MERRF/MELAS overlap syndrome: a double pathogenic mutation in mitochondrial tRNA genes.

BACKGROUND: Myoclonic epilepsy with ragged-red fibres (MERRF) and mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS) are established phenotypes of mitochondrial encephalomyopathy. The m.8356T>C transition in the mitochondrial tRNA(Lys) gene is a pathogenic mutations of MERRF. The m.3243A>G transition in the mitochondrial tRNA(Leu) gene is detected in most MELAS patients. Although previous analyses of double mutations in mitochondrial DNA (mtDNA) were useful for discussing their nature, many unsolved questions remain. OBJECTIVE: To describe the clinical and genetic features of a family with the above mtDNA double-point mutations and discuss the role of double mtDNA mutations in diverse clinical features in the family. PATIENTS AND METHODS: The proband was a 23-year-old woman with MERRF harbouring m.8356T>C and m.3243A>G transitions in mitochondrial tRNA genes. We assessed clinical aspects of her and those of her three relatives and performed mutation analyses on their mtDNA. RESULTS: Phenotypes of the four patients were MERRF, MERRF/MELAS overlap syndrome and asymptomatic carrier. We hypothesise that the course of the phenotype of this family begins with MERRF and is followed by MELAS. This double mutation was heteroplasmic in blood of all four patients but with different rates in each patient, while m.8356T>C appeared homoplasmic and m.3243A>G was heteroplasmic in muscle of the two examined cases. No other mutations were detected in the total mtDNA sequence in this family. CONCLUSIONS: This is the first reported case of a double-point mutation in mtDNA, both of which were heteroplasmic and pathogenic for the established phenotypes.

Voltage-dependent Ca2+ channels in the plasma membrane and the vacuolar membrane of Arabidopsis thaliana.

Voltage-dependent Ca2+ channels in the plasma membrane and the vacuolar membrane of Arabidopsis thaliana have been studied at the single-channel level using the patch-clamp technique. The Ca2+ channel in the plasma membrane opened for extracellular Ca2+ influx. The Ca2+ channel in the vacuolar membrane opened for cytoplasmic Ca2+ influx.

Dissociation of smooth pursuit and vestibulo-ocular reflex cancellation in SCA-6.

OBJECTIVE: To study gaze in SCA-6 patients during pursuit and passive whole-body rotation. BACKGROUND: Smooth pursuit and vestibularly induced eye movements interact to maintain the accuracy of eye movements in space (i.e., gaze). Previous studies have implicated the cerebellum, particularly the floccular lobe and dorsal vermis, in the control of gaze velocity during pursuit and vestibulo-ocular reflex (VOR) cancellation. SCA-6 has recently been identified genetically and characterized as pure cerebellar ataxia that affects the cerebellar cortex selectively. METHODS: Using infrared oculography, eye movements of five SCA-6 patients and five age-matched normal control subjects were recorded during sinusoidal pursuit and passive whole-body rotation in the horizontal plane (amplitude, +/- 10 deg; frequency, 0.2 Hz). Eye and gaze gain (eye and gaze velocity/stimulus velocity) were calculated after deleting saccades. RESULTS: Eye gain of all SCA-6 patients during pursuit was significantly lower than those of the control subjects (mean +/- SD, 0.26+/-0.06 versus 0.91+/-0.07). In contrast, eye gain of the patients was not significantly different from that of the control subjects either during VOR cancellation, when the subjects tracked a target that moved with the same amplitude and phase, like a chair (0.21+/-0.05 versus 0.12+/-0.07), or during visually enhanced VOR (x1), when the target remained stationary in space (0.85+/-0.06 versus 0.95+/-0.05). Moreover, there was no significant difference in mean VOR gain in total darkness between the two groups. Gaze gain of patients (0.26+/-0.06 versus 0.81+/-0.06) but not control subjects (0.91+/-0.07 versus 0.88+/-0.08), was significantly different during pursuit and VOR cancellation. CONCLUSION: SCA-6 patients show dissociation in the control of gaze tracking during smooth pursuit and VOR cancellation.

The hereditary spinocerebellar ataxias in Japan.

In Japan, multiple system atrophy (MSA) accounts for 40% of all spinocerebellar ataxias (SCAs) and hereditary disorders account for 30%. Among the latter, autosomal dominant disorders are common and recessive ataxias are rare. Although the frequency of SCA genotypes differs between geographic regions throughout Japan, SCA6, SCA3/MJD, and DRPLA are the three major disorders, while SCA7, SCA8, SCA10, SCA12, and SCA17 are infrequent or almost undetected. SCA1 predominantly occurs in the northern part of Japan. Overall, 20-40% of dominant SCAs are due to unknown mutations. From this cluster, pure cerebellar ataxias linked with the SCA4, SCA14, and SCA16 locus have been isolated. Among the recessive SCAs, patients with AVED and EAOH have been detected. However, FRDA associated with GAA repeat expansion in the frataxin gene has not been reported so far.

Genetic polymorphisms of IL-1beta and IL-1 receptor antagonist in association with multiple sclerosis in Japanese patients.

In the present study, we have investigated the association of specific polymorphisms of the interleukin (IL)-1beta and IL-1 receptor antagonist (ra) gene with both the susceptibility to and the clinical characteristics of multiple sclerosis (MS) in Japanese patients. We collected and analyzed DNA from 98 MS patients and 104 healthy controls for distribution of IL-1beta or IL-1ra polymorphisms. Our results show no significant differences in the distribution of the polymorphisms between MS patients and controls. Furthermore, no association was observed between IL-1beta or IL-1ra polymorphisms and clinical characteristics, such as age at disease onset, clinical course and severity. Together, our findings suggest that IL-1beta or IL-1ra gene polymorphisms may not be relevant in the susceptibility to MS or the clinical characteristics of Japanese patients with MS.

Membrane-bound respiratory system of Enterobacter cloacae strain HO1 grown anaerobically with chromate.

Chromate has been demonstrated to be an electron acceptor in the respiratory chain of anaerobically grown Enterobacter cloacae strain HO1. By using potentiometric titration and low temperature spectroscopy, the spectral absorption of the anaerobic membrane vesicles of this organism in the presence of chromate was resolved into six peaks at 548, 549, 550, 555, 556, and 558 nm in the alpha band of the reduced minus oxidized spectra. The spectra elicited by chromate are attributed to cytochromes c548, c549, c550, b555, b556, and b558. Among these cytochromes, c548 was found to be specifically involved in electron transfer to chromate.

Genomic HLA profiles of MS in Hokkaido, Japan: important role of DPB1*0501 allele.

The polymorphism of the HLA class II genes was investigated in 97 patients with multiple sclerosis (MS) in Hokkaido, the northernmost main island of Japan. Of these, 80 patients were classified as having conventional MS and 17 as having opticospinal MS (OS-MS). Our findings confirmed a previous report that the DPB 1*0501 allele is positively associated with OS-MS (P = 0.0043). The frequency of DPB 1*0501 was also found to be higher in conventional MS patients than in controls (79% vs. 58%, P = 0.0084), although the differences were not statistically significant. Our results indicate that OS-MS is a DPB 1*0501-associated subgroup of MS, and that DPB1*0501 is also correlated with risk of conventional MS in Japanese.

Mosaicism of unstable CAG repeats in the brain of spinocerebellar ataxia type 2.

Spinocerebellar ataxia type 2 (SCA2) is caused by expansion of unstable CAG repeats within the coding region of the novel gene, ataxin-2, on chromosome 12q24.1. We analyzed CAG repeat size of the SCA2 allele in two deceased patients (father and daughter) to investigate the repeat mosaicism in CNS regions. The CAG repeat size was examined using lymphoblastoid cell lines, frozen brain tissues, and paraffin-embedded tissues. In each patient the major repeat size of the expanded allele varied within the brain or spinal cord (father, 39-42; daughter, 39-47 repeats), and was smaller by three to eight repeats in the cerebellum than in other CNS regions. Our results are in agreement with the findings in other polyglutamine disorders showing somatic mosaicism.

Prevalence of triplet repeat expansion in ataxia patients from Hokkaido, the northernmost island of Japan.

Approximately 44% of cases of spinocerebellar ataxia (SCA) in Hokkaido, the northernmost island of Japan, were estimated to be inherited. To determine the prevalence of triplet repeat expansion in hereditary SCA patients, we genotyped seven genetically defined dominant SCAs in 349 patients, including 266 patients from 77 families, 78 probands from unrelated families with hereditary late-onset SCA, and five patients in whom a family history of SCA was not demonstrated. The frequency of each disorder in a total of 155 unrelated families was 23.9% for Machado-Joseph disease (MJD), 29.0% for SCA6, 9.7% for SCA1, 7.7% for SCA2, and 2.6% for dentatorubral-pallidoluysian atrophy. Abnormal expansion of triplet repeats for SCA7 and SCA8 was not detected. A total of 27.1% of the patients had still unknown SCA mutations. In addition, the GAA repeat in the frataxin gene was not abnormally expanded in 13 early-onset SCA patients with clinical features similar to those of Friedreich ataxia. Comparison of our results with those from other centers handling SCA showed that MJD is prevalent throughout Japan, but the frequencies of other dominant SCAs differ considerably even within Japan.

Estrogen receptor gene polymorphism in Japanese patients with multiple sclerosis.

Estrogen has been reported to have immunosuppressive functions, and to inhibit the progression of experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). Since estrogen shows its biological effects via estrogen receptors (ER), we investigate the possible role of ER genes (ERG) in the pathogenesis of MS. PvuII and XbaI polymorphisms in ERG were detected by PCR-RFLP from the DNA of 79 conventional MS patients and 73 healthy controls. The [P] allele in the profiles in PvuII was significantly more prevalent in MS patients than in the controls (P<0.0005). In the study of XbaI polymorphism, the onset age of MS patients with the Xx genotype was earlier than that of the xx genotype group (mean age+/-S.D.; 22.60+/-8.04, and 27.49+/-9.14, respectively) (P<0.05) by ANOVA followed by Fisher's PLSD. Although the Xx genotype group tended to earlier onset age than the XX genotype group (29.60+/-11.10), this difference did not reach. On the basis of these results, PvuII polymorphism might be associated with susceptibility to MS, and XbaI polymorphism with onset age of MS. ERG polymorphism should be further studied in other populations to improve strategies for treatment of MS.

Vitamin D receptor gene polymorphism in multiple sclerosis and the association with HLA class II alleles.

We have previously reported that the association between Bsm I polymorphism, one of the vitamin D receptor genes (VDRG) polymorphism, and multiple sclerosis (MS). In this report, we investigated the further possible role or relevance of VDRG in the pathogenesis of MS. Apa I polymorphism was detected by PCR-RFLP from the DNA of 77 conventional MS patients and 95 healthy controls. The study of the Bsm I and Apa I haplotypes was carried out by employing previously reported Bsm I data. The AA genotype and the [A] allele in the profiles were significantly more prevalent in MS patients than in controls (P=0.0070 and P=0.0321, respectively). In the [A] allele-positive MS patients, the positive rate of DPB1*0501 in HLA was significantly higher than that of the [A] allele-positive controls and that of the [A] allele-negative MS patients even when the corrected P value (P(corr)) was applied (P(corr)=0.0220 and P(corr)=0.0077, respectively). The frequency of DRB1*1501 was higher in the [A] allele-positive patients than in the [A] allele-positive controls and the [A] allele-negative patients (P(uncorr)=0.0431 and P(uncorr)=0.0089, respectively), but the P values did not reach statistical significance after P corrections. The rate of Bsm I and Apa I haplotypes was much higher in bA/bA-positive MS patients than in the controls (P=0.0003), and in the bA positive MS patients, the positive rate of DPB1*0501 was higher than that of the bA-positive controls and that of the bA-negative MS patients (P(corr)=0.0308 and P(corr)=0.0033, respectively). These results indicate that VDRG polymorphism may be associated with susceptibility to MS, and HLA alleles may correlate with risk for MS together with VDRG.

Association of vitamin D receptor gene polymorphism with multiple sclerosis in Japanese.

1,25-Dihydroxyvitamin D3 (1,25(OH)2D3), the biologically active form of vitamin D, exerts an immunosuppressive effect and can completely prevent experimental autoimmune encephalomyelitis (EAE). 1,25(OH)2D3 exerts most of its actions only after it has bound to its specific nuclear receptors. To investigate the possible role of vitamin D receptor gene (VDRG) polymorphism in susceptibility to or disease-modulation of MS, we evaluated 77 Japanese patients with 'conventional' MS and 95 controls. A VDRG allelic polymorphism was assessed by Bsm1 endonuclease restriction after specific PCR amplification. Genotypic polymorphism was clearly defined as BB (absence of restriction site on both alleles), bb (presence of restriction site on both alleles), or Bb (heterozygous). We found overexpression of the b allele (92.9 vs. 84.2%: P=0.0138) and homozygote bb (85.7 vs. 71.6%; P=0.0263) in MS patients compared with controls. The results indicate for the first time an association of MS with VDRG polymorphism, which may be involved in pathogenesis of MS, or in the linkage disequilibrium of VDRG to another pathogenic gene loci. The role of VDR gene polymorphism should be further studied in other populations, and the distribution of other polymorphism, such as Apa I, Taq I, should be also analyzed to confirm another susceptibility gene for MS and to obtain more adequate strategies for treatment of MS.

SCA6 mutation analysis in a large cohort of the Japanese patients with late-onset pure cerebellar ataxia.

Spinocerebellar ataxia type 6 (SCA6) is caused by small CAG repeat expansion in the gene encoding the alpha1A-voltage-dependent-calcium channel subunit (CACNLIA4) on chromosome 19p13, and is a subgroup of the late-onset pure cerebellar ataxia (ADCA III). To investigate the prevalence of SCA6 in the Japanese, we analyzed this mutation in 23 families and 12 probands with ADCA III. The specificity and stability of the CAG repeat were examined in additional individuals and families with other miscellaneous dominant SCAs. The CAG expansion of SCA6 gene was exclusively observed in 12 of 23 families (52%) and 12 proband cases with ADCA III, but not in others. The CAG repeat was 21-33 in the disease-associated alleles (n=56), and 4-18 in normal alleles (n=1148). Expanded alleles were stable during transmission, and a significant inverse correlation for CAG repeat number with age at onset was noted. Our results indicate that SCA6 shares approximately half of the ADCA III in the Japanese, and that gene mutations causing the remaining, have yet to be identified.

CTLA-4 gene polymorphism may modulate disease in Japanese multiple sclerosis patients.

Multiple sclerosis (MS) is widely believed to have a T-cell-mediated autoimmune etiology. The CTLA-4 gene is a strong candidate for involvement in autoimmune diseases because it plays an important role in the termination of T-cell activation. To examine the genetic association of the CTLA-4 gene locus with MS, we analyzed the CTLA-4 gene exon 1 A/G polymorphism in 74 Japanese MS patients and 93 controls. We also investigated the possible interactions of the CTLA-4 gene polymorphism with clinical course and severity, with MRI findings, with another genetic marker-HLA antigens, and with oligoclonal bands (OCB) in the cerebrospinal fluid (CSF). The CTLA-4 exon 1 polymorphism was similar between MS patients and controls. Conversely, clinical disability was significantly more severe in AA homozygous patients than in the other patients, and the allele frequency and the phenotype frequency of the A allele were significantly higher in patients with severe-grade MRI findings of cerebral white matter than in patients with mild-grade MRI findings. The allele frequency and the phenotype frequency of the A allele were significantly higher in patients with OCB than in patients without. This CTLA-4 polymorphism may modulate the prognosis of patients with MS and may be relevant to generation of OCB in the CSF.

Fluid viscosity of Aureobasidium pullulans cultures obtained at two different initial pH values.

Aureobasidium pullulans IAM 5060 grown in media with initial pHs of 6 and 7 differed in its production of exopolysaccharides (EPS). Under the latter condition, EPS of a high molecular weight was produced in an especially large amount. The viscosity of the culture broths and the EPS solutions obtained by removing the microbial cells exhibited a marked non-Newtonian and complex behavior depending on the measurement method. The nature of the viscosity of the fluids is explained by means of several structural models of their constitutive particles.

[A case of benign intracranial hypertension with fluctuated symptoms and CSF pressure synchronized with menstrual cycle].

A 39-year-old woman presented with a 2-month history of repeated severe headache, nausea and diplopia. On admission she was obese with bilateral papilledma and abducens weakness. Mass lesion and sinus thrombosis were ruled out by brain CT and angiography. CSF pressure was normal initially. CSF pressure fluctuated with menstrual cycle, sometimes showing over 600 mmH2O with worsening of the symptoms. She was diagnosed as benign intracranial hypertension (BIH). Diuretics did not improve the symptoms, and visual disturbances ensued and deteriorated. A spinal subarachnoid space-peritoneal shunt was inserted to control CSF pressure, showing rapid improvement of headache and diplopia but visual disturbances remained almost unchanged. Optic nerve sheath fenestration was performed without improvement of visual deterioration. We postulated multiple factors such as obesity, menstrual abnormality, iron deficiency anemia and analgesic drugs played important roles to produce BIH in this case. Careful quantitative perimetry should be done to decide a suitable time for surgical treatment in BIH.

[Periodic alternating nystagmus in spinocerebellar ataxia type 6 (SCA 6)].

We report a 61-year-old man with SCA 6 manifesting periodic alternating nystagmus (PAN). He first noted transient, recurrent episodes of "dizziness" at age 56. The symptom appeared several times a day, lasting for 3 years. At age 59, unsteady gait developed insidiously. On neurological examination, he showed limb and truncal ataxia, marked gaze nystagmus, and positional nystagmus. Thereafter, his ataxia became worse and PAN developed. Brain MRI showed pathologic atrophy which was confined to the cerebellum. PAN was rarely reported in spinocerebellar ataxia, being not described in SCA 6. The episodic "dizziness" at the initial stage has not gained much attention. Our observation indicates that the initial manifestation of SCA 6 overlaps with that of episodic ataxia type 2, an allelic disorder of SCA 6. PAN and fluctuating symptoms, as seen in our patient, must be carefully examined to see whether or not they can be parts of clinical presentations in SCA 6.

[Initial symptoms and mode of neurological progression in spinocerebellar ataxia type 6 (SCA6)].

Spinocerebellar ataxia type 6 (SCA6) is genetically defined as a group of SCA characterized by late-onset pure cerebellar ataxia clinically and by a small CAG repeat expansion in the gene encoding the alpha 1A-voltage-dependent-Ca channel subunit (CACNL1A4) on chromosome 19p13.1 genetically. We analyzed the initial symptoms and the mode of progression in this disorder on 25 genetically verified patients. The initial symptoms were recurrent episodes of transient vertigo (72%) or unsteady gait (28%). Neurologically, they showed apparent gaze-evoked nystagmus (92%), transient positional nystagmus (83%), and periodic alternating nystagmus (4%), in addition to cerebellar ataxia. In addition to these episodic symptoms, all patients developed progressive cerebellar ataxia over years. These fluctuating symptoms at the initial stage of the illness were clearly different from those of other SCA, rather overlapping with those of episodic ataxia type 2 (EA2), an allelic disorder of SCA6. The clinical similarity indicates that there might be a common mechanism at least in part causing these two disorders. The mode of progression and their neurological features were also presented.

[A clinical trial of acetazolamide for SCA6].

Spinocerebellar ataxia type 6 (SCA 6) is an allelic disorder of episodic ataxia type 2 (EA 2) and is caused by a small CAG repeat expansion in the gene encoding the alpha 1A-voltage-dependent-Ca channel subunit (CACNA 1 A) on chromosome 19p13.1. The disorder starts at adulthood with progressive cerebellar ataxia, and the symptoms often fluctuate at early stage. These clinical features overlap with those of EA 2, which has been known as acetazolamide-responsive ataxia. On this background, we studied the clinical effectiveness of acetazolamide for SCA 6 in 9 consecutive patients. Their clinical severity was serially evaluated by ARS (ataxia rating scale) and gravimetric test, over 32 weeks of oral administration of acetazolamide (250-500 mg/day). Consequently, a significant improvement was observed in ARS and postural sway. Our results indicate that acetazolamide is temporally effective for ameliorating the symptoms of SCA 6. However, its effects for the disease progression need to be examined in more large scales in number and duration.