Cloning and characterization of mammalian 8-hydroxyguanine-specific DNA glycosylase/apurinic, apyrimidinic lyase, a functional mutM homologue.

8-Hydroxyguanine (8-OH-G) is one of the major DNA oxidation products implicated in mutagenesis induced by oxygen radical-forming agents, including ionizing radiation. It is also believed to be involved in spontaneous mutation induced by metabolically produced oxygen radicals. A mammalian homologue of 8-OH-G glycosylase/apurinic, apyrimidinic lyase (mutM homologue, MMH) has been identified in the EST database (for expressed sequence tags) through a homology search with yeast OGG1 protein. The human MMH protein (hMMH), 34% identical to the yeast OGG1 protein, is a member of the DNA repair protein superfamily. The hMMH gene was composed of seven exons, with the alternate last exon, exon 8, producing three major alternative splicing isoforms, because splicing of the sixth intron was optional. The hMMH protein expressed in Escherichia coli revealed the glycosylase activity and apurinic, apyrimidinic lyase activity on duplex DNA containing 8-OH-G. The hMMH protein can rescue a spontaneous mutator strain of E. coli lacking mutM and mutY. By the introduction of recombinant hMMH, the rate of mutation, the formation of rifampicin-resistant revertants, was reduced by 4-7 fold. Genomic structure analysis showed that 3' exons of the hMMH gene are transcribed on the antisense strand of the calcium-dependent calmodulin kinase 1 gene.

The maternal origins of the triploid ginbuna (Carassius auratus langsdorfi): phylogenetic relationships within the C. auratus taxa by partial mitochondrial D-loop sequencing.

The hyper-variable segments (323-327 bp) of the mitochondrial D-loop for 169 Carassius auratus fishes in Japan were amplified by the polymerase chain reaction and the amplified products were sequenced directly and compared. A dendrogram showing three major clusters was generated with the sequence data for 37 haplotypes at 66 polymorphic sites. One cluster (cluster I) exclusively consisted of the gengorobuna, which was regarded as an independent (sub) species. The triploid ginbuna belonged to two remaining clusters, mainly in the diploid ginbuna cluster (cluster III) and partially in the goldfish cluster (cluster II). This finding suggests that the triploid ginbuna has been derived from two different maternal lineages. The triploid ginbuna was considered to have come into existence during the last ice age on the basis of this phylogenetic data. No geographic differentiation was observed with respect to the triploid ginbuna sampled at three different localities in Japan; the Shibuta River in Kanagawa, Lake Imba in Chiba and Lake Biwa in Shiga. The phylogenetic tree also demonstrated a monophyletic relationship amongst the nigorobuna, the nagabuna and the ginbuna, sharing cluster III. The nigorobuna and nagabuna populations have most likely arisen from geographic and temporal variations within the ginbuna populations. We also discuss the evolutionary origin of the triploid in view of its paternal ancestors.

Nucleotide sequence and polymerase chain reaction/restriction fragment length polymorphism analyses of Aleutian disease virus in ferrets in Japan.

Two ferrets with spontaneous Aleutian disease (AD) were found in Japan. The diagnosis was verified by polymerase chain reaction (PCR) amplification of part of the capsid gene specific to AD virus (ADV). The nucleotide sequences (365 bp in length) of the amplified fragments from the 2 ferrets differed by a single nucleotide, producing an amino acid alteration. Compared with other types of ADV, these isolates had 96% sequence similarity to a published ferret ADV (FADV) in contrast to <91% homology to various types of mink ADV (MADV). The phylogenetic tree of ADVs indicates that these 2 isolates and the published FADV belong to the same genetic group and definitely are divergent from MADVs. The predicted amino acid sequence of the hypervariable segment in the capsid gene was conserved among the 3 types of FADV. These results indicated that the 2 isolates found in Japan were new DNA types of FADV and could have been derived from FADV(s). A restriction fragment length polymorphism (RFLP) method to distinguish the ferret types of ADV from the mink types of ADV was developed on the basis of differences in their nucleotide sequences. Digestion of the PCR products with Afal or ScaI provided different cleavage patterns for FADV and MADV. This PCR/RFLP analysis of the ADV capsid gene will be a valuable asset for diagnosis of this virus infection in ferrets.

Development of species-specific PCR techniques for the detection of tortoise herpesvirus.

Previously, a nested polymerase chain reaction (PCR) was employed with consensus degenerate primers targeting highly conserved motifs within herpesviral DNA polymerase genes to detect a newly described tortoise herpesvirus. However, nucleotide sequence information obtained from the final amplified fragment was restricted to a small region of 181 bp. In the present study, additional sequences flanking this segment were determined from a PCR product successfully amplified using a set of known degenerate primers, which covered a 692-bp region within the tortoise herpesviral DNA polymerase gene. Polymerase chain reaction primers for specific amplification of the tortoise herpesviral DNA were designed on the basis of these nucleotide sequences and successfully amplified tortoise herpesviral DNA from the tissues of tortoises that were well characterized histopathologically with herpesviral infection. The lower limit of detection was 1,000 herpesviral DNA equivalents in the presence of normal tortoise genomic DNA. Furthermore, a more sensitive and specific PCR technique for the identification of herpesviral infections in tortoises was developed employing a heminested form, which will enable the detection of latent infections or herpesvirus carriers in tortoises.

Reliable sex identification of dogs by modified PCR/RFLP analysis.

To find definitive RFLP sites for canine sex determination, DNA segments corresponding to parts of the canine ZFX and ZFY genes were amplified by PCR and were directly sequenced. According to the newly defined sequence data, the combination of Haelll and Cfr13I sites was found to be useful for not only identifying the sex of the canine DNA samples but also distinguishing them from the human DNA. Conveniently, these two enzymes worked simultaneously in the same single buffer. The double-digestion of the ZFX/ZFY PCR products with HaeIII and Cfr13I showed banding patterns unique to males and females in Canis familialis. This PCR/RFLP method was confirmed to be applicable to various breeds of dog.

Severe retinopathy of prematurity and visual outcomes in British Columbia: a 10-year analysis.

OBJECTIVE: To describe the incidence trend and long-term visual outcomes of infants diagnosed with stages 3 to 4 retinopathy of prematurity (ROP) or laser-treated ROP born in British Columbia (Canada). STUDY DESIGN: Data from all (n=1384) neonates with birth weight (BW) <1250 g, admitted to British Columbia Children's Hospital between period 1 (January 1992 to December 1996) and period 2 (January 1997 to December 2001) were analyzed. Ophthalmologic records of infants with stages 3 to 4 ROP or laser-treated ROP were abstracted. chi(2)- and t-test were used to compare neonatal characteristics between periods. Logistic regression was used to identify risk factors associated with visual impairment (defined as visual acuity

The utility of QTL-Linked markers to detect selective sweeps in natural populations--a case study of the EDA gene and a linked marker in threespine stickleback.

Sequence polymorphisms in coding genes and variability in quantitative trait loci (QTL)-linked markers can be used to uncover the evolutionary mechanisms of traits involved in adaptive processes. We studied sequence variation in the EDA gene and allelic variation in 18 microsatellites - one of which (Gac4174) is linked with the EDA QTL - in low, partially and completely plated morphs from eight threespine stickleback European populations. The results agree with previous studies in that EDA polymorphism is closely related to plate number variation: EDA sequences grouped populations into low and completely plated morphs, whereas microsatellites failed to do so. Furthermore, partially plated fish were heterozygous with respect to the distinctive EDA alleles for completely and low plated morphs, indicating that completely plated morph alleles are not entirely dominant in controlling the expression of lateral plate number. An examination of population differentiation in plate number with quantitative genetic methods revealed that the degree of differentiation exceeded that expected from genetic drift alone (Q(ST) > F(ST)). Our results support the adaptive genetic differentiation of plate morphs and the view that distinctive EDA gene polymorphism occurs in similar sites across the distribution range of this species. Yet, allele frequency differentiation in the Gac4174 microsatellite locus, informative in experimental crosses for plate number variation, did not differ from that of neutral markers and, was therefore unable to detect the signature of natural selection responsible for population divergence.

Argon laser photocoagulation for retinopathy of prematurity: long-term outcome.

PURPOSE: To assess the visual, refractive, ocular structural, and neurodevelopmental outcome in a group of children who were screened, treated with laser photocoagulation for threshold retinopathy of prematurity (ROP), and followed up at our institution. METHODS: The 21 survivors of a cohort of 23 children were recalled at the age of 5 years or more. They underwent a full ophthalmologic examination. A paediatric neurologist and/or developmental paediatrician performed a neurodevelopmental assessment and a neuropsychologist performed psychological testing. RESULTS: A total of 30 eyes (71.4%) had a best-corrected visual acuity (BCVA) of 20/40 or better. In all, 26 (62%) eyes were myopic; the overall mean spherical equivalent was -4.95 D. No eye had Stage 4 findings and only one eye (2.4%) progressed to stage 5 despite photocoagulation. In total, 14 patients (66.6%) showed evidence of stereopsis. Strabismus was seen in six patients (28.5%) and nystagmus in three (14.3%). Periventricular leukomalacia (PVL) was identified in five patients (23.8%), cerebral palsy (CP) in seven (33.3%), and intraventricular haemorrhage (IVH) in 13 (62%). Cerebral palsy and IVH associated strongly with visual acuity of less than 20/40 (P=0.009 and 0.047). There was also a strong association between visual acuity of 20/40 or above and a better cognitive outcome (P=0.013). CONCLUSIONS: Retinal scarring and detachment are relatively rare causes of visual morbidity 5 years or more after laser treatment for threshold ROP, but the neurological sequelae of extreme prematurity and amblyopia remain important causes of impaired visual function.

Visual impairment due to a dyskinetic eye movement disorder in children with dyskinetic cerebral palsy.

Neurological lesions that cause dyskinetic cerebral palsy (CP) commonly involve ocular movements. This report describes a group of 14 children (nine males, five females) whose CP is associated with severe dyskinetic eye movements. Ages ranged from 4 months to 13 years (mean 6.9 years). Clinical features of this eye movement disorder are discussed and defined. The visual function of these children is slow, variable, and highly inefficient. They are often misdiagnosed as blind, due to cortical visual impairment. Early recognition of dyskinetic eye moment disorder and appropriate developmental and educational management are important.

Effect of secretin on children with autism: a randomized controlled trial.

To determine the effect of intravenous porcine secretin on autistic behaviours in children aged 2 to 7 years, the effects of secretin on (1) performance on a standardized language measure, and (2) autistic behaviours, as rated by parents and child development professionals was examined. Employing a randomized, double-blind, placebo-controlled design, 95 participants were assigned to one of two groups and administered a single dose of either secretin or placebo. A follow-up assessment was conducted 3 weeks after the injection. No significant differences in language or autistic behaviour measures were observed at the 3-week follow-up between the groups. Also, there was no significant difference in the proportion of individuals who improved by > or = 6 points on the language measure at follow-up. This study showed no significant effects of secretin on children with autism. Our results are consistent with a systematic review of randomized controlled trials evaluating the effect of secretin in children with autism.

New DNA polymorphisms of human MMH/OGG1 gene: prevalence of one polymorphism among lung-adenocarcinoma patients in Japanese.

MMH/OGG1 is an 8-hydroxyguanine-specific DNA glycosylase/AP-lyase, one of the mutator enzymes for the excision repair of 8-hydroxyguanine. DNA polymorphisms in human MMH/OGG1 gene were newly identified and analyzed to examine a possible association with lung-cancer risk by a population-based study. Polymorphic allele 3 in hMMH/OGG1 exon 1 was significantly prevalent among Japanese patients with adenocarcinoma of the lung [odds ratio (OR): 3.152, 95% confidence interval (CI): 1.266-7.845], indicating that the excision repair of 8-hydroxyguanine may play a role in predisposition to lung cancer.