In vitro studies on mangiferin protection against cadmium-induced human renal endothelial damage and cell death via the MAP kinase and NF-κB pathways.

The therapeutic effects of the natural antioxidant mangiferin (a xanthonoid and potent oxygen free radical scavenger), which is widely distributed in mango fruit, against CdCl(2)-induced toxicity in human renal glomerulus endothelial cells (HRGEC) were investigated. The viability of HREGCs that were treated with CdCl(2) (25 µ mol) and co-treated with mangiferin (75 µ mol) for 24 h was measured by crystal violet dye. The exposure of human glomerulus renal endothelial cells to cadmium promotes a polarized apical secretion of IL-6 and IL-8, two pivotal proinflammatory cytokines known to play a significant role in renal inflammation. Proinflammatory cytokine secretion by human renal glomerulus endothelial cells could be the result of cadmium-induced IL-6 secretion via an NF-κB-dependent pathway. However, IL-8 secretion involves the phosphor-JNK phospho-p38 signaling pathway. The results of the current study reveal that mangiferin could prevent both cadmium-induced IL-6 and IL-8 secretion by human glomerulus endothelial cells and be used to prevent renal inflammation.

Efficacy of pyruvate therapy in patients with mitochondrial disease: a semi-quantitative clinical evaluation study.

BACKGROUND: Disorders of oxidative phosphorylation (OXPHOS) cause an increase in the NADH/NAD(+) ratio, which impairs the glycolysis pathway. Treatment with pyruvate is expected to decrease the ratio and thereby restore glycolysis. There are some case reports on the efficacy of pyruvate treatment for mitochondrial diseases. However, few of these reports assessed their results using a standardized scale. METHODS: We monitored 4 bedridden patients with OXPHOS disorders who continued therapies of 0.5-1.0 g/kg/day of sodium pyruvate for more than 12 months. The efficacies of these treatments were evaluated with the Newcastle Pediatric Mitochondrial Disease Scale and the Gross Motor Function Measure with 88 items. RESULTS: The ages of the patients at the treatment initiation ranged from 8-100 months. Of the 4 patients, 3 exhibited improvements within 1-3 months from the initiation of treatment. Among these 3 patients, one maintained the improvement for over 2 years. The remaining 2 regressed 3-6 months after the initiation of treatment. The blood lactate/pyruvate ratios did not correlate with the efficacy of treatment. CONCLUSION: Pyruvate was effective even in bedridden patients with OXPHOS disorders, at least in the short term. Clinical trials with more patients and less severe disabilities are necessary to evaluate the long-term efficacy of this treatment. Biomarkers other than lactate and pyruvate need to be identified to biochemically monitor the efficacy of this treatment.

Extended screening for major mitochondrial DNA point mutations in patients with hereditary hearing loss.

Hearing loss (HL) is the most common sensory disorder in humans. Many patients with mitochondrial diseases have sensorineural HL (SNHL). The HL of these patients manifests as a consequence of either syndromic or nonsyndromic mitochondrial diseases. Furthermore, the phenotypes vary among patients even if they are carrying the same mutation. Therefore, these features make it necessary to analyze every presumed mutation in patients with hereditary HL, but the extensive analysis of various mutations is laborious. We analyzed 373 patients with suspected hereditary HL by using an extended suspension-array screening system for major mitochondrial DNA (mtDNA) mutations, which can detect 32 other mtDNA mutations in addition to the previously analyzed 29 mutations. In the present study, we detected 2 different mtDNA mutations among these 373 patients; m.7444G>A in the MT-CO1 gene and m.7472insC in the MT-TS1 gene in 1 patient (0.3%) for each. As these two patients had no clinical features other than HL, they had not been suspected of having mtDNA mutations. This extended screening system together with the previous one is useful for the genetic diagnosis and epidemiological study of both syndromic and nonsyndromic HL.

Pyruvate therapy for Leigh syndrome due to cytochrome c oxidase deficiency.

BACKGROUND: Recently we proposed the therapeutic potential of pyruvate therapy for mitochondrial diseases. Leigh syndrome is a progressive neurodegenerative disorder ascribed to either mitochondrial or nuclear DNA mutations. METHODS: In an attempt to circumvent the mitochondrial dysfunction, we orally applied sodium pyruvate and analyzed its effect on an 11-year-old female with Leigh syndrome due to cytochrome c oxidase deficiency accompanied by cardiomyopathy. The patient was administered sodium pyruvate at a maintenance dose of 0.5 g/kg/day and followed up for 1 year. RESULTS: The exercise intolerance was remarkably improved so that she became capable of running. Echocardiography indicated improvements both in the left ventricle ejection fraction and in the fractional shortening. Electrocardiography demonstrated amelioration of the inverted T waves. When the pyruvate administration was interrupted because of a gastrointestinal infection, the serum lactate level became elevated and the serum pyruvate level, decreased, suggesting that the pyruvate administration was effective in decreasing the lactate-to-pyruvate ratio. CONCLUSIONS: These data indicate that pyruvate therapy was effective in improving exercise intolerance at least in a patient with cytochrome c oxidase deficiency. GENERAL SIGNIFICANCE: Administration of sodium pyruvate may prove effective for other patients with cytochrome c oxidase deficiency due to mitochondrial or nuclear DNA mutations.

A functionally dominant mitochondrial DNA mutation.

Mutations in mitochondrial DNA (mtDNA) tRNA genes can be considered functionally recessive because they result in a clinical or biochemical phenotype only when the percentage of mutant molecules exceeds a critical threshold value, in the range of 70-90%. We report a novel mtDNA mutation that contradicts this rule, since it caused a severe multisystem disorder and respiratory chain (RC) deficiency even at low levels of heteroplasmy. We studied a 13-year-old boy with clinical, radiological and biochemical evidence of a mitochondrial disorder. We detected a novel heteroplasmic C>T mutation at nucleotide 5545 of mtDNA, which was present at unusually low levels (<25%) in affected tissues. The pathogenic threshold for the mutation in cybrids was between 4 and 8%, implying a dominant mechanism of action. The mutation affects the central base of the anticodon triplet of tRNA(Trp) and it may alter the codon specificity of the affected tRNA. These findings introduce the concept of dominance in mitochondrial genetics and pose new diagnostic challenges, because such mutations may easily escape detection. Moreover, similar mutations arising stochastically and accumulating in a minority of mtDNA molecules during the aging process may severely impair RC function in cells.

Extensive and rapid screening for major mitochondrial DNA point mutations in patients with hereditary hearing loss.

Sensorineural hearing loss (HL) is one of the most frequent clinical features in patients with mitochondrial diseases caused by mitochondrial DNA (mtDNA) mutations, and hearing is impaired in over half of all cases with mitochondrial disorders. This study analyzed 373 patients with suspected hereditary HL using an extensive and rapid suspension-array screening system for 29 major mtDNA mutations, including the m.1555A>G homoplasmic mutation in the MT-RNR1 gene, which causes non-syndromic sensorineural HL and aminoglycoside-induced HL, and the m.3243A>G heteroplasmic mutation in the MT-TL1 gene. This method is rapid and suitable for large-scale screening because universal 96-well plates are available for use, and because an analysis of each plate can be completed within 1 h. This system detected five different mtDNA mutations in 24 of the 373 (6.4%) patients. The m.1555A>G and m.3243A>G mutations were detected in 11 (2.9%) and 9 (2.7%) patients, respectively. In addition, three mutations, that is, m.8348A>G in the MT-TK gene, m.11778G>A in the MT-ND4 gene and 15498G>A in the MT-CYB gene were detected in one patient for each. This screening system is useful for the genetic diagnosis and epidemiological study of both syndromic and non-syndromic HL.

Macrophages that survive hyperoxia exposure have higher superoxide dismutase activities in their mitochondria.

Prolonged exposure to hyperoxia, which is routinely used in patients with severe respiratory failure, leads to the generation of excessive reactive oxygen species, resulting in lung injury. In the present study, we focused on macrophages and their survival, superoxide dismutase (SOD) activity in mitochondria (Mn-SOD activity), and mitochondrial DNA (mtDNA) mutation after exposure to hyperoxia. Macrophages were cultured under two different conditions: normoxia and intermittent hyperoxia. The number of cells exposed to intermittent hyperoxia for 3 weeks significantly decreased, compared with the number of cells exposed to normoxia. The Mn-SOD activity of the cells that survived intermittent hyperoxia exposure was significantly higher than that of the cells exposed to normoxia. Direct sequencing and a PCR-RFLP assay did not provide any evidence of mutation in the cells that survived intermittent hyperoxia exposure. In conclusion, an increase in the antioxidative activity of mitochondria is important for the survival of macrophages exposed to hyperoxia, and the increased activity level possibly enhances protective effects against mtDNA mutations in surviving cells.

Cytoprotective role of astaxanthin against glycated protein/iron chelate-induced toxicity in human umbilical vein endothelial cells.

Astaxanthin (ASX), a red carotenoid pigment with no pro-vitamin A activity, is a biological antioxidant that occurs naturally in a wide variety of plants, algae and seafoods. This study investigated whether ASX could inhibit glycated protein/iron chelate-induced toxicity in human umbilical-vein endothelial cells (HUVEC) by interfering with ROS generation in these cells. Glycated fetal bovine serum (GFBS) was prepared by incubating fetal bovine serum (FBS) with high-concentration glucose. Stimulation of cultured HUVECs with 50 mm 1 mL of GFBS significantly enhanced lipid peroxidation and decreased antioxidant enzyme activities and levels of phase II enzymes. However, preincubation of the cultures with ASX resulted in a marked decrease in the level of lipid peroxide (LPO) and an increase in the levels of antioxidant enzymes in an ASX concentration-dependent manner. These results demonstrate that ASX could inhibit LPO formation and enhance the antioxidant enzyme status in GFBS/iron chelate-exposed endothelial cells by suppressing ROS generation, thereby limiting the effects of the AGE-RAGE interaction. The results indicate that ASX could have a beneficial role against glycated protein/iron chelate-induced toxicity by preventing lipid and protein oxidation and increasing the activity of antioxidant enzymes.

Association of a polymorphism of the apolipoprotein E gene with chronic kidney disease in Japanese individuals with metabolic syndrome.

The purpose of the present study was to identify genetic variants that confer susceptibility to chronic kidney disease (CKD) in Japanese individuals with metabolic syndrome. The study population comprised 2150 Japanese individuals with metabolic syndrome, including 411 subjects with CKD [estimated glomerular filtration rate (eGFR) <50 mL/min/1.73m(2)] and 1739 controls (eGFR >/=60 mL/min/1.73m(2)). The genotypes for 100 polymorphisms of 80 candidate genes were determined. The chi-square test, multivariable logistic regression analysis with adjustment for covariates, as well as a stepwise forward selection procedure revealed that nine polymorphisms of APOE, ABCA1, PTGS1, TNF, CPB2, AGTR1, OR13G1, and GNB3 were associated (P<0.05) with the prevalence of CKD. Among these polymorphisms, the -219G-->T polymorphism of APOE (rs405509) was most significantly associated with CKD in Japanese individuals with metabolic syndrome.

A randomized phase II trial of cisplatin plus gemcitabine versus carboplatin plus gemcitabine in patients with completely resected non-small cell lung cancer: Hokkaido Lung Cancer Clinical Study Group Trial (HOT0703).

PURPOSE: This study evaluated the efficacy and safety of platinum plus gemcitabine (P/G) combinations as postoperative adjuvant chemotherapies for non-small cell lung cancer. METHODS: Patients with postoperative stage IB-IIIA non-small cell lung cancer were randomly assigned to receive either cisplatin plus gemcitabine (GP arm) or carboplatin plus gemcitabine (GC arm) every 3 weeks for four cycles. The primary endpoint was 2-year disease-free survival (DFS). Secondary endpoints were safety, feasibility, overall survival (OS), and biomarker analyses. RESULTS: A total of 102 patients were randomized (stage IB, 22%; II, 36%; IIIA, 42%; histology: 74% adenocarcinoma). Of the 51 patients in each arm, 37 (73%) completed 4 cycles. During follow-up (median 5.8 years; range 0.1-9.7 years), estimated DFS and OS rates at 2 years were 59.6% and 86.3% with GP and 68.0% and 86.3% with GC, respectively. No significant difference in DFS was noted between arms (P = 0.163), although 3-, 4-, and 5-year DFS rates were higher with GC. Hematological toxic effects were comparable and non-hematological toxic effects were infrequent. DFS was significantly higher in the excision repair cross-complementation group 1 (ERCC1)-low group than in the ERCC1-high group for the GP arm (P = 0.045). CONCLUSION: Both P/G combination regimens were feasible and well-tolerated, and thus may represent valid options for postoperative adjuvant treatment of non-small cell lung cancer. Although no significant differences in DFS were evident between regimens, the present data favor the adoption of GC for further evaluation. CLINICAL TRIAL REGISTRATION: UMIN-CTR ( https://www.umin.ac.jp/ctr/ ) identifier: UMIN000000913.

Association of genetic variants with myocardial infarction in Japanese individuals with chronic kidney disease.

Chronic kidney disease (CKD) is a serious clinical condition that is associated with a high incidence of cardiovascular disease and end-stage renal disease. Although CKD has been recognised as a risk factor for myocardial infarction (MI), genetic factors for predisposition to MI in individuals with CKD have remained largely unknown. The purpose of the present study was to identify genetic variants that confer susceptibility to MI in Japanese individuals with CKD. The study subjects comprised 1,339 Japanese individuals with CKD, including 496 subjects with MI and 843 controls. The genotypes for 248 polymorphisms of 181 candidate genes were determined by a method that combines the polymerase chain reaction and sequence-specific oligonucleotide probes with suspension array technology. An initial screen of allele frequencies by the chi-square test revealed that the 11496G-->A (Arg353Gln) polymorphism of F7 (rs6046) was significantly (false discovery rate <0.05) associated with the prevalence of MI in individuals with CKD. Subsequent multivariable logistic regression analysis with adjustment for covariates and a stepwise forward selection procedure also revealed that this polymorphism was significantly (p <0.005) associated with MI, with the variant A (Gln) allele protecting against this condition. Determination of genotype for the 11496G-->A (Arg353Gln) polymorphism of F7 may prove informative for assessment of the genetic risk for MI in individuals with CKD.

Association of genetic variants with chronic kidney disease in Japanese individuals with type 2 diabetes mellitus.

Although diabetes mellitus has been recognized as a risk factor for chronic kidney disease (CKD), genetic factors for predisposition to CKD in individuals with diabetes mellitus remain elucidated. The purpose of the present study was to identify genetic variants that confer susceptibility to CKD among individuals with type 2 diabetes mellitus. The study population comprised 1742 Japanese individuals, including 636 subjects with CKD [estimated glomerular filtration rate (eGFR)<60 ml/min/1.73 m2] and 1106 controls (eGFR>or=60 ml/min/1.73 m2). The genotypes for 24 polymorphisms of 22 candidate genes were determined. An initial screen of allele frequencies by the Chi-square test revealed that four polymorphisms were significantly (false discovery rate<0.05) associated with the prevalence of CKD in individuals with type 2 diabetes mellitus. Subsequent multivariable logistic regression analysis with adjustment for covariates as well as a stepwise forward selection procedure revealed that the 8733T-->C polymorphism of ALOX5AP (rs3803278), the C-->T (Ser532Leu) polymorphism of IRAK1 (rs1059703), and the 2445G-->A (Ala54Thr) polymorphism of FABP2 (rs1799883) were significantly (P<0.05) associated with the prevalence of CKD. Our results suggest that ALOX5AP, IRAK1, and FABP2 are susceptibility loci for CKD among Japanese individuals with type 2 diabetes mellitus.

Association of gene polymorphisms with chronic kidney disease in high- or low-risk subjects defined by conventional risk factors.

The purpose of the present study was to identify genetic variants which confer susceptibility to chronic kidney disease (CKD) in high- or low-risk subjects defined by conventional risk factors separately. The study population comprised 2828 Japanese individuals, including 434 subjects with CKD [estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m(2)] and 2394 controls (eGFR > or =60 ml/min/ 1.73 m(2)). The 1012 high-risk subjects had both hypertension and diabetes mellitus, and the 1816 low-risk subjects had none of these conditions. The genotypes for 296 polymorphisms of 202 candidate genes were determined. The Chi-square test, multivariable logistic regression analysis with adjustment for covariates, as well as a stepwise forward selection procedure revealed that ten different polymorphisms were associated (P<0.05) with the prevalence of CKD in high- or low-risk subjects: the -519Aright curved arrow G polymorphism of MMP1, the 1061Aright curved arrow G (Ile405Val) polymorphism of CETP, the Aright curved arrow G (Lys45Glu) polymorphism of MMP3, the -219Gright curved arrow T polymorphism of APOE, the Aright curved arrow G (Ile1205Val) polymorphism of COL3A1, the -863Cright curved arrow A polymorphism of TNF, and the 1454Cright curved arrow G (Leu125Val) polymorphism of PECAM1 in high-risk subjects; and the 1167Cright curved arrow T (Asn389Asn) polymorphism of TGFBR2, the 2386Aright curved arrow G (Ile796Val) polymorphism of SCAP, and the TAAAright curved arrow del polymorphism of PDE4D in low-risk subjects. Among these polymorphisms, the -519Aright curved arrow G polymorphism of MMP1 and the 1167Cright curved arrow T (Asn389Asn) polymorphism of TGFBR2 were most significantly associated with CKD in high- or low-risk individuals, respectively. These results suggest that polymorphisms associated with CKD may differ among high- or low-risk subjects. Stratification of subjects according to conventional risk factors may thus be important for personalized prevention of CKD based on genetic information.

Association of genetic variants with chronic kidney disease in individuals with different lipid profiles.

The purpose of the present study was to identify genetic variants that confer susceptibility to chronic kidney disease (CKD) in individuals with low or high serum concentrations of triglycerides (TG), high-density lipoprotein (HDL)-cholesterol, or low-density lipoprotein (LDL)-cholesterol, thereby contributing to the personalized prevention of CKD in such individuals. The study population comprised 5944 Japanese individuals, including 1706 subjects with CKD [estimated glomerular filtration rate (eGFR)<60 ml/min/1.73 m2] and 4238 controls (eGFR>or=60 ml/min/1.73 m2). The genotypes for 296 polymorphisms of 202 candidate genes were determined. The Chi-square test, multivariable logistic regression analysis with adjustment for covariates, and a stepwise forward selection procedure revealed that seven different polymorphisms were significantly (P<0.005) associated with the prevalence of CKD in individuals with low or high serum concentrations of TG or HDL- or LDL-cholesterol: the Aright curved arrow G (Glu23Lys) polymorphism of KCNJ11 and the 125592Cright curved arrow A (Thr431Asn) polymorphism of ROCK2 in individuals with low serum TG; the 734Cright curved arrow T (Thr254Ile) polymorphism of ACAT2 and the Cright curved arrow G (Gln27Glu) polymorphism of ADRB2 in individuals with high serum TG; the -1607/1Gright curved arrow 2G polymorphism of MMP1 in individuals with low serum HDL-cholesterol; the Gright curved arrow A (Val158Met) polymorphism of COMT in individuals with low serum LDL-cholesterol; the 584Gright curved arrow A (Gln192Arg) polymorphism of PON1 in individuals with high serum LDL-cholesterol. No polymorphism was associated with CKD in individuals with high serum HDL-cholesterol. These results suggest that polymorphisms associated with CKD may differ among individuals with different lipid profiles. Stratification of subjects according to lipid profiles may thus be important for personalized prevention of CKD based on genetic information.

[Evaluation of galactomannan antigen and beta-D-glucan value for diagnosis of chronic necrotizing pulmomary aspergillosis].

In order to establish the reliable cut-off value of galactomannan (GM) antigen as well as that for beta-D-glucan for CNPA diagnosis, we conducted the following study. From 2001 to 2008, in a total of 1511 patients we measured GM and anti-aspergillus antibody simultaneously. These patients had chronic pulmonary disease including old tuberculosis, nontuberculous mycobacteriosis, COPD, and had bullous lung, interstitial lung disease or were suspected to have suspected to have interstitial lung disease. We designated cases as probable CNPA when the sample represented a positive anti-aspergillus antibody. We then analyzed the sensitivity and specificity according to various GM antigen values. When using the GM antigen cut-off value at 0.5, the sensitivity and specificity for CNPA were 63.4% and 68.6% respectively. Using 1.0 for cut-off value resulted in the better specificity for CNPA diagnosis. Similar analysis was performed on beta-D-glucan for CNPA diagnosis. When using D-glucan cut-off value as 20 pg/ml, the sensitivity and specificity for CNPA. These results indicate that the cut-off value of serological examination for infectious disease should be considered by the type of disease.

[Mitochondrial genome and longevity].

In humans, mitochondrial DNA (mtDNA) is a 16,569-bp double-stranded circular molecule, encoding 37 genes, and is exclusively transmitted from the mother. According to the recent findings from many studies of mitochondrial diseases caused by nuclear gene mutations, the accumulation of somatic mtDNA mutations in tissues has been expected to contribute toward age-associated mitochondrial dysfunction and a life span.

Women with mitochondrial haplogroup N9a are protected against metabolic syndrome.

To identify mitochondrial haplogroups that confer resistance against or susceptibility to metabolic syndrome, we performed a large-scale association study on 1,337 unrelated Japanese individuals, including 871 subjects with metabolic syndrome and 466 control subjects. Metabolic syndrome was diagnosed according to modified National Cholesterol Education Program Adult Treatment Panel III guidelines, using the cutoff point for obesity as a BMI of >/=25 kg/m(2) instead of waist circumference. The genotypes for 25 polymorphisms in the coding region of the mitochondrial genome were determined, and the haplotypes were classified into 10 major haplogroups, i.e., F, B, A, N9a, M7a, M7b, G1, G2, D5, and D4. Multivariate logistic regression analysis revealed that the haplogroup N9a was significantly associated with resistance against metabolic syndrome in women with an odds ratio (OR) of 0.21 (95% CI 0.07-0.58, P = 0.0042). Women with haplogroups G1 and D5 tended to be resistant against metabolic syndrome with an OR of 0.22 (0.06-0.68, P = 0.0129) for G1 and with an OR of 0.32 (0.10-0.96, P = 0.0469) for D5, respectively. These results indicate that mitochondrial haplogroup N9a may be a protective factor against metabolic syndrome in Japanese women.

Resistin is closely related to systemic inflammation in obstructive sleep apnea.

BACKGROUND: Obstructive sleep apnea (OSA) is closely related to systemic inflammation. Resistin is an adipocyte-derived cytokine (adipokine) that may link obesity with inflammation. OBJECTIVE: We aimed to investigate whether incremental changes in OSA severity, from normal to severe, primarily affect the levels of resistin and other adipokines. METHODS: Serum levels of resistin, interleukin-6 (IL-6) and leptin were examined in 31 men with OSA and 10 men without OSA, matched for age, body mass index (BMI) and several metabolic profiles. In 11 of the 31 men with OSA, these mediators were reexamined after 3 months of nasal continuous airway pressure (nCPAP) therapy. RESULTS: Levels of resistin and IL-6 were simultaneously elevated in men with OSA compared with those in men without OSA (p < 0.05), while levels of leptin did not differ. The resistin and IL-6 levels tended to increase with increasing disease severity (p < 0.05), which was based on the apnea-hypopnea index (AHI). The average oxyhemoglobin saturation during sleep (p < 0.01) and IL-6 (p < 0.05) emerged as significant determinants of resistin, even after adjustments for age, BMI, leptin levels and metabolic risk factors. After nCPAP therapy, the elevated levels of resistin and IL-6 decreased, reaching almost baseline levels of controls. Before treatment, AHI correlated positively with the reduction rate in resistin (p < 0.05). CONCLUSION: In OSA patients, resistin production can be enhanced by hypoxic stress during sleep, possibly mediating systemic inflammatory processes. nCPAP therapy may play a beneficial role in the control of resistin production.

[Analysis of chronic necrotizing pulmonary aspergillosis (CNPA) cases complicated with non-tuberculous mycobacteriosis (NTM)].

OBJECTIVE: To clarify the clinical feature of chronic necrotizing pulmonary aspergillosis (CNPA) complicated with non-tuberculous mycobacteriosis (NTM). SUBJECTS AND METHODS: Forty-one CNPA cases underlying NTM were analyzed according to their clinical backgrounds. RESULTS: Concerning the radiological type of prior NTM, CNPA cases were classified into two groups; 1) resembling pulmonary tuberculosis that usually shows cavitary lesion and 2) micronodule and bronchiectasis pattern, and more than half of cases (61.0%) were classified as the latter type. Average duration between prior NTM and CNPA was 1354 days. Isolation of Aspergillus spp. from sputum was 15 out of 41 (36.6%). Positive rates for Aspergillus galactomannan antigen and anti-aspergillus antibody were 58.5%, 46.3% respectively. With regard to subspecies of mycobacteria, M. avium was most frequent (82.9%). Since 6.8% of NTM cases develop CNPA within 10 years, careful observation of CNPA was required for the management of NTM.

Site-specific somatic mitochondrial DNA point mutations in patients with thymidine phosphorylase deficiency.

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disorder caused by loss-of-function mutations in the gene encoding thymidine phosphorylase (TP). This deficiency of TP leads to increased circulating levels of thymidine (deoxythymidine, dThd) and deoxyuridine (dUrd) and has been associated with multiple deletions and depletion of mitochondrial DNA (mtDNA). Here we describe 36 point mutations in mtDNA of tissues and cultured cells from MNGIE patients. Thirty-one mtDNA point mutations (86%) were T-to-C transitions, and of these, 25 were preceded by 5'-AA sequences. In addition, we identified a single base-pair mtDNA deletion and a TT-to-AA mutation. Next-nucleotide effects and dislocation mutagenesis may contribute to the formation of these mutations. These results provide the first demonstration that alterations of nucleoside metabolism can induce multiple sequence-specific point mutations in humans. We hypothesize that, in patients with TP deficiency, increased levels of dThd and dUrd cause mitochondrial nucleotide pool imbalances, which, in turn, lead to mtDNA abnormalities including site-specific point mutations.