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Biomedical subjects

Atsushi Yoshida

Publications and source records attributed to Atsushi Yoshida.

At least 19 recordsLinked to original sources
PubMed2007

Isolation and identification of adenovirus from conjunctival scrapings over a two-year period (between 2001 and 2003) in Yokohama, Japan.

Over a 2-year period between 2001 and 2003, a total of 115 conjunctival scrapings were collected from patients with keratoconjuctivitis from several hospitals in Yokohama, Japan. Out of 115, 94 (82.4%) cases of adenoviruses were detected by polymerase chain reaction (PCR); 60 (52.1%) by cell culture isolation; and 16 (14.0%) by enzyme-linked immunosorbent assay (ELISA). The serotypes were determined by PCR- restriction fragment length polymorphism analysis (PCR-RFLP) and by the neutralization test (NT). PCR-RFLP was performed using a combination of endonucleases such as HhaI, AluI, and HaeIII. Of the 94 PCR-positive samples, the serotypes of 91 (96.8%) were identified by PCR-RFLP analysis (adenovirus 3: 50%, 4: 11%, and 8: 32%). Out of the 115 samples, 60 samples were identified by the neutralization (adenovirus 3, 4, 7, and 8). When both PCR-RFLP and the neutralization techniques were used, 53.2%, 11.7%, 1.1%, and 34% of the samples were identified as adenovirus 3, 4, 7, and 8, respectively. In contrast to the results of a nationwide surveillance report, adenovirus 3 was found as a major cause of keratoconjunctivitis in the Yokohama area. The nationwide surveillance report did not reflect accurately the epidemiological situation in the local area. In order to obtain surveillance data that would be useful for the prevention of an adenovirus conjunctivitis epidemic, it seems that local epidemiology is more important than that nationwide surveillance.

Adenovirus Infections, Human↗
PubMed2006

Spatial distribution patterns of excitatory and inhibitory synapses in the dendritic tree differ between jaw-closing and -opening motoneurons.

This paper reviews recent data on the spatial distribution of inhibitory and excitatory synapses on the dendritic tree of jaw-closing (JC) and -opening (JO) motoneurons in the cat, in which a combination of techniques employing intracellular injections of horseradish peroxidase and postembedding immunogold labelling was used. The dendritic tree is divided into three segments: primary and distal dendrites and intermediate dendrites between the two segments. The proportion of inhibitory boutons (immunoreactive for GABA and/or glycine) is slightly higher than proportion of excitatory boutons (immunoreactive for glutamate) in JC motoneurons, but this trend is reversed in JO motoneurons. In the two kinds of motoneuron, boutons immunoreactive to glycine alone are more numerous than boutons double-labelled to GABA and glycine, which, in turn, occur more frequently than boutons immunoreactive to GABA alone. In JC motoneurons, the packing density (number of boutons per 100 microm(2)) of the inhibitory boutons decreases somatofugally, but this trend is not applicable to the excitatory boutons. In contrast, the packing density of the inhibitory and excitatory boutons in JO motoneurons does not significantly differ among the three dendritic compartments, though it is slightly higher for the excitatory than the inhibitory ones on each dendritic segment. These differences have important implications for synaptic integration in JC and JO motoneurons.

Animals↗
PubMed2006

Successful treatment of primitive neuroectodermal tumor-associated microangiopathy with multiple bone metastases.

We report here a 16-year-old male with primitive neuroectodermal tumor (PNET)-associated probable microangiopathy with multiple bone metastases. Laboratory findings excluded the possibility of amegakaryocytic or immune thrombocytopenia and/or disseminated intravascular coagulation. He was first treated with plasma-exchange (PE), followed by platelet transfusions, steroid pulse therapy and combined chemotherapy. PE and steroid pulse therapy reduced his plasma CRP level. Combined chemotherapy drastically increased his platelet count until it had almost normalized without further transfusion. The plasma level of von Willebrand factor-cleaving protease (ADAMTS13) activity measured before PE was not severely deficient (48% of normal) and an unusually large von Willebrand factor multimer (UL-VWFM) was detected. We consider that this therapeutic strategy has the following benefits: (1) reduction of plasma levels of factors that are harmful to both platelet activation and endothelial cell injury; and (2) the safe transfusion of platelet concentrate in thrombotic microangiopathy. This strategy should be confirmed in further cases.

Adolescent↗
PubMed2006

Induction of robust immune responses against human immunodeficiency virus is supported by the inherent tropism of adeno-associated virus type 5 for dendritic cells.

The ability of adeno-associated virus serotype 1 to 8 (AAV1 to AAV8) vectors expressing the human immunodeficiency virus type 1 (HIV-1) Env gp160 (AAV-HIV) to induce an immune response was evaluated in BALB/c mice. The AAV5 vector showed a higher tropism for both mouse and human dendritic cells (DCs) than did the AAV2 vector, whereas other AAV serotype vectors transduced DCs only poorly. AAV1, AAV5, AAV7, and AAV8 were more highly expressed in muscle cells than AAV2. An immunogenicity study of AAV serotypes indicates that AAV1, AAV5, AAV7, and AAV8 vectors expressing the Env gp160 gene induced higher HIV-specific humoral and cell-mediated immune responses than the AAV2 vector did, with the AAV5 vector producing the best responses. Furthermore, mice injected with DCs that had been transduced ex vivo with an AAV5 vector expressing the gp160 gene elicited higher HIV-specific cell-mediated immune responses than did DCs transduced with AAV1 and AAV2 vectors. We also found that AAV vectors produced by HEK293 cells and insect cells elicit similar levels of antigen-specific immune responses. These results demonstrate that the immunogenicity of AAV vectors depends on their tropism for both antigen-presenting cells (such as DCs) and non-antigen-presenting cells (such as muscular cells) and that AAV5 is a better vector than other AAV serotypes. These results may aid in the development of AAV-based vaccine and gene therapy.

Animals↗
PubMed2006

Clinical outcome of infants with confined placental mosaicism and intrauterine growth restriction of unknown cause.

The purpose of this study was to know a role of confined placental mosaicism (CPM) in perinatal outcome and postnatal growth and development of infants with intrauterine growth restriction (IUGR). We selected 50 infants with IUGR (<-2.0 SD) from 3,257 deliveries in a regional medical center during the past 10-year period, and carried out cytogenetic and molecular analyses in their placenta and cord blood. Of the 50 infants, 8 had CPM (CPM group) and were composed of five single (CPM2, 7, 13, 22, and 22), one double (CPM7/13), and one quadruple trisomy (CPM2/7/15/20), and one partial monosomy [del(2)(p16)]. The origin of an extra chromosome of trisomy was maternal in six cases of CPM, paternal in one, and undetermined in one. Uniparental disomy in disomic cell lines was ruled out in all these mosaics. We also compared clinical parameters for perinatal outcome between CPM group and infants without evidence of CPM (non-CPM group), such as maternal and gestational age, birth weight, Apgar score, cord blood pH, gender, and uterine artery patterns by Doppler ultrasonography, as well as weight, height, and developmental quotient (DQ) by Denver Developmental Screening Test at age 12 months. Phenotypic abnormalities were noted in two infants with CPM and three infants of non-CPM group: One with CPM22 had ASD and hypospadias, one with CPM7/13 had Russell-Silver syndrome (RSS), and one without CPM had polydactyly, and two without CPM had RSS. All but one infant with CPM are alive at age 12 months. Among the clinical parameters, the detection rate of a notch waveform pattern of the uterine artery was significantly higher in the CPM group (P < 0.05). However, no significant difference was noted in perinatal outcome of pregnancy and in DQ at age 12 months between the two groups. Interestingly, short stature (<-2 SD) at age 12 months was more frequently seen in CPM group (7/8 infants with CPM vs. 8/15 infants without CPM), although no statistically significant difference was obtained. The information obtained will be useful for perinatal care and genetic counseling for infants with IUGR and CPM.

Adult↗
PubMed2006

Early pancreas transplant outcomes with histidine-tryptophan-ketoglutarate preservation: a multicenter study.

Little is known about the use of histidine-tryptophan-ketoglutarate (HTK) preservation solution for pancreas preservation. We compared early pancreas graft outcomes at four pancreas transplant programs within the state of Michigan in 2002 and 2003 (University of Wisconsin [UW] era) with those in 2004 (HTK era). The primary endpoint was early graft loss. The UW group (n=41) and the HTK group (n=36) had similar outcomes with respect to: technical graft loss (9.8% vs. 8.3%, P=NS), 90-day graft function (90.2% vs. 86.1%, P=NS), and rate of pancreatic leak/abscess (12.2% vs. 11.1%, P=NS). There were also no significant differences in postoperative amylase and lipase levels between the two groups. The HTK group did have significantly more acute rejection within the first 180 days (25.0% vs. 9.8%, P<0.05). HTK is a suitable substitute for UW in the preservation of pancreas allografts.

Adult↗
PubMed2006

Successful vancomycin desensitization with a combination of rapid and slow infusion methods.

Vancomycin, an antibiotic to which methicillin-resistant Staphylococcus aureus (MRSA) is sensitive, frequently induces hypersensitivity reactions. Lowering the vancomycin infusion rate and/or premedicating with antihistamine effectively reduce hypersensitivity in most cases. However, vancomycin desensitization is sometimes the only way to ensure safe use. Two types of desensitization protocols have been reported, and these utilize different infusion intervals; rapid desensitization and slow desensitization. We herein report a case of vancomycin hypersensitivity with methicillin-resistant Staphylococcus aureus infection. A combination of the two desensitization protocols, rapid desensitization followed by slow desensitization, effectively inhibited the hypersensitivity reaction during vancomycin infusion, and methicillin-resistant Staphylococcus aureus was successfully eradicated.

Adult↗
PubMed2006

Lipopolysaccharide stimulates histamine-forming enzyme (histidine decarboxylase) activity in murine dental pulp and gingiva.

To examine the potential role of the histamine-forming enzyme, histidine decarboxylase (HDC), in oral inflammation and disease, we studied HDC activity in oral tissue after induction by bacterial agents. Following injection of E. coli-derived lipopolysaccharide (LPS) into mice, we measured the quantitative changes in HDC activity over time in dental pulp and gingiva. Oral tissue taken from individual mice was insufficient for detecting precise HDC activity, thus, we combined dental pulp or gingival tissues from four mice and assayed them over the course of 24 h. Our results indicate that LPS stimulated marked elevations of HDC activity in dental pulp and gingiva. This increase reached a maximum at 6 h after LPS injection and remained detectable at for least 24 h. Since mast cells are known to produce histamine through a difference mechanism than HDC induction, we compared LPS-induced HDC activity in dental pulp and gingiva to that in ear skin (a tissue rich in mast cells) and liver (a tissues lacking in mast cells). LPS also induced a marked increase in the HDC activity in liver and ear skin at 6 h after LPS injection. By contrast, saline injection had no effect on the HDC activity in any of the four tissues, although basal levels of HDC activity in ear skin was markedly higher than basal HDC activity in the other three kinds of tissues. Still, the relative increase in LPS-induced HDC activity in dental pulp and gingiva were much greater than that in ear skin. Since liver are devoid of mast cells and ear skin is considered the tissue richest in mast cells, the differences in HDC activity between tissues indicates that histamine induced by LPS may be produced by cells other than mast cells through another mechanism of action. These results also suggest that histamine produced in oral tissues in response to bacterial agents such as LPS could be involved in development of pulpitis or gingivitis (periodontitis), the most common diseases in the dental clinic, and that efforts to inhibit HDC activity, which elevates histamine levels in oral tissues, might offer the basis for novel treatment strategies.

Animals↗
PubMed2006

Post-traumatic big toe reconstruction using free flaps.

The big toe is of great importance for good stability and gait, but few reports have documented reconstruction of big toe defects. In this study, seven male patients, aged 17 to 59 years at surgery (average: 35 years), were treated for big toe defects. The metatarsophalangeal (MTP) joints of the big toe were intact in all patients. Five patients were treated with free peroneal flaps (including one perforator flap), and two with free scapular flaps; flap sizes ranged from 9 x 4 to 24 x 6 cm. Follow-up periods ranged from 10 to 29 months, (average: 16.6 months). The iliac was used as the grafted bone in four patients and the scapula in one. Six flaps survived completely, and bone unions were achieved within 3 months. One flap became partially necrotic due to arterial thrombosis. All patients returned to their original jobs, and the cosmetic appearances of all toes were acceptable.

Adolescent↗
PubMed2006

[The efficacy of safety winged steel needles on needlestick injuries].

Safety winged steel needles were introduced at the University of Tokyo Hospital in January 2001. We studied their effect in needlestick injuries. A total of 952 'needlestick and sharp-object injuries were reported. From January 1999 to December 2004, Cases of injury with winged steel needles decreased dramatically soon after safety devices were introduced, from 19.8% in Apr.-Dec.2000 to 6.7% in 2001 and 5.5% in 2002 (p < .01). They began to increase, however, in July 2002, decreased again after medical staff members mere given lectures and notices by e-mail. Due to the introduction of safety devices, cases classified as a "while recapping a used needle" and "when puncturing rubber stoppers" decreased. Among 17 injuries with safety winged steel needles, the most common cases were "safety mechanism not activated". We estimated that 76.5% of cases with safety winged steel needles could be prevented if they were used properly. In conclusion, the introduction of safety winged steel needles effectively reduced cases of injury with such needles. It is thus important to regularly remind hospital staff of safety device techniques and information reduce the such injuries.

Equipment Design↗
PubMed2006

[Emm typing by genetic identification of Streptococcus dysgalactiae subsp. equisimilis and susceptibility to oral antibiotics].

A total of 593 beta-hemolytic streptococci belonging to Lancefield group A (GAS), group C (GCS) or group G (GGS) according to agglutination tests were collected from 11 medical institutions between September 2003 and October 2005. In total, 128 strains were identified as Streptococcus dysgalactiae subsp. equisimilis (S. equisimilis) using physiological tests. Of these strains, 5 strains were agglutinated to Lancefield group A, 17 strains to group C, and 106 strains to group G. Most of these strains were largely isolated from clinical specimens collected from young patients with respiratory infections and middle-aged patients (in their 40s); most of the strains were isolated from blood, atretic pus, or joint fluid. Genetic analysis of the emm gene encoding the M protein revealed that these strains could be classified into 27 types. Also, many emm types were found in strains isolated from normally aseptic clinical specimens. In addition, all strains tested had slo, sagA, and skcg genes, which contributed to their virulence. The susceptibility of the strains to oral penicillin and cephalosporin antibiotics was excellent, with MICs ranging from 0.016 to 0.031mg/mL. In contrast, strains carrying the macrolide resistant elements of the ermA, ermB, and mefA genes and strains showing a high resistance to levofloxacin were also confirmed in this study. These results suggest that beta-hemolytic streptococci, except for S. pyogenes and S. agalactiae, should be reconsidered as a causative pathogen in streptococcal infections.

Administration, Oral↗
PubMed2006

Immunogenicity and antigenicity of allogeneic amniotic epithelial transplants grafted to the cornea, conjunctiva, and anterior chamber.

PURPOSE: To determine the immunogenic characterization of amniotic epithelium (AE), by examining the fate of allogeneic AE grafts heterotopically transplanted in the eye. METHODS: Intact AE from enhanced green fluorescence protein (EGFP) transgenic mice (C57BL/6 background) and wild-type C57BL/6 mice were transplanted onto cornea or conjunctiva, or inserted into the anterior chamber (AC) of normal BALB/c mice, C57BL/6 mice, or BALB/c mice presensitized to donor antigens. For repeated AE transplantation experiments, AE was grafted in the other eye 7 days after the first grafting. Graft fate was assessed clinically and histologically at selected intervals after grafting. Infiltrating inflammatory cells were examined immunohistochemically. Sensitization to alloantigens by AE was assessed by the delayed hypersensitivity (DH) response. RESULTS: In normal recipients, GFP+ cells were absent in EGFP donor-derived AE grafts by day 21 on cornea and by day 7 on conjunctiva. AE grafts implanted in the AC survived for >8 weeks. In presensitized recipients and recipients that underwent repeated AE implantation, graft survival was markedly shorter than in normal recipients. DH was induced at 2 weeks, but failed to be induced at 4 weeks after grafting on cornea or at 8 weeks after grafting on conjunctiva and in the AC of normal recipients. CONCLUSIONS: Fresh allogeneic AE expressed immunogenicity when placed on the ocular surface, although no memory of allospecific DH was acquired. Allogeneic AE is clearly vulnerable to immune rejection in specifically sensitized recipients.

Amnion↗
PubMed2005

The synaptic microcircuitry associated with primary afferent terminals in the interpolaris and caudalis of trigeminal sensory nuclear complex.

Previous ultrastructural studies indicating a higher number of axoaxonic contacts on individual low-threshold mechanoreceptive afferents in the principalis (Vp) than in the oralis (Vo) of cat trigeminal sensory nuclear complex (TSNC) suggest that the synaptic microcircuitry associated with primary afferents manifests unique differences across the sensory nuclei of TSNC. To address this issue, we analyzed synaptic microcircuits associated with fast adapting vibrissa afferent terminals in the interpolaris (Vi) and caudalis (Vc, laminae III/IV) by using intraaxonal injections of horseradish peroxidase (HRP) in cats. Forty-two and 65 HRP-labeled boutons were analyzed in the Vi and Vc, respectively. The labeled boutons contained clear, spherical vesicles. They most frequently formed asymmetric axodendritic synapses and were commonly postsynaptic to unlabeled axon terminals containing pleomorphic vesicles (p-endings) with symmetric junctions. The examination of synaptic contacts over the entire surface of individual boutons indicated that the afferent boutons made contacts with an average of two postsynaptic targets in the Vi and Vc. In contrast, axoaxonic contacts, and labeled boutons participating in synaptic triads, where p-endings contacted both the boutons and their postsynaptic targets, were, on average, higher in the Vi than in the Vc. These results suggest that the output of sensory information conveyed through low-threshold mechanoreceptive afferents is more strongly controlled at the level of the first synapse by presynaptic and postsynaptic mechanisms in the Vi responsible for sensory discriminative functions than in the Vc for sensorimotor reflexive functions.

Afferent Pathways↗
PubMed2005

Ultrastructure of jaw muscle spindle afferents within the rat trigeminal mesencephalic nucleus.

This study examined the ultrastructures of neuronal elements within trigeminal mesencephalic nucleus by labeling masseteric mesencephalic neurons and masseter motoneurons with injection of horseradish peroxidase into masseteric muscle. Of eight horseradish peroxidase-labeled muscle spindle afferents examined, four terminals showed synaptic contact with labeled dendrites of masseteric motoneurons, two with labeled somata, and the remaining two with unlabeled dendrites. A few of the labeled dendrites showed intimate contact with the somata of the trigeminal mesencephalic nucleus neurons. These results provide morphological evidence of synaptic contact of recurring masseteric muscle spindle afferents with the trigeminal mesencephalic nucleus somata and also suggest the presence of electrical synapses between the somata of the trigeminal mesencephalic nucleus neurons and dendrites of jaw-closing motoneurons.

Animals↗
PubMed2005

Neural mechanisms controlling jaw-jerk reflex in the cat.

Signal substances of axon terminals presynaptic to jaw spindle Ia afferents and their ultrastructural features were examined using a combination of intra-axonal horseradish peroxidase injection and postembedding immunogold-labeling techniques in cats. A total of 35 axon terminals presynaptic to 22 horseradish peroxidase-labeled Ia boutons were examined. Of the 35 presynaptic axon terminals, 14 (40%) were immunoreactive for both gamma-aminobutyric acid and glycine, 9 (26%) for gamma-aminobutyric acid alone and 9 (26%) for glycine alone. The bouton volume, mitochondrial volume, active zone area, and apposed surface area were larger for Ia boutons than for presynaptic axon terminals, while each of the values is similar among the three types of presynaptic axon terminals. These results suggest that gamma-aminobutyric acid and glycine play an important role for modulating the jaw-jerk reflex presynaptically and that the smaller size of presynaptic axon terminals is important to prevent action potential generation from Ia afferents.

Analysis of Variance↗
PubMed2005

Bilateral projection of functionally characterized trigeminal oralis neurons to trigeminal motoneurons in cats.

Intracellular Neurobiotin-injections were used to label functionally identified neurons in the rostro-dorsomedial part of the trigeminal oral nucleus (Vo.r) in the cat. The labeled Vo.r neurons with the mechanoreceptive field in oral tissues innervated bilaterally either jaw-opening motoneurons or jaw-closing motoneurons. This result suggests that Vo.r neurons play an important role in sensory-motor reflexes responsible for coordination of bilaterally symmetrical jaw movements.

Animals↗
PubMed2005

GABA and glycine in synaptic microcircuits associated with physiologically characterized primary afferents of cat trigeminal principal nucleus.

Previous studies suggest that sensory information conveyed through trigeminal afferents is more strongly controlled at the level of the first synapse by GABA-mediated presynaptic mechanisms in the trigeminal principal sensory nucleus (Vp) than other sensory nuclei. However, it is unknown if such a mechanism is common to functionally different classes of primary afferent in the same nucleus or across the nuclei. To address these issues, the present study focused on synaptic microcircuits associated with slowly adapting (SA) mechanosensory afferents innervating the periodontal ligaments in the cat Vp and attempted to examine GABA, glycine, and glutamate immunoreactivity in axon terminals involved in the circuits. Afferents were physiologically characterized before injection of horseradish peroxidase (HRP) and preparation for electron microscopy. HRP-labeled afferent boutons were serially sectioned and immunostained with antibodies against GABA, glycine, and glutamate using a postembedding immunogold method. All the afferent boutons examined contacted non-primary dendrites and they were frequently postsynaptic to unlabeled axons (p-endings). Axodendritic and axoaxonic contacts per afferent bouton were 1.3 (46/35) and 2.0 (70/35), respectively. Most p-endings were immunoreactive for GABA (63/70) and also glycine was co-stained in the majority of the p-endings (49/63). Thirty percent of p-endings with the colocalization of GABA and glycine participated in synaptic triads where a p-ending formed a synapse with the same dendrite as the afferent bouton. None of the p-endings was immunoreactive for glutamate. Most afferent boutons were enriched with glutamate but were immunonegative for GABA and glycine. This study provides evidence suggesting that transmission from SA afferents is strongly controlled presynaptically by GABAergic interneurons with colocalized glycine, and that a proportion of these interneurons, involved in synaptic triads, may also have postsynaptic inhibitory actions on target neurons of the SA afferents.

Afferent Pathways↗