Biomedical subjects

H Sekiya

Publications and source records attributed to H Sekiya.

33 records · Page 2Linked to original sources

PubMed1994

Genetic drift in hypervariable region 1 of the viral genome in persistent hepatitis C virus infection.

The hypervariable region 1 (HVR1) of the putative second envelope glycoprotein (gp70) of hepatitis C virus (HCV) contains a sequence-specific immunological B-cell epitope that induces the production of antibodies restricted to the specific viral isolate, and anti-HVR1 antibodies are involved in the genetic drift of HVR1 driven by immunoselection (N. Kato, H. Sekiya, Y. Ootsuyama, T. Nakazawa, M. Hijikata, S. Ohkoshi, and K. Shimotohno, J. Virol. 67:3923-3930, 1993). We further investigated the sequence variability of the HCV genomic region that entirely encodes the envelope proteins (gp35 and gp70); these sequences were derived from virus isolated during the acute and chronic phases of hepatitis in one patient, and we found that HVR1 was a major site for genetic mutations in HCV after the onset of hepatitis. We carried out epitope-mapping experiments using the HVR1 sequence derived from the acute phase of hepatitis and identified two overlapping epitopes which are each composed of 11 amino acids (positions 394 to 404 and 397 to 407). The presence of two epitopes within HVR1 suggested that epitope shift happened during the course of hepatitis. Four of six amino acid substitutions detected in HVR1 were located within the two epitopes. We further examined the reactivities of anti-HVR1 antibodies to the substituted amino acid sequences within the two epitopes. HVR1 variants in both epitopes within the HVR1 escaped from anti-HVR1 antibodies that were preexisting in the patient's serum.

Adult↗

PubMed1994

Sensitivity of nasal and temporal hemiretinas in latent nystagmus and strabismus evaluated using the light reflex.

To determine visual sensitivity in patients with latent nystagmus with or without esotropia or exotropia, and in patients with esotropia or exotropia, pupillary reactions to 5 degrees diameter light stimuli given to the retina at the fovea (centre), at 5 degrees nasal to the centre, and at 5 degrees temporal to the centre, were measured using electronic infrared pupillography; then pupillary constriction rates and maximum velocity of pupillary constrictions were calculated and analysed. In non-dominant eyes, visual sensitivities of the nasal retina and temporal retina were higher compared with normal eyes, and they also tended to be higher than the sensitivities at the fovea (centre), particularly in patients with latent nystagmus with esotropia. In patients with esotropia or exotropia, visual sensitivities in non-dominant eyes of the nasal retina, and temporal retina increased to a level similar to those at the fovea (centre). The magnitude of these abnormalities was greater in patients with latent nystagmus with esotropia, those with latent nystagmus, and those with latent nystagmus with exotropia, esotropia, and exotropia, in that order. From these results, it was assumed that this imbalance is transmitted to the motor system, resulting in the onset of latent nystagmus.

Adolescent↗

PubMed1993

Possible role of preS2 peptides presented by MHC class I antigen in the pathogenesis of chronic hepatitis B.

Many variations exist in the first 39 nucleotides of the preS2 (pre-S2; 1-39) region of the HBV genome. Based on the similarities of their coding amino acid sequences to those of prototype HBV, they were classified into 3 different types, adr-preS2, adw-preS2 and ayw-preS2. To clarify the meaning of these variabilities in the preS2 region, we studied the HLA class I phenotype of chronic hepatitis B patients having high levels of serum ALT. Our results indicated that in 12 of 14 chronic hepatitis patients infected with HBV type adr-preS2 had HLA-A24 phenotype whereas all of 7 patients infected with either adw- or ayw-preS2 HBV had HLA-A2 phenotype. This strong association between HLA class I phenotype and certain preS2 types of HBV infection was found only in patients with high serum ALT levels but not in patients with almost normal levels of serum ALT. Our results therefore suggest that in the generation of chronic hepatitis B a suitable combination between a fragment of preS2 antigen and HLA class I antigens of the infected host, such as adr-preS2 with HLA-A24 and either adw- or ayw-preS2 with HLA-A2, might be required.

Base Sequence↗

PubMed1993

Humoral immune response to hypervariable region 1 of the putative envelope glycoprotein (gp70) of hepatitis C virus.

We recently found that alterations of amino acids in hypervariable region 1 (HVR1) of the putative envelope glycoprotein (gp70) of hepatitis C virus (HCV) occurred sequentially in the chronic phase of hepatitis at intervals of several months. This finding suggests that mutations in HVR1 are involved in the mechanism of persistent chronic HCV infection involving escape from the immunosurveillance system. To explore this possibility, we examined the humoral immune response to HVR1 with our assay system, in which immunoprecipitation was carried out with sera from patients by using an HVR1 (27-amino-acid) dihydrofolate reductase fusion protein synthesized by in vitro transcription and translation. Results showed that HVR1 contains a sequence-specific immunological epitope that induces the production of antibodies restricted to the specific viral isolate. Furthermore, analysis of the kinetics of the appearance of antibodies in two patients with chronic hepatitis, with whom successive alterations of amino acids of HVR1 have been observed, showed that the titers of anti-HVR1 antibodies usually reached maximal levels several months after the isolation of HCV having the specific sequence of HVR1. This observation suggests that anti-HVR1 antibodies are involved in the genetic drift of HVR1 (minor antigenic variation) by immunoselection. However, the coexistence of HVR1 as an antigen and its specific antibody was sometimes observed. The possibility that HVR1 acts as a neutralizing epitope is discussed.

Adult↗

PubMed1993

[The effect of organophosphorus pesticide (fenthion) on GABA-cells in the central nuclei].

Organophosphorus pesticide (OP) produces abnormal eye movements. This is possibly due to an inhibition of central cholinergic neurons as well as GABAnergic neurons. Using anti-GABA-antibody, the authors studied the effect of OP on GABA-positive cells in the central nervous system. Fenthion (dimethyl 4-methylthion-m-tolyl-phosphorothionate, 20 mg/kg body weight), was given subcutaneously to the dorsal portion of Wistar rats for 30 days. After staining, the number of GABA-positive cells were counted at the superior colliculus (SC), the cerebellum, and the substantia nigra reticularis (SNR) on day 6, 10, 14, 18, 22, 26 and 30 respectively. The number of GABA-positive cells reduced in the cerebellum, SNR and SC decreasing remarkably after the initiation of fenthion administration. The number of GABA-positive cells also decreased in lateral geniculate nucleus and pretectal nuclei. Those results suggest that the reduction of GABA-positive cells produces abnormal eye movements in human OP intoxication.

Animals↗

PubMed1992

Characterization of hypervariable regions in the putative envelope protein of hepatitis C virus.

We previously identified two hypervariable regions [HVR1 (27 amino acids) and HVR2 (7 amino acids)] in the putative envelope glycoprotein (gp70) by comparison of the amino acid sequences of many isolates of the HCV-II genotype. To understand the functional features of these HVRs, using the polymerase chain reaction we analyzed the rate of actual sequence variability in the region including HVR1 and HVR2 of HCV isolated successively at intervals of several months from two patients with chronic C-type hepatitis. In both patients, the amino acid sequence of HVR1, but not HVR2, was found to change dramatically during the observation period (about one amino acid per month). However, no alteration of the amino acid sequence of HVR1 of HCV was observed in a patient in the acute phase of chronic hepatitis. Restriction digestion analysis of sequence diversity showed that a HCV genome with a newly introduced mutation in HVR1 often became the predominant population at the next time of examination. Alterations of amino acids in HVR1 occurred sequentially in the two patients in the chronic phase. These findings suggest that mutations in HVR1 are involved in the mechanism of persistent chronic HCV infection.

Alanine Transaminase↗

PubMed1992

Bilateral innervation of the musculus levator palpebrae superioris by single motoneurons in the monkey.

The location of motoneurons innervating the musculus levator palpebrae superioris (LPS) was studied in the monkey (Macaca irus) by using Fast blue (FB) and propidium iodide (PI) as retrograde neuronal tracers. In each monkey, FB was injected into the LPS of one eye and PI into the LPS of the other eye. Neuronal cell bodies labeled with FB and/or PI were seen intermixed bilaterally through the entire rostrocaudal extent of the central caudal nucleus. While single-labeled (70%) cell bodies predominated, many double-labeled (30%) cell bodies were also encountered. Each of the double-labeled neurons was concluded to supply the LPS on both sides by way of axon collaterals.

Animals↗

PubMed1992

[Free synovium grafting for the repair of the avascular portion of canine knee joint meniscus].

To evaluate the effect of free synovium on repair of avascular portion of the meniscus in the knee, two round full-thickness defects of 2 mm phi were made in the medial menisci of 57 dogs, followed by transplantation of free synovium or blood clots in the holes. Defects with no grafting served as control. Specimens were evaluated histologically at intervals from 1 day to 12 weeks after grafting. The portions of the medial menisci filled with blood clots gradually retracted after surgery and showed no complete repair 6 and 12 weeks after the operation as in the control. In the group which received synovial graft, however, fibrous reparation was observed in 62% of total 13 defects 3 weeks after grafting. Six and 12 weeks after the synovial transplantation, complete reparation by fibrocartilaginous tissue with no signs of tissue retraction was observed in more than 65% of total 17 defects. Therefore, synovial grafting seemed to be a potential method for the repair of the avascular portion of the canine knee joint meniscus.

Animals↗

PubMed1991

[Localization of motoneurons of the vertical yoke muscles in a brainstem of the cat--a double labeling study].

Motor neurons innervating the vertical yoke muscles in cats were investigated using fluorescent dyes by the double labeling method. In 4 cats, the right superior rectus muscle (SR) and left inferior oblique muscle (IO) were injected with 3% fast blue (FB) and 5% diamidino yellow dihydrochloride (DY), respectively, for observing motoneurons innervating yoke muscles involving upward gaze. In 4 other cats, the left inferior rectus muscle (IR) and right superior oblique muscle (SO) were injected with 3% FB and 5% DY, respectively, to observe motoneurons innervating yoke muscles involving downward gaze. After SR and SO injections labeled cells were found in the bilateral oculomotor nucleus and the bilateral trochlear nucleus, respectively, predominantly on the contralateral side. Following IR and IO injections labeled cells were found only in the ipsilateral oculomotor nucleus. No double labeled cell was observed in any labeled neurons, which indicates that each of the yoke muscles was innervated by independent individual motoneurons. According to the present observation and past reports on rats, cats and monkeys, motoneurons innervating SR and SO have developed from lower mammals such as the rat into predominantly contralateral innervation in the monkey, from a phylogenetic point of view. On the other hand, compared to contralateral innervation in lower mammals, motoneurons innervating IR and IO have developed into ipsilateral innervation in the monkey.

Amidines↗

PubMed1990

The center for controlling the near reflex in the midbrain of the monkey: a double labelling study.

The center for controlling the near reflex was studied in the midbrain of the monkey using Diamidino yellow dihydrochloride (DY) and Fast blue (FB) as retrograde neuronal tracers. After injection of DY into the ciliary ganglion, many labelled neurons were found ipsilaterally in the anteromedian nucleus, the Edinger-Westphal nucleus, and the nucleus of Perlia. In contrast, after injection of FB into the medial rectus muscle, labelled cells were found ipsilaterally only in the Edinger-Westphal nucleus of the visceral nuclei as well as in the somatic ipsilateral nuclei. No double labelling of cells was noted in the Edinger-Westphal nucleus, establishing the premise that FB-labelled cells were subserving medial rectus muscle and pupillary/accommodative functions and DY cells were subserving pupillary/accommodative functions independently.

Amidines↗

PubMed1989

[Inhibition of acetylcholinesterase at pupil-related central nuclei by organophosphorus pesticide (fenthion)--an experimental study].

An organophosphorus pesticide (OP) inhibits acetylcholinesterase (AChE) of various organs, especially in cholinergically innervated organs. Pupil constriction is a major sign of an ocular symptom in the patient with acute OP intoxication, but the etiology is unknown. The present experiments were intended to elucidate a central mechanism of pupil size in which AChE and OP are involved. Fenthion (dimethyl 4-methylthion-m-tolyl phosphorothionate) of 5mg/day body weight) was subcutaneously administered dorsally in Wistar rats for 14 days consecutively in the longest group. Histochemical staining and microspectrophotometry were used to analyze the intensity of the AChE activity in the iris, the pretectal nucleus and Edinger-Westphal (EW) nucleus on the 2nd, 4th, 6th, 10th and 14th day of administration. The pupil was measured after 20 minutes of dark adaptation. The pupil constricted on the 6th day and most remarkably on the 10th day. The AChE activity in the iris decreased remarkably on the 4th day. Miosis was not seen on the 4th day. The AChE activity in the pretectal nucleus decreased remarkably on the 6th day. The AChE activity in the EW nucleus reduced gradually from the 6th day and 62% reduction of initial value was seen on the 14th day. Intense miosis was seen on the 10th day. In conclusion inhibition of AChE activity was detected first in the iris, thereafter in the pretectal nucleus and the EW nucleus in close correlation with the miotic pupil. Therefore, miosis associated with OP intoxicated patients may parallel the central inhibition of AChE in pupil-related centers.

Acetylcholinesterase↗

PubMed1985

An HRP study in the monkey of olivary projections from the mesodiencephalic structures with particular reference to pretecto-olivary neurons.

The cells of origin of the olivary projection from mesodiencephalic structures have been demonstrated in the Japanese monkey (Macaca fuscata) with the horseradish peroxidase (HRP) method. Particular attention has been paid to the pretecto-olivary projection which is entirely ipsilateral and originates from the nucleus of the optic tract (NOT), the posterior (or principal) pretectal nucleus (PPN), the sublentiform nucleus (SL), and the (pretectal) ventral lateral zone (VLZ). Pretecto-olivary cells are small-medium sizes of oval or fusiform types. To facilitate comparison among the findings of several experiments, a diagram of the macaque olive, as visualized unfolded, was constructed (Fig. 1). Although a topographic correlation has not emerged clearly from the present experiments, the pattern of the pretecto-olivary projection in the monkey appears to be similar to that found in the cat. Participation of some of the pretectal nuclei in the optokinetic nystagmus and the vestibulo-ocular reflex is discussed in connection with the pretecto-olivary and olivocerebellar projections.

Animals↗

PubMed1984

Projections from the Edinger-Westphal complex of monkeys as studied by means of retrograde axonal transport of horseradish peroxidase.

By means of retrograde axonal transport of horseradish peroxidase, an experimental study was made in the Japanese monkey of the projection from the anteromedian nucleus (AM) and Edinger-Westphal nucleus (EW) to the ciliary ganglon, cerebellar nuclei and spinal cord. Special attention was paid on the labeled cell forms. Neurons projecting to the cerebellar nuclei or the spinal cord were small (8-11 microns in diameter) and spindle-shaped, and they were located in almost the entire parts of both AM and EW. On the other hand, cells which gave off their axons to the ciliary ganglion were large (25-40 microns in diameter) and oval/round in shape. Their locations were confined to the medial parts of both AM and EW, except for the most caudal part of EW. In addition, a few cells in the "nucleus of Perlia" were found to project to the ciliary ganglion.

Accommodation, Ocular↗

PubMed1983

[Bacteriological and clinical evaluation of cefoxitin in the treatment of infections in 39 obstetric and gynecological patients].

A total of 39 patients was admitted to the obstetric and gynecological wards of Nagoya University Hospital and the University's 5 related hospitals during the period from July 1981 to March 1982. The efficacy of cefoxitin sodium was evaluated in the 39 patients with a wide variety of obstetric and gynecological infections. The findings are the follows: Of the 39 patients, the responses in 7 were judged "excellent", 28 "good" and 4 "poor" with the clinical efficacy rate of 89.7%. The causative pathogens in 23 of the cases were isolated from clinical materials submitted to the Institute of Anaerobic Bacteriology, School of Medicine, Gifu University. In these 23 cases, it was found that 8 were due to aerobic bacteria only (34.8%), 8 mixed aerobic-anaerobic bacteria (34.8%) and the remaining 6 anaerobic bacteria only (26.1%), i.e. a substantial percentage (60.9%) was due to anaerobic bacteria or mixed aerobic-anaerobic bacteria. Cefoxitin was active against most strains of Bacteroides spp. and was not affected by the inoculum size. On the other hand, most strains of Bacteroides spp. were resistant to cefazolin when the inoculum size was increased from 10(6)/ml to 10(8)/ml. Lincomycin was also found to be active against many fo the strains of Bacteroides spp. Cefoxitin and cefazolin were fairly active against anaerobic bacteria other than Bacteroides spp., while these same bacteria were resistant to sulbenicillin and many of them showed resistance to lincomycin. Cefoxitin was well tolerated and no untoward side effects were observed. The clinical and bacteriological results indicate that cefoxitin is a very effective antibiotic in the treatment of a wide variety of obstetric and gynecological infections and is a suitable choice as initial antibiotic therapy in these conditions.

Adolescent↗

PubMedDate not supplied

An in vitro biomechanical study of a hinged external fixator applied to an unstable elbow.

Details of the mechanical properties of hinged external fixators are essential to use the fixator properly in the clinical setting. A hinged external fixator (Dynamic Joint Distractor 2) was attached to the lateral side of 7 cadaveric elbows. Cantilever lateral bending tests were performed at 3 flexion angles in varus and valgus directions. Varied states of joint contact and axial loading were studied. Stiffness of the construct was calculated with uniaxial loading. Stiffness decreased with increased elbow flexion. Gap creation made the system less stiff. Axial loading made the system stiffer, especially in valgus testing. Stiffness in varus was approximately 4 times that in valgus. Lateral fixator application with half pins is most effective for protecting against varus-producing forces. When using the external fixator for unstable elbows, attention should be paid to the status of the articular surfaces and the integrity of the ligaments, and this should also be noted for elbow position during rehabilitation.

Aged↗