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Over two decades have elapsed since the first mtDNA point mutation was associated with Leber’s hereditary optic neuropathy (LHON) in 1988. We have subsequently witnessed a substantial understanding of the molecular basis of hereditary optic neuropathies, as well as of their clinical features and pathogenic mechanisms. It became clear that the large majority of genetic optic neuropathies have a primary or an indirect involvement of mitochondrial functions, justifying the definition of “mitochondrial optic neuropathies”. Despite this progress many unsolved features remain to be understood, such as incomplete penetrance and variable clinical expressivity in LHON and dominant optic atrophy (DOA), gender prevalence in LHON, and complex gene/environment interactions in both LHON and DOA. The most recent advancement in our understanding of the molecular basis of mitochondrial optic neuropathies is the topic of this review. In particular, we analyze the role that mitochondrial biogenesis may play in the compensatory mechanisms that underlie incomplete penetrance and clinical expressivity, a scenario relevant for the possible design of future therapeutic approaches.

To investigate the mechanisms underlying myoclonus in Leber hereditary optic neuropathy (LHON).

The previously unrecognised association of myoclonus in two patients with LHON with the 11778/ND4 pathogenic mutation is described. EEG failed to disclose epileptic figures, and a back averaging study suggested that myoclonus was cortical in origin in both patients.

The pathogenic role of `secondary' mitochondrial DNA (mtDNA) point mutations, when occurring in patients with Leber's hereditary optic neuropathy (LHON) in association with `primary' mutations, is still controversial. We used phosphorus magnetic resonance spectroscopy to establish whether two of these `secondary' LHON mtDNA mutations, 4216/ND1 and 13708/ND5 (haplogroup J), further affect in vivo mitochondrial oxidative metabolism in subjects with the `primary' 11778/ND4 mtDNA mutation. Brain and skeletal muscle energy metabolism was assessed in 10 subjects homoplasmic for the 11778/ND4 mtDNA mutation and 10 subjects homoplasmic for the same mutation occurring on the haplogroup J mtDNA background. Brain phosphocreatine concentration and phosphorylation potential were significantly reduced and brain inorganic phosphate concentration was significantly increased compared with controls in both groups of 11778/ND4-positive subjects. The degree of reduction in the phosphocreatine concentration and phosphorylation potential and of increase in the inorganic phosphate concentration was, however, similar in the two groups with the 11778/ND4 mtDNA mutation with or without the haplogroup J. Similarly, the rate of muscle phosphocreatine resynthesis after exercise, a sensitive index of the rate of mitochondrial ATP production, was reduced by the same extent in both groups of LHON subjects. This in vivo study does not support synergism of the 4216/ND1 and 13708/ND5 `secondary' mutations with the 11778/ND4 `primary' mutation in determining the deficit of energy metabolism in LHON.

We investigated the biochemical phenotype of the mtDNA T8993G point mutation in the ATPase 6 gene, associated with neurogenic muscle weakness, ataxia, and retinitis pigmentosa (NARP), in three patients from two unrelated families. All three carried >80% mutant genome in platelets and were manifesting clinically various degrees of the NARP phenotype. Coupled submitochondrial particles prepared from platelets capable of succinate-sustained ATP synthesis were studied using very sensitive and rapid luminometric and fluorescence methods. A sharp decrease (>95%) in the succinate-sustained ATP synthesis rate of the particles was found, but both the ATP hydrolysis rate and ATP-driven proton translocation (when the protons flow from the matrix to the cytosol) were minimally affected. The T8993G mutation changes the highly conserved residue Leu(156) to Arg in the ATPase 6 subunit (subunit a). This subunit, together with subunit c, is thought to cooperatively catalyze proton translocation and rotate, one with respect to the other, during the catalytic cycle of the F(1)F(0) complex. Our results suggest that the T8993G mutation induces a structural defect in human F(1)F(0)-ATPase that causes a severe impairment of ATP synthesis. This is possibly due to a defect in either the vectorial proton transport from the cytosol to the mitochondrial matrix or the coupling of proton flow through F(0) to ATP synthesis in F(1). Whatever mechanism is involved, this leads to impaired ATP synthesis. On the other hand, ATP hydrolysis that involves proton flow from the matrix to the cytosol is essentially unaffected.

We report the effect on complex I function of the 14484 Leber's hereditary optic neuropathy (LHON) mutation affecting the ND6 subunit gene. The same gene was also reported to carry another mutation, at position 14459, associated with the LHON/dystonia phenotype that induces a reduction of complex I–specific activity and increases the sensitivity to the product decylubiquinol. Given the proximity of both mutations in the ND6 gene, we tested the specific activity of complex I and its sensitivity to myxothiazol and nonylbenzoquinol, both inhibitors at the ubiquinol product site, in platelet submitochondrial particles from nine 14484 homoplasmic individuals, 8 Italians with Caucasian mtDNA haplogroup J (adjunctive 4216 and 13708 mutations), and 1 Tunisian with an African mtDNA haplogroup. The specific activity of complex I was not affected by the 14484 mutation, but the sensitivity to both inhibitors was significantly increased compared with control subjects regardless of the presence of haplogroup J polymorphisms. Analysis of 70 different amino acid sequences of the ND6 subunit indicated that the 14484 mutation affects an amino acid belonging to its most conserved region, which shows local similarities with cytochrome b regions interacting with ubiquinone or ubiquinol in complex III. Our results suggest that both 14484 and 14459 mutations may affect amino acids forming the interaction site of ubiquinol product, and the 14484 mutation produces a biochemical defect resembling in part that already reported for the common 11778/ND4 LHON mutation. Ann Neurol 1999;45:320–328

We report the effect on complex I function of the 14484 Leber's hereditary optic neuropathy (LHON) mutation affecting the ND6 subunit gene. The same gene was also reported to carry another mutation, at position 14459, associated with the LHON/dystonia phenotype that induces a reduction of complex I–specific activity and increases the sensitivity to the product decylubiquinol. Given the proximity of both mutations in the ND6 gene, we tested the specific activity of complex I and its sensitivity to myxothiazol and nonylbenzoquinol, both inhibitors at the ubiquinol product site, in platelet submitochondrial particles from nine 14484 homoplasmic individuals, 8 Italians with Caucasian mtDNA haplogroup J (adjunctive 4216 and 13708 mutations), and 1 Tunisian with an African mtDNA haplogroup. The specific activity of complex I was not affected by the 14484 mutation, but the sensitivity to both inhibitors was significantly increased compared with control subjects regardless of the presence of haplogroup J polymorphisms. Analysis of 70 different amino acid sequences of the ND6 subunit indicated that the 14484 mutation affects an amino acid belonging to its most conserved region, which shows local similarities with cytochrome bregions interacting with ubiquinone or ubiquinol in complex III. Our results suggest that both 14484 and 14459 mutations may affect amino acids forming the interaction site of ubiquinol product, and the 14484 mutation produces a biochemical defect resembling in part that already reported for the common 11778/ND4 LHON mutation. Ann Neurol 1999;45:320–328

The release through silicone rubber membranes of benzocaine suspended in carbomer hydrogels containing different concentrations of low molecular weight polyols (ethylene glycol, propylene glycol, glycerol, and sorbitol) was studied to establish general principles and procedures for control of the effects on percutaneous absorption caused by changes in drug solubility and/or diffusivity in the vehicle. The effect of the additives on the release is expressed in terms of the relative released amount, i.e., the ratio, Q/Qw, of the amount of drug released from each additive-containing gel to the amount released at the same time from the additive-free gel. The experimental Q/Qwvalues are correlated with values calculated by a simple equation involving known or readily measurable parameters such as the drug concentration in the gel, the drug solubility in the pure liquid phase, and the viscosity of this phase. Derivation of such a relationship from a known equation describing the vehicle-controlled release of suspended drugs was possible because an inverse proportionality was observed between drug diffusivity in the gels and the viscosity of the respective solvents. This relationship is interpreted with respect to current theories on drug diffusion in diluted gels.

The nicotinamide nucleotide dimers (NAD)2 and (NADP)2, obtained by electrochemical reduction of NAD+ and NADP+, are able to reduce such single-electron acceptors as the proteins cytochrome c, azurin and methaemoglobin, though at different rates. Under the same conditions the reduced nicotinamide coenzymes NADH and NADPH are not able to reduce these proteins at measurable rates unless a catalyst (phenazine methosulphate or NADH-cytochrome c reductase in the case of cytochrome) is present. The redox mechanism seems to involve the formation of an NAD(P). radical that in the presence of O2 gives rise to superoxide (O2.-), since superoxide dismutase inhibited these reactions.

We collected two clinically matched samples of patients, one sample affected by migraine with aura the other by migraine without aura, to investigate the genetic determination of these conditions. A maternal and X-linked transmission for both these diseases was considered unlikely after pedigree analysis. Classical segregation analysis indicated a likely autosomal recessive kind of transmission for both. Reduced penetrance and the h2values, however, imply the presence of additional genetic and/or environmental factors controlling the phenotypic expression of migraine.

The enhancement effects of some chemicals on the percutaneous absorption of alprazolam through human skin was investigated in vitro. Linoleic acid, oleic acid, Comperlan F® (linoleic acid diethanolamide), Comperlan KD® (coconut fatty acid diethanolamide) and Ethomeen C12® (bis-(2-hydroxyethyl)cocamine) were evaluated for their enhancing effect either as neat solvents or combined with propylene glycol. The effects of skin pretreatment with the enhancers on the percutaneous absorption of alprazolam from a drug suspension in an aqueous gel were also investigated: skin pretreatment with some enhancers has shown potentially interesting aspects. The determination of alprazolam partitioning into untreated and pretreated horny layer supported the idea that, with oleic and linoleic acid, a contribution to the modification of the diffusional resistance of the skin was given by an increase of the drug solubility in the stratum coraeum.

To clarify the bioenergetic relevance of mtDNA mutations in Leber's hereditary optic neuropathy (LHON), we investigated affected individuals and healthy carriers from six Italian LHON families harboring the 11778/ ND4 and the 3460/ND1 mtDNA mutations. The enzymatic activities of mitochondrial complex I and its sensitivity to the potent inhibitors rotenone and rolliniastatin-2 were studied in mitochondrial particles from platelets, in correlation with mtDNA analysis of platelets and leukocytes. In platelets homoplasmic for mutant mtDNA, both 11778/ND4 and 3460/ND1 mutations induced resistance to rotenone and the 3460/ND1 mutation also provoked a marked decrease in the specific activity of complex I. Individuals heteroplasmic in platelets for either mutation showed normal biochemical features, indicating functional complementation of wild-type mtDNA. There was no correlation between the clinical status and mtDNA homoheteroplasmy in platelets, but the biochemical features correlated with the mitochondrial genotype of platelets. In some cases, the degree of mtDNA heteroplasmy differed in platelets and leukocytes from the same individual with a prevalence of wild-type mtDNA in the platelets. These results imply that biochemical studies on mitochondrial diseases should always be integrated with mtDNA analysis of the same tissue investigated and also suggest that the mtDNA analysis on the leukocyte fraction, as usually performed in LHON, does not necessarily reflect the mutant genotype level of other tissues. The differential tissue heteroplasmy may be more relevant than previously thought in determining disease penetrance.

Horseradish peroxidase catalyses the oxidation of NAD dimers, (NAD)2, to NAD+ in accordance with a reaction that is pH-dependent and requires 1 mol of O2 per 2 mol of (NAD)2. Horseradish peroxidase also catalyses the peroxidation of (NAD)2 to NAD+. In contrast, bacterial NADH peroxidase does not catalyse the peroxidation or the oxidation of (NAD)2. A free-radical mechanism is proposed for both horseradish-peroxidase-catalysed oxidation and peroxidation of (NAD)2.

We analyse a model for neural activity including forgetting and self-inhibition processes. The analysis concerns the static and dynamic performances. The theoretical predictions are compared with previously published experimental data on the neural encoding in the ommatidia of the Limulus lateral eye. We conclude that the analysed model could reproduce the experimental behaviour, but different models cannot be excluded. Moreover an independent normalisation factor has to be assumed to account for the experimental gains.

This study aimed to determine if cerebellar ataxia, hypogonadism and chorioretinopathy (AHCR) is associated with mutations in mitochondrial DNA or in genes responsible for spinocerebellar ataxias (SCA1, SCA2, SCA3 and Friedreich’s ataxia). Two brothers with cerebellar ataxia, hypogonadism and chorioretinopathy and their unaffected parents underwent molecular analysis for duplications and deletions in mitochondrial DNA (mtDNA), point mutations in the ATP ase 6 gene, and expansions of CAG repeats (at 6p22-p23, 12q24.1, 14q32.1) and of GAA repeats (at gene X25 on chromosome 9q13). The research was negative for all mutations. Our findings confirm that AHCR is a distinct disease within the inherited cerebellar ataxias.

ObjectiveTo determine whether a multisystemic bioenergetic deficit is an underlying feature of familial hypobetalipoproteinaemia. MethodsBrain and skeletal muscle bioenergetics were studied by in vivo phosphorus MR spectroscopy (³¹P-MRS) in two neurologically affected members (mother and son) and in one asymptomatic member (daughter) of a kindred with familial hypobetalipoproteinaemia. Plasma concentrations of vitamin E and coenzyme Q₁₀ (CoQ₁₀) were also assessed. ResultsBrain ³¹P-MRS disclosed in all patients a reduced phosphocreatine (PCr) concentration whereas the calculated ADP concentration was increased. Brain phosphorylation potential was reduced in the members by about 40%. Skeletal muscle was studied at rest in the three members and during aerobic exercise and recovery in the son and daughter. Only the mother showed an impaired mitochondrial function at rest. Both son and daughter showed an increased end exercise ADP concentration whereas the rates of postexercise recovery of PCr and ADP were slow in the daughter. The rate of inorganic phosphate recovery was reduced in both cases. Plasma concentration of vitamin E and CoQ₁₀ was below the normal range in all members.ConclusionsStructural changes in mitochondrial membranes and deficit of vitamin E together with reduced availability of CoQ₁₀ can be responsible for the multisystemic bioenergetic deficit. Present findings suggest that CoQ₁₀ supplementation may be important in familial hypobetalipoproteinaemia.

Leber′s hereditary optic neuropathy (LHON) has been associated with "primary" and "secondary" mtDNA missense point mutations, and a synergistic role has been proposed for secondary mutations. No previous study has investigated the effects of LHON primary or primary plus secondary mutations on the respiratory competence of cell lines. We constructed and compared cybrid cell lines obtained from two unrelated LHON patients both carrying the common 11778/ND4 primary mutation. One of the patients also carried the 13708/ND5 and 4216/ND1 secondary mutations. The cybrid clones were evaluated for growth efficiency, oxygen consumption, complexes I, III and IV enzymatic activity and mitochondrial protein synthesis. Complex activity and mitochondrial protein synthesis were not significantly changed in cybrid clones from the patients. Oxygen consumption was significantly decreased in all clones carrying the 11778/ND4 primary mutation demonstrating its pathogenic role in impairing cell respiration. Clones also carrying the secondary mutations showed an even lower oxygen consumption and a significantly higher doubling time, suggesting that the co-presence of the secondary mutations could be relevant in further reducing the cell fitness.

The authors identified two novel heterozygous missense transitions in the gene for the mitochondrial polymerase gammaA subunit (POLG) in a family with an autosomal recessive syndrome comprising progressive external ophthalmoplegia (PEO), polyneuropathy, ataxia, sensorineural hearing loss, and affective disorders. These mutations were not detected in 120 healthy control subjects.

Occipital lobe and calf muscle energy metabolism were studied in vivo by magnetic resonance spectroscopy (³¹P-MRS) in four members of a family harbouring the mitochondrial DNA G3460A mutation causing Leber's hereditary optic neuropathy (LHON). Three siblings carried 100% mutated mitochondrial DNA (homoplasmy), while their mother had coexistence of mutated and wild-type mitochondrial DNA (heteroplasmy). Indices of brain energy metabolism on ³¹P-MRS were abnormal in all subjects examined, but the muscle oxidative phosphorylation rate was normal. These findings indicate a tissue specific distribution of the biochemical expression of the G3460A LHON mutation and suggest that extramitochondrial factors, such as nuclear genes, may influence expression of this mutation in vivo.

Colpocephaly is an abnormal congenital enlargement of the occipital horns of the lateral ventricles, which has typically been associated with learning disability, seizures, and motor and visual abnormalities. This study describes familial colpocephaly in two siblings with different fathers in a Dominican family. There were no other neurological problems in their relatives. Child 1 is a 7‐year‐old girl, who has had partial epileptic seizures since 4 years of age. She attends a mainstream school. She has coloboma and chorioretinic atrophy in her right eye and a right microphthalmia. MRI revealed colpocephaly and hypogenesis of the corpus callosum. Her brother, aged 2 years 8 months showed a mild delay in speech acquisition. He has had three febrile convulsions and two non‐febrile tonic‐clonic seizures since 6 months of age. Neurological and ophthalmological examinations were normal. MRI documented colpocephaly with right occipital horn prevalence. There are only two literature reports of genetically transmitted colpocephaly hypothesised in two identical twins and in two brothers. In the children in this study, a genetic basis for colpocephaly is confirmed. We hypothesised a maternal transmission with X‐linked or autosomal dominance with an incomplete penetrance model of inheritance.

Colpocephaly is an abnormal congenital enlargement of the occipital horns of the lateral ventricles, which has typically been associated with learning disability, seizures, and motor and visual abnormalities. This study describes familial colpocephaly in two siblings with different fathers in a Dominican family. There were no other neurological problems in their relatives. Child 1 is a 7-year-old girl, who has had partial epileptic seizures since 4 years of age. She attends a mainstream school. She has coloboma and chorioretinic atrophy in her right eye and a right microphthalmia. MRI revealed colpocephaly and hypogenesis of the corpus callosum. Her brother, aged 2 years 8 months showed a mild delay in speech acquisition. He has had three febrile convulsions and two non-febrile tonic–clonic seizures since 6 months of age. Neurological and ophthalmological examinations were normal. MRI documented colpocephaly with right occipital horn prevalence. There are only two literature reports of genetically transmitted colpocephaly hypothesised in two identical twins and in two brothers. In the children in this study, a genetic basis for colpocephaly is confirmed. We hypothesised a maternal transmission with X-linked or autosomal dominance with an incomplete penetrance model of inheritance.

Without Abstract:

Background As yet, no population-based prospective studies have been conducted to investigate the incidence and clinical outcome of glioblastoma (GBM) or the diffusion and impact of the current standard therapeutic approach in newly diagnosed patients younger than aged 70 years. Methods Data on all new cases of primary brain tumors observed from January 1, 2009, to December 31, 2010, in adults residing within the Emilia-Romagna region were recorded in a prospective registry in the Project of Emilia Romagna on Neuro-Oncology (PERNO). Based on the data from this registry, a prospective evaluation was made of the treatment efficacy and outcome in GBM patients. Results Two hundred sixty-seven GBM patients (median age, 64 y; range, 29–84 y) were enrolled. The median overall survival (OS) was 10.7 months (95% CI, 9.2–12.4). The 139 patients ≤aged 70 years who were given standard temozolomide treatment concomitant with and adjuvant to radiotherapy had a median OS of 16.4 months (95% CI, 14.0–18.5). With multivariate analysis, OS correlated significantly with KPS (HR = 0.458; 95% CI, 0.248–0.847; P = .0127), MGMT methylation status (HR = 0.612; 95% CI, 0.388–0.966; P = .0350), and treatment received in a high versus low-volume center (HR = 0.56; 95% CI, 0.328–0.986; P = .0446). Conclusions The median OS following standard temozolomide treatment concurrent with and adjuvant to radiotherapy given to (72.8% of) patients aged ≤70 years is consistent with findings reported from randomized phase III trials. The volume and expertise of the treatment center should be further investigated as a prognostic factor.

□ The ability of ethylene glycol; glycerin; polyethylene glycols 200, 400, and 6000; polysorbate 80; and lactose dispersed in silicone rubber, to promote water sorption into the polymer was investigated in water and in isotonic (pH7.4) phosphate buffer. Polyethylene glycols 200 and 400, lactose, and, especially, glycerin were effective water carriers. Marked differences in the kinetics of rubber swelling were observed, depending on the carrier. The swelling patterns relative to ethylene glycol, glycerin, and polyethylene glycol 200 showed a maximum due to significant leaching of these additives from the polymer. Steady swelling degrees were afforded by polyethylene glycols 400 and 6000 and by polysorbate 80. The interdependent processes of polymer imbibition and carrier release were speeded up without altering their kinetic patterns by increasing the initial surface–volume ratio of the devices. A proportionality resulted between maximal swelling and initial carrier concentration, although the swelling patterns were substantially unaffected by this variable.

LINEAR polyamides, in the form of fibres or fine powders, are able to absorb polar substances from solution1, with the formation of hydrogen bonds. The sorption is restricted to the amorphous regions, where a solution process of the polar substance into the polymer takes place. The Flory–Huggins relation2: has been found1to hold, when the volume fractions v1and v2of the polymer and the polar substance are corrected for the degree of crystallinity of the polymer.