degenerative diseases and carcinogenesis.

METHODS

Polymerase chain reaction (PCR) techniques were applied to detect mtDNA deletions in hair follicles, an appendage of skin, from 162 patients with ESRD.

RESULTS

The incidences of the 4977 bp deletion of mtDNA in hair follicles were found to increase with age in normal control and ESRD patients. As compared with normal subjects, ESRD patients had 3.5, 2.3, 2.7, 2.3 and 1.4 times higher incidences of the 4977 bp deletion of mtDNA in the age groups of 20-30, 31-40, 41-50, 51-60 and 61-70 years, respectively. Moreover, the difference in the proportion of mtDNA with the 4977 bp deletion was statistically significant between ESRD patients and normal subjects >50 years of age.

CONCLUSION

We suggest that the 4977 bp deletion of mtDNA in hair follicles may serve as one of the tissue biomarkers of genetic instability of the mitochondrial genome in ESRD patients.

Renal cell carcinoma in an end-stage kidney of a patient with a functional transplant: cytogenetic and molecular genetic findings

Renal cell carcinomas (RCCs) occur at an increased rate and at a younger age in patients with end-stage renal disease (ESRD) than in the general population. A papillary RCC from a patient with ESRD treated by hemodialysis and then by renal transplantation was karyotyped and showed a 55,XY,+2,+4,+7,+10,+12,+16,+17,+17,+20 mainline. No loss of gene sequences in the short arm of chromosome 3 was identified by chromosomal or molecular genetic analysis. Together with one prior report of a cytogenetic study of a RCC in an end-stage kidney, the findings indicate that papillary RCCs that arise in ESRD patients have genetic changes that are similar to those found in sporadic tumors. The increased frequency of tumors and the younger age of the patients may be due to an increased rate at which abnormal mitoses occur in diseased renal tissues.

Monoclonality of parathyroid tumors in chronic renal failure and in primary parathyroid hyperplasia

The pathogeneses of parathyroid disease in patients with uremia and nonfamilial primary parathyroid hyperplasia are poorly understood. Because of multigland involvement, it has been assumed that these common diseases predominantly involve polyclonal (non-neoplastic) cellular proliferations, but an overall assessment of their clonality has not been done. We examined the clonality of these hyperplastic parathyroid tumors using X-chromosome inactivation analysis with the M27 beta (DXS255) DNA polymorphism and by searching for monoclonal allelic losses at M27 beta and at loci on chromosome band 11q13. Fully 7 of 11 informative hemodialysis patients (64%) with uremic refractory hyperparathyroidism harbored at least one monoclonal parathyroid tumor (with a minimum of 12 of their 19 available glands being monoclonal). Tumor monoclonality was demonstrable in 6 of 16 informative patients (38%) with primary parathyroid hyperplasia. Histopathologic categories of nodular versus generalized hyperplasia were not useful predictors of clonal status. These observations indicate that monoclonal parathyroid neoplasms are common in patients with uremic refractory hyperparathyroidism and also develop in a substantial group of patients with sporadic primary parathyroid hyperplasia, thereby changing our concept of the pathogenesis of these diseases. Neoplastic transformation of preexisting polyclonal hyperplasia, apparently due in large part to genes not yet implicated in parathyroid tumorigenesis and possibly including a novel X-chromosome tumor suppressor gene, is likely to play a central role in these disorders.

DNA repair and recovery of RNA synthesis in uremic patients

A high frequency of cancer appears among uremic patients. As depressed DNA repair ability is thought to be one of the causes for malignancy in cancer prone diseases, the present study was undertaken to examine DNA repair in uremic patients. Unscheduled DNA repair synthesis in peripheral lymphocytes was measured after both ultraviolet (UV) and gamma irradiations. In hemodialysis (HD) patients the repairs were normal, but in chronic renal failure (CRF) patients not yet on dialysis treatment, both UV- and gamma-induced DNA repair abilities were depressed to about 60% of the control. Recovery of RNA synthesis after UV irradiation followed the same pattern: it was reduced in CRF but normal in HD cells. When CRF lymphocytes were incubated in normal plasma, the UV-stimulated DNA repair improved to a nearly normal level, whereas incubation of normal cells in CRF plasma depressed their repair capacity to 70% of the initial level. These results suggest that a plasmatic substance such as the carcinogenic heterocyclic amines may be involved in the impairment of DNA repair in chronic renal failure.

Sister chromatid exchange in Waldenström's macroglobulinemia

Results on sister chromatid exchange (SCE) frequency and interchromosomal distribution in bone marrow and peripheral blood cultures from patients with Waldenström's macroglobulinemia are reported. PHA-stimulated bone marrow cultures showed increased SCE frequencies in all 12 patients examined. The increase was particularly high in two cases (17.07 and 16.77 SCE/cell, respectively) and, in one of them, a very high SCE level was found in PHA-stimulated peripheral blood culture (40.81 SCE/cell). In LPS-stimulated cultures, increased SCE levels were observed in some patients. Comparison between SCE frequency in bone marrow cell cultures with either mitogen showed a significant increase in PHA-stimulated cultures. Analysis of the interchromosomal SCE distribution revealed significant differences with respect to the control values; however, these differences were variable in the different patients. In pooled data of PHA-stimulated bone marrow cultures, there were differences between expected and observed SCEs in chromosomes 1 and 2 and in B, E, F, and G chromosome groups. Results of cell cycle modifications are also reported.