Bolivian kindred with combined spinocerebellar ataxia types 2 and 10

BACKGROUND

Spinocerebellar ataxias (SCA) are a group of rare hereditary neurodegenerative disorders. Rare cases of two SCA mutations in the same individual have been reported in the literature, however, family descriptions are lacking.

AIMS

To characterize a family with combined SCA2 and SCA10 mutations.

MATERIALS & METHODS

Analysis of the clinical features and genetic findings of a Bolivian family expressing both SCA2 and SCA10 mutations.

RESULTS

The index case and his mother had both SCA2 and SCA10 mutations with a combined clinical phenotype of both disorders, including slow saccades (SCA2) and seizures (SCA10). The uncle of the index case had only an SCA10 mutation.

DISCUSSION

Although the presence of two SCA mutations in the same individuals may be coincidental, the low probability of having both mutations suggests that these mutations might be particularly prevalent in Bolivian population.

CONCLUSION

This is the first description of a family with two SCA mutations with affected subjects having a combined SCA2 and SCA10 phenotype.

Consensus paper: pathological mechanisms underlying neurodegeneration in spinocerebellar ataxias

Intensive scientific research devoted in the recent years to understand the molecular mechanisms or neurodegeneration in spinocerebellar ataxias (SCAs) are identifying new pathways and targets providing new insights and a better understanding of the molecular pathogenesis in these diseases. In this consensus manuscript, the authors discuss their current views on the identified molecular processes causing or modulating the neurodegenerative phenotype in spinocerebellar ataxias with the common opinion of translating the new knowledge acquired into candidate targets for therapy. The following topics are discussed: transcription dysregulation, protein aggregation, autophagy, ion channels, the role of mitochondria, RNA toxicity, modulators of neurodegeneration and current therapeutic approaches. Overall point of consensus includes the common vision of neurodegeneration in SCAs as a multifactorial, progressive and reversible process, at least in early stages. Specific points of consensus include the role of the dysregulation of protein folding, transcription, bioenergetics, calcium handling and eventual cell death with apoptotic features of neurons during SCA disease progression. Unresolved questions include how the dysregulation of these pathways triggers the onset of symptoms and mediates disease progression since this understanding may allow effective treatments of SCAs within the window of reversibility to prevent early neuronal damage. Common opinions also include the need for clinical detection of early neuronal dysfunction, for more basic research to decipher the early neurodegenerative process in SCAs in order to give rise to new concepts for treatment strategies and for the translation of the results to preclinical studies and, thereafter, in clinical practice.

Affective communication deficits associated with cerebellar degeneration

The cerebellum has extensive connections with the frontal lobes. Cerebellar injury has been reported to induce frontal-executive cognitive dysfunction and blunting of affect. We examined a patient with idiopathic cerebellar degeneration with impaired family relationships attributed to an "emotional disconnection." Examination revealed ataxia, dysmetria, and adiadochokinesia more severe on the left and frontal-executive dysfunction; memory and cognitive functions were otherwise normal. Testing of emotional communication included assessments of emotional semantic knowledge, emotional prosody, and emotional facial expressions. Comprehension was normal but expression was severely impaired. Cerebellar dysfunction can cause a defect in facial and prosodic emotional communication.

Divalent cations enhance fluoride binding to Streptococcus mutans and Streptococcus sanguinis cells and subsequently inhibit bacterial acid production

One preventive effect of topical fluoride application is derived from the fact that fluoride can inhibit bacterial acid production. Furthermore, divalent cations such as Ca(2+) and Mg(2+) increase the binding of fluoride to bacterial cells. These findings suggest that exposure of oral bacteria to fluoride in the presence of divalent cations increases fluoride binding to bacterial cells and subsequently enhances fluoride-induced inhibition of bacterial acid production. This study investigated the effects of fluoride exposure (0-20,000 ppm F) in the presence of Ca(2+) or Mg(2+) prior to glucose challenge on pH fall ability by bacterial sugar fermentation, as well as fluoride binding to bacterial cells by exposure to fluoride, and fluoride release from bacterial cells during bacterial sugar fermentation, using caries-related bacteria, Streptococcus mutans and Streptococcus sanguinis. The pH fall by both streptococci was inhibited by exposure to over 250 ppm F in the presence of Ca(2+) (p < 0.01), whereas in the presence of Mg(2+), the pH fall by S. mutans and S. sanguinis was inhibited after exposure to over 250 and 950 ppm F, respectively (p < 0.05). The amounts of fluoride binding to and released from streptococcal cells increased with the concentration of fluoride the cells were exposed to in the presence of Mg(2+), but were high enough even after 250 ppm F exposure in the presence of Ca(2+). The enhanced inhibition of acid production in the presence of divalent cations is probably due to the improved efficiency of fluoride binding to bacterial cells being improved via these divalent cations.

CAG repeat expansion in Huntington disease determines age at onset in a fully dominant fashion

OBJECTIVE

Age at onset of diagnostic motor manifestations in Huntington disease (HD) is strongly correlated with an expanded CAG trinucleotide repeat. The length of the normal CAG repeat allele has been reported also to influence age at onset, in interaction with the expanded allele. Due to profound implications for disease mechanism and modification, we tested whether the normal allele, interaction between the expanded and normal alleles, or presence of a second expanded allele affects age at onset of HD motor signs.

METHODS

We modeled natural log-transformed age at onset as a function of CAG repeat lengths of expanded and normal alleles and their interaction by linear regression.

RESULTS

An apparently significant effect of interaction on age at motor onset among 4,068 subjects was dependent on a single outlier data point. A rigorous statistical analysis with a well-behaved dataset that conformed to the fundamental assumptions of linear regression (e.g., constant variance and normally distributed error) revealed significance only for the expanded CAG repeat, with no effect of the normal CAG repeat. Ten subjects with 2 expanded alleles showed an age at motor onset consistent with the length of the larger expanded allele.

CONCLUSIONS

Normal allele CAG length, interaction between expanded and normal alleles, and presence of a second expanded allele do not influence age at onset of motor manifestations, indicating that the rate of HD pathogenesis leading to motor diagnosis is determined by a completely dominant action of the longest expanded allele and as yet unidentified genetic or environmental factors.

ABO-incompatible adult living donor liver transplantation for hepatocellular carcinoma

Living donor liver transplantation (LDLT) offers timely transplantation for patients with hepatocellular carcinoma (HCC). If ABO-incompatible LDLT is feasible, the need for pretransplantation treatment may be eliminated, which may reduce overall morbidity. In this article, we have described 8 adult HCC patients who successfully underwent LDLT from ABO-incompatible donors. Antirejection therapy included multiple preoperative plasmaphereses, splenectomy, and an immunosuppressive regimen with tacrolimus, methylprednisolone, and mycophenolate mofetil. The maintenance dose of immunosuppression did not differ from that of the ABO-identical cases. In addition, we also performed intrahepatic arterial infusion of prostaglandin E1. In 5 patients, we administered a single dose of rituximab, a chimeric CD20 monoclonal antibody. As a result of this treatment, 6/8 patients are still alive. Our experience has shown that it is possible to control antibody-mediated humoral rejection and other complications in adult ABO-incompatible LDLT.

Functioning adrenocortical oncocytoma: the first documented case producing interleukin-6 and review of the literature

Adrenocortical oncocytoma is an extremely rare and predominantly non-functioning tumor. We herein report the first case of an adrenocortical oncocytoma that produces interleukin (IL)-6. A 38-yr-old woman was referred for treatment of a 4-cm adrenal mass. Laboratory test results showed elevated inflammatory parameters. Intriguingly, IL-6 serum level was also high at 30 pg/ml (normal 0-4 pg/ml). The patient underwent laparoscopic right adrenalectomy. Microscopic examination showed that the tumor was an adrenocortical oncocytoma with a unique peripheral lymphoid cuff with germinal centers. Electron microscopy demonstrated that the cytoplasm of the neoplastic cells was packed with numerous abnormal mitochondria. Three observations lead us to consider that this tumor was the primary source of serum IL-6. First, the IL-6 level in blood collected from the right adrenal vein was highest (527 pg/ml) among intra-operative blood samples. Second, neoplastic cells stained positively for IL-6. Third, the serum IL-6 returned to normal levels immediately after surgery.

Genetic and physical mapping of the partial resistance gene, pi34, to blast in rice

ABSTRACT Partial resistance to rice blast in the Oryza sativa japonica group cv. Chubu 32 is controlled by Pi34, a major quantitative trait locus (QTL) on chromosome 11, and several uncharacterized QTLs. The objectives of the study were (i) high-resolution genetic and physical mapping of Pi34 and (ii) identification of new QTL imparting resistance to rice blast. Chubu 32 was crossed with a susceptible chromosomal segment substitution line (CSSL) of cv. Koshihikari. From 4,012 of segregating individuals, 213 recombinants in the Pi34 region were screened by using polymerase chain reaction-based markers and tested resistance in the field and greenhouse. The Pi34 locus is located in the 54.1-kb region on the genomic sequence of cv. Nipponbare. We constructed a bacterial artificial chromosome (BAC) library of Chubu 32, selected the clone containing Pi34, and sequenced it. The Pi34 locus consequently was located on an interval of 65.3 kb containing 10 predicted open reading frames (ORFs). Two of these ORFs were predicted only in Chubu 32 and encoded transposable elements. The other eight ORFs were found in both Chubu 32 and Nipponbare and one of them, which encoded an unknown protein, showed significantly different amino acid sequences between two cultivars. The new QTL, Piq6(t), was detected on the short arm of chromosome 6 and the genetic distance of flanking markers was 16.9 centimorgans in Nipponbare. Pi34 and Piq6(t) acted additively on resistance to rice blast but the effect of Piq6(t) was relatively small compared with Pi34.

The Role of Plasmapheresis Therapy for Perioperative Management in ABO-Incompatible Adult Living Donor Liver Transplantation

BACKGROUND

Although living donor liver transplantation (LDLT) was established as a treatment for end-stage liver disease in Japan, the indication for LDLT across an ABO-incompatible barrier remains controversial. The purpose of this study was to elucidate the role of plasmapheresis in incompatible LDLT.

METHODS

Eleven adult patients (seven men and four women) who underwent incompatible LDLT were enrolled in this study. Of these three patients had hepatocellular carcinoma, three chronic hepatitis C, one Wilson's disease, one autoimmune hepatitis, one chronic hepatitis B, one hemochromatosis, and one fulminant hepatic failure. The immunosuppressive regimen consisted of tacrolimus, prednisolone, mycophenolate mofetil (or cyclophosphamide), and prostaglandin E1 in all patients. Multiple plasmapheresis was performed perioperatively to reduce the recipient's antibody titers against the donor's blood type.

RESULTS

Plasmapheresis was useful for the reduction of the recipient's antibody titers to x 16 or lower before and after transplantation. There was no difference in transplant outcome between the 11 patients with incompatible blood group and 30 patients with identical or compatible blood groups.

DISCUSSION

Major postoperative complications such as intrahepatic biliary complications and hepatic necrosis may occur in incompatible transplantation. Several investigators suggested that anti-immunoglobulin (Ig) M and anti-IgG antibody titers sustained these complications. The antibody titers must be decreased sufficiently with plasmapheresis. An elevation of anti-ABO titers after transplantation may be a predictive risk factor for increased mortality and morbidity. In order to perform LDLT in a safer manner, plasmapheresis is an indispensable treatment to improve the outcome of ABO-incompatible cases.

The role of ataxin 10 in the pathogenesis of spinocerebellar ataxia type 10

BACKGROUND

Spinocerebellar ataxia type 10 (SCA10) is an autosomal dominant disorder characterized by cerebellar ataxia and seizures. SCA10 is caused by an expansion of an ATTCT pentanucleotide repeat in intron 9 of the ataxin 10 (ATXN10) gene encoding an approximately 55-kd protein of unknown function. However, how this mutation leads to SCA10 is unknown.

METHODS

In an effort to understand the pathogenic mechanism of SCA10, the authors conducted a series of experiments to address the effect of repeat expansion on the transcription and RNA processing of the ATXN10 gene. In addition, we generated Sca10 (mouse ataxin 10 homolog)-null mice and addressed the role of Sca10 gene dosage on the cerebellum.

RESULTS

Mutant ATXN10 allele is transcribed at the normal level, and the pre-mRNA containing an expanded repeat is processed normally in patient-derived cells. Sca10-null mice exhibited embryonic lethality. Heterozygous mutants were overtly normal and did not develop SCA10 phenotype

CONCLUSION

A simple gain of function or loss of function of ATXN10 is unlikely to be the major pathogenic mechanism contributing to the spinocerebellar ataxia type 10 phenotype.

Pi35(t), a new gene conferring partial resistance to leaf blast in the rice cultivar Hokkai 188

The japonica rice cultivar Hokkai 188 shows a high level of partial resistance to leaf blast. For mapping genes conferring the resistance, a set of 190 F2 progeny/F3 families was developed from the cross between the indica rice cultivar Danghang-Shali, with a low level of partial resistance, and Hokkai 188. Partial resistance to leaf blast in the F3 families was assessed in upland nurseries. From a primary microsatellite (SSR) linkage map and QTL analysis using a subset of 126 F2 progeny/F3 families randomly selected from the above set, one major QTL located on chromosome 1 was detected in the vicinity of SSR marker RM1216. This QTL was responsible for 69.4% of the phenotypic variation, and Hokkai 188 contributed the resistance allele. Segregation analysis in the F3 families for partial resistance to leaf blast was in agreement with the existence of a major gene, and the gene was designated as Pi35(t). Another QTL detected on chromosome 8 was minor, explained 13.4% of the phenotypic variation, and an allele of Danghang-Shali increased the level of resistance in this QTL. Additional SSR markers of the targeted Pi35(t) region were further surveyed in the 190 F2 plants, and Pi35(t) was placed in a 3.5-cM interval flanked by markers RM1216 and RM1003.

Measuring Friedreich ataxia: complementary features of examination and performance measures

OBJECTIVE

To examine the potential validity of performance measures and examination-based scales in Friedreich ataxia (FA) by examining their correlation with disease characteristics.

METHODS

The authors assessed the properties of a candidate clinical outcome measure, the Friedreich Ataxia Rating Scale (FARS), and simple performance measures (9-hole peg test, the timed 25-foot walk, PATA test, and low-contrast letter acuity) in 155 patients with FA from six institutions, and correlated the scores with disease duration, functional disability, activity of daily living scores, age, and shorter GAA repeat length to assess whether these measures capture the severity of neurologic dysfunction in FA.

RESULTS

Scores for the FARS and performance measures correlated significantly with functional disability, activities of daily living scores, and disease duration, showing that these measures meet essential criteria for construct validity for measuring the progressive nature of FA. In addition, the FARS and transformed performance measures scores were predicted by age and shorter GAA repeat length in linear regression models accounting for sex and testing site. Correlations between performance measures were moderate in magnitude, suggesting that each test captures separate yet related dimensions of neurologic function in FA and that a composite measure might better predict disease status. Composite measures created using cohort means and standard deviations predicted disease status better than or equal to single performance measures or examination-based measures.

CONCLUSIONS

The Friedreich Ataxia Rating Scale, performance measures, and performance measure composites provide valid assessments of disease progression in Friedreich ataxia.

Clinical phenotype of Brazilian families with spinocerebellar ataxia 10

Spinocerebellar ataxia type 10 (SCA10) is an autosomal dominant ataxia caused by an ATTCT repeat expansion in an intron of the SCA10 gene. SCA10 has been reported only in Mexican families, in which the disease showed a combination of cerebellar ataxia and epilepsy. The authors report 28 SCA10 patients from five new Brazilian families. All 28 patients showed cerebellar ataxia without epilepsy, suggesting that the phenotypic expression of the SCA10 mutation differs between Brazilian and Mexican families.

Pharmacokinetic differences between morning and evening administration of cyclosporine and tacrolimus therapy

We performed 24-hour monitoring of cyclosporine (NEO) and tacrolimus (TAC) blood concentrations, evaluating pharmacokinetic parameters and characterizing circadian variations. The monitoring was performed in 10 instances on nine patients administered NEO and 12 out of 11 patients administered TAC. All cases were administered equally divided doses of drugs twice daily orally. Blood samples were taken before and 1, 2, 3, 4, 6, and 12 hours after NEO or TAC administration in the morning and evening. The pharmacokinetic parameters were compared between morning and evening administrations of both drugs. AUC0-12, AUC0-4, C(max), C2, and C(max)/C(min) of NEO and TAC were significantly lower during the evening compared with morning administrations. C(min) values were significantly higher in the evening. T(max) of NEO was longer in evening, although there was not a significant difference; T(max) of TAC was significantly longer in the evening. We found that NEO and TAC administrations in the evening resulted in reduced bioavailability and delayed absorption when compared with drug administrations in the morning. It was thought that the difference in bioavailability between morning and evening administrations was smaller with TAC, because TAC shows lower peak levels and a flatter blood concentration curve than NEO. C(min) was higher after evening administration than morning because of delayed absorption, though the bioavailability of both drugs decreased in the evening. These results suggest that we have to appreciate apparently high trough levels.

Clinical evaluation of idiopathic paroxysmal kinesigenic dyskinesia: new diagnostic criteria

BACKGROUND

Paroxysmal kinesigenic dyskinesia (PKD) is a rare disorder characterized by short episodes of involuntary movement attacks triggered by sudden voluntary movements. Although a genetic basis is suspected in idiopathic cases, the gene has not been discovered. Establishing strict diagnostic criteria will help genetic studies.

METHODS

The authors reviewed the clinical features of 121 affected individuals, who were referred for genetic study with a presumptive diagnosis of idiopathic PKD.

RESULTS

The majority (79%) of affected subjects had a distinctive homogeneous phenotype. The authors propose the following diagnostic criteria for idiopathic PKD based on this phenotype: identified trigger for the attacks (sudden movements), short duration of attacks (<1 minute), lack of loss of consciousness or pain during attacks, antiepileptic drug responsiveness, exclusion of other organic diseases, and age at onset between 1 and 20 years if there is no family history (age at onset may be applied less stringently in those with family history). In comparing familial and sporadic cases, sporadic cases were more frequently male, and infantile convulsions were more common in the familial kindreds. Females had a higher remission rate than males. An infantile-onset group with a different set of characteristics was identified. A clear kinesigenic trigger was not elicited in all cases, antiepileptic response was not universal, and some infants had attacks while asleep.

CONCLUSIONS

The diagnosis of idiopathic paroxysmal kinesigenic dyskinesia (PKD) can be made based on historical features. The correct diagnosis has implications for treatment and prognosis, and the diagnostic scheme may allow better focus in the search for the PKD gene(s).

Optimal Dose and Target Trough Level in Cyclosporine and Tacrolimus Conversion in Renal Transplantation as Evaluated by Lymphocyte Drug Sensitivity and Pharmacokinetic Parameters

We evaluated the relative clinical potency of cyclosporine (CyA) and tacrolimus (Tac) using pharmacodynamic and pharmacokinetic parameters of the drug to obtain the most suitable converting dose and target trough level. The relative pharmacodynamic potency was examined by the mean ratio of drug concentrations giving 50% inhibition of blastogenesis of lymphocytes (IC50) in 66 chronic renal failure patients. The relative potency estimated from clinical pharmacokinetic parameters was examined by the mean ratio of each pharmacokinetic parameter value of CyA versus Tac. The pharmacokinetic parameters were estimated by 12-hour monitoring of drug blood concentrations in seven CyA patients and seven Tac patients. The mean IC50 ratio of CyA and Tac (CyA/Tac of IC50) was 25.1. The mean area under the concentration-time curve (AUC) ratio (CyA/Tac of AUC) was 25.5, the mean trough level (C(min)) ratio (CyA/Tac of C(min)) was 13.2, and the mean dose per body weight ratio was 25.2. The relative potency estimated from AUC that is the most reliable pharmacokinetic parameter for the estimation of clinical efficacy of calcineurin inhibitors appeared to agree with the relative pharmacodynamic potency estimated from IC50. The data suggest that TAC 25-fold more potent than CyA, which represents a suitable converting dose ratio, and that target trough level of CyA is about 13-fold greater than Tac based on CyA/Tac of C(min). We conclude that these relative values may be useful to estimate the suitable dose and target trough levels to convert between CyA and Tac.

Evaluation of Appropriate Blood Level in Continuous Intravenous Infusion From Trough Concentrations After Oral Administration Based on Area Under Trough Level in Tacrolimus and Cyclosporine Therapy

The target blood concentrations of tacrolimus (TAC) and cyclosporine (CYA) during continuous intravenous infusion (C(ss)) have been determined based on clinical experience. However, it is desirable that C(ss) should be set so that the AUC after intravenous infusion is equal to the AUC after oral administration (AUC(po)). Accordingly, we performed 12-hour monitoring of blood concentrations to calculate C(ss) from the blood trough levels (C(TL)) on 15 kidney recipients administered TAC and 12 recipients administered CYA (Neoral). We used an area under the trough level (AUTL) as a new pharmacokinetic parameter. The C(ss) was evaluated from C(TL), AUC(po), and AUTL was calculated to be C(ss) = C(TL) x (AUC(po)/AUTL). In addition, AUTL/AUC(po) ratio and blood peak/trough level ratio (C(max)/C(min)) were examined to compare pharmacokinetics of TAC and CYA. The formula for TAC was C(ss) = C(TL) x 1.40 and that for CYA, C(ss) = C(TL) x 2.55. The calculated target C(ss) of TAC was 1.40 times that of C(TL), which was similar to the present clinical C(TL). In contrast, the calculated target C(ss) of CYA was 2.55 times the C(TL), and therefore an extremely high C(ss) was necessary to obtain a sufficient AUC that will be available after oral administration. Consequently, intravenous administration of CYA twice a day was considered to be more appropriate to obtain sufficient CYA pharmacokinetics, rather than a continuous intravenous administration. We conclude that the formula, C(ss) = C(TL) x (AUC(po)/AUTL) was useful to calculate the target blood concentration of calcineurin inhibitors when changing from continuous intravenous infusion to oral administration of these drugs.

Measuring Friedreich ataxia: Interrater reliability of a neurologic rating scale

Measuring the severity of neurologic dysfunction in patients with inherited ataxias, including Friedreich ataxia (FA), is difficult because of the variable rate of progression, the variable age at onset and the variety of neural systems that may be affected. The authors discuss the problems related to rating scales in the ataxias, report a neurologic rating scale for FA, and demonstrate acceptable interrater reliability of the instrument.

Germline mutational dynamics in myotonic dystrophy type 1 males: allele length and age effects

BACKGROUND

The CTG repeat expansion causing myotonic dystrophy type 1 is unstable in the germline, and frequent intergenerational length changes are observed, giving rise to the unusual genetics of the disorder. The repeat is also somatically unstable, and expanded alleles accumulate throughout life, thus compromising simple measures of intergenerational stability.

OBJECTIVE

To gain a better understanding of the intergenerational dynamics of the DM1 repeat in the male germline.

METHODS

We used sensitive small pool PCR procedures to analyze sperm and somatic DNA from 22 DM1 men of different ages, CTG repeat length, and clinical form.

RESULTS

High levels of repeat length variation heavily biased toward further expansions were observed in the sperm of all DM1 men. Progenitor allele length was revealed as a major modifier of interindividual variation, with the largest length changes observed for premutation and protomutation alleles and the highest frequency of contractions in full mutation alleles. However, despite clear increases in the degree of somatic mosaicism, no differences were observed in replicate sperm samples obtained from two men during a 4-year period.

CONCLUSIONS

Progenitor allele length is a major modifier of the mutational dynamics of the DM1 repeat in the male germline, but surprisingly age is not. Therefore, other as yet unidentified modifiers must be responsible for the considerable residual interindividual variation that cannot be accounted for by these factors.

Radial flow bioreactor for the creation of bioartificial liver and kidney

A radial flow bioreactor (RFB) is used for a three-dimensional perfusion culture of hepatocellular carcinoma (HCC) cells and renal cells, to create a bioartificial liver and kidney. The cylindrical reactor is filled with porous cellulose microcarrier. RFB can be characterized as a system in which the medium flows from the periphery toward the center of the reactor, thereby delivering an adequate supply of oxygen and nutrients to cells at the center as well as at the periphery. HCC cells incubated in the RFB system at high density maintained viability for long periods of time. Proximal tubular cells (LLC-PK1) as well as HCC cells, but not human immortalized mesangial cells (HMC) were cultured in the RFB for more than 14 days. The mRNA expression of some enzymes involved in the urea cycle, cytochrome P450s in HCC cells, and the 1-alpha-hydroxylase (CYP27B1) in LLC-PK1 cells was higher than that in monolayer cultures. These results suggest that the RFB system composed of HCC cells or renal cells may be useful for a bioartificial liver and kidney.

Length-dependent structure formation in Friedreich ataxia (GAA)n*(TTC)n repeats at neutral pH

More than 15 human genetic diseases have been associated with the expansion of trinucleotide DNA repeats, which may involve the formation of non-duplex DNA structures. The slipped-strand nucleation of duplex DNA within GC-rich trinucleotide repeats may result in the changes of repeat length; however, such a mechanism seems less likely for the AT-rich (GAA)n*(TTC)n repeats. Using two-dimensional agarose gels, chemical probing and atomic force microscopy, we characterized the formation of non-B-DNA structures in the Friedreich ataxia-associated (GAA)n*(TTC)n repeats from the FRDA gene that were cloned with flanking genomic sequences into plasmids. For the normal genomic repeat length (n = 9) our data are consistent with the formation of a very stable protonated intramolecular triplex (H-DNA). Its stability at pH 7.4 is likely due to the high proportion of the T.A.T triads which form within the repeats as well as in the immediately adjacent AT-rich sequences with a homopurine. homopyrimidine bias. At the long normal repeat length (n = 23), a family of H-DNAs of slightly different sizes has been detected. At the premutation repeat length (n = 42) and higher negative supercoiling, the formation of a single H-DNA structure becomes less favorable and the data are consistent with the formation of a bi-triplex structure.

Huntington's disease-like 2 can present as chorea-acanthocytosis

Three patients from a previously described family with autosomal dominant chorea-acanthocytosis were found to have the CTG trinucleotide repeat expansion mutation of the junctophilin-3 gene associated with Huntington's disease-like 2 (HDL2). One of six previously identified patients with HDL2 had acanthocytosis on peripheral blood smear, suggesting that HDL2 should be considered in the differential of chorea-acanthocytosis.

The clinical significance of sialyl Lewis antigen expression in the spread of gastric cancer. Flow cytometric DNA analysis

We previously reported significant relationships between sialyl Lewis antigen expression on gastric cancer cells and both hepatic metastasis and clinical prognosis. The purpose of this study was to compare the expression of sialyl Lewis antigens on gastric cancer cells to elucidate the possible role of sialyl Lewis antigens in predicting the spread of a tumor with regard to histological findings. Subjects consisted of 38 patients with gastric cancer. For comparison we measured the values for sialyl Lewisa (sLea) and sialyl Lewisx (sLex) expression on the surface of about 10,000-30,000 cancer cells. Monoclonal antibodies CA19-9 and KM-93 were used to determine the frequency (%) and quantity (channel) of the expression by flow cytometry. We assessed the correlation of sLea and sLex expression with histological findings (depth of tumor invasion (pT), lymphatic invasion (ly), venous invasion (v), and lymph node metastasis (pN)), by comparing sLea and sLex expression in relation to the grade of histological findings. A significant relationship was found between lymphatic invasion and the frequency of sLea expression (r = 0.40, p<0.05). The mean values of sLea frequency in cases categorized as ly 2 (36.30) and ly 3 (31.81) were statistically higher than those in ly 1 cases (12.74) (p<0.05). A significant relationship was also observed between lymph node metastasis and the frequency of sLea expression (r = 0.46, p<0.01). The mean value of sLea frequency in pN 3 cases (44.14) was statistically higher than those in pN 0 (17.11) and pN 1 (19.03) cases (p<0.05). Neither the depth of tumor invasion nor venous invasion showed any correlation with the expression of sialyl Lewis antigens. In conclusion the frequency of sLea expression on the surface of gastric cancer cells was greater in those patients who developed lymphatic invasion and lymph node metastasis. However, the mechanism by which sialyl Lewisa expression is upregulated remains unclear.

Association of homozygous 7048G7049 variant in the intron six of Nurr1 gene with Parkinson's disease

OBJECTIVE

To determine whether the Nurr1 gene, which is critical for the development and maintenance of nigral dopaminergic neurons, is a risk factor associated with PD.

BACKGROUND

The Nurrl gene is highly expressed in the dopaminergic neurons in the midbrain. Knockout of the gene results in agenesis of nigral dopaminergic neurons and heterozygous knockout mice increases 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity.

METHODS

This study included 105 patients with familial PD (fPD) and 120 patients with sporadic PD (sPD) and 221 age-matched healthy control subjects. The polymorphisms and mutations of the Nurr1 gene in patients with PD were initially examined by heteroduplex analysis and sequencing analysis from PCR-amplified Nurr1 gene fragments. A polymorphism in the BseRI restriction site was identified, and a relatively large-scale analysis then was conducted by three independent investigators who were blinded to the clinical status of the subjects.

RESULTS

A homozygous 7048G7049 polymorphism was found in intron 6 of the Nurr1 gene, which was significantly higher in fPD (10/105; 9.5%) and in sPD (5/120; 4.2%) compared with healthy control subjects (2/221; 0.9%). The mean age and the SD at onset of these homozygote patients with PD was 52 +/- 15 years for fPD and 46 +/- 7 years for sPD. The clinical features of these homozygote patients with PD did not differ from those of typical PD.

CONCLUSIONS

The homozygote polymorphism of 7048G7049 in intron 6 of the Nurr1 gene is associated with typical PD.

Mapping of the QTL (quantitative trait locus) conferring partial resistance to leaf blast in rice cultivar Chubu 32

The rice cultivar Chubu 32 possesses a high level of partial resistance to leaf blast. The number and chromosomal location of genes conferring this resistance were detected by restriction fragment length polymorphism (RFLP) linkage mapping and quantitative trait locus (QTL) analysis. For the mapping, 149 F(3) lines derived from the cross between rice cultivar Norin 29, with a low level of partial resistance, and Chubu 32 were used, and their partial resistance to leaf blast was assessed in upland nurseries. A linkage map covering six chromosomes and consisting of 36 RFLP markers was constructed. In the map, only one significant QTL (LOD>2.0) for partial resistance was detected on chromosome 11. This QTL explained 45.6% of the phenotypic variation. The segregation ratio of the F3 lines was 3:1 for partial resistance to susceptibility. These results suggest that the partial resistance in Chubu 32 is controlled by a major gene.

[Spinocerebellar ataxia type 10 (SCA10): a disease caused by a novel pentanucleotide repeat expansion]

Spinocerebellar ataxia type 10 (SCA10) is an autosomal dominant progressive disorder characterized by ataxia, seizures and anticipation, mapped to chromosome 22q13.3. We have found that the mutation of SCA10 is an unstable and massive expansion (800-4,500 repeats) of the ATTCT pentanucleotide repeat in intron 9 of SCA 10 (also known as E46L), a novel gene of unknown function. The mutation, so far, has only been found in the population of the Mexican descent with a founder effect supported by haplotype data. The expansion size of the repeat inversely correlates with age of disease onset and SCA10 is highly expressed throughout the central nervous system. Expanded ATTCT repeats in SCA10 patients show repeat size instability in their somatic and germline cells as well as time-dependent instability in blood. This novel type of microsatellite repeat expansion is the largest found to date in human diseases. Its epidemiological, clinical, genetic and pathophysiological features need to be further investigated.

Alcohol dehydrogenase polymorphism and Parkinson's disease

A particular alcohol dehydrogenase (ADH) polymorphism (allele A1) in the promoter region of the gene has been recently demonstrated to be associated with increased risk of Parkinson's disease (PD). In a case control study, we examine frequencies of ADH A1 allele in 100 PD patients (i.e. 200 alleles), 100 diseased controls (i.e. 200 alleles), and 194 healthy controls (i.e. 388 alleles). In addition, we study possible association of a combined non-amyloid component of plaque (NACP-Rep 1) allele and ADH A1 allele with risk of PD. There was no statistical significance of the frequencies of ADH A1 allele between PD patients 12/200 (6%), diseased controls 13/200 (6.5%), and healthy controls 20/388 (5.2%). No strong evidence of an association was found between ADH A1 allele and PD susceptibility in our study patients. There was also no suggestion of linkage disequilibrium between NACP-Rep 1 and ADH A1 alleles.

Clinical and genetic analysis of four Mexican families with spinocerebellar ataxia type 10

Spinocerebellar ataxia type 10 (SCA10) is an autosomal dominant disorder caused by expansion of an unstable ATTCT repeat. SCA10 has been described as a pure cerebellar syndrome accompanied by seizures and has been recognized only in families of Mexican origin. We describe clinical and molecular findings of 18 patients in four Mexican families with SCA10. Affected individuals had an average age at onset of 26.7 years (range 14-44 years) and ATTCT repeats ranging from 920 to 4,140 repeats. We could not detect significant anticipation or correlation between repeat size and age at onset, probably due to the small sample size. In addition to pure cerebellar ataxia and seizures, patients often showed soft pyramidal signs, ocular dyskinesia, cognitive impairment, and/or behavioral disturbances. Brain magnetic resonance imaging showed predominant cerebellar atrophy, and nerve conduction studies indicated polyneuropathy in 66% of patients. One family showed hepatic, cardiac, and hematological abnormalities in affected members. These findings suggest that a wide range of tissues may be affected in SCA10, including those outside of the cerebellum and cerebral cortex.

"Mitotic drive" of expanded CTG repeats in myotonic dystrophy type 1 (DM1)

In myotonic dystrophy type 1 (DM1), an expanded CTG repeat shows repeat size instability in somatic and germ line tissues with a strong bias toward further expansion. To investigate the mechanism of this expansion bias, 29 DM1 and six normal lymphoblastoid cell lines (LBCLs) were single-cell cloned from blood cells of 18 DM1 patients and six normal subjects. In all 29 cell lines, the expanded CTG repeat alleles gradually shifted toward further expansion by "step-wise" mutations. Of these 29 cell lines, eight yielded a rapidly proliferating mutant with a gain of large repeat size that became the major allele population, eventually replacing the progenitor allele population. By mixing cell lines with different repeat expansions, we found that cells with larger CTG repeat expansion had a growth advantage over those with smaller expansions in culture. This growth advantage was attributable to increased cell proliferation mediated by Erk1,2 activation, which is negatively regulated by p21(WAF1). This phenomenon, which we designated "mitotic drive" , is a novel mechanism which can explain the expansion bias of DM1 CTG repeat instability at the tissue level, on a basis independent of the DNA-based expansion models. The lifespans of the DM1 LBCLs were significantly shorter than normal cell lines. Thus, we propose a hypothesis that DM1 LBCLs drive themselves to extinction through a process related to increased proliferation.

RNA CUG repeats sequester CUGBP1 and alter protein levels and activity of CUGBP1

An RNA CUG triplet repeat binding protein, CUGBP1, regulates splicing and translation of various RNAs. Expansion of RNA CUG repeats in the 3'-untranslated repeat of the mutant myotonin protein kinase (DMPK) mRNA in myotonic dystrophy (DM) is associated with alterations in binding activity of CUGBP1. To investigate whether CUGBP1 is directly affected by expansion of CUG repeats in DM tissues, we examined the intracellular status of CUGBP1 in DM patients as well as in cultured cells over expressing RNA CUG repeats. The analysis of RNA-protein complexes showed that, in control tissues, the majority of CUGBP1 is free of RNA, whereas in DM patients the majority of CUGBP1 is associated with RNA containing CUG repeats. Similarly to DM patients, overexpression of RNA CUG repeats in cultured cells results in the re-allocation of CUGBP1 from a free state to the RNA.protein complexes containing CUG repeats. CUG repeat-dependent translocation of CUGBP1 into RNA-protein complexes is associated with increased levels of CUGBP1 protein and its binding activity. Experiments with cyclohexamide-dependent block of protein synthesis showed that the half-life of CUGBP1 is increased in cells expressing CUG repeats. Alteration of CUGBP1 in DM is accompanied by alteration in translation of a transcription factor CCAAT/enhancer-binding protein beta (C/EBPbeta), which has been previously described to be a target of CUGBP1. Analysis of C/EBPbeta isoforms in DM patients with altered levels of CUGBP1 showed that translation of a dominant negative isoform, LIP, is induced by CUGBP1. Results of this paper demonstrate that the expansion of CUG repeats in DM affects RNA-binding proteins and leads to alteration in RNA processing.

Genetic testing in spinocerebellar ataxias: defining a clinical role

Although genetic tests for known spinocerebellar ataxia (SCA) genes are increasingly available, their exact clinical role has received much less attention. Currently available DNA tests can define the genotypes of up to two thirds of patients with dominantly inherited SCAs. Certain characteristic clinical features and ethnic predilection of some of the SCA subtypes may help prioritize specific SCA gene testing. Available data on genotype-phenotype correlation suggest that currently available DNA tests cannot accurately predict age of onset or prognosis. Because of the mostly adult-onset symptoms and the absence of effective treatment, genetic counseling is essential for addressing ethical, social, legal, and psychological issues associated with SCA DNA testing.