Biomedical subjects

Toshihiro Horiguchi

Publications and source records attributed to Toshihiro Horiguchi.

At least 19 recordsLinked to original sources

PubMed2006

Ecological risk assessments of endocrine disrupting organotin compounds using marine neogastropods in Hong Kong.

As active ingredients of anti-fouling paints that are widely used on ship hulls, organotin compounds, in particular tributyltin (TBT), are well-known endocrine disruptors causing sex changes in marine organisms and widespread in coastal waters and sediments worldwide. In this study, a comprehensive ecological risk assessment (ERA) of organotins was conducted in Hong Kong waters through determining the imposex status, sex ratio and tissue burdens of these compounds in the neogastropods, Thais clavigera and Thais luteostoma collected from 29 coastal sites. We also investigated the historical trend of organotin effects on these gastropods, and performed a probabilistic ERA based on tissue burden of TBT in the animals. Our results demonstrated that imposex indices were positively correlated with the body burden of organotins in the gastropods. Across all sites, the sex ratio (female:male) decreased significantly with increasing imposex levels or tissue burden of organotins, implying that such pollutants can result in a male-biased population, potentially leading to local extinction in extreme cases. Based on the ERA, 5.4% of all populations of T. clavigera are at risk due to exposure to TBT; the risks include growth inhibition, impairment of immune functions and reduced fitness. Seriously impacted areas included Aberdeen, Repulse Bay, Butterfly Beach, Mui Wo and Ha Mei Wan. A comparison with historical data revealed that there had been some improvement in the areas with low marine traffic, and distant from the major harbour/port. This could partly be due to the restriction on the use of TBT on small vessels (<25m in length) since 1992. Nevertheless, the organotin contamination still remains severe in areas with high marine traffic or adjacent to large harbours/ports. In particular, the situation in the northeastern waters of Hong Kong has been getting worst since 1996 that is probably associated with the rapid development of the cargo container port at Yantian in China.

Animals↗

PubMed2006

Horizontal distribution of steroid estrogens in surface sediments in Tokyo Bay.

A monitoring survey was conducted to investigate the distribution of steroid estrogens and their conjugates in surface sediments of Tokyo Bay for the first time, which is known as one of the most heavily polluted marine embayments in the world. The surface sediment samples were collected at 20 locations covering the whole area of Tokyo Bay and analyzed for steroid estrogens and their conjugates using liquid chromatography-tandem mass spectrometry. The concentrations of 17beta-estradiol (beta-E2) and estrone (E1) ranged from ND (below the detection limit; <0.07) to 0.59 and from 0.05 to 3.60 ng g-1 dry, respectively. Those concentrations were higher in the northern part of the bay, which is directly receiving huge quantities of pollutants from adjacent rivers containing a large amount of municipal and industrial wastewater. 17alpha-Estradiol (alpha-E2) and estrone-3-sulfate (E1-3S) were detected in some of the samples, whereas neither of the other conjugates, estriol (E3) or 17alpha-ethynylestradiol (EE2), was found.

Chromatography, Liquid↗

PubMed2006

Impact of tributyltin and triphenyltin on ivory shell (Babylonia japonica) populations.

We histopathologically examined gonads and chemically determined organotin compounds in tissues of the ivory shell, Babylonia japonica. Imposex (a superimposition of male-type genital organs on females) occurred in approximately 80-90% of B. japonica specimens that we examined, with the penis and vas deferens both well developed. No oviduct blockage by vas deferens formation was observed. Ovarian spermatogenesis and suppressed ovarian maturation were observed in the females that exhibited imposex, although no histopathological abnormalities were found in males. Tissue distributions of organotin compounds [tributyltin (TBT), triphenyltin (TPhT), and their metabolites] were different for butyltins and phenyltins; a remarkably high accumulation of TBT was observed in the ctenidium, osphradium, and heart, whereas high concentrations of TPhT were detected in the ovary and digestive gland. More than one-third of TBT accumulated in the digestive glands of both males and females, followed by the testis, ctenidium, muscle, and heart tissues in males and in the muscle, ovary, ctenidium, and head tissues (including the central nervous system ganglia) in females. In both males and females, more than half of total TPhT accumulated in the digestive glands, followed by the gonads. The next highest values were in the muscle, ctenidium, and heart tissues in males and in the muscle, oviduct, and head tissues in females. Both TBT and TPhT concentrations in the gonads were positively correlated with penis length in females. Our findings strongly suggest that reproductive failure in adult females accompanied by imposex, possibly induced by TBT and TPhT from antifouling paints, may have caused the marked decline of B. japonica populations in Japan.

Animals↗

PubMed2006

Masculinization of female gastropod mollusks induced by organotin compounds, focusing on mechanism of actions of tributyltin and triphenyltin for development of imposex.

Imposex, the superimposition of male-type genital organs (penis and vas deferens) on female gastropods, is cause-specific and induced by low concentrations of certain organotins, such as tributyltin (TBT) and triphenyltin (TPT) from antifouling paints. Reproductive failure may be observed at severely affected stages. The history of imposex study and the legislation of organotins are summarized. The present statuses of gastropod imposex and organotin pollution in Japan, together with endocrine disruption observed in abalones, are also summarized, on the basis of the results of the field studies of the rock shell (Thais clavigera) conducted at 174 locations along the Japan coast between January 1999 and November 2001, the histopathological and analytical chemical studies of the ivory shell (Babylonia japonica), and both field and laboratory studies of the abalone (Haliotis madaka and H. gigantea). The fundamental knowledge of the endocrinology of gastropod mollusks is briefly described. Four hypotheses, such as that of aromatase-inhibition, regarding the induction mechanism of imposex induced by organotins in gastropods are reviewed. Finally, a new hypothesis that states that retinoid X receptor (RXR) plays an important role in inducing the development of imposex, i.e., the differentiation and growth of male-type genital organs in female gastropods, is reviewed and discussed to clarify the entire mode of action of TBT or TPT in the development of imposex in gastropods.

Animals↗

PubMed2006

[Assessment of families' need of social life support for persons with intellectual disabilities and physical handicaps].

To study the need for community support for the users of facilities for people with intellectual disabilities and physical handicaps, the author surveyed facility users' families using a mail-in questionnaire. The International Classification of Functioning, Disabilities and Health (ICF) guidelines were used to describe each user. Younger users were found to achieve the best ICF levels of social participation, while rehabilitation facilities and workshops attracted a larger number of adults with fixed participation whose performance level was equivalent to their capacity. In the latter group, the users' families requested accommodation at a group home and the continuous use of the facilities. Among the respondents, a demand for medical support was common, regardless of the type of facilities being used. To support self-decision and the full participation of users, the supervisors of facilities must coordinate their own needs with those of users and their families and provide improved medical support.

Child↗

PubMed2005

Three-dimensional distributions of sewage markers in Tokyo Bay water--fluorescent whitening agents (FWAs).

Three-dimensional distributions of fluorescent whitening agents (FWAs: more specifically, DSBP and DAS1), which are sewage-derived water-soluble markers, were observed in Tokyo Bay water through multi-layer sampling of water at 20 locations. In summer, FWAs predominated in the surface layers, with trace but significant concentration of FWAs in bottom water due to stratification of seawater. In winter, on the other hand, FWAs were extensively mixed into the bottom layers because of the vertical mixing of seawater. In the surface layer, FWA concentrations and the DSBP/DAS1 ratio (the concentration ratio of DSBP to DAS1) were lower in summer than in winter, suggesting more efficient photodegradation of FWAs in euphotic zones during the summer due to stronger solar radiation. Horizontally, FWAs were widely distributed over the surface layer of Tokyo Bay. Surface water with DSBP concentrations above 50ng/L, corresponding to <200 times dilution of sewage effluent, was found to have spread up to 10km from the coastline. In addition, an offshore decline in FWA concentrations was observed, showing a half-distance of 10-20km. The decrease was caused by dilution by seawater of fresh water containing FWAs. The eastern part of the bay was different with respect to surface layers, with higher concentrations seen in northeastern parts. Furthermore, dispersion of combined sewer overflow (CSO)-derived water mass was observed in Tokyo Bay after heavy rain.

Benzenesulfonates↗

PubMed2005

Continuing observation of disturbed reproductive cycle and ovarian spermatogenesis in the giant abalone, Haliotis madaka from an organotin-contaminated site of Japan.

Histological examination of gonads as well as chemical analysis of organotin compounds in tissues of the giant abalone, Haliotis madaka, was conducted to evaluate continuing endocrine disruption in abalone populations in Japan. Abalone specimens were collected from two different areas, Tsushima as a reference site and Jogashima as a site representative of declining abalone populations where serious organotin contamination had been observed, each month from January 1998 to March 1999. Scores were given to the development stages of reproductive cells in the ovary and testis. The degree of sexual maturation was evaluated by calculating the mean value of a histogram of these scores for the reproductive cells of each abalone. The temporal variations in degree of sexual maturation showed that female and male abalone from Tsushima matured synchronously, while those from Jogashima did not, which were similar to results of the previous study during September 1995-November 1996. Approximately 19% of the female abalone from Jogashima were masculinized with an ovo-testis, which was also similar to the result of the previous study. The masculinization of female abalone is reported to be induced by tributyltin (TBT) and triphenyltin (TPhT) from antifouling paints. Concentrations of the sum of butyltins (TBT, dibutyltin (DBT) and monobutyltin (MBT): SigmaBTs) and the sum of phenyltins (TPhT, diphenyltin (DPhT) and monophenyltin (MPhT): SigmaPhTs) in the muscle of abalone from Jogashima (n = 73) of 7.8+/-9.0 ng/g wet wt. and 4.5+/-6.8 ng/g wet wt., respectively, were significantly higher than those from Tsushima (n = 87) of 4.7+/-4.9 ng/g wet wt. and 0.8+/-1.7 ng/g wet wt., respectively (p < 0.05 for SigmaBTs; p < 0.001 for SigmaPhTs), although concentrations of TBT and TPhT in the muscle of abalone from Jogashima (n = 73) of 2.2+/-2.5 ng/g wet wt. and 5.8+/-5.1 ng/g wet wt., respectively, were insignificantly and significantly higher than those from Tsushima (n = 87) of 0.4+/-0.6 ng/g wet wt. and 0.5+/-0.9 ng/g wet wt., respectively, (p > 0.05 for TBT; p < 0.001 for TPhT). Thus, endocrine disruption as well as contamination by organotins in the giant abalone from Jogashima is still persisting.

Analysis of Variance↗

PubMed2005

["Early" diagnosis and "early" intervention in children with mental retardation--when is early enough to diagnose them?].

Patients with mental retardation (MR) cannot always be diagnosed accurately by physicians who are specialized in child neurology and/or developmental disorders at their first visit to the clinic. Precise examination such as psychological tests and chromosomal analysis are often necessary to diagnose them. Some patients with autistic disorders without MR often are misdiagnosed as having MR. Patients with mild to moderate MR are sometimes diagnosed late in their late teens or twenties. Timely diagnosis and timely/continuous intervention is more important than early diagnosis and early intervention for the mentally retarded.

Adult↗

PubMed2005

[Assessment of chromosome and gene analysis for the diagnosis of the fragile X syndrome in Japan: annual incidence].

We assessed the utilization of diagnostic analyses for fragile X syndrome by a mail-in questionnaire on 1) the number of patients analyzed and diagnosed with the syndrome in the past year, 2) types of diagnostic analyses used, 3) clinical features that made physicians to decide analyses, 4) purpose of analyses, and 5) informed consent for analyses. Facilities for the mentally handicapped, as well as hospitals and physicians specialized in genetics, completed our questionnaire. Among 101 responders, total of 543 cases underwent analyses. Nine cases (including 3 cases over 20 years old) were finally diagnosed in a year. The rate of positive findings was 0.6% for chromosomal analyses, and 8% for gene analyses. Physicians dicided to make analyses based on clinical features such as mental retardation, characteristic face, and autistic features, in order to find the cause (s) of the subjects' condition. For gene analyses, more than a half of physicians obtained a form of informed consent. Specialists should have interest in this syndrome because the analyses identified new adult cases. Establishment of a guideline for diagnosis of this syndrome requires gene analyses based on evidence and informed consent.

Autistic Disorder↗

PubMed2004

Involvement of the retinoid X receptor in the development of imposex caused by organotins in gastropods.

Organotin compounds released from antifouling paints, such as tributyltin (TBT) and triphenyltin (TPT), are potent inducers of imposex (a superimposition of male genital tracts, such as penis and vas deferens, on females) in marine gastropods. Little is known about the induction mechanism of gastropod imposex. Here, we show that organotins bind the human retinoid X receptors (hRXRs) with high affinity and that injection of 9-cis retinoic acid (RA), the natural ligand of hRXRs, into females of the rock shell (Thais clavigera) induces the development of imposex. Cloning of the RXR homologue from T. clavigera revealed that the ligand-binding domain of rock shell RXR was very similar to vertebrate RXR and bound to both 9-cis RA and to organotins. These suggest that RXR plays an important role in inducing the development of imposex, namely, the differentiation and growth of male genital tracts in female gastropods.

Animals↗

PubMed2004

Human auditory evoked mismatch field amplitudes vary as a function of vowel duration in healthy first-language speakers.

Previous auditory studies demonstrated that vowel shortening elicited a more prominent mismatch component than its lengthening in event-related potentials (ERP) and magnetoencephalography (MEG). Based on these findings, the current study investigated whether the magnetic mismatch field (MMF) component would be generated by vowel shortening of various degrees to determine a neuronal response threshold of pre-attentive deviation detection. Behavioral pre-test data revealed that while listening to Japanese short-duration (100%: reference), long-duration (180%), and other in-between duration-synthesized types, healthy native speakers of Japanese failed to clearly categorize 140-124% durations as either short or long words, while categorizing 108-116% durations as short words and 148-172% durations as long. Following these results, MEG responses were recorded with a whole-head 148-channel magnetometer, as subjects listened to 100% standard and five deviant durations (124, 132, 140, 148, 180%). MEG results showed that the above-32% duration decrements (180-->100%, 148-->100%) elicited a more prominent MMF than the others, the MMF amplitudes increasing linearly to the degree of duration deviance, and that neuronal responses correlated with behavioral word-categorization accuracy.

Acoustic Stimulation↗

PubMed2004

Numerical simulation of organic chemicals in a marine environment using a coupled 3D hydrodynamic and ecotoxicological model.

For ecotoxicological risk assessment in a marine ecosystem, we constructed a coupled three-dimensional hydrodynamic and ecotoxicological model (EMT-3D), and applied it to Tokyo Bay. The model was calibrated with field data obtained in 2002. The results of sensitivity analysis for dissolved Bisphenol A showed that biodegradation rate was the most important factor for concentration change. Bioconcentration coefficient was the most important factor for Bisphenol A in phytoplankton. Therefore, the parameters must be carefully considered in the modeling. The mass balance results showed that standing stocks of Bisphenol A in water, in particulate organic carbon and in phytoplankton are 7.85 x 10(4), 1.78 x 10(2) and 3.44 x 10(-1) g, respectively. With respect to flux, biodegradation in the water column had the highest value of 1.06 x 10(3) g/day, and next were effluent to the open sea, partition to particulate organic carbon, and bioconcentration in phytoplankton.

Benzhydryl Compounds↗

PubMed2004

[Guidelines for medical examination of children with mental retardation in pediatric clinics which are specialized for developmental disorders--recommendation based on the current selection and usefulness of diagnostic examinations for children with mental retardation and/or pervasive developmental disorder].

We assessed the present status of choice and usefulness of medical examinations of children with mental retardation (MR) and/or pervasive developmental disorder (PDD). Children with severe MR received more examinations than those with mild MR. Many abnormal findings were demonstrated by MRI in cases of severe MR. Cases of PDD without MR rarely showed abnormal results. Cases of PDD with MR underwent fewer examinations, but showed more abnormal results. We presented guidelines regarding medical examinations for children with MR in pediatric clinics which are specialized for developmental disorders, including psychological tests, hearing tests, EEG, genetic tests and neuroimaging. Physicians should select appropriate medical examinations based on evidence. The goal of testing is to provide useful information concerning medical treatment, therapeutic rearing, and education, and to support patients and their families in cooperation with relevant facilities.

Child↗

PubMed2004

[Assessment of social networks between developmental physicians and welfare facilities/specialists for children with intellectual disabilities in Japan].

The social networks between Japanese child neurologists and welfare facilities/specialists for children with mental retardation (MR) were assessed. A total of 113 physicians answered our mail-in questionnaire. Most of the doctors had various connections with nursery homes for children with MR or severe motor and intellectual disabilities (SMID) and with public health centers, and often collaborated with teachers of schools and kindergartens. On the other hand, most physicians had little relation with residential and vocational facilities for adults with MR, and with specialists in residential or community care. There was a statistical correlation between the number of facilities or collaborated specialists and the number of persons seen by each physician; however, the physicians' experience and affiliations had no relation. In view of 'social participation', physicians who usually see children with developmental disorders can play an important role in decision making of their life-style with their families.

Child↗

PubMed2004

[Abnormal findings of dichotic listening test in patients with childhood adrenoleukodystrophy].

Ten Japanese boys with childhood-onset adrenoleukoqdystrophy (ALD) were evaluated with dichotic listening test (DLT). Six cases showed abnormal findings especially of laterality index (L.I.) calculated from the score of each ear. Some of them showed no abnormal findings with other auditory examinations containing auditory brainstem responses (ABR). One patient showed abnormal L.I. of DLT at an early stage. The abnormality of laterality index was similar to the so-called "strong left-ear suppression" in patients who underwent callosotomy. Although all of these six patients had a high signal lesion at the splenium of the corpus callosum in a T3-weighted MRI sequence, it was difficult to evaluate the width of demyelinated area. DLT could detect the early damage of connecting fibers mediating inter-hemispheric transfer of auditory information, and might be a useful method for evaluating the cerebral function of auditory processing in patients with childhood ALD.

Adolescent↗

PubMed2004

[Japanese physicians'attitude for utilization of social support services for persons with intellectual disabilities].

We assessed physicians'attitude for the utilization of social (medical, educational, and financial) support services for persons with intellectual disabilities supplied by the Japanese government. A total of 113 physicians specializing in pediatric neurology answered our mail-in questionnaire. Medical care benefits for psychiatric outpatients and short-time stay were the most common services utilized. Whereas most physicians used various public support services regardless of their experience and affiliations, the selection of services by an individual physician correlated with the number and state of patients they usually cared. Physicians were less familiar with the services regarding residential or community care and advocacy. Knowledge of the specialists on each service will enrich assistance appropriate to the life styles of each patient with intellectual disabilities.

Child↗

PubMed2003

An MEG study of P300 activity during a color discrimination task 2: source localization study.

In this study, we described developmental changes in an event-related magnetic source of P300 activity during a visual oddball paradigm using magnetoencephalography. The maximum and minimum points of each peak of target P300 activity were scattered in a more anterior temporal area in children than in adults. The single dipole source analysis successfully estimated a dipole in the vicinity of the thalamus and the cingulate gyrus in adults. The location differed in children, although the dipole had overall greater moment in children than in adults. Our findings suggest that the thalamus plays an important role in generating P300 activity specific to color discrimination processing, and that in children the source is not consistent during development.

Adult↗

PubMed2003

Neuropsychological developmental change in a case with Noonan syndrome: longitudinal assessment.

The authors describe the neuropsychological development of a 10-year-old boy with Noonan syndrome. The subject's IQ showed normal intelligence, although there was a discrepancy between verbal and performance IQs. Visual perception was delayed, with clumsiness and inattention affecting his performance. Both visual perception and hyperactivity improved with the subject's general development, but his inattention seemed to increase after the age of 9. The behavioral features and cognitive profile of our case resembled those of attention-deficit/hyperactivity disorder. We recommend that clinicians should evaluate cautiously the specific profile of cognitive development in Noonan syndrome with particular focus on controlling the patient's inattention.

Attention↗