Biomedical subjects

N Tachi

Publications and source records attributed to N Tachi.

At least 19 recordsLinked to original sources

PubMed2005

Structural analysis of leucine-rich-repeat variants in proteins associated with human diseases.

A number of human diseases have been shown to be associated with mutation in the genes encoding leucine-rich-repeat (LRR)-containing proteins. They include 16 different LRR proteins. Mutations of these proteins are associated with 19 human diseases. The mutations occur frequently within the LRR domains as well as their neighboring domains, including cysteine clusters. Here, based on the sequence analysis of the LRR domains and the known structure of LRR proteins, we describe some features of different sequence variants and discuss their adverse effects. The mutations in the cysteine clusters, which preclude the formation of sulfide bridges or lead to a wrong paring of cysteines in extracellular proteins or extracellular domains, occur with high frequency. In contrast, missense mutations at some specific positions in LRRs are very rare or are not observed at all.

Genetic Diseases, Inborn↗

PubMed2005

Effects of shift schedules on fatigue and physiological functions among firefighters during night duty.

To examine the effects of shift schedules on fatigue and physiological functions among firefighters a 17-day field study at a fire station was carried out. Eleven firefighters, who were engaged in firefighting emergency services, participated in this study. At the fire station, night duty (22:00-07:00) was divided into 5 periods (P1: 22:00-00:00; P2: 23:45-01:45; P3: 01:30-03:30; P4: 03:15-05:15; P5: 05:00-07:00). The participants were assigned to one of these 5 periods and awakened to answer calls from the city's central information centre. They took naps in individual rooms during night duty, except when on night shift or when called out on an emergency. Subjective complaints of fatigue, critical flicker fusion frequencies, 3-choice reaction times, and oral temperature were measured before and after work and following breaks during their 24 working hours. Heart rate variability was also recorded to evaluate autonomic nerve activity. The results show that during P3 and P4, participants who had to wake up at midnight took shorter naps. The rates of subjective complaints regarding P3 and P4 tended to be higher than those for P1, P2, and P5. The ratios of the low frequency component of heart rate variability to the high frequency component during P4 were significantly lower than those during P5. It is assumed that such an irregular sleeping pattern causes many complaints of subjective fatigue, and adversely affects physiological functions. A night-duty shift schedule ensuring undisturbed naps should be considered.

Adult↗

PubMed2001

Homozygosity mapping of Portuguese and Japanese forms of ataxia-oculomotor apraxia to 9p13, and evidence for genetic heterogeneity.

Ataxia with oculomotor apraxia (AOA) is characterized by early-onset cerebellar ataxia, ocular apraxia, early areflexia, late peripheral neuropathy, slow progression, severe motor handicap, and absence of both telangiectasias and immunodeficiency. We studied 13 Portuguese families with AOA and found that the two largest families show linkage to 9p, with LOD scores of 4.13 and 3.82, respectively, at a recombination fraction of 0. These and three smaller families, all from northern Portugal, showed homozygosity and haplotype sharing over a 2-cM region on 9p13, demonstrating the existence of both a founding event and linkage to this locus, AOA1, in the five families. Three other families were excluded from this locus, demonstrating nonallelic heterogeneity in AOA. Early-onset cerebellar ataxia with hypoalbuminemia (EOCA-HA), so far described only in Japan, is characterized by marked cerebellar atrophy, peripheral neuropathy, mental retardation, and, occasionally, oculomotor apraxia. Two unrelated Japanese families with EOCA-HA were analyzed and appeared to show linkage to the AOA1 locus. Subsequently, hypoalbuminemia was found in all five Portuguese patients with AOA1 with a long disease duration, suggesting that AOA1 and EOCA-HA correspond to the same entity that accounts for a significant proportion of all recessive ataxias. The narrow localization of AOA1 should prompt the identification of the defective gene.

Alleles↗

PubMed2001

Variables That Influence Visual Acuity After Macular Hole Surgery.

Purpose: To evaluate the variables that influence visual acuity and visual improvement after macular hole surgery.Methods: Our study included 421 eyes in which macular holes were successfully closed after surgery and followed up at least 1 year after the last surgery. Surgical techniques were conventional methods (Group 1: 350 eyes) with retinal pigment scalping of the macular hole basis added in the refractory cases (Group 2: 71 eyes). The variables used for the multiple regression were gender, age, preoperative visual acuity, hole stage, duration of symptoms, hole size, and axial length.Results: The variables that most influenced postoperative visual acuity were as follows: Group 1: gender (r = -0.011, P =.016), age (r = -0.17, P =.005), preoperative visual acuity (r = 0.51, P <.0001), duration of symptoms (r = -0.015, P <.0001), and axial length (r = -0.090, P =.045). Group 2: age (r = -0.18, P =.047), and preoperative visual acuity (r = 0.47, P <.0001).Conclusions: The variables that influenced visual acuity and visual improvement after macular hole surgery were common. In Group 1: gender, age, preoperative visual acuity, duration of symptoms, and axial length; in Group 2: age and preoperative visual acuity.

Journal Article↗

PubMed2001

Expression of peripheral myelin protein zero in sural nerve of patients with Charcot-Marie-Tooth disease 1B.

A Charcot-Marie-Tooth disease 1B (CMT1B) family with a mutation of the Po gene is presented. A to G substitution of nucleotide 389 in exon 3 resulted in Lys 131 Arg substitution. Immunostaining for Po in biopsied sural nerve from one family member with CMT1B was expressed in a small number of myelinated fibers. Immunoblot analysis for Po revealed that it was of normal molecular weight (29 kDa) although significantly reduced in amount. This heterozygous mutation could lead to a reduction in the total amount of normal protein in peripheral nerves through a mechanism of loss of function.

Amino Acid Substitution↗

PubMed2001

Fukuyama muscular dystrophy associated with lack of C-terminal domain of dystrophin.

The first reported female patient with the Fukuyama type of congenital muscular dystrophy associated with a lack of C-terminal domain of dystrophin is presented. Clinically, the patient had characteristic features and magnetic resonance imaging findings of Fukuyama muscular dystrophy. Dystrophin analysis revealed a lack of the C-terminal domain but preserved N-terminal and rod domains of dystrophin in biopsied muscle. Moreover, she had reduced expression of merosin, syntrophin, and beta-dystroglycan in the skeletal muscle. Reverse transcriptase-polymerase chain reaction analysis of mRNA in the patient's muscle illustrated a complete lack of exons 71-74 of the dystrophin gene. These deletions, which remove the beta-dystroglycan and syntrophin binding site, may cause changes in the function of both beta-dystroglycan and syntrophin in human muscle.

Alcohol Oxidoreductases↗

PubMed2001

A double mutation in a patient with X-linked myotubular myopathy.

In this report a double mutation was identified in a patient with X-linked myotubular myopathy. The mutations present in the patient were a C-->T substitution of nucleotide 163, which led to an Arg 55 stop codon (nonsense mutation), and an "A" insertion at nucleotide 440, which caused a shift of the reading frame and a premature stop at codon 153 (frameshift mutation). The nonsense mutation was heterozygously present in the mother but not identified in the father or in normal controls. The frameshift mutation was not identified in either parent or normal controls (de novo mutation). These mutations are predicted to truncate the myotubularin protein.

Codon, Nonsense↗

PubMed2001

Antihypertensive effect of ACE inhibitory oligopeptides from chicken egg yolks.

Oligopeptides of 1 KDa or less were obtained by hydrolysis of chicken egg yolks with a crude enzyme, and by dialysis with a semipermeable membrane filter. Since the extracted peptides had an inhibitory action on the activity of angiotensin I-converting enzyme (ACE) in vitro, they were orally administered at 20, 100 and 500 mg/kg body weight to spontaneously hypertensive rats (SHR) for 12 weeks to analyze the physiological role on cardiovascular functions. The administered oligopeptides suppressed the development of hypertension at all dosages. After 12 weeks at 500 mg/kg body weight, the values for systolic, mean, and diastolic blood pressure were approximately 10% less in SHRs administered than controls. Furthermore, serum ACE activity of the peptide-administered groups was significantly lower than that of the control group in a dose-related manner. Our results imply that oligopeptides extracted from hen's egg yolks could potentially suppress the development of hypertension in SHR, and this effect might be induced by the inhibition of ACE activity.

Aging↗

PubMed2001

The gene mutated in ataxia-ocular apraxia 1 encodes the new HIT/Zn-finger protein aprataxin.

The newly recognized ataxia-ocular apraxia 1 (AOA1; MIM 208920) is the most frequent cause of autosomal recessive ataxia in Japan and is second only to Friedreich ataxia in Portugal. It shares several neurological features with ataxia-telangiectasia, including early onset ataxia, oculomotor apraxia and cerebellar atrophy, but does not share its extraneurological features (immune deficiency, chromosomal instability and hypersensitivity to X-rays). AOA1 is also characterized by axonal motor neuropathy and the later decrease of serum albumin levels and elevation of total cholesterol. We have identified the gene causing AOA1 and the major Portuguese and Japanese mutations. This gene encodes a new, ubiquitously expressed protein that we named aprataxin. This protein is composed of three domains that share distant homology with the amino-terminal domain of polynucleotide kinase 3'- phosphatase (PNKP), with histidine-triad (HIT) proteins and with DNA-binding C2H2 zinc-finger proteins, respectively. PNKP is involved in DNA single-strand break repair (SSBR) following exposure to ionizing radiation and reactive oxygen species. Fragile-HIT proteins (FHIT) cleave diadenosine tetraphosphate, which is potentially produced during activation of the SSBR complex. The results suggest that aprataxin is a nuclear protein with a role in DNA repair reminiscent of the function of the protein defective in ataxia-telangiectasia, but that would cause a phenotype restricted to neurological signs when mutant.

Amino Acid Sequence↗

PubMed2001

Short or continuous social stress: suppression of continuously available ethanol intake in subordinate rats.

We explored the effects of short, intermediate, and continuous social stress on daily ethanol and water intake in rats. The study was designed to: (1) detect increases in intake during hours when animals were not stressed; and (2) detect shifts in preference from solutions with high to low alcohol content. Male Long-Evans rats acquired ethanol self-administration using a sucrose-fading procedure, which was followed by continuous access to 10% and 3% ethanol solutions and water. After intake stabilized, rats were exposed to three periods of five consecutive days of social stress, with 8-10 days without stress in between. Short social stress consisted of being attacked and defeated by an aggressive opponent, followed by 30 min exposure to threats by the aggressive male while in a protective cage. Intermediate and continuous social stress consisted of a 6 h or 24 h 'threat of attack' exposure, respectively. All stress exposures reduced daily intake of 10% ethanol, did not cause changes in intake of 3% ethanol, and caused increases in water intake. No compensatory ethanol consumption was observed on stress days or after stress exposure was discontinued. These results are at variance with the hypothesis for increased alcohol consumption during or following social stress episodes.

Alcohol Drinking↗

PubMed2001

[Factors related to intraoperative retinal breaks in macular hole surgery].

PURPOSE: To evaluate the factors of intraoperative retinal breaks in macular hole surgery. METHODS: This study included 558 eyes of 506 patients who underwent idiopathic macular hole surgery by one surgeon. Multiple regression was performed using the variables of gender, age, affected eye, lens status, stage, duration of symptoms, hole size, axial length, and lattice degeneration. RESULTS: The rate of retinal breaks was higher in stage 3 (16.0%) than in stage 4 (8.2%) (p = 0.014). In eyes with lattice degeneration intraoperative retinal breaks occurred in about 40% of the cases. Major factors were as follows: lattice degeneration (r = 0.24, p < 0.0001) in all eyes, stage (r = 0.090, p = 0.048) in eyes without lattice degeneration, and gender (r = -0.18, p = 0.035) in eyes of stage 4 without lattice degeneration. CONCLUSIONS: The factors of intraoperative retinal breaks in macular hole surgery were lattice degeneration in all eyes and stage 3 in eyes without lattice degeneration. The high incidence of intraoperative retinal breaks in stage 3 was mainly due to the occurrence of posterior vitreous detachment. Male gender was a significant factor associated with intraoperative retinal breaks.

Adult↗

PubMed2001

[Operculum in idiopathic macular holes].

PURPOSE: To detect the factors related to the operculum in idiopathic macular holes and present a pathogenesis of idiopathic macular holes. METHODS: This study included 583 eyes of idiopathic macular hole that underwent macular hole surgery. To detect the factor related to the operculum, the variables of age, duration of symptoms, hole size, preoperative visual acuity, refraction, axial length, refraction axial length ratio were used for the comparison between two groups and multiple regression. The success rate of surgery and postoperative visual acuity were examined whether the operculum was present or not. RESULTS: The variables that were significantly related to the operculum were as follows: refraction axial length ratio (r = 0.18, p = 0.0092) in women of stage 3, duration of symptoms (r = -0.44, p < 0.001), preoperative visual acuity (r = -0.33, p = 0.0025), and refraction axial length ratio (r = -0.22, p = 0.020) in women of stage 4, and age (r = 0.19, p = 0.047) in men of stage 3. There were no significant differences in the success rate of surgery and postoperative visual acuity whether the operculum was present or not. CONCLUSIONS: Generally, operculum tends to occur in aged and round eyes and possibly does not occur in younger and back projected eyes because of retinal fissure. In women of stage 4, the operculum is possibly a torn retina and does not occur in atrophic holes.

Adult↗

PubMed2001

Incidence of Reopening and Variables That Influence Reopening After Macular Hole Surgery.

Purpose: To evaluate the incidence and variables of reopening of macular holes after macular hole surgery.Methods: Our study included 467 eyes in which macular holes were successfully closed after surgery. Surgical techniques consisted of conventional methods (358 eyes) and scalping methods (109 eyes) with retinal pigment scalping of the macular hole basis added in such cases: reoperation, hole size (more than 0.4 disc diameter), duration of symptoms (more than 2 years). Long term incidence of reopening was predicted by life table method. After we compared reopened cases with non-reopened cases, the variables of gender, stage, biocular occurrence, age, duration of symptoms, hole size, preoperative visual acuity, refraction axial length ratio, and intraoperative retinal tears were used for the multiple regression.Results: Reopening was found in 20 eyes (5.6%) treated by conventional methods and in 10 eyes (9.2%) treated by scalping methods. Survival ratio was 87% for the conventional methods in 6 years and 79% for the scalping methods in 5 years. The variables influencing reopening were as follows: conventional methods: gender (r = 0.065, P =.19), biocular occurrence (r = 0.12, P =.026), and refraction axial length ratio (r = -0.11, P =.045); scalping methods: hole size (r = 0.14, P =.25).Conclusions: Incidence of reopening in scalping methods was high. The variables that influenced reopening after macular hole surgery were biocular occurrence and refraction axial length ratio in conventional methods. The shape of the eye may be related to reopening.

Journal Article↗

PubMed2001

[Clinical features of idiopathic macular holes-differences between sexes and stages].

PURPOSE: The purpose of this study was to evaluate the differences in the clinical features of idiopathic macular holes between sexes and stages. METHODS: Five hundred and twenty-six eyes of 480 patients with stage 3 or 4 idiopathic macular hole that had undergone vitrectomy were observed consecutively in this study. The each stage ratio, bilaterality, and affected eye were examined and the differences in age, hole duration, hole size, visual acuity, refractive power, axial length, and corneal refractive power were evaluated. RESULTS: Twenty-six % of the cases were stage 4 in males and 31% in females. There were no significant differences in bilaterality or affected eye between the sexes. Younger age and larger size were found in females of stage 3. Larger size was found in stage 4. More myopic eye and longer axial length were found in males of stage 4. There were no significant differences in hole duration and visual acuity between sexes or stages. CONCLUSIONS: In females the onset of macular hole occurred at a younger age than in males, size of the hole was larger from an earlier stage, and refractive power was less myopic. More myopic eye and longer axial length were found in stage 4, especially in males. This fact might be related to the existence of posterior vitreous detachment. We concluded that there were some differences in the mechanism of the onset and the progression of idiopathic macular hole between males and females.

Adult↗

PubMed2000

Hereditary cerebellar ataxia with peripheral neuropathy and mental retardation.

We present here 5 patients with hereditary cerebellar ataxia with peripheral neuropathy and mental retardation as determined by clinical, pathological, and molecular studies. The most characteristic features of this disorder, in contrast to Friedreich's ataxia, were early onset of ataxic gait, mental retardation, and a marked atrophy of the cerebellum. Sural nerve biopsy showed a reduction of myelinated fibers. The expansion of a GAA triplet repeat within the first intron of the frataxin gene, which causes Friedreich's ataxia, was not identified in any of the patients. Hereditary cerebellar ataxia with peripheral neuropathy and mental retardation represents a specific clinical entity that so far has only been described in Japan.

Adolescent↗

PubMed2000

[Variables that influence visual acuity after macular hole surgery].

PURPOSE: To evaluate the variables that influence visual acuity and visual improvement after macular hole surgery. METHODS: Our study included 421 eyes in which maculor holes were successfully closed after surgery and followed up at least 1 year after the last surgery. Surgical techniques were conventional methods (Group 1: 350 eyes) with retinal pigment scalping of the macular hole basis added in the refractory cases (Group 2: 71 eyes). The variables used for the multiple regression were gender, age, preoperative visual acuity, hole stage, duration of symptoms, hole size, and axial length. RESULTS: The variables that most influenced postoperative visual acuity were as follows: Group 1: gender (r = -0.011, p = 0.016), age (r = -0.17, p = 0.005), preoperative visual acuity (r = 0.51, p < 0.0001), duration of symptoms (r = -0.015, p < 0.0001), and axial length (r = -0.090, p = 0.045). Group 2: age (r = -0.18, p = 0.047), and preoperative visual acuity (r = 0.47, p < 0.0001). CONCLUSIONS: The variables that influenced visual acuity and visual improvement after macular hole surgery were common. In Group 1: gender, age, preoperative visual acuity, duration of symptoms, and axial length; in Group 2: age and preoperative visual acuity.

Adult↗

PubMed2000

[Incidence of reopening and variables that influence reopening after macular hole surgery].

PURPOSE: To evaluate the incidence and variables of reopening of macular holes after macular hole surgery. METHODS: Our study included 467 eyes in which maculor holes were successfully closed after surgery. Surgical techniques consisted of conventional methods (358 eyes) and scalping methods (109 eyes) with retinal pigment scalping of the macular hole basis added in such cases: reoperation, hole size (more than 0.4 disc diameter), duration of symptoms (more than 2 years). Long term incidence of reopening was predicted by life table method. After we compared reopened cases with non-reopened cases, the variables of gender, stage, biocular occurrence, age, duration of symptoms, hole size, preoperative visual acuity, refraction axial length ratio, and intraoperative retinal tears were used for the multiple regression. RESULTS: Reopening was found in 20 eyes (5.6%) treated by conventional methods and in 10 eyes (9.2%) treated by scalping methods. Survival ratio was 87% for the conventional methods in 6 years and 79% for the scalping methods in 5 years. The variables influencing reopening were as follows: conventional methods: gender (r = 0.065, p = 0.19), biocular occurrence (r = 0.12, p = 0.026), and refraction axial length ratio (r = -0.11, p = 0.045); scalping methods: hole size (r = 0.14, p = 0.25). CONCLUSIONS: Incidence of reopening in scalping methods was high. The variables that influenced reopening after macular hole surgery were biocular occurrence and refraction axial length ratio in conventional methods. The shape of the eye may be related to reopening.

Adult↗

PubMed2000

[Factors related to initial success in macular hole surgery].

PURPOSE: To evaluate the factors of initial success in macular hole surgery. METHODS: This study included 526 eyes of 480 patients who underwent idiopathic macular hole surgery by one and the same surgeon. Surgical methods included conventional method (392 eyes), retinal pigment epithelium (RPE) scalping (61 eyes), internal limiting membrane (ILM) removal (62 eyes), and RPE scalping combined with ILM removal (11 eyes). To evaluate the factors of initial success multiple regression was performed using the variables of (gender, age, stage, duration of symptoms, hole size, axial length, and preoperative visual acuity). RESULTS: The rate of initial success was 81.4% in all eyes, 80.9% in the conventional method, 78.7% in RPE scalping, 83.9% in ILM removal, and 100% in RPE scalping combined with ILM removal. Significant factors of initial success were as follows: gender (r = -0.091, p = 0.053), age (r = -0.14, p = 0.0062), duration of symptoms (r = -0.23, p < 0.0001), hole size (r = -0.23, p < 0.0001), and axial length (r = -0.21, p < 0.0001) in the conventional method, hole size (r = -0.56, p = 0.0006) in ILM removal and stage (r = -0.43, p = 0.0011) and preoperative visual acuity (r = 0.30, p = 0.018) in RPE scalping. CONCLUSIONS: Significant factors of initial success were being male being young, shorter duration of symptoms, smaller hole size, and shorter axial length in the conventional method, smaller hole size in ILM removal and stage 4 and better preoperative visual acuity in RPE scalping method.

Adult↗