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Biomedical subjects

J Yamada

Publications and source records attributed to J Yamada.

At least 235 records · Page 13Linked to original sources
PubMed1994

Improvement of poor operant performance by continual intake of phenobarbital in spontaneously epileptic rats.

Spontaneously epileptic rats (SER) are a double mutant (zi/zi, tm/tm) obtained by mating the tremor rats with another tremulous mutant, zitter rats, and spontaneously exhibit absence-like seizures, tonic convulsions and wild jumping or running episodes. In addition, SER exhibit retardation in learning ability under differential reinforcement at a low rate (DRL)-5 sec schedule of food reinforcement in operant behavior at 14 to 15 weeks of age. We examined the long-term effects of phenobarbital (PB) on total bar presses, reinforcements and inter-response time distribution to assess whether the poorness of learning ability in SER can be ascribed to frequent occurrence of seizures. Food pellets containing 0.1% PB were given ad libitum to male SER from 7 weeks, and operant behavior was examined at 13 to 14 weeks of age. Tonic seizures and wild jumping or running episode were inhibited effectively and poor operant performance was significantly improved by continual intake of PB in SER.

Administration, Oral↗
PubMed1994

Structure of the enteric nervous system in the sheep omasum as revealed by neurofilament protein-like immunoreactivity.

The general structure of the enteric nervous system in the omasum of sheep was investigated by immunohistochemical techniques using antineurofilament protein antibody. The myenteric plexus consisted of polygonal ganglia and interganglionic nerve bundles. The meshwork of the plexus in the oral region was denser than the middle and aboral regions. Intraganglionic laminar endings were present in the myenteric ganglia. The submucosal plexus was divided into sublaminar and intralaminar plexuses. The latter was denser near the free border of the omasal laminae than in the region near the omasal wall. There were no ganglion cells showing neurofilament protein-like immunoreactivity in the submucosal and mucosal layers. Probable mucosal receptors were found in the horny omasal papillae near the reticulo-omasal orifice. The findings demonstrate a complicated structure for the enteric nervous system in the omasum, presumably reflecting its regulatory activities.

Animals↗
PubMed1993

Supercritical fluid chromatographic determination of cholesterol and cholesteryl esters in serum on ODS-silica gel column.

Cholesterol and cholesteryl esters in human serum were determined by supercritical fluid chromatography on an inert ODS-silica gel column using supercritical carbon dioxide as a mobile phase without a modifier. Chromatograms were obtained by monitoring the eluent simultaneously with an FID and UV detector at the wavelength of 190 nm. The retention behavior of cholesterol and cholesteryl esters was investigated in terms of the density of CO2 mobile phase. The separation mode was found to be reversed phase, as in liquid chromatography. The amounts of cholesterol and cholesteryl esters extracted from human serum reference material (NIST SRM 909) were determined individually using cholesteryl laurate as an internal standard to give good agreement of total cholesterol with the value certified by NIST.

Cholesterol↗
PubMed1993

Induction of peroxisomal beta-oxidation by structural analogues of dehydroepiandrosterone in cultured rat hepatocytes: structure-activity relationships.

The structural requirements of dehydroepiandrosterone (DHEA) for the induction of peroxisomal beta-oxidation were studied in cultured rat hepatocytes. The hepatocytes were incubated for 5 days with various steroids, including 3- and 17-substituted analogues and 5-hydrogenated analogues of DHEA, and the activities of peroxisomal beta-oxidation and carnitine acetyltransferase were measured. Among the steroids examined, DHEA, DHEA sulfate (DHEAS), dehydroandrosterone sulfate, androstenediol 3-sulfate, epiandrosterone sulfate and androsterone sulfate significantly induced the enzymes; 4.6- to 14.2-fold for beta-oxidation and 5.1- to 10.9-fold for carnitine acetyltransferase at 50 microM. All of the sulfated steroids were more effective than the corresponding unsulfated forms. DHEAS was the most potent inducer. The 3-sulfuric group was required for the marked induction of peroxisomal beta-oxidation, and the 17-carbonyl group was also important. Furthermore, the relatively planar conformation of the steroidal hydrophobic backbone was crucial for inducing the enzyme. The configuration of the 3-sulfuric group (beta-configuration) and the presence of a double bond at position C5 were not primary determinants for the action of DHEAS. On the other hand, the introduction of bulky substituents to position C17 or aromatization of ring A led to a loss of inducing activity. Thus, there are strict structural requirements for the DHEA induction of peroxisomal beta-oxidation, suggesting the presence of a certain specific recognition site in the cell for DHEAS, which mediates the peroxisome proliferator action of DHEA.

Animals↗
PubMed1993

Cells of origin of the spinoparabrachial fibers in the rat: a study with fast blue and WGA-HRP.

The internal lateral (IL) subnucleus of the parabrachial nucleus (PB), which is one of the seven lateral subnuclei of the PB, receives information from the spinal cord. The IL subnucleus perhaps relays nociceptive signals to the intralaminar nuclei of the thalamus, apparently being implicated in the motivational-affective component of pain reaction. However, cells of origin of spinal fibers to the IL subnucleus have not been investigated sufficiently. We intended to clarify these cells by injection of fast blue or wheat germ agglutinin-conjugated horseradish peroxidase into the IL subnucleus and/or other lateral subnuclei in the rat. When the tracer was injected into the IL subnucleus, many cells were labeled bilaterally in laminae I, V, and VII, and in the dorsolateral and dorsomedial parts of the lateral funiculus throughout the entire length of the spinal cord. A small number of labeled cells appeared ipsilaterally in laminae II-IV and VI in the upper cervical segments and contralaterally in laminae VIII and X throughout the spinal cord. Labeled cells in lamina I were more numerous ipsilaterally than contralaterally in the first two cervical segments but were more numerous contralaterally than ipsilaterally in the remaining spinal segments. Labeled cells were seen with a contralateral predominance in lamina VII, but with an ipsilateral predominance in lamina V and in the dorsolateral and dorsomedial parts of the lateral funiculus. With tracer injected into the lateral subnuclei of the PB, excluding the IL subnucleus, labeled cells were found primarily in lamina I throughout the entire length of the spinal cord. These results show that cells giving rise to spinoparabrachial fibers were more numerous and more widely distributed than previously reported.

Afferent Pathways↗
PubMed1993

Local cerebral glucose utilization in the interictal state of the spontaneously epileptic rat (SER).

Local cerebral glucose utilization (LCGU) in spontaneously epileptic rats (SER) and in their parent strains, zitter (ZI) and Kyoto-Wistar (KW) rats was studied by autoradiography with [14C]2-deoxyglucose. Compared to the LCGU in age-matched KW rats, LCGU in 8-week-old SERs, which had not yet exhibited epileptic seizures, was low in all brain regions examined, and there were no significant differences among the regions. Moreover, there were no differences in LCGU among all regions examined in both SERs and in ZI rats. By contrast, the interictal LCGU in 13-week-old SERs, which did exhibit epileptic seizures, was generally lower than in the other two strains, particularly in the hippocampus and amygdala. These findings suggest that the epileptogenic focus in SERs may lie in the hippocampus and amygdala.

Animals↗
PubMed1993

Abnormal excitability of hippocampal CA3 pyramidal neurons of spontaneously epileptic rats (SER), a double mutant.

The spontaneously epileptic rat (SER:zi/zi, tm/tm), a double mutant, shows both tonic convulsions and absence-like seizures characterized by low-voltage fast waves and by 5-7 Hz spike and wave-like complexes in the cerebral cortical and hippocampal EEG, respectively. Characteristics of hippocampal CA3 pyramidal neurons were examined to determine whether these neurons are abnormally excitable. When a single stimulus was given to the mossy fiber, there was repetitive firing and a depolarization shift in neurons of mature SER (over 12 weeks old), in which epileptic seizures had fully developed. However, in young SER (7-8 weeks old) and littermates (zi/zi, tm/+), which did not show any seizures, only a single spike was elicited with each single stimulation of the mossy fiber. Intracellular recording showed that the resting membrane potential was not significantly different among young and mature SER and littermates, but a long-lasting (100-200 ms) depolarizing shift accompanied by repetitive firing was observed following a single stimulation of the mossy fiber in half of the CA3 neurons of mature SER. Furthermore, the input impedance of the CA3 neurons in mature SER was lower than that in young SER and in littermates. These results indicate that SER hippocampal CA3 neurons become abnormally excitable in conjunction with the development of epileptic seizures.

Animals↗
PubMed1993

DNA segments mapped by reciprocal use of microsatellite primers between mouse and rat.

Rat microsatellite primers were used for detection of homologous DNA segments in the mouse species (Mus laboratorius, Mus musculus musculus, and Mus spretus). Twenty five (16.3%) of 153 rat primer pairs amplified specific DNA segments, when genomic DNA of mice was used as a template in the polymerase chain reaction (PCR). Size variation among inbred strains of mice was found for 13 DNA segments (8.5%). Eight out of the 13 polymorphic DNA segments were mapped to a particular chromosome with two sets of recombinant inbred strains, AKXL or BXD. Similarly, mouse microsatellite primers were used for detection of homologous DNA segments in rats (Rattus norvegicus). Twenty (12.0%) of 166 primer pairs amplified specific DNA segments from rat genome. Size variation among inbred strains of rats was found for seven DNA segments (4.2%). Eleven of these 20 DNA segments were mapped with a rat x mouse somatic cell hybrid clone panel and/or linkage analysis by use of backcross progeny. Our results suggest that the mapped DNA segments are really homologs between mouse and rat. These polymorphic DNA segments are useful genetic markers.

Animals↗
PubMed1993

GABA-gated chloride ion influx in brains of tremor rats.

We measured the GABA-gated chloride ion influx and GABA concentrations in the cerebral cortex and the hippocampus of young (5 weeks old) and older (15 weeks old) tremor rats. GABA-gated chloride ion influx in these tremor rats was significantly greater than in the controls of both the 5 week- and 15 week-old groups. GABA concentrations in the cerebral cortex and hippocampus of the tremor rats increased compared with controls of 5 weeks and decreased compared with controls of 15 weeks. These findings suggest that the GABAergic presynaptic neurons in the cortex and hippocampus of the tremor rat are disturbed with aging. This change may be related to the appearance of absence-like seizures in the rats. The increased GABA-gated chloride ion influx in tremor rats may be a compensatory mechanism against the genetically-determined seizure susceptibility of these rats. Furthermore, the increased GABA levels and GABA-gated chloride ion influx found in 5 week-old tremor rats may be related to the tremor movements.

Animals↗
PubMed1993

Changes of NMDA receptor binding in spontaneously epileptic rat and parent strains.

We measured the binding of [3H]3-[(+/-)2-carboxypiperazin-4-yl] propyl-1-phosphonic acid ([3H]CPP), a competitive ligand for N-methyl-D-aspartate (NMDA) receptors, in double mutant spontaneously epileptic rats (SER: zi/zi, tm/tm) and their parent strains, zitter rats and tremor rats, and WTC rats (control rats from tremor rats derived from Kyoto:Wistar rats) before and after the onset of seizures in tremor rats and SER. Significantly lower [3H]CPP binding receptor density (Bmax) was found in the cortex of SER and zitter rats at 12-15 weeks of age than in that of WTC rats and tremor rats, and at 4 weeks of age the Bmax in zitter rats was lower than that in the other strains. The reduction of Bmax in SER at 12-15 weeks of age may reflect a down regulation of NMDA receptors due to repetitive tonic seizures in SER.

Animals↗
PubMed1993

Peripherally administered serotonin induces hyperglucagonemia in mice.

Peripherally administered serotonin (5-HT) induced a marked increase in the plasma glucagon level in mice. The hyperglucagonemic effects of 5-HT were completely antagonized by methysergide, ketanserin and ritanserin which have a high affinity for 5-HT2 receptors. However, the 5-HT3 receptor antagonist ICS 205-930 and MDL 72222 were without effect. These findings suggest that the activation of the peripheral 5-HT2 receptor induces the increase in plasma glucagon level and that these receptors may play a role in the release of glucagon.

Animals↗
PubMed1993

Immunohistochemical localization of lactoferrin in bovine exocrine glands.

The localization of lactoferrin (LF) was studied in bovine exocrine glands by the peroxidase-antiperoxidase method. In general, LF immunoreactivity was demonstrated in most of the serous demilunes of the mixed glands and in some but not all acinar cells of the serous glands. LF was not detected in the acinar cells of the mucous glands. LF immunoreactive cells were seen in the nasal and tracheal glands. The lacrimal and mammary glands were stained intensely, while the sweat glands were not stained. In the major and minor salivary glands, LF immunoreactivity was demonstrated in the serous demilunes and acini of the mixed glands and in some serous cells of the pure serous parotid gland. LF immunoreactivity was not seen in the gastrointestinal tract and pancreas, but the serous gland in the lamina propria of the bile duct was stained positively. In the male reproductive tracts, the prostate and bulbourethral glands were stained positively, but the vesicular gland was negative. In the female reproductive system, the uterine and Bartholin glands, the epithelial cells of the cervix and ampulla of the uterine tube reacted positively. However, the lesser vestibular gland did not react for LF. The present findings, that LF was demonstrated in the exocrine glands located mainly in the gateways of the digestive, respiratory and reproductive systems, may morphologically support the antibacterial role of LF.

Animals↗
PubMed1993

Cineradiographic study of wrist motion after fracture of the distal radius.

Residual dorsal tilt is one of the main deformative factors in the malunion of fractures of the distal radius. We investigated the effect of such tilt on the range of wrist motion and on carpal alignment in a cineradiographic study of wrist motion in 30 patients with extra-articular Colles' fracture. With increased dorsal tilt, the range of wrist motion became more restricted and abnormalities of carpal alignment during wrist motion became apparent. When the dorsal tilt was less than 10 degrees, the effects on the range of motion and on the dynamic carpal alignment were small.

Adolescent↗
PubMed1993

In vitro consistency of the Periotest instrument.

PURPOSE: The consistency of measuring the damping characteristics using the Periotest (Siemens AG, Bensheim, Germany) was studied. MATERIALS AND METHODS: Periotest values (PTV) of three rods embedded in various depths of impression material were recorded by seven dentists. RESULTS: There is no statistically significant difference among the subjects in measuring PTV of any of the three rods. However, the variation in the occlusal-gingival position of impact resulted in statistically significant different PTV measurements of each of the three rods. Assessment of mobility of the same objects using a clinical criterion was found to be less consistent as the mobility of the object increased. CONCLUSION: In vitro PTV measurements are consistent provided that the position of impact is controlled.

Analysis of Variance↗
PubMed1993

Regional mapping of the Rowett nude gene (RONU) to rat chromosome 10q24-->q32 by localizing linked SYB2 and GH loci.

The Rowett nude gene (RONU) has been mapped on rat chromosome (Chr) 10 by linkage analysis using (ACI x F344/N-RONU/RONU)F1 x F344/N-RONU/RONU backcross progeny. The gene order on the chromosome was RR92- (16.1 cM) - RR24 - (17.9 cM) - MYHSE (myosin heavy chain, embryonic) - (1.0 cM) - SYB2 (synaptobrevin 2) - (1.0 cM) - SHBG (sex hormone-binding globulin) - (4.0 cM) - RONU (Rowett nude) - (29.0 cM) - AEP (anion exchange protein), PPY (pancreatic polypeptide) - (3.0 cM) - ACE (angiotensin I converting enzyme), GH (growth hormone). The RONU locus was localized to 10q24-->q32 by fluorescence in situ hybridization of the closely linked SYB2 and loosely linked GH loci on the opposite side. Conserved linkage of homologous loci mapped to rat Chr 10 and mouse Chr 11 supports the hypothesis that the RONU locus is a rat homolog of the mouse nu locus.

Animals↗
PubMed1993

Three-dimensional architecture of the subepithelial connective tissue in the omasal laminae of sheep and cattle.

The three-dimensional architecture of the subepithelial connective tissue in the omasal laminae of sheep and cattle was studied by scanning electron microscopy after treatment with 2 N NaOH solution. The omasal laminae were equipped with highly undulated subepithelial connective tissue showing various projections or ridges. In the sheep, the subepithelial connective tissue in the omasal papillae formed flat papillary projections in the oral and middle regions of the laminae. Ridges were arranged in cellular or rosette-like form in the aboral region. In the interpapillary space, the subepithelial connective tissue formed papillary projections in the oral region, parallel ridges with dentate projections in the middle region and smooth low ridges in the aboral region. In the cattle, the projections of the subepithelial connective tissue were more developed than in the sheep. The reticular or cellular ridges were uniformly arranged. The omasal papillae with horny tips located near the reticulo-omasal orifice showed various shapes of papillary projections. In the interpapillary space, round-edged and complex folded ridges with high undulations and deep grooves were observed. These findings may indicate regional and interspecies diversities in the function of the omasal mucosa.

Animals↗