Biomedical subjects

J Yamada

Publications and source records attributed to J Yamada.

At least 145 records · Page 8Linked to original sources

PubMed1998

An osteometrical study of the cranium and mandible of the lesser mouse deer (Chevrotain), Tragulus javanicus.

The lesser mouse deer (Tragulus javanicus) is one of the most primitive ruminants. Skulls of lesser mouse deer were measured to evaluate their growth. The age was estimated from the eruption and attrition of molars on the mandible. A total of 95 specimens was divided into five age groups, and the growth pattern in each sex was established for some measurements. The relative growth coefficients were calculated for the head and body length and several parts of the cranium and mandible against the profile length. Sexual dimorphism could not be found on the skull in any age group except for measurements related to the upper canine. However, females showed a higher value in head and body length in the oldest group. This feature was consistent with an interpretation of mouse deer society as monogamous. Growth was more rapid in length than in width. Various statistical analyses showed that the visceral cranium related to masticatory facility was much better developed than the neurocranium. However, observations on the shape of the mandible ramus and of the premolars implied that the masticatory function was not suitable for taking roughage. This speculation agreed with previous reports on the feeding habits and digestive organs of the mouse deer.

Age Determination by Teeth↗

PubMed1998

Monoclonal antibody TSd-1 is specific to elongating and matured spermatids in testis of common tree shrew (Tupaia glis).

The monoclonal antibody (MAb), named TSd-1, specific to spermatogenic cells of the common tree shrew (Tupaia glis) was established and characterized using immunohistochemistry and immunoblotting. MAb TSd-1 reacted with elongating and matured spermatids in a stage-dependent manner. TSd-1 recognized a 94 kilodalton (kDa) peptide in the plasma membrane and cytosol. Additionally, an extremely weak 107 kDa band was detected only in the cytosol. The reactions were not detected in round spermatids. In elongating Stage VI spermatids, the plasma membrane and the granular structure within the cytoplasm were intensely positive, and most intense after the appearance of new round spermatids in the lower layer (Stage I). The reactions were observed neither in the other organs of the common tree shrew nor in the testes of other animals, indicating that TSd-1 antigen is specific to the spermatogenic cells of the common tree shrew, and may act on elongating or matured spermatids.

Animals↗

PubMed1998

Expression of inhibin alpha-subunit in horse testis.

Inhibin is believed to play roles in the pituitary secretion of FSH and in the paracrine regulation of testicular function. Although it has been generally accepted that inhibin is produced in Sertoli cells, there was a recent evidence for the localization of inhibin in Leydig cells of primates, rat and sheep. However, there is no report on the expression of inhibin in the adult horse testis. Therefore, using immunohistochemistry, western blotting and in situ hybridization techniques, the present study examined inhibin alpha-subunit (Ih-alpha) expression in the adult horse testis. For the detection of Ih-alpha protein, we used anti-porcine Ih-alpha antibody in immunohistochemistry and western blotting. Furthermore, digoxigenin-labeled complementary RNA probes were prepared to detect intracellular messenger RNA (mRNA) of Ih-alpha. Immunostainings for Ih-alpha were found not only in Leydig cells but also in Sertoli cells. The intensity in Leydig cells was stronger than in Sertoli cells. Immunoreactivities for Ih-alpha were found at approximately 46 kDa, 56 kDa and 90 kDa in the homogenates from testicular interstitial tissues. The bands at 56 kDa and 90 kDa agree with previous report, but not at 46 kDa. Signals for mRNA of Ih-alpha by in situ hybridization were detected in Leydig cells and in the basal region of seminiferous epithelium including Sertoli cells. These results suggest that Ih-alpha is expressed in Leydig cells and Sertoli cells of horse testis, and the expression level should be higher in Leydig cells than Sertoli cells.

Animals↗

PubMed1998

Irreversible potent activation and reversible inhibition of trypsin-like activity of 20S proteasome purified from Xenopus oocytes by fatty acid.

The 20S proteasome purified from animal cells has various latent peptidase activities. Fatty acids such as linoleic, linolenic and oleic acids strongly activate both the chymotrypsin-type and peptidylglutamylpeptide (PGP) hydrolase-type activities, but have been reported to have little activation or inhibition of the trypsin-type activity. We show here that an increase of the fatty acid concentration produces activation of chymotrypsin-type and PGP hydrolase-type in a biphasic fashion: no effect until the threshold concentration and then a sharp activation. In contrast, the trypsin-type activity was markedly inhibited at low concentrations of fatty acid, slightly activated at higher concentrations, and inhibited again at even higher concentrations. The inhibition was removed when the concentration of fatty acid was reduced by dilution after pre-incubation with the fatty acid. As a result, the activation pattern became biphasic, which was identical to that of chymotrypsin-type and PGP hydrolase-type activities. These results suggest that in the chymotrypsin-type and PGP hydrolase-type peptidase fatty acids bind first to a class of sites without direct effect on the peptidase activity, but after saturation of this class it permits more fatty acid to bind to another class of sites involved in the activation. In the trypsin-type peptidase an additional class of fatty acid binding sites is uniquely present, which is involved in the enzyme inhibition. The dilution procedure described above removes the fatty acid molecules bound to the inhibition sites, but not the fatty acid molecules bound to the activation sites; this results in the fatty acid activation profile indistinguishable from that of the chymotrypsin- and PGP hydrolase-type peptidases.

Animals↗

PubMed1998

Semantic activation by Japanese kanji: evidence from event-related potentials.

In a character-judgment paradigm, the subject quickly pressed a key when a hiragana (Japanese syllabary) appeared on a display and did nothing when a kanji (Japanese logograph) appeared. The amplitude of the N400 component was compared when four types of visual stimuli were used: (Type 1) single kanji--Grade 1- to 3-level words, (Type 2) single kanji--Grade 1- to 3-level bound morphemes, (Type 3) single kanji--high school- and college-level bound morphemes, and (Type 4) obsolete kanji. Analysis showed that N400 was largest in the temporal-occipital areas for the Type 1 stimuli and larger in the right parietal area for Type 2 than Type 3 stimuli. The analyses of N400 to semantic stimulations have been conducted and discussed in terms of their meaningfulness, age when writing of these kanji was mastered, and linguistic status (kanji versus nonkanji). Most interestingly, the Types 3 and 4 kanji did not activate semantic responses, showing that they did not function as linguistic units, i.e., kanji, in the mental lexicon.

Evoked Potentials↗

PubMed1998

Effect of ease-of-acquisition on naming latency for Japanese kanji: a reanalysis of Yamazaki, et al.'s (1997) data.

Yamazaki, Ellis, Morrison, and Lambon Ralph in 1997 found two age-of-acquisition measures exerted greater independent effects on the naming latency of kanji than well-established variables such as word frequency. The current study is a sequel to that study but has reached a different conclusion. To find a better predictor than the two age-of-acquisition measures, Yamazaki, et al.'s data were reanalyzed with the new variable, ease-of-acquisition. The main finding was that the correlation between ease-of-acquisition at age 13 and naming latency was high .67 (df = 145, p < .001). The status of ease-of-acquisition and its possible role in psycholinguistic research are briefly discussed.

Adolescent↗

PubMed1998

Interleukin-1 receptor antagonist suppresses Langerhans cell activity and promotes ocular immune privilege.

PURPOSE: To determine whether the capacity of Langerhans cells (LCs) to abrogate ocular immune privilege can be suppressed by the topical application of interleukin-1 receptor antagonist (IL-1ra). METHODS: Cautery was applied to corneas of BALB/c mice on day 0 to induce centripetal migration of LCs. Immune privilege was tested by the ability to induce anterior chamber-associated immune deviation (ACAID) to intracamerally injected soluble antigen 1 to 2 weeks after cautery application. The number of LCs was enumerated by immunofluorescent staining. In other experiments, freshly procured Thy-1-depleted epidermal cells, with or without LC depletion, were injected directly into virgin murine corneas before testing for ACAID. All test animals were randomized for treatment with either topical IL-1ra or placebo in a masked fashion for 1 to 2 weeks after induction of LC migration and before intracameral injection of antigen. RESULTS: Intracorneal injection of freshly procured LC-depleted epidermal cells into normal eyes failed to abrogate ACAID, whereas LC-containing cell populations uniformly led to loss of immune privilege (P < 0.01). Topical treatment with IL-1ra led to retention of the cauterized eyes' capacity for ACAID induction (P < 0.01) and to a profound (>80%) suppression of LC migration compared with untreated controls (P < 0.01). Additionally, topical IL-1ra treatment of eyes with intracorneally injected LCs preserved immune privilege and ACAID induction (P < 0.001). CONCLUSIONS: IL-1 mediates mechanisms of immunity in corneal inflammation that subvert the normal eye's immune privileged state. However, its antagonism with topical administration of IL-1ra preserves ocular immune privilege and ACAID through suppression of LC function.

Administration, Topical↗

PubMed1998

[Manifestation of Chiari II symptoms following peritoneal shunt tube extension].

A 5-year-old boy with hydrocephalus and a lumbar myelomeningocele underwent extension of peritoneal tube of ventriculoperitoneal (VP) shunt system. Prior to the operation he had been able to walk independently with the use of braces, to speak complex sentences and to sing songs. After the surgery, he lost consciousness and became critically ill with irregular respiration. He was artificially ventilated for 10 days, and then recovered, with sequelae of right facial paresis and slight dysarthria. T1 weighted magnetic resonance image showed high intensities of the medial part of the inferior lobe of the cerebellum and medulla oblongata, which were interpreted as representing edema. This case illustrates that Chiari II malformation can become symptomatic after a VP shunt trouble.

Acute Disease↗

PubMed1998

[A case of congenital toxoplasmosis confirmed by detection of Toxoplasma gondii in placenta].

We report a case of congenital toxoplasmosis with a prenatal diagnosis of fetal hydrocephalus. A CT scan performed at birth revealed ventricular dilation with calcification. The serum and CSF Toxoplasma specific IgM were elevated. The diagnosis was confirmed by the presence of Toxoplasma cysts in the placenta, and detection of the Toxoplasma SAG1 gene by a polymerase chain reaction (PCR) (placenta, positive; CSF, negative). Signs of active central nervous system infection, such as the decreased CSF glucose, and elevated CSF protein, neuron specific enolase and LDH, resolved after initiation of treatment with pyrimethamine and sulfazoxine. A PCR test using the placental tissue may be useful for the rapid diagnosis of congenital toxoplasmosis.

Adult↗

PubMed1997

The involvement of 5-HT1B receptors in the inhibitory effects of nitric oxide synthase inhibitor on 2-deoxy-D-glucose-induced hyperphagia in rats.

We found previously that the nitric oxide (NO) synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME) significantly reduced 2-deoxy-D-glucose (2-DG)-induced hyperphagia in rats. To clarify the involvement of 5-HT, we investigated the effects of 5-HT receptor antagonists on inhibitory effects of L-NAME on 2-DG-induced hyperphagia. The effects of L-NAME on 2-DG-induced hyperphagia were inhibited by the 5-HT1B receptor antagonist metergoline. However, the 5-HT2 receptor antagonist ritanserin had no such effect. These results suggest that the anorectic effects of L-NAME may be related to serotonergic mechanisms.

Analysis of Variance↗

PubMed1997

Involvement of nitric oxide in 2-deoxy-D-glucose-induced hyperphagia in rats.

The effects of a nitric oxide (NO) synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) on 2-deoxy-D-glucose (2-DG)-induced hyperphagia were investigated in rats. L-NAME dose-dependently inhibited 2-DG-induced eating in non-food-deprived rats, although the inactive isomer D-NAME on 2-DG-induced hyperphagia were inhibited by co-administration of L-arginine. The neuronal NO synthase inhibitor 7-nitroindazole also inhibited 2-DG-induced hyperphagia. These results suggest that 2-DG-induced hyperphagia is linked with NO and that brain NO may participate in this hyperphagic model.

Animals↗

PubMed1997

Differences of the primate flocculus and ventral paraflocculus in the mossy and climbing fiber input organization.

Potential sources of cerebellar cortical afferent fibers were identified in the vestibular ganglion, medulla oblongata, pons, and cerebellar nucleus of seven anesthetized Macaca fuscata after local injections of wheat germ agglutinin-conjugated horseradish peroxidase or Fast Blue into the flocculus (FL) or ventral paraflocculus (VP). There were differences in the sources of mossy fibers to the FL and VP. Labeled neurons, after injections into the FL, were located mainly in the ipsilateral vestibular ganglion, bilaterally in the vestibular and prepositus hypoglossal nuclei, nucleus reticularis tegmenti pontis, and the central part of the mesencephalic reticular formation including the raphe nuclei. Labeled neurons were rarely seen in the pontine nuclei after injections into the FL. By contrast, after injections into the VP, numerous labeled neurons were located in the contralateral pontine nuclei, but relatively few in the vestibular nuclei bilaterally. Sources of climbing fibers to the FL and VP were completely contralateral to the injection side. After the injection into the FL and VP, labeled neurons were located in the dorsal cap, ventrolateral outgrowth, and ventral part of the medial accessory olivary nucleus. The projections from these three olivary areas were generally consistent with a zonal pattern of terminations in the FL and VP. The present results are consistent with a hypothesis that the FL is mainly involved in the control of vestibulo-ocular reflex and that the VP is mainly involved in the control of smooth pursuit eye movements.

Afferent Pathways↗

PubMed1997

Topical interleukin 1 receptor antagonist promotes corneal transplant survival.

BACKGROUND: Interleukin (IL)-1 is a potent proinflammatory cytokine that plays a critical role in initiating and maintaining immunogenic inflammation. We performed a series of experiments to determine whether the topical application of IL-1 receptor antagonist (IL-1ra) can prolong corneal transplant survival in the murine model of orthotopic allotransplantation. METHODS: For all experiments, C57BL/6 corneas were transplanted into BALB/c (major histocompatibility and minor histocompatibility-disparate) eyes. "High-risk" transplants were transplants that had been sutured into BALB/c recipient beds with corneal neovascularization induced by placement of three interrupted sutures in the host cornea 2 weeks earlier. Both risk groups were divided in a masked fashion into treatment subgroups that received either 20 mg/ml of IL-1ra mixed in 0.2% sodium hyaluronate vehicle (n=28) or placebo alone (n=25). All transplants were evaluated for 8 weeks after surgery for signs of rejection. At the end of follow-up, corneal specimens were processed for enumeration of Langerhans cells and histopathological evaluation. RESULTS: Survival rates of both normal-risk and high-risk transplants increased significantly among the IL-1ra-treated animals compared with untreated controls by both stratified Mantel-Haenszel (P=0.02) and Kaplan-Meier survival (P=0.03) analyses. Furthermore, both normal- and high-risk IL-1ra-treated grafts had significantly less inflammation and Langerhans cells infiltration compared with untreated controls. CONCLUSIONS: Topical treatment with IL-1ra has a significantly positive effect in promoting corneal allograft survival.

Administration, Topical↗

PubMed1997

Photoaffinity labeling of peroxisome proliferator binding proteins in rat hepatocytes; dehydroepiandrosterone sulfate- and bezafibrate-binding proteins.

To detect the cellular sites which directly interact with peroxisome proliferators (PPs) and mediate their inducing effect on peroxisomal enzymes in rat hepatocytes, two kinds of radiolabeled ligands, AD12 (7alpha-N-(4-azido-2-hydroxy-5-iodo[125I]benzyl)-aminomethyl-5-and rostene-3beta-ol-17-one-O-3-sulfate) and BZ5 (2-[p-[2-(4'-azido-3',5'-diiodo[125I]benzamido-2'-hydroxy)ethyl]phenoxy] -2-methylpropionic acid), were developed for photoaffinity labeling. These compounds were derivatives of dehydroepiandrosterone sulfate (DHEAS) and bezafibrate, respectively, with an azido group as the photoreactive functional group. Upon UV-irradiation following incubation with rat liver cytosol and nuclei, both the ligands effectively radiolabeled several proteins analyzed by SDS-polyacrylamide gel electrophoresis/radioluminography. When [125I]AD12 was used at a concentration of 0.2 microM, two cytosolic proteins with molecular masses of 55 and 28 kDa and a nuclear protein of 40 kDa were specifically labeled, as coincubation with a 1000-fold excess of DHEAS inhibited labeling. Photoaffinity labeling of the cytosolic 28-kDa protein was also affected by Wy-14,643, but not by unsulfated dehydroepiandrosterone or androsterone sulfate, consistent with our previous findings obtained in competitive binding studies of [3H]DHEAS-binding detected in rat liver cytosol (Yamada et al. (1994) Biochim. Biophys. Acta 1224, 139-146). On the other hand, [125I]BZ5 specifically labeled a cytosolic protein of 31 kDa, which was inhibited by coincubation with bezafibrate, clofibric acid and Wy-14,643, but not with DHEAS. Thus, [125I]AD12 and [125I]BZ5 labeled several proteins which recognized DHEAS and bezafibrate, respectively, in rat liver cytosol and nuclei, providing a useful means to investigate PP-binding proteins.

Affinity Labels↗

PubMed1997

Hyperglycemia induced by the 5-HT receptor agonist, 5-methoxytryptamine, in rats: involvement of the peripheral 5-HT2A receptor.

The effects of the 5-HT receptor agonist, 5-methoxytryptamine, on plasma glucose levels were investigated in rats. 5-Methoxytryptamine induced a significant hyperglycemia above the dosage of 1 mg/kg. 5-Methoxytryptamine-induced hyperglycemia was antagonized by pretreatment with the 5-HT1 and 5-HT2 receptor antagonist, methysergide, or the 5-HT2A receptor antagonist, ketanserin, whereas the 5-HT3 and 5-HT4 receptor antagonist, tropisetron, and the 5-HT4 receptor antagonist, SDZ 205-557 (2-methoxy-4-amino-5-chloro-benzoic acid 2-(diethylamino) ethyl ester), showed no effect. In addition, the peripheral 5-HT2 receptor antagonist, xylamidine, reduced 5-methoxytryptamine-induced hyperglycemia. These results suggest that 5-methoxytryptamine-induced hyperglycemia is mediated by the peripheral 5-HT2A receptor, although it has a high affinity for the 5-HT4 receptor. Adrenodemedullation abolished the 5-methoxytryptamine-induced hyperglycemia. 5-Methoxytryptamine did not affect the blood levels of the pancreatic hormones, insulin and glucagon. The hyperglycemia induced by 5-methoxytryptamine was not affected by pretreatment with dexamethasone which inhibits corticosterone release. These results indicate that 5-methoxytryptamine-induced hyperglycemia is elicited by a facilitated adrenaline release from the adrenal gland. Therefore, it is suggested that the 5-HT2A receptor may be partly involved in the pharmacological effects induced by the 5-HT4 receptor agonist, 5-methoxytryptamine.

5-Methoxytryptamine↗

PubMed1997

Molecular cloning and expression of cDNAs encoding rat brain and liver cytosolic long-chain acyl-CoA hydrolases.

cDNAs encoding the long-chain acyl-CoA hydrolases (ACHs) from rat brain and liver, referred to as rBACH and rLACH1, respectively, were isolated and sequenced. The rBACH cDNA contained an open reading frame encoding a 338-amino acid polypeptide with a calculated molecular weight of 37,559, of which the deduced amino acid sequence matched partial amino acid sequences directly determined for peptides generated by tryptic digestion or CNBr cleavage of purified rBACH. The rLACH1 cDNA contained an open reading frame encoding a 343-amino acid polypeptide with a molecular weight of 38,240. When expressed in Escherichia coli, these cDNAs produced palmitoyl-CoA hydrolase activity and 44-kDa proteins with molecular masses similar to those of purified rBACH and rLACH1 (43 kDa). These expressed proteins and enzyme activity were immunoblotted and neutralized, respectively, by anti-rBACH or anti-rLACH1 antibodies. rLACH1 cDNA had 84 and 94% identity with rBACH cDNA at the nucleotide and amino acid levels, respectively. However, the 5'-end of the former cDNA which contained the N-terminal coding region of rLACH1 was entirely different from the corresponding region of rBACH cDNA, suggesting that these enzymes may be generated by alternative use of exons of the same gene. Northern blot analysis showed that ACH mRNA was expressed constitutively in the rat brain and testis, whereas its expression in the liver was inducible by treatment with the peroxisome proliferator. This study demonstrated the molecular diversity of ACH and suggested the presence of tissue-specific mechanisms to regulate the ACH gene expression.

Amino Acid Sequence↗

PubMed1997

Cardiac-like musculature of the intrapulmonary venous wall of the long-clawed shrew (Sorex unguiculatus), common tree shrew (Tupaia glis) and common marmoset (Callithrix jacchus).

BACKGROUND: The cardiac-like musculature is distributed not only in the heart wall but also in the intrapulmonary venous wall in a few species of insectivores. It has been suggested that the evolutionary origin of venous cardiac-like musculature may be traceable to a basic stock of certain mammalian lines of descent. So, it is important to clarify whether the musculature may be a common structure in lower mammals from insectivores to primates and to examine the functional significance of the structure. METHODS: The distribution of cardiac-like musculature in the intrapulmonary venous wall of the long-clawed shrew (Sorex unguiculatus), common tree shrew (Tupaia glis), and common marmoset (Callithrix jacchus) was observed by light and electron microscopy. The presence of atrial natriuretic polypeptide (ANP) was examined in the musculature by immunohistochemistry. RESULTS: All three species contained cardiac-like myocytes in the tunica media of intrapulmonary venous wall. In the common tree shrew and the common marmoset, cardiac-like musculature was found in the small intrapulmonary vein of 150-200 microns in diameter, while, in the long-clawed shrew, it was distributed even in the intrapulmonary vein of 30 microns in diameter. Ultrastructure of myocytes was fundamentally similar to that of atrial myocytes in the long-clawed shrew and the common tree shrew. The presence of atrial natriuretic polypeptide (ANP) was also demonstrated by immunohistochemistry in the intrapulmonary venous walls of common tree shrews. CONCLUSIONS: The results indicate that the pulmonary venous cardiac-like musculature occurs in the lower eutherian mammals from insectivores to primitive primates. The musculature is thought to act as a regulatory pump in pulmonary circulation and as an endocrine apparatus of ANP.

Animals↗

PubMed1997

Location of efferent terminals of the primate flocculus and ventral paraflocculus revealed by anterograde axonal transport methods.

Efferents of the flocculus (FL) and ventral paraflocculus (VP) were examined in seven anesthetized Macaca fuscata by anterograde axonal transport method using wheat germ agglutinin-conjugated horseradish peroxidase or phaseolus vulgaris leucoagglutinin. Several major foci of axon terminals were found in the vestibular nuclear complex and cerebellar nuclei. A difference was seen in the location of efferent terminals between the FL and VP. When the tracer covered the FL, labeled axon terminals were located within the medial and ventrolateral parts of the medial vestibular nucleus, superior vestibular nucleus and y-group. When the tracer covered the VP, labeled axon terminals were located within the caudo-ventral part of posterior interpositus and dentate nuclei, in addition to the medial and ventrolateral parts of the medial vestibular nucleus, superior vestibular nucleus and y-group. Labeled terminals were virtually absent in the basal interstitial nucleus of the cerebellum. On the points of neo- or paleo-cerebellar cortex fiber connections, these results correspond to our previous anatomical observations that the FL received mossy fiber afferents mainly from the vestibular system and nucleus reticularis tegmenti pontis and very little from the pontine nuclei, whereas the VP received mossy afferents mainly from the nucleus reticularis tegmenti pontis and pontine nuclei and very little from the vestibular system. These anatomical observations are consistent with a hypothesis in our previous anatomical and physiological study that the primate FL and VP mediate rather different functional roles in the oculomotor control.

Animals↗