Biomedical subjects

S Hirano

Publications and source records attributed to S Hirano.

At least 127 records · Page 7Linked to original sources

PubMed1998

Influence of unilateral deafness on auditory evoked magnetic field.

To investigate the effect of unilateral deafness on central auditory mechanisms, we examined patients with unilateral deafness of various durations. Auditory evoked magnetic fields (AEF) were recorded using a whole-head neuromagnetometer. In patients who had unilateral deafness for more than 3 weeks, the average N100m latency in the ipsilateral hemisphere did not differ from that in the contralateral hemisphere. In addition, in some patients with congenital or early onset deafness, the equivalent current dipole (ECD) moment was larger in the ipsilateral hemisphere than in the contralateral hemisphere. These findings suggest that unilateral deafness may cause reorganization of the central auditory pathway. They also suggest that central auditory pathway in adults has some plasticity, though not as much as in childhood.

Adult↗

PubMed1998

Effects of intratracheal pretreatment with yttrium chloride (YCl3) on inflammatory responses of the rat lung following intratracheal instillation of YCl3.

We investigated pulmonary clearance of yttrium (Y) and acute lung injury following intratracheal instillation (i.t.) of yttrium chloride (YCl3) in saline- or YCl3-pretreated rats (30 days before the second challenge). About 67% of the initial dose of Y remained in the lung even 31 days after the i.t. treatment. The pretreatment with YCl3 significantly reduced i.t.-YCl3-induced increases in biochemical inflammatory indicators in bronchoalveolar lavage fluid (BALF), such as lactate dehydrogenase, beta-glucuronidase, and alkaline phosphatase activities and protein concentration, while the pretreatment increased the number of polymorphonuclear leukocyte (PMN) in BALF. These results suggest that the augmentation of PMN infiltration does not play an important role, if any, in i.t. YCl3-induced increases in biochemical indicators in BALF. The reduction of the increases in those biochemical inflammatory indicators may be due, at least in part, to the increase of manganese-superoxide dismutase (Mn-SOD) activity in the lung tissue, because the lung Mn-SOD activity in the YCl3-pretreated group was two times higher than that of the saline-pretreated group.

Animals↗

PubMed1998

Aberrant muscle activation in patients after resection of non-primary motor areas: demonstration by surface electromyography.

Two patients presented with a tumor involving mainly the supplementary motor area or the premotor cortex. Shortly after tumor resection, each developed transient impairment of voluntary movements. An electromyogram, with the skin electrodes placed over the muscles of the upper arms and forearms, demonstrated aberrant ipsilateral, contralateral or bilateral muscle activation during unilateral motor tasks in both patients. The bilateral activation was more prominent in the patient who had an intact dominant hemisphere. The present study suggests for the first time the importance of non-primary motor areas of the human brain in activating the proper set of muscles on the proper side of the body.

Adult↗

PubMed1998

Stereotyped axonal bundle formation and neuromeric patterns in embryos of a cyclostome, Lampetra japonica.

Early embryonic development of the nervous system of a lamprey, Lampetra japonica, was studied by using immunohistochemical techniques and by scanning electron microscopy. The earliest appearance of axons was detected at Tahara's stage 21-, when dorsolateral and ventral longitudinal fasciculi were present in the hindbrain and spinal cord regions. The branchiomeric nerve roots began to appear at stage 22; the fibers were joined to the dorsolateral fasciculus proximally and also extended distally into each pharyngeal arch. The anterior neural tube was divided into several neuromeres: the mid-hindbrain sulcus became apparent first, then the portion rostral to this sulcus was subdivided into two portions by the syn-parencephalic boundary. In the hindbrain around stage 23, rhombomeres developed transiently, of which, rhombomere 4 was the most distinctive. Putative crest cells forming the octavofacial nerve root anlage were selectively adhering to rhombomere 4, whereas no crest cells were found on rhombomere 3. The assignment of the crest-derived nerve anlage to rhombomeres is conserved between gnathostomes and L. japonica. The neuromerical scheme of the neural tube of L. japonica is also mostly in accordance with that in gnathostomes, sharing the basic developmental patterning of axon bundles at early developmental stages. The most distinct difference between these two groups is the topographical relationships between the hindbrain neuraxis and pharyngeal arches, as well as the otic placode.

Acetylation↗

PubMed1998

Rostral truncation of a cyclostome, Lampetra japonica, induced by all-trans retinoic acid defines the head/trunk interface of the vertebrate body.

The effect of all-trans retinoic acid on embryogenesis was studied in a cyclostome, Lampetra japonica. Treatment with 0.05-0.5 microM retinoic acid on early gastrula and early neurula resulted in loss of the pharynx and in the rostral truncation of the neural tube. The mouth, pharynx, esophagus, heart, endostyle, and rostral brain were missing with graded severity. In the severest case, the embryo consisted only of trunk segments, especially myotomes that extended to the rostral end of the axis. The effect appeared to be dose- and stage-dependent: Rostral pharyngeal arches were more vulnerable to a lower amount of retinoic acid, and earlier treatment resulted in severer defects. The initial protrusion of the anterior axis started equally in control and retinoic acid-treated embryos, implying that the head morphogenesis is omitted in treated embryos. By identifying the number of myotomes based on the differentiation of hypobranchial muscles, there seemed to be no myotomes lost by retinoic acid-induced truncation. The rostral truncation, therefore, was not simply a limitation of the anterior axis but was restricted to the ventral portion; only the branchial arches disappeared with normally developing myotomes dorsally. The absent region can be defined as the vertebrate head in a morphological sense, including the branchiomeric and preotic paraxial regions as well as the heart. The results suggest the presence of distinct programs between somitomeric and branchiomeric portions of the body, providing a developmental basis for the dual-metamerical body plan of vertebrates.

Animals↗

PubMed1998

Otx cognates in a lamprey, Lampetra japonica.

Gnathostomes have two lineages of Otx genes, Otx1 and Otx2, as cognates of a Drosophila head gap gene, orthodenticle. Previous studies with mutant mice have demonstrated that they play essential roles in the development of rostral head. To shed lights on the evolution of the rostral head in vertebrates we isolated their cognates in the Japanese marine lamprey, Lampetra japonica. The lamprey genome appeared to have two Otx cognantes, LjOtxA and LjOtxB. Phylogenetic analyses suggest that LjOtxA clusters with gnathostome Otx2 genes, but LjOtxB does not belong to either the Otx1 or Otx2 lineage. LjOtxA was expressed in the forebrain and midbrain with the caudal limit possibly at the midbrain/hindbrain junction as gnathostome Otx cognates are, but LjOtxB was not expressed in the brain. No Otx1 or Otx2 cognates are known in gnathostomes that are not expressed in the brain. Both LjOtxA and LjOtxB were expressed in the olfactory placode, epiphysis, optic stalks, and lower and upper lips. LjOtxB was also expressed in the eyes, where no LjOtxA transcripts were detected. Thus, Otx1 and Otx2 functions for the development of forebrain and midbrain in gnathostomes appear to be shouldered by LjOtxA alone in the lamprey. LjOtxB may have diverged from the stem of the Otx1 and Otx2 lineages and evolved independently.

Amino Acid Sequence↗

PubMed1998

Normal ontogenic observations on the expression of Eph receptor tyrosine kinase, Cek8, in chick embryos.

The spatio-temporal pattern of expression for the Eph receptor tyrosine kinase, Cek8, was observed in normal chick embryos from H-H stage 6 to 23 by immunohistochemical techniques. Expression of Cek8 was already present in embryos at H-H stage 6, where it was located in the neural plate of the brain region, paraxial mesoderm, and the primitive streak. Regions expressing Cek8 subsequently increased during development to include the neural folds of the brain, rhombomeres 3 and 5, the caudal part of the neural plate, neural crest cells related to the formation of glossopharyngeal nerve ganglia, invaginated cells throughout the primitive groove and the epithelium of the rudiment of the gall bladder. Cek8 was also expressed in the mesenchymal cells of the pharyngeal arches, allantoic stalk and limb buds as well as in the areas surrounding the eye vesicles and nasal pits. Furthermore, cells in the tail bud progressing to the secondary neurulation expressed Cek8. Thus, the spatiotemporal patterns of Cek8 expression appears to have intimate relationships with tissue rebuilding, the maturation of differentiated cells, and the spatial organization of tissues. Consequently, it appears that Cek8 plays an integral role in the developmental events leading to the formation of a wide--though not inclusive--variety of tissues and organ systems.

Animals↗

PubMed1998

In vitro wear of resin denture teeth.

STATEMENT OF PROBLEM: One of the most important physical properties of artificial teeth used in the restoration of the edentulous patient is wear resistance, and the ability of these teeth to maintain a stable occlusal relationship over time. PURPOSE: This study compared the in vitro wear of four different resin denture teeth against human enamel. MATERIAL AND METHODS: Five denture tooth samples opposing five enamel abraders were positioned in a mechanical wear testing device for two 5,000 cycle wear periods (total of 10,000 cycles) under a 13.4 N load. All tests were conducted in human saliva, and the wear was measured at the end of each test period. RESULTS: The wear of the Classic and Kenson acrylic resin denture teeth was much greater than the DB Plus and MLI composite teeth after 10,000 cycles. The wear of the KENSON denture tooth was also greater than the Classic tooth. No wear differences were found between the two composite teeth. CONCLUSIONS: The wear of DB Plus and MLI resin denture teeth was approximately 50% less than the wear of Classic and Kenson teeth when opposed by human enamel.

Acrylic Resins↗

PubMed1998

Cerebral revascularization using omentum and muscle free flap for ischemic cerebrovascular disease.

BACKGROUND: Indirect cerebral revascularization has been generally accepted in the management of brain ischemia in moyamoya disease. We performed indirect cerebral revascularization by using omental flap and muscle flap techniques for the treatment of ischemic cerebrovascular disease. METHODS: Ten patients with ischemic cerebrovascular disease including three with adult moyamoya disease underwent this procedure (omental flap on eight sides and muscle flap on five sides). The muscle used for the flap was the serratus anterior muscle on two sides and shaved latissimus dorsi muscle on three sides. Angiography and cerebral blood flow studies were performed in all patients preoperatively and postoperatively. All patients demonstrated severely impaired cerebrovascular reserve capacity due to occlusive disease. RESULTS: There was one patient each with perioperative death and intracranial infection following omental flap loss, and two patients had perioperative strokes. The average follow-up period was 23.2 months. Of the nine surviving patients, all eight except for the one with flap loss had good outcome with complete resolution of neurologic episodes. CONCLUSIONS: It is concluded that this method seems to be effective in selected patients with ischemic cerebrovascular disease.

Adult↗

PubMed1998

Dysfunctional parenting as a risk factor to lifetime depression in a sample of employed Japanese adults: evidence for the 'affectionless control' hypothesis.

BACKGROUND: Although many case-control studies have replicated an association between dysfunctional parenting and a lifetime diagnosis of depression, few epidemiological studies have explored the association. In addition, little is known about the association in non-western countries. METHODS: Using logistic regression analyses, additive and interactive contributions of parental child-rearing behaviours, as measured by the Parental Bonding Instrument (PBI), toward the risk for having a lifetime diagnosis of major depressive disorder were explored in 418 employed Japanese adults. The diagnosis was provided by using the Inventory to Diagnose Depression, lifetime version. The analyses were conducted for male and female subjects separately. RESULTS: Parental care rather than parental protection was primary in predicting lifetime depression in both male and female subjects. An interactive combination of low care and high protection ('affectionless control') was a significant risk factor for lifetime depression in male respondents' reporting child-rearing behaviours of both parents and female respondents' reporting paternal child-rearing behaviours. Model improvements when entering the PBI scores were larger in male subjects than in female subjects. CONCLUSIONS: The results suggested that a combination of low care and over-protection increases a risk to lifetime depression even in a non-clinical sample; that an association between dysfunctional parenting (particularly low care) and the development of depression is independent of culture; and that Japanese boys are more sensitive than Japanese girls to dysfunctional parenting as regards the development of depression.

Adolescent↗

PubMed1998

Nitric oxide-mediated cytotoxic effects of alveolar macrophages on transformed lung epithelial cells are independent of the beta 2 integrin-mediated intercellular adhesion.

It is known that murine macrophages produce nitric oxide (NO) when stimulated with lipopolysaccharide (LPS) or interferon-gamma (IFN-gamma), and NO mediates the tumoricidal activity of activated macrophages. The present study was designed to investigate whether the intercellular adhesion is necessary for activated rat alveolar macrophages to exert the full cytotoxic effects. Rat alveolar macrophages produced NO dose dependently in response to either LPS or IFN-gamma, and caused DNA fragmentation in rat type II pneumocytes transformed with SV40 (SV40T2). Chemically produced NO also caused the DNA fragmentation and viability loss in SV40T2, and both of them were inhibited by a NO radical scavenger. The cytotoxicity of activated macrophages was reduced by NG-monomethyl-L-arginine, a competitive nitric synthase inhibitor, and neither superoxide dismutase nor catalase modulated the cytotoxicity. Although alveolar macrophages stimulated with either LPS or IFN-gamma caused DNA fragmentation of SV40T2, only LPS increased the intercellular adherence between macrophages and SV40T2. The intercellular adhesion was reduced by both anti-CD18 and anti-CD11a. However, those antibodies did not affect the cytotoxicity of LPS-stimulated macrophages. These results clearly indicate that NO-mediated cytotoxicity is caused predominantly by diffusion of NO, and the beta 2 integrin-mediated intercellular adhesion does not play an important role, if any, in activated macrophage-mediated cytotoxic effects on SV40T2.

Animals↗

PubMed1998

Influence of speech-coding strategy on cortical activity in cochlear implant users: a positron emission tomographic study.

The effects of a speech-coding strategy of cochlear implant (CI) on cortical activity were evaluated using positron emission tomography. The CIs used in the present study were those of a 22-channel system using the Multipeak speech-coding strategy (MPEAK) and the spectral peak strategy (SPEAK). On comparing the 2 groups, it was found that the speech-tracking performance was significantly higher in the SPEAK group than in the MPEAK group. Regional cerebral blood flow (rCBF) was measured during the silent resting, noise stimulus and speech stimulus periods. The increase in rCBF was localized mainly in the primary auditory area during the noise stimulus period. The increase in rCBF in the auditory association area during the speech stimulus period was stronger in the SPEAK group than in the MPEAK group. This finding suggests that the SPEAK strategy activates more speech processing neuronal networks in the auditory association area than the MPEAK strategy.

Acoustic Stimulation↗

PubMed1998

Ectopic prostatic tissue outside the urinary tract: a case report.

A 64-year-old man with a 4-month history of dysuria and urinary frequency had a mass behind the bladder. The preoperative diagnosis was a tumor of the left seminal vesicle, but a histologic examination revealed benign prostatic tissue. This is the seventh reported case of ectopic prostatic tissue situated outside the urinary tract.

Acid Phosphatase↗

PubMed1998

Synthesis and biological evaluation of phenylacetyl derivatives having low central nervous system permeability as potent and selective M2 muscarinic receptor antagonists.

A series of phenylacetyl derivatives containing the 5,10-dihydro-11H-dibenzo[b,e,][1,4]diazepin-11-one or 5,11-dihydro-6H-pyrido[2,3-b][1,4]benzodiazepin-6-one skeleton was prepared and evaluated for their binding affinities to muscarinic receptors in vitro and for antagonism of bradycardia, salivation and tremor in vivo. Among them, compounds 56 and 66 had high affinity for M2 muscarinic receptors in the heart (pKi = 8.7 and 8.9, respectively) with low affinity for M3 muscarinic receptors in the submandibular gland. A structure-activity relationship (SAR) study suggested that the high M2 selectivity over the M3 muscarinic receptors of 56 may be attributed to the direction of the carboxamide carbonyl group. In in vivo studies, 56 and 66 antagonized oxotremorine-induced bradycardia in rats on both intravenous and oral administration, and their heart rate increasing effect in dogs with nocturnal bradycardia was about 3-fold greater than that of AF-DX 116. Furthermore, they had almost no influence on oxotremorine-induced tremor in mice, presenting no evidence of central transfer.

Animals↗

PubMed1998

Decrease in circulating and urine adrenomedullin concentrations in stroke-prone spontaneously hypertensive rats.

Adrenomedullin (AM) is a peptide with potent vasodilatory and hypotensive properties. Plasma AM levels in rats with experimentally induced hypertension, such as Dahl salt-sensitive rats and two-kidney, one-clip hypertensive rats, are higher than those in normotensive rats. We previously noted, however, that plasma AM levels in spontaneously hypertensive rats (SHR) are similar to those in Wistar-Kyoto rats. To define the role of AM in rats with severe hypertension, we investigated changes in circulating and tissue AM levels in stroke-prone spontaneously hypertensive rats (SHRSP/Izm). The immunoreactive rat AM levels in plasma, urine, and tissue measured with a sensitive radioimmunoassay, and the AM mRNA levels in various tissues in 15-wk-old SHRSP/Izm were compared with those in age-matched Wistar-Kyoto rats (WKY/Izm). The plasma and urinary AM levels in SHRSP/Izm were significantly lower than those in WKY/Izm [plasma AM, 2.14+/-0.06 (SE) vs. 3.24+/-0.16 fmol/ml, p< 0.001; urinary AM, 16.36+/-3.21 vs. 36.12+/-6.09 fmol/ml, p< 0.01]. A negative correlation was found between the plasma AM level and the systolic blood pressure in both SHRSP/Izm and WKY/Izm. Reverse-phase high-performance liquid chromatography showed that the molecular components of plasma immunoreactive AM in SHRSP/Izm were similar to those in WKY/Izm. Furthermore, tissue AM levels in various organs in SHRSP/Izm were not lower than those in WKY/Izm. In conclusion, low levels of circulating AM may contribute to the maintenance of high blood pressure in 15-wk-old SHRSP/Izm. These low plasma AM levels may be caused by accelerated metabolism of circulating AM in SHRSP/Izm.

Adrenomedullin↗

PubMed1998

Physical properties of resin-modified glass-ionomers.

The physical properties and shear bond strength of two resin-modified glass-ionomers: RMGIs (FJL and VT) and as a control, a conventional glass-ionomer: CGI (FJ), were evaluated. Ninety percent of the setting shrinkage under dry conditions and nominal hygroscopic expansion in water during 360 h occurred within the first 24 h. The nominal hygroscopic expansion of CGI was 0.38% while the RMGIs demonstrated over 1%, but considering the setting shrinkage the total hygroscopic expansion of CGI and the RMGIs were over 7 times and about 2.5 times, respectively. The thermal expansion of the RMGIs after water immersion was greater than that under dry condition. In contrast, FJ demonstrated expansion less than under dry condition. There was no significant difference between FJL and VT (P < 0.05) as regard water absorption. The shear bond strength of the RMGIs to enamel and dentin were superior to FJ, except for VT to dentin.

Absorption↗

PubMed1998

[Ganglioneuroma arising in the adrenal medulla: a case report].

We report a case of adrenal ganglioneuroma. A 33-year-old woman visited our clinic with a complaint of epigastralgia. Abdominal computed tomography (CT) and magnetic resonance imaging (MRI) revealed a round mass, 4 cm in diameter, in the left suprarenal fossa. Laboratory data including endocrinological study were normal except for a mild increase of urinary excretion of dopamine. Under the diagnosis of left non-functioning adrenal tumor, surgery was performed on August 9, 1996 through flank incision. The excised tumor was well-demarcated and weighed 36.6 g. The cut surface revealed an ash-colored round tumor surrounded by thin stretched adrenal tissue. Histological diagnosis of the tumor was a ganglioneuroma originating from the adrenal medulla.

Adrenal Gland Neoplasms↗

PubMed1997

Peripheral development of cranial nerves in a cyclostome, Lampetra japonica: morphological distribution of nerve branches and the vertebrate body plan.

The development of peripheral nerves was studied in a Japanese marine lamprey, Lampetra japonica, in whole-mount and sectioned embryos from hatching until the earliest ammocoete. Nerve fibers were immunohistochemically stained with a monoclonal antibody against acetylated tubulin. Branchiomeric nerves first developed in a simple metamerical pattern, each associated with a single pharyngeal arch. Of those, the ophthalmicus profundus, maxillomandibular, and facial nerves later developed a highly modified branching pattern, whereas postotic nerves were less specialized and showed the stereotypical branching pattern of post-trematic nerves. The early distribution of melanocytes in myotome-free space largely overlapped with the morphology of the cranial nerve and ganglion anlage, and resembled the cephalic crest cell distribution pattern in the early chick embryo. It was suggested that the cephalic crest cell distribution, which is also inhibited by myotomes in the lamprey, would be the common basis for branchiomeric nerve patterning. In later development of the lamprey embryo, myotomes 1 through 3, which had originated in the postotic region, grew rostrally into the preotic region, laterally covering all of the branchiomeric nerves. This results in a deep position of the cranial nerves, which is not observed in gnathostomes.

Animals↗