bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of child sexual abuse on mental health
Authors: Spataro Josie , Mullen Paul E. , Burgess Philip M. , Wells David L. , Moss Simon A.
Published: May 2004

Background

The lack of prospective studies and data on male victims leaves major questions regarding associations between child sexual abuse and subsequent psychopathology.

Aims

To examine the association between child sexual abuse in both boys and girls and subsequent treatment for mental disorder using a prospective cohort design.

Method

Children (n=16L2; 1327 female) ascertained as sexually abused at the time had their histories of mental health treatment established by data linkage and compared with the general population of the same age over a specified period.

Results

Both male and female victims of abuse had significantly higher rates of psychiatric treatment during the study period than general population controls (12.4% v. 3.6%). Rates were higher for childhood mental disorders, personality disorders, anxiety disorders and major affective disorders, but not for schizophrenia. Male victims were significantly more likely to have had treatment than females (22.8% v. 10.2%).

Conclusions

This prospective study demonstrates an association between child sexual abuse validated at the time and a subsequent increase in rates of childhood and adult mental disorders.
Impact of compulsory community treatment on admission rates
Authors: Kisely Stephen R. , Xiao Jianguo , Preston Neil J.
Published: May 2004

Background

There is controversy as to whether compulsory community treatment for psychiatric patients reduces hospital admission rates.

Aims

To examine whether community treatment orders (CTOs) reduce admission rates, using a two-stage design of matching and multivariate analyses to take into account socio-demographic factors, clinical factors, case complexity and previous psychiatric and forensic history.

Method

Survival analysis of CTO cases and controls from three linked Western Australian databases of health service use, involuntary treatment and forensic history. We used two control groups: one matched on demographic characteristics, diagnosis, past psychiatric history and treatment setting, and consecutive controls matched on date of discharge from in-patient care.

Results

We matched 265 CTO cases with 265 matched controls and 224 consecutive controls (totaln=754). The CTO group had a significantly higher readmission rate: 72%v.65% and 59% for the matched and consecutive controls (log-rank χ2=4.7,P=0.03). CTO placement, aboriginal ethnicity, younger age, personality disorder and previous health service use were associated with increased admission rates.

Conclusions

Community treatment orders alone do not reduce admissions.
Comparison of liaison psychiatry service models for older patients
Authors: Mujic Fedza , Hanlon Charlotte , Sullivan Danny , Waters Gina , Prince Martin
Published: May 2004

Aims and Method

At a London teaching hospital, the existing off-site consultation model psychiatric liaison service for older people was replaced with an on-site liaison model service in December 2000. Several indicators of the functioning of the service were audited using identical methods before and after this change.

Results

The case-load increased by 50%, but the liaison psychiatrists were more satisfied with the appropriateness of referrals. The case mix did not change. The new service achieved target waiting times more consistently, particularly for urgent referrals. Referring teams were more satisfied with the speed of response, while the new service maintained the salience and clarity of advice.

Clinical Implications

Findings are on the whole favourable, and support the wider introduction of specialist old-age liaison psychiatric services.
Work-related mental ill health and development of the Surveillance of Occupational Stress and Mental Illness (SOSMI) reporting scheme
Authors: Agius Raymond , Turner Susan
Published: May 2004

This paper describes a systematic, voluntary and confidential reporting scheme of new cases of occupational stress and mental illness in the UK (SOSMI). This scheme was designed to gather information on specific types and frequency of ill health seen by consultants within the specialty of psychiatric and psychological medicine. Information obtained from reporting schemes such as SOSMI is crucial in the recognition, understanding and prevention of work-related diseases, as this might come to the attention of specialists long after the patient has left the workplace responsible for the illness.
Mitochondrial Genome Single Nucleotide Polymorphisms and Their Phenotypes in the Japanese
Authors: TANAKA MASASHI , TAKEYASU TAKESHI , FUKU NORIYUKI , LI‐JUN GUO , KURATA MIYUKI
Published: May 2004

Abstract: Polymorphisms in the human mitochondrial genome have been used for the elucidation of phylogenetic relationships among various ethnic groups. Because analysis by mitochondrial genetics has detected pathogenic mutations causing mitochondrial encephalomyopathy or cardiomyopathy, most of the mitochondrial single nucleotide polymorphisms (mtSNPs) found in control subjects have been regarded as merely normal variants. However, we cannot exclude the possibility that the mitochondrial functional differences among individuals are ascribable at least in part to the mtSNPs of each individual. Human lifespan in ancient history was much shorter than that at the present time. Therefore, it is reasonable to speculate that certain mtSNPs that predispose one toward susceptibility to adult‐ or elderly‐onset diseases, such as Parkinson's disease and Alzheimer's disease, have never been a target for natural selection in the past. Similarly, thrifty mtSNPs that had been advantageous for survival under severe famine or cold climate conditions might turn out to be related to satiation‐related diseases, such as diabetes mellitus and obesity. To examine these hypotheses, we have constructed a mtSNP database by sequencing the entire mitochondrial genomes of 672 subjects: 96 in each of seven groups (i.e., centenarians, young obese or non‐obese subjects, diabetic patients with or without major vascular involvement, patients with Parkinson's disease, and those with Alzheimer's disease).
Mitochondrial DNA Variation in the Aboriginal Populations of the Altai‐Baikal Region: Implications for the Genetic History of North Asia and America
Authors: ZAKHAROV ILIA A. , DERENKO MIROSLAVA V. , MALIARCHUK BORIS A. , DAMBUEVA IRINA K. , DORZHU CHODURAA M. , RYCHKOV SERGEY Y.
Published: May 2004

Abstract: The discovery of mtDNA types common to Asians and Amerinds (types A, B, C, and D) forced investigators to search for those nations of Asia which, though not considered the ancestors of the Amerinds, have retained a close genetic resemblance with them. We collected samples and studied the gene pools of the Turkic‐speaking nations of South Siberia: Altaians, Khakassians, Shorians, Tuvinians, Todjins, Tofalars, Sojots, as well as Mongolian‐speaking Buryats. The data indicate that nearly all Turkic‐speaking nations of Siberia and Central Asia, as well as the Buryats, have types A, B, C, and D in their gene pool. The highest total frequency of these types is observed in the Tuvinians and Sojots. They, as well as the Buryats, also have the lowest frequency of the europeoid types. The most mixed Asian‐Europeoid gene pool examined turned out to be that of the Shorians. An important finding was the presence of type X in the Altaians, which had not yet been detected in Asia. As shown by computer analysis, this DNA sequence is not a late European admixture. Rather, the Altai variant X is ancient and can be close to the ancestral form of the variants of contemporary Europeans and Amerinds. The presented results prove that of all nations in Asia, the Turkic‐speaking nations living between Altai and Baikal along the Sayan mountains are genetically closest to the Amerinds.
Mitochondrial ALDH2 Deficiency as an Oxidative Stress
Authors: OHTA SHIGEO , OHSAWA IKUROH , KAMINO KOUZIN , Ando FUJIKO , SHIMOKATA HIROSHI
Published: May 2004

Abstract: Mitochondrial aldehyde dehydrogenase 2 (ALDH2) plays a major role in ethanol metabolism. It is involved in acetaldehyde detoxification. A polymorphism of the ALDH2 gene is specific to North‐East Asians. Sensitivity to ethanol is highly associated with this polymorphism (ALDH2*2 allele), which is responsible for a deficiency of ALDH2 activity. We first show that this deficiency influences the risk for late‐onset Alzheimer's disease (LOAD) by a case‐control study in a Japanese population. In a comparison of 447 patients with sex, age, and region‐matched non‐demented controls, the genotype frequency for the ALDH2*2 allele was significantly higher in the patients than in the controls (P=0.001). Next, we examined the combined effect of the ALDH2*2 and the apolipoprotein E4 allele (APOE‐ε4), which has been confirmed to be a risk factor for LOAD. The ALDH2*2 allele more significantly affected frequency and age at onset in patients with APOE‐ε4 than in those without it. These results indicate that the ALDH2 deficiency is a risk factor for LOAD, acting synergistically with the APOE‐ε allele. Next, to elucidate the molecular mechanism involved, we obtained ALDH2‐deficient cell lines by introducing mouse mutant ALDH2 cDNA into PC12 cells. We speculate that ALDH2 may act to oxidize toxic aldehyde derivatives. Then, we found that the ALDH2‐deficient transfectants were highly vulnerable to exogenous 4‐hydroxy‐2‐nonenal, an aldehyde derivative generated from peroxidized fatty acids. In addition, the ALDH2‐deficient transfectants were sensitive to oxidative insult induced by antimycin A, accompanied by an accumulation of proteins modified with 4‐hydroxy‐2‐nonenal. Mitochondrial ALDH2 functions as a protector against oxidative stress.
Mitochondrial Reactive Oxygen Species Generation and Calcium Increase Induced by Visible Light in Astrocytes
Authors: JOU MEI‐JIE , JOU SHUO‐BIN , GUO MEI‐JIN , WU HONG‐YUEH , PENG TSUNG‐I
Published: May 2004

Abstract: Mitochondria contain photosensitive chromophores that can be activated or inhibited by light in the visible range. Rather than utilizing light energy, however, mitochondrial electron transport oxidation‐reduction reaction and energy coupling could be stimulated or damaged by visible light. Our previous work demonstrated that reactive oxygen species (ROS) were generated in cultured astrocytes after visible laser irradiation. With confocal fluorescence microscopy, we found that ROS were generated mostly from mitochondria. This mitochondrial ROS (mROS) formation plays a critical role in photoirradiation‐induced phototoxicity and apoptosis. In this study, we measured changes of mitochondrial calcium level ([Ca2+]m) in cultured astrocytes (RBA‐1 cell line) irradiated with blue light and examined the association between mROS formation and [Ca2+]m level changes. Changes of intracellular ROS and [Ca2+]m were visualized using fluorescent probes 2′,7′‐dichlorodihydrofluorescein (DCF), and rhod‐2 After exposure to visible light irradiation, RBA‐1 astrocytes showed a rapid increase in ROS accumulation particularly in the mitochondrial area. Increase in [Ca2+]m was also induced by photoirradiation. The levels of increase in DCF fluorescence intensity varied among different astrocytes. Some of the cells generated much higher levels of ROS than others. For those cells that had high ROS levels, mitochondrial Ca2+ levels were also high. In cells that had mild ROS levels, mitochondrial Ca2+ levels were only slightly increased. The rate of increase in DCF fluorescence seemed to be close to the rate of rhod‐2 fluorescence increase. There is a positive and close correlation between mitochondrial ROS levels and mitochondrial Ca2+ levels in astrocytes irradiated by visible light.
Radical Metabolism Is Partner to Energy Metabolism in Mitochondria
Authors: XU JIAN‐XING
Published: May 2004

Abstract: It has been shown that cytochrome c plays a role in scavenging O2−. and H2O2 in mitochondria through two electron leak pathways of the respiratory chain. Based on the two electron leak pathways and the superoxide metabolic routes in nature, it is suggested that the concept of radical metabolism should be added as a partner to the energy metabolism of mitochondria. A total of four reactive pathways of superoxide anion have been identified, collected, and linked to electron leaks in the respiratory chain. A view is presented that envisions mitochondria working on ATP synthesis by means of transferring electrons inside the respiratory chain while at the same time working on ROS generation and elimination as electrons leak out of the chain.
Mitochondrial Nucleoid and Transcription Factor A
Authors: KANKI TOMOTAKE , NAKAYAMA HIROSHI , SASAKI NARIE , TAKIO KOJI , ALAM TANFIS ISTIAQ , HAMASAKI NAOTAKA , KANG DONGCHON
Published: May 2004

Abstract: Nuclear DNA is tightly packed into nucleosomal structure. In contrast, human mitochondrial DNA (mtDNA) had long been believed to be rather naked because mitochondria lack histone. Mitochondrial transcription factor A (TFAM), a member of a high mobility group (HMG) protein family and a first‐identified mitochondrial transcription factor, is essential for maintenance of mitochondrial DNA. Abf2, a yeast counterpart of human TFAM, is abundant enough to cover the whole region of mtDNA and to play a histone‐like role in mitochondria. Human TFAM is indeed as abundant as Abf2, suggesting that TFAM also has a histone‐like architectural role for maintenance of mtDNA. When human mitochondria are solubilized with non‐ionic detergent Nonidet‐P40 and then separated into soluble and particulate fractions, most TFAM is recovered from the particulate fraction together with mtDNA, suggesting that human mtDNA forms a nucleoid structure. TFAM is tightly associated with mtDNA as a main component of the nucleoid.
Regulation of Mitochondrial Transcription Factor A Expression by High Glucose
Authors: CHOI YON SIK , LEE KI‐UP , PAK YOUNGMI KIM
Published: May 2004

Abstract: Mitochondrial transcription factor A (Tfam, previously mtTFA) is a key regulator of mitochondrial DNA (mtDNA) transcription and replication. We have reported that overexpression of nuclear respiratory factor‐1 (NRF‐1) and high concentration (50 mM) of glucose increased the promoter activity of the rat Tfam in L6 rat skeletal muscle cells. In this study, we investigated the mechanism of high glucose‐induced Tfam transactivation. The addition of 50 mM glucose for 24 h increased Tfam promoter activity up to twofold. The glucose‐induced Tfam expression was dose‐dependent and cell‐type specific. Glucose increased the Tfam promoter‐driven transactivity in L6 (skeletal muscle), HIT (pancreatic beta‐cell), and CHO (ovary) cells, but not in HepG2 (hepatoma), HeLa, and CV1 (kidney) cells. Among various monosaccharides, only glucose and fructose increased the Tfam promoter activity. Oxidative stress might not be involved in glucose‐induced Tfam expression since treatment with antioxidants such as vitamin C, vitamin E, probucol, or α‐lipoic acid did not suppress the induction. None of the inhibitors of protein kinase C, MAP kinase, and PI3 kinase altered the glucose‐induced Tfam promoter activity, suggesting that general phosphorylation is involved in its signaling. However, a dominant negative mutant of NRF‐1, in which 200 amino acids of C‐terminus were truncated, completely suppressed the glucose‐induced Tfam induction. It was concluded that high glucose‐induced Tfam transcription in L6 cells might be mediated by NRF‐1.
Regulation and Role of the Mitochondrial Transcription Factor in the Diabetic Rat Heart
Authors: NISHIO YOSHIHIKO , KANAZAWA AKIO , NAGAI YOSHIO , INAGAKI HIDETOSHI , KASHIWAGI ATSUNORI
Published: May 2004

Abstract: To clarify the mechanism of abnormalities in mitochondrial expression and function in diabetic rat heart, we have studied the transcriptional activities of mitochondrial DNA using isolated intact mitochondria from the heart of either diabetic or control rats. The transcriptional activity of cardiac mitochondria isolated from diabetic rats decreased to 40% of the control level (P < 0.01. Consistently, in the heart of diabetic rats, the content of cytochrome b mRNA encoded by mitochondrial DNA was reduced to 50% of control (P < 0.01. This abnormal transcriptional activity of mitochondrial DNA could not be explained by mRNA or protein contents of mitochondrial transcription factor (mtTFA), but mtTFA binding to the promoter sequence of mitochondrial DNA, assessed by gel‐shift assay, was attenuated in diabetic rats. In contrast, the mRNA expression of nuclear‐encoded mitochondrial genes, such as ATP synthase‐β, was not affected by diabetes. Although O2 consumption of the mitochondria from diabetic rats was decreased, H2O2 production in these rats was increased compared with the control. Insulin treatment reversed all the abnormalities found in diabetic rats. These results clearly indicate that an impairment of binding activity of mtTFA to the promoter sequence has a key role in the abnormal mitochondrial gene expression, which might explain the mitochondrial dysfunction found in diabetic heart.
The Mitochondrial Production of Reactive Oxygen Species in Relation to Aging and Pathology
Authors: GENOVA MARIA LUISA , PICH MILENA MERLO , BERNACCHIA ANDREA , BIANCHI CRISTINA , BIONDI ANNALISA , BOVINA CARLA , FALASCA ANNA IDA , FORMIGGINI GABRIELLA , CASTELLI GIOVANNA PARENTI , LENAZ GIORGIO
Published: May 2004

Abstract: Mitochondria are known to be strong producers of reactive oxygen species (ROS) and, at the same time, particularly susceptible to the oxidative damage produced by their action on lipids, proteins, and DNA. In particular, damage to mtDNA induces alterations to the polypeptides encoded by mtDNA in the respiratory complexes, with consequent decrease of electron transfer, leading to further production of ROS and thus establishing a vicious circle of oxidative stress and energetic decline. This deficiency in mitochondrial energetic capacity is considered the cause of aging and age‐related degenerative diseases. Complex I would be the enzyme most affected by ROS, since it contains seven of the 13 subunits encoded by mtDNA. Accordingly, we found that complex I activity is significantly affected by aging in rat brain and liver mitochondria as well as in human platelets. Moreover, due to its rate control over aerobic respiration, such alterations are reflected on the entire oxidative phosphorylation system. We also investigated the role of mitochondrial complex I in superoxide production and found that the one‐electron donor to oxygen is most probably the Fe‐S cluster N2. Short chain coenzyme Q (CoQ) analogues enhance ROS formation, presumably by mediating electron transfer from N2 to oxygen, both in bovine heart SMP and in cultured HL60 cells. Nevertheless, we have accumulated much evidence of the antioxidant role of reduced CoQ10 in several cellular systems and demonstrated the importance of DT‐diaphorase and other internal cellular reductases to reduce exogenous CoQ10 after incorporation.
Biological Significance of the Defense Mechanisms against Oxidative Damage in Nucleic Acids Caused by Reactive Oxygen Species: From Mitochondria to Nuclei
Authors: NAKABEPPU YUSAKU , TSUCHIMOTO DAISUKE , ICHINOE AKIMASA , OHNO MIZUKI , IDE YASUHITO , HIRANO SEIKI , YOSHIMURA DAISUKE , TOMINAGA YOHEI , FURUICHI MASATO , SAKUMI KUNIHIKO
Published: May 2004

Abstract: In mammalian cells, more than one genome in a single cell has to be maintained throughout the entire life of the cell, namely, one in the nucleus and the other in the mitochondria. The genomes and their precursor nucleotides are highly exposed to reactive oxygen species, which are inevitably generated as a result of the respiratory function in mitochondria. To counteract such oxidative damage in nucleic acids, cells are equipped with several defense mechanisms. Modified nucleotides in the nucleotide pools are hydrolyzed, thus avoiding their incorporation into DNA or RNA. Damaged bases in DNA with relatively small chemical alterations are mainly repaired by the base excision repair (BER) system, which is initiated by the excision of damaged bases by specific DNA glycosylases. MTH1 protein hydrolyzes oxidized purine nucleoside triphosphates, such as 8‐oxo‐dGTP, 8‐oxo‐dATP, and 2‐hydroxy (OH)‐dATP to the monophosphates, and MTH1 are located in the cytoplasm, mitochondria, and nucleus. We observed an increased susceptibility to spontaneous carcinogenesis in Mth1‐deficient mice and an alteration of MTH1 expression along with the accumulation of 8‐oxo‐dG in patients with various neurodegenerative diseases. Enzymes for the BER pathway, namely, 8‐oxoG DNA glycosylase (OGG1), 2‐OH‐A/adenine DNA glycosylase (MUTYH), and AP endonuclease (APEX2) are also located both in the mitochondria and in the nuclei, and the expression of mitochondrial OGG1 is altered in patients with various neurodegenerative diseases. We also observed increased susceptibilities to spontaneous carcinogenesis in OGG1 and MUTYH‐deficient mice. The increased occurrence of lung tumor in OGG1‐deficient mice was completely abolished by the concomitant disruption of the Mth1 gene.
Mitochondrial Swelling and Generation of Reactive Oxygen Species Induced by Photoirradiation Are Heterogeneously Distributed
Authors: PENG TSUNG‐I , JOU MEI‐JIE
Published: May 2004

Abstract: Abundant evidence has been gathered to show that overproduction of reactive oxygen species (ROS) can lead to the opening of the mitochondrial permeability transition pore (MPTP) and result in apoptosis in mammalian cells. The information regarding spatial and temporal regulation of intracellular ROS formation related to the MPTP opening, however, is relatively limited. In this study, we used a fluorescent probe, dihydro‐2′,7′‐dichloroforescin (DCF), to detect intracellular ROS levels in different compartments of the cell in a time‐resolved manner. The roles of mitochondrial ROS (mROS) in the MPTP opening and mitochondrial membrane potential drop were investigated by using H2DCFDA coloaded with a mitochondrial marker dye MitoTracker Red, and by a mitochondrial membrane potential dye tetramethyl rhodamine ethyl ester. We applied multiphoton laser scanning microscopy to avoid autooxidation and bleaching of DCF so that long‐term visualization of intracellular ROS formation could be performed. Moreover, we noted that the resting mROS levels of different mitochondria were not homogeneous. After cells had been exposed to photoirradiation, the intracellular ROS gradually increased but the heterogeneity of mROS was maintained. Later, swelling was observed in mitochondria that contained higher levels of ROS, indicating the opening of the MPTP. In cells in which all the mitochondria swelled, they were translocated to the perinuclear area, which became the site of ROS production. At this stage, mROS reached the highest level concomitantly with a complete loss of mitochondrial membrane potential, indicating full opening of the MPTP. At the end, photoirradiation resulted in apoptotic cell death. In summary, we demonstrated by multiphoton laser scanning microscopy that photoirradiation induces heterogeneous intracellular ROS formation and mitochondrial permeability transition pore opening in single intact cells. These observations imply the existence of a microdomain in the regulation of mROS formation and subsequent opening of the MPTP.
Mitochondrial Dysfunction via Disruption of Complex II Activity during Iron Chelation—Induced Senescence‐like Growth Arrest of Chang Cells
Authors: YOON YOUNG‐SIL , CHO HYESEONG , LEE JAE‐HO , YOON GYESOON
Published: May 2004

Abstract: When cells are deprived of iron, their growth is invariably inhibited. However, the mechanism involved remains largely unclear. Recently, we have reported that subcytotoxic concentration of deferoxamine mesylate (DFO), an iron chelator, specifically inhibited transition of Chang cell, a normal hepatocyte cell line, from G1 to S phase, which was accompanied by irreversible appearance of senescent biomarkers. To investigate factors responsible for the irreversible arrest, we examined mitochondrial activities because they require several irons for their proper structure and function. After exposure to 1 M DFO, total cellular ATP level was irreversibly decreased with concurrent disruption of mitochondrial membrane potential (ΔΨm), implying that it might be one of the crucial factors involved in the arrest. DFO did not directly inhibit the mitochondrial respiratory activities in vitro. Among the respiratory activities, complex II activity was specifically inhibited through a down‐regulation of the expression of its iron‐sulfur subunit. We also observed that mitochondrial morphology was drastically changed to highly elongated form. Our results suggest that mitochondrial function is sensitive to cellular iron level and iron deprivation might be involved in inducing the senescent arrest. In addition, complex II, which is a part of both oxidative phosphorylation and the Krebs cycle, could be one of the critical factors that regulate mitochondrial function by responding to iron levels.
Mitochondrial DNA Mutation and Depletion Increase the Susceptibility of Human Cells to Apoptosis
Authors: LIU CHUN‐YI , LEE CHENG‐FENG , HONG CHIUNG‐HUI , WEI YAU‐HUEI
Published: May 2004

Abstract: Mitochondrial diseases, such as MELAS, MERRF, and CPEO syndromes, are associated with specific point mutations or large‐scale deletions of mitochondrial DNA (mtDNA), which impair mitochondrial respiratory functions and result in decreased production of ATP in affected tissues. Recently, mitochondria have been recognized to act as key players in the regulation of cell death. To investigate whether a pathogenic mutation of mtDNA exerts any effect on the process of apoptosis of human cells, we constructed a series of cybrid human cells harboring different proportions of mtDNA with the A3243G or the A8344G transition, or with the 4,977‐bp deletion, by cytoplasmic fusion of patients' skin fibroblasts with mtDNA‐depleted ρ0 cells of an immortal human osteosarcoma cell line (143B). We observed that the decrease in cell viability upon staurosporine treatment or exposure to ultraviolet (UV) irradiation was more pronounced in the cybrids harboring high levels of mutated mtDNA compared with the control cybrids. Using DNA fragmentation analysis, we found that the cell death induced by treatment with 100 nM staurosporine or by exposure to UV irradiation at 20 J/m2 was caused by apoptosis, not necrosis. Moreover, we demonstrated activation of caspase 3 by Western blot and enhanced release of cytochrome c after 100 nM staurosporine treatment or 20 J/m2 UV irradiation of the cybrids harboring high levels of the three mtDNA mutations. Furthermore, as compared with parental osteosarcoma 143B cells, the ρ0 cells were found to be more susceptible to apoptosis, which was accompanied by caspase 3 activation and cytochrome c release. This indicates that mtDNA plays an important role in the regulation of apoptosis in human cells. Taken together, these findings suggest that mutation and depletion of mtDNA increase the susceptibility of human cells to apoptosis triggered by exogenous stimuli such as UV irradiation or staurosporine.
Resistance of ρ0 Cells against Apoptosis
Authors: LEE MYUNG‐SHIK , KIM JA‐YOUNG , PARK SUN YOUNG
Published: May 2004

Abstract: Mitochondrion is one of the master players in both apoptosis and necrosis. However, most previous articles report that mitochondrial DNA‐depleted cells without oxidative phosphorylation underwent apoptosis by several apoptotic effectors as efficiently as their parental cells, suggesting that intact mitochondrial function is dispensable for the progression of apoptosis. We studied the role of mitochondrial function in several apoptosis models. TRAIL, a recently identified member of the TNF family with cytotoxicity on a wide variety of transformed cells, killed SK‐Hep1 cells with characteristic features of apoptosis such as DNA fragmentation, sub‐G1 ploidy peak, and cytochrome c translocation. In contrast with parental cells, mitochondrial DNA‐deficient SK‐Hep1 ρ0 cells were resistant to TRAIL‐induced apoptosis. Dissipation of mitochondrial potential or cytochrome c translocation did not occur in ρ0 cells after TRAIL treatment. Bax translocation also was absent in ρ0 cells, accounting for the failure of cytochrome c release in ρ0 cells. SK‐Hep1 ρ0 cells were resistant to other death effectors such as staurosporine. Our results indicate that apoptosis of SK‐Hep1 hepatoma cells is dependent on intact mitochondrial function. Because aged cells or tumor cells have frequent mutations or deletions of mitochondrial DNA, they might acquire the ability to evade apoptosis or tumor surveillance imposed by TRAIL or other death effectors in vivo, accounting for the selection advantage of cancer cells and frequent development of cancer in aged individuals.
Mitochondrial DNA 4,977‐bp Deletion in Paired Oral Cancer and Precancerous Lesions Revealed by Laser Microdissection and Real‐Time Quantitative PCR
Authors: SHIEH DAR‐BIN , CHOU WEN‐PIN , WEI YAU‐HUEI , WONG TONG‐YIU , JIN YING‐TAI
Published: May 2004

Abstract: Oral cancer is the fourth leading cause of cancer deaths among men in Taiwan and is closely associated with areca quid chewing habits. Recent studies showed that mitochondrial DNA (mtDNA) mutations occur in various tumors, including oral cancers, and that the accumulation of mtDNA deletions could be an important contributor to carcinogenesis. Using laser microdissection, we have analyzed mtDNA deletions by pairwise comparisons in oral cancer, precancerous cells, and their adjacent submucosal stoma tissues in 12 patients with areca quid chewing history. Real‐time quantitative polymerase chain reaction (RTQPCR) was performed to detect and quantify mtDNA with the 4,977‐bp deletion in the histologically defined specified cell groups. Quantitative analysis of 60 samples by RTQPCR revealed that the average proportions of 4,977‐bp deleted mtDNA over total mtDNA were 0.137%, 0.367%, and 0.001% in cancer, precancer cells, and lymphocytes of lymph node biopsies, respectively. Pairwise analysis of the proportion of mtDNA deletion in cancer, precancer, and their stroma tissues revealed a consistent trend among these patients. All of the patients (12/12) presented a higher proportion of mtDNA with 4,977‐bp deletion in the lesions than in the lymphocytes, with average increases of 198‐fold in cancer and 546‐fold in precancer cells. A decrease in the proportion of deleted mtDNA was observed in 8 of 12 patients when the disease progressed from precancer to cancer lesions. Interestingly, 7 of 12 cancer tissues and 8 of 12 precancer lesions exhibited an average of 6.3‐fold and 17.4‐fold increases in the proportion of 4,977‐bp deleted mtDNA in the stromal cells than in the lesion cells, respectively. The observation that the proportion of 4,977‐bp deleted mtDNA in all oral lesions was higher than normal and consistently decreased during cancer progression from precancer to primary cancer suggests that accumulation and subsequent cytoplasmic segregation of the mutant mtDNA during cell division may play an important role in oral carcinogenesis. This study also demonstrates that laser microdissection combined with RTQPCR is an efficient and sensitive tool to gain insight into the role that mtDNA mutation may play in carcinogenesis.
Role of Oxidative Stress in Pancreatic β‐Cell Dysfunction
Authors: KAJIMOTO YOSHITAKA , KANETO HIDEAKI
Published: May 2004

Abstract: Oxidative stress is produced under diabetic conditions and is likely involved in progression of pancreatic β‐cell dysfunction found in diabetes. Possibly caused by low levels of antioxidant enzyme expressions, pancreatic β‐cells are vulnerable to oxidative stress. When β‐cell‐derived HIT‐T15 cells or isolated rat islets were exposed to oxidative stress, insulin gene expression was markedly decreased. To investigate the significance of oxidative stress in the progression of pancreatic β‐cell dysfunction in type 2 diabetes, we evaluated the effects of antioxidants in diabetic C57BL/KsJ‐db/db mice. According to an intraperitoneal glucose tolerance test, the treatment with antioxidants retained glucose‐stimulated insulin secretion and moderately decreased blood glucose levels. Histological analyses of the pancreata revealed that the β‐cell mass was significantly larger in the mice treated with the antioxidants, and the antioxidant treatment suppressed apoptosis in β‐cells without changing the rate of β‐cell proliferation. The antioxidant treatment also preserved the amounts of insulin content and insulin mRNA, making the extent of insulin degranulation less evident. As possible mechanism underlying the phenomena, expression of pancreatic and duodenal homeobox factor‐1 (also known as IDX‐1/STF‐1/IPF1), an important transcription factor for the insulin gene, was more clearly visible in the nuclei of islet cells after the antioxidant treatment. Under diabetic conditions, JNK is activated by oxidative stress and involved in the suppression of insulin gene expression. This JNK effect appears to be mediated in part by nucleocytoplasmic translocation of PDX‐1, which is also downstream of JNK activation. Taken together, oxidative stress and consequent activation of the JNK pathway are involved in progression of β‐cell dysfunction found in diabetes. Antioxidants may serve as a novel mechanism‐based therapy for type 2 diabetes.
Initiation of Apoptotic Signal by the Peroxidation of Cardiolipin of Mitochondria
Authors: NAKAGAWA YASUHITO
Published: May 2004

Abstract: Overexpression of phospholipid hydroperoxide glutathione peroxidase (PHGPx) in mitochondria of RBL2H3 cells (M15 cells) prevented the release of cytochrome c (cyt.c), the activation of caspase‐3, and apoptosis caused by 2‐deoxyglucose (2DG), whereas cells overexpressing nonmitochondrial PHGPx(L9) and control (S1) cells were induced to apoptosis. Hydro‐peroxide levels in mitochondria of L9 and S1 cells were significantly enhanced by 2DG‐induced apoptosis. In contrast, generation of hydroperoxide in mitochondria was protected in M15 cells, which also showed resistance to apoptosis by etoposide, staurosporine, UV irradiation, cycloheximide, and actinomycin D, stimuli that induce apoptosis by the liberation of cyt.c from mitochondria. Cyt.c preferentially binds to the monolayer of cardiolipin (CL), the specific phospholipid of the inner membrane of mitochondria. The amount of cyt.c bound to the monolayer of cardiolipin hydroperoxide (CL‐OOH) was much lower than that bound to CL. Cyt.c bound to liposome containing CL was released by peroxidation with a radical initiator. Adenine nucleotide translocator (ANT), which regulates the opening and closing the permeability transition (PT) pore, potentially was inactivated in apoptosis‐induced S1 cells 4 h after the addition of 2DG, coincidentally with cyt.c release from mitochondria. ANT activity was suppressed by the fusion of isolated mitochondria with liposomes containing CL‐OOH. ANT activity was expressed in proteoliposomes containing 10% CL, but it was competitively inhibited by the addition of CL‐OOH. This study suggests that CL peroxidation might have an initiating role in the liberation of cyt.c from the inner membrane, and in the opening of the PT pore via inactivation of ANT. Mitochondrial PHGPx might play a role as an anti‐apoptotic factor by protecting CL and reducing CL‐OOH.
Diabetes Mellitus with Mitochondrial Gene Mutations in Japan
Authors: SUZUKI SUSUMU
Published: May 2004

Abstract: Diabetes mellitus due to the mitochondrial DNA 3243(A‐G) mutation is reported to represent 0.5‐1% of the general diabetic population in Japan. To further elucidate the clinical symptoms and course of diabetes mellitus with the 3243 mutation, we undertook a nationwide cross‐sectional case‐finding study and observational study of a genetically defined subject group. One hundred sixteen Japanese diabetic patients with the mutation were registered and analyzed. The patients had a higher maternal inheritance of diabetes or deafness, short stature, thin habitus, and early middle‐aged onset of diabetes or deafness. Eighty‐six percent of the patients required insulin therapy because of progressive insulin secretory defect. Although half of the patients had the phenotype of type 1 diabetes or slowly progressive type 1 diabetes, the patients lacked the presence of autoantibodies to glutamic acid decarboxylase. Diabetes in the mothers was characterized by early middle‐aged onset, reduction in the insulin secretory capacity, early requirement of insulin therapy, and increases in the daily insulin dose. The heteroplasmic ratio of the 3243 mutation in leukocytes was low. The patients had mitochondria‐related complications such as sensorineural deafness, cardiomyopathy, cardiac conductance disorders, encephalomyopathy, macular pattern dystrophy, and mental disorders. The patients also had advanced microvascular complications. Thus, this study has revealed that (1) diabetes mellitus with the 3243 mutation is a subtype of diabetes mellitus with mitochondria‐related complications and (2) insulin secretory ability is more severely impaired in the patients whose mothers were also diabetic.
Accumulation of Somatic Mutation in Mitochondrial DNA and Atherosclerosis in Diabetic Patients
Authors: NOMIYAMA TAKASHI , TANAKA YASUSHI , PIAO LIANSHAN , HATTORI NOBUTAKA , UCHINO HIROSHI , WATADA HIROTAKA , KAWAMORI RYUZO , OHTA SHIGEO
Published: May 2004

Abstract: A point mutation of mitochondrial DNA at nucleotide position 3243 A to G is responsible for the genetic cause of diabetes. Otherwise, this mutation is also reported to occur as a somatic mutation, possibility because of oxidative stress. Because diabetes may cause oxidative stress, we hypothesized that accumulation of the somatic A3243G mutation in mitochondrial DNA may be accelerated by diabetes. DNA was extracted from blood samples of 290 nondiabetic healthy subjects (aged 0‐60 years) and from 383 type 2 diabetic patients (aged 18‐80 years). Then, the extent of somatic A3243G mutation in total mitochondrial DNA was detected by real‐time polymerase chain reaction (PCR) using the TaqMan probe. The genotyping of ACE I/D or p22phox C242T was done by PCR or PCR‐restriction fragment length polymorphism. Although the level of the A3243G mutation was negligible in the newborn group, it increased in healthy subjects aged 20‐29 and 41‐60 years. In diabetic patients, the mutational rate increased along with age and the duration of diabetes. In the middle‐aged group (41‐60 years old), the A3243G mutation accumulates fourfold higher in the diabetic patients than in the healthy subjects. Moreover, multiple regression analysis revealed that the most critical factor associated with this mutation in diabetic patients was the duration of diabetes. Furthermore, the genotype of DD, DI‐CC (ACE‐p22phox) has the highest mutational rate and the thickest intima‐media thickness of the carotid artery. In conclusion, diabetes accelerates the accumulation of the somatic A3243G mutation in mitochondrial DNA, and this somatic mutation may be a marker for the duration of diabetes and atherosclerosis.
Changes of Mitochondrial DNA Content in the Male Offspring of Protein‐Malnourished Rats
Authors: PARK HYEONG KYU , JIN CHENG JI , CHO YOUNG MIN , PARK DO JOON , SHIN CHAN SOO , PARK KYONG SOO , KIM SEONG YEON , CHO BO YOUN , LEE HONG KYU
Published: May 2004

Abstract: Nutritional deprivation of the fetus and infant is associated with susceptibility to the development of impaired glucose tolerance or type 2 diabetes in adult life. Quantitative changes in mitochondrial DNA (mtDNA) seem to be associated with type 2 diabetes, but the effect of protein malnutrition on mtDNA content is not known. This study investigated the effects of protein malnutrition in fetus and early life on mtDNA content and glucose‐insulin metabolism in adult life. Male offspring of dams fed a low‐protein (LP) diet (8% casein) during pregnancy and lactation were weaned onto either a control (18% casein) diet (recuperated group, R) or a LP diet, and they were compared with the control group (C). The mtDNA content in the liver was lower in the R and LP groups than in the C group at 5 weeks of age, but higher in the R and LP groups than in the C group at 15 weeks of age. The mtDNA content in skeletal muscle and pancreas was significantly lower in the R and LP groups than in the C group at 25 weeks of age. Fetal‐malnourished rats showed decreased pancreatic β‐cell mass and reduced insulin secretory responses to glucose load, but no differences in glucose tolerance or insulin sensitivity. Our findings imply that protein malnutrition in utero causes changes in mtDNA content, impaired β‐cell development, and insulin secretion, which may contribute to the development of type 2 diabetes in later life.
Mitochondrial Encephalomyopathies: Diagnostic Approach
Authors: DIMAURO SALVATORE , TAY STACEY , MANCUSO MICHELANGELO
Published: May 2004

Abstract: Mitochondrial diseases have extremely heterogeneous clinical presentations due to the ubiquitous nature of mitochondria and the dual genetic control of the respiratory chain. Thus, mitochondrial disorders can be multisystemic (mitochondrial encephalomyopathies) or confined to a single tissue, and they can be sporadic or transmitted by mendelian or maternal inheritance. Mendelian disorders are usually inherited as autosomal recessive traits, tend to present earlier in life, and usually “breed true” in each family. By contrast, mitochondrial DNA‐related diseases usually start later and vary in their presentation within members of the same family. Precise diagnosis is often a challenge; we go through the traditional steps of the diagnostic process, trying to highlight clues to mitochondrial dysfunction in the family history, physical and neurological examinations, routine and special laboratory tests, and histo‐chemical and biochemical results of the muscle biopsy. The ultimate goal is to reach, whenever possible, a definitive molecular diagnosis, which permits rational genetic counseling and a prenatal diagnosis.
Mitochondrial Encephalomyopathies: Therapeutic Approach
Authors: DIMAURO SALVATORE , MANCUSO MICHELANGELO , NAINI ALI
Published: May 2004

Abstract: Therapy for mitochondrial diseases is woefully inadequate. How‐ever, lack of cure does not equate with lack of treatment. In this review, we consider sequentially several different therapeutic approaches. Palliative therapy is dictated by good medical practice and includes anticonvulsant medication, control of endocrine dysfunction, and surgical procedures. Removal of noxious metabolites is centered on combating lactic acidosis, but it extends to other metabolites, such as thymidine in patients with the mitochondrial neurogastrointestinal encephalomyopathy syndrome. Attempts to bypass blocks in the respiratory chain by administration of artificial electron acceptors have not been successful, but this concept may be amenable to genetic engineering. Administration of metabolites and cofactors is the mainstay of real‐life therapy and includes both components of the respiratory chain and other natural compounds. There is increasing interest in the administration of reactive oxygen species scavengers both in primary mitochondrial diseases and in neurodegenerative diseases directly or indirectly related to mitochondrial dysfunction. Aerobic exercise and physical therapy prevent or correct deconditioning and improve exercise tolerance in patients with mitochondrial myopathies due to mtDNA mutations. Gene therapy is a challenge because of polyplasmy and heteroplasmy, but interesting experimental approaches are being pursued and include, for example, decreasing the ratio of mutant to wild‐type mitochondrial genomes (gene shifting), converting mutated mtDNA genes into normal nDNA genes (allotropic expression), importing cognate genes from other species, or correcting mtDNA mutations with specific restriction endonucleases. Germline therapy raises ethical problems but is being seriously considered to prevent maternal transmission of mtDNA mutations. Preventive therapy through genetic counseling and prenatal diagnosis is still limited for mtDNA‐related disorders but is becoming increasingly important for nDNA‐related disorders.
Comprehensive Molecular Diagnosis of Mitochondrial Disorders: Qualitative and Quantitative Approach
Authors: Wong Lee‐Jun C.
Published: May 2004

Abstract: Mitochondrial disorders can be caused by mutations in nuclear or mitochondrial encoded genes. Point mutations and large deletions in mitochondrial DNA (mtDNA) are responsible for a small portion of the molecular defects in the mitochondrial oxidative phosphorylation system. A significant number of molecular defects of respiratory chain disorders are probably due to mutations in nuclear genes. Molecular diagnosis of mitochondrial disorders has been difficult because of broad genetic and clinical heterogeneity. Mutational analysis of common point mutations of mtDNA such as A3243G, A8344G, and T8993G/C is routinely performed. However, many patients who clearly have clinical manifestations and muscle pathology consistent with oxidative phosphorylation deficiency do not have detectable common mtDNA point mutations. A more comprehensive mutation screening method, temporal temperature gradient gel electrophoresis, was used to scan for unknown mutations in the entire mitochondrial genome. Novel mutations have been discovered but only account for a small portion of patients with suspected mitochondrial RC disorders. Real‐time quantitative PCR analysis was used to measure cellular mtDNA content. Abnormal levels of mtDNA were found in many patients with respiratory chain disorders. Molecular analysis revealed that mutations in the thymidine phosphorylase gene are not seen in young patients with severe mtDNA depletion who do not demonstrate clinical features of mitochondrial neurogastrointestinal encephalomyopathy. It was also noted that an increase in the size or number of mitochondria was not necessarily associated with an increase in mtDNA content. On the contrary, in some cases the mtDNA was depleted. Respiratory activity in patients with a defective mitochondrial genome due to either point mutations or deletions may be compensated by amplification of mtDNA. Therefore, a comprehensive molecular analysis of mitochondrial respiratory chain disorders should include qualitative identification of the mutation and quantitative measurement of both the degree of mutant heteroplasmy and the total amount of mtDNA.
Molecular Pathogenetic Mechanism of Maternally Inherited Deafness
Authors: GUAN MIN‐XIN
Published: May 2004

Abstract: Mutations in the mitochondrial DNA (mtDNA) have been shown to be one important cause of deafness. In particular, mutations in the mtDNA have been associated with both syndromic and nonsyndromic forms of sensori‐neural hearing loss. The deafness‐linked mutations often occur in the mitochondrial 12S rRNA gene and in tRNA genes. Mutations in the 12S rRNA gene account for most of the cases of aminoglycoside ototoxicity. The other hot spot for mutations associated with hearing impairment is the tRNASer(UCN) gene, as five deafness‐linked mutations have been identified in this gene. Nonsyndromic deafness‐linked mtDNA mutations are often homoplasmic or at high levels of heteroplasmy, indicating a high threshold for pathogenicity. Phenotypic expression of these mtDNA mutations requires the contribution of other factors such as nuclear modifier gene(s), environmental factor(s), or mitochondrial haplotype(s).