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Biomedical subjects

Y Takeuchi

Publications and source records attributed to Y Takeuchi.

At least 991 records · Page 55Linked to original sources
PubMed1983

Immunohistochemical demonstration of serotonin neurons in the central nervous system of the turtle (Clemmys japonica).

The location of the somata, course of the main tracts, and fiber distribution of the serotonin neurons in the turtle brain were studied using the peroxidase-antiperoxidase (PAP) immunohistochemical method with antibodies against serotonin (5-hydroxytryptamine). The somata of the serotonin neurons were distributed in the reticular formation of the brainstem from the mesencephalon to the lower medulla level and in a resticted region of the hypothalamus, viz. the paraventricular organ (PVO). In the PVO the serotonin neurons were seen to have the appearance of cerebrospinal fluid-contacting neurons. Analysis of serial sections cut in the frontal and sagittal planes revealed a widespread distribution of the serotonin immunoreactive fibers in the turtle brain. Prominent concentrations of the serotonin immunoreactive fibers were found in the lateral portion of the striatum, the ventral portion of the septum, the nucleus corporis geniculati lateralis, the nucleus pretectalis, the nucleus isthmi parvocellularis, the optic tectum, and the lateral edge of the reticular formation of the brainstem. Ascending and descending serotonin pathways could be defined: the ascending pathway originated mainly from the nucleus profundus mesencephali caudalis, nucleus lemnisci lateralis, nucleus reticularis isthmi and, less prominently, from the nucleus raphe superior pars lateralis, and the descending pathway arose predominantly from the nucleus raphe inferior. The fibers of the ascending pathway projected widely in the prosencephalon and mesencephalon, via the medial forebrain bundle. The descending pathway ran through the ventral and lateral portion of the medulla oblongata and spinal cord.

Animals↗
PubMed1983

Motoneurons innervating the cremaster muscle of the rat are characteristically densely innervated by serotoninergic fibers as revealed by combined immunohistochemistry and retrograde fluorescence DAPI-labelling.

The lumbar spinal cord of the rat was studied by combined retrograde fluorescent labelling with 4',6-diamidino-2-phenylindole-2HCl (DAPI) and immunoperoxidase procedure using serotonin antiserum. A peculiar small neuronal group endowed more densely than other anterior horn neurons with serotonin-like immunoreactive fibers was recognized in the anterior column of lumbar segments L1-L2. At the same time, this small nucleus was shown to contain the motoneurons innervating the cremaster muscle by means of retrograde labelling with DAPI. It is tentatively suggested that the bulbospinal descending serotonin system is particularly intimately connected with the function of the cremaster muscle.

Animals↗
PubMed1983

Serotonin distribution in the circumventricular organs of the rat. An immunohistochemical study.

Serotonin-immunoreactive structures in the circumventricular organs (organum vasculosum laminae terminalis, subfornical organ, subcommisural organ and area postrema) of the rat were demonstrated using a modified peroxidase-antiperoxidase immunohistochemical method. Various densities of serotonin fibers were demonstrated in all four circumventricular organs; however, serotonin-positive cells were evident in the area postrema only after nialamide treatment. Serotonergic supraependymal fibers were observed on the surface of the organum vasculosum laminae terminalis and that of the subfornical organ, but not on the subcommissural organ and area postrema. The organ, but not on the subcommissural organ and area postrema. The serotonergic plexus of the basal portion of the subcommisural organ was considered to be continuous with the supraependymal plexus.

Animals↗
PubMed1983

Serotonergic innervation on the motoneurons in the mammalian brainstem. Light and electron microscopic immunohistochemistry.

A comparative study of serotonergic innervation on motoneurons in the brainstem of various mammals (mouse, rat, guinea pig, dog, cat and monkey) was carried out using a sensitive immunohistochemical method. Except for the extraocular muscle nuclei, the motor nuclei of the cranial nerves received rich inputs from serotonin neurons, in all species examined--rodent, carnivore and primate. The motoneurons of the monkey were innervated by varicose serotonin fibers, in a manner different from that of other species, i.e. their cell bodies and proximal dendrites were tightly encircled by a large number of serotonin-containing varicose fibers. At the ultrastructural level, a predominant population of axosomatic contacts was confirmed in the cranial motor nuclei of the monkey, particularly in the nucleus ambiguus.

Animals↗
PubMed1983

A study on biological monitoring of n-hexane exposure.

n-Hexane is one of the solvents widely used in industry and well known to be neurotoxic. Recently it was clearly revealed that n-hexane is metabolized in vivo and its metabolites are excreted in the urine. However, the relationship between the exposed dose of n-hexane and the metabolites in the urine has not yet been substantially determined. Therefore, in this investigation we intended to clarify the above relationship in order to establish its usefulness for biological monitoring of n-hexane exposure. The exposed dose was measured by means of a personal monitoring badge worn by workers in seven factories manufacturing vinyl sandals. The time-weighted average (TWA) concentration of n-hexane was 0.2-47.4 ppm. The n-hexane metabolites in the urine of 22 workers were measured with modified Perbellini's method [12] in the early morning (6:00-7:00 hrs) and at 17:00 hrs. 2,5-Dimethylfuran, 2,5-hexanedione and gamma-valerolactone were identified by gas chromatography and mass spectrometory. At 17:00 hrs the means +/- SD of the metabolites were 0.21 +/- 0.11 mg/l for 2,5-dimethylfuran, 1.13 +/- 0.71 mg/l for 2,5-hexanedione, and 2.04 +/- 2.31 mg/l for gamma-valerolactone. The metabolites were also found in the urine in the early morning. 2-Hexanol was not detected in the urine of any worker examined. A strong correlation between TWA concentration of n-hexane and 2,5-hexanedione in the urine was found at 17:00 hrs (r = 0.895, P less than 0.001). The results suggest that the urinary metabolites of n-hexane, especially 2,5-hexanedione, could be useful indicators for biological monitoring of n-hexane exposure. Furthermore the present study offers the advantage of a better estimate of n-hexane TWA.

Adolescent↗
PubMed1983

Changes of n-hexane metabolites in urine of rats exposed to various concentrations of n-hexane and to its mixture with toluene or MEK.

It is well known that n-hexane produces peripheral neuropathy, and 2,5-hexanedione, one of the metabolites of n-hexane, is thought to be the main causative agent. Recently, the metabolites of n-hexane in urine have been measured by gas chromatography, and 2,5-hexanedione was proved to be useful for the biological monitoring of n-hexane exposure. In the present experiment, we intended to clarify the change of n-hexane metabolites in the urine of rats exposed to various concentrations of n-hexane and to its mixture with toluene of MEK. In the first experiment, five separate groups of five rats each were exposed to 100, 500, 1000, or 3000 ppm of n-hexane, or fresh air respectively in an exposure chamber for 8 h a day. Urinary samples were gathered during exposure, 16, 24, and 40 h after exposure. Half of each sample was analyzed by gas chromatography after hydrolysis with acid and enzymes, and the other half was analyzed without hydrolysis. 2,5-Dimethylfuran, MBK, 2-hexanol, 2,5-hexanedione, and gamma-valerolactone could be identified as n-hexane metabolites in the urine. The main metabolites were 2-hexanol and 2,5-hexanedione. 2-Hexanol was mostly excreted during exposure, while most of the 2,5-hexanedione was excreted after the end of exposure. The amount of metabolites in the urine correlatively increased with the concentration of n-hexane from 100 to 1000 ppm, but the amount of metabolites scarcely increased when the concentration of n-hexane increased from 1000 to 3000 ppm.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Identification of EC cells in the human intestine: a comparative study between immunohistochemical and silver impregnation techniques.

Selective immunohistochemical identification of enterochromaffin (EC) cells in the human duodenum and colon has been carried out, using a highly specific rabbit antiserotonin serum and the unlabeled peroxidase-antiperoxidase complex (PAP) technique. The sensitivity of the reaction, and morphology of the cells, were compared with those of the argentaffin or argyrophil reactions on the same sections at the light microscopic level. All argentaffin cells were argyrophil and PAP positive, but a small number of PAP-positive cells were neither argentaffin nor argyrophil. In addition, a few EC cells stained by the PAP method were shown to be argyrophil but not argentaffin. The PAP method permitted the clear morphological identification of the entire cell, particularly its cytoplasmic processes, whereas both the argentaffin and argyrophil reactions were basically seen in the basal regions of the cells and often failed to demonstrate the cytoplasmic processes. These findings indicate that the immunohistochemical method is more sensitive and advantageous than silver impregnations for the selective demonstration of EC cells.

Chromaffin System↗
PubMed1983

Immunohistochemical demonstration of serotonin-containing CSF-contacting neurons in the submammalian paraventricular organ.

The distribution and morphological aspects of the serotonin-containing neurons in the paraventricular organ of the carp, frog, turtle and chicken were studied by means of an immunoperoxidase technique using serotonin antiserum. In all species the serotonin-containing neurons were seen to have the appearance of the CSF-contacting neurons and to be distributed in the pars ependymalis and the pars hypendymalis of the organ. Particularly, in the frog, the serotonin-containing CSF-contacting neurons, mostly bipolar in shape, were also observed in the pars distalis. Their proximal processes protruded into the ventricular lumen through the ependymal layer with a globular- and triangular-shape. The distal processes projected ependymofugally to the pars distalis and formed a fine plexus in the neuropil of this part. The density of the serotonin fibers in the pars distalis was greater in the carp than in the other species.

Animals↗
PubMed1983

Brush border Mg2+-HCO-3-ATPase, supernatant carbonic anhydrase and other enzyme activities isolated from rat intestinal mucosa: effect of adrenalectomy and aldosterone administration.

The possible role of Mg2+-HCO3-ATPase, carbonic anhydrase and several other enzymes in rat intestinal mucosa as mediators of the action of aldosterone has been examined. The small-intestinal tract was cut into seven segments, 15 cm each in length and the mucosa was scraped off, homogenized in 50 mM D-mannitol-2 mM Tris-HCl buffer (pH 7.1), differentially fractionated and a crude brush border was obtained. The mucosa from the colon and rectum was combined and used as the large-intestinal sample. Five days after the adrenalectomy, activities of brush border Mg2+-HCO3-ATPase and supernatant carbonic anhydrase from the upper small intestine decreased to about 60 and 40% of normal values, respectively. Activities of Na+-K+-ATPase, beta-glycerophosphatase and succinate dehydrogenase were all decreased. Two and 4 h after i.p. injection of aldosterone (40 micrograms/kg) to adrenalectomized rats, all enzyme activities increased except for Na+-K+-ATPase in the upper small intestine. In contrast, Mg2+-HCO-3-ATPase and carbonic anhydrase activities were unchanged 3 h after i.p. injection of dexamethasone (200 micrograms and 1 mg/kg). The activation of both Mg2+-HCO3-ATPase and carbonic anhydrase by a single injection of aldosterone was blocked by pretreatment with cycloheximide (1 mg/kg). These results suggest that aldosterone may induce the synthesis of enzyme proteins in the intestinal mucosa.

Adenosine Triphosphatases↗
PubMed1983

Effect of epidural analgesia on metabolic response to major upper abdominal surgery.

Blood concentrations of glucose, lactate, non-esterified fatty acids (NEFA) and insulin (IRI) were measured in two groups of ten patients undergoing elective gastrectomy under general anesthesia with halothane (Group G) or epidural analgesia extending from Th3-4 to L1-2 without halothane (Group E). The rise in blood glucose and the rise in NEFA in group E during operation were significantly less than in Group G. Blood lactate levels during operation were lower in group E than in group G although the difference was not statistically significant. The increase in IRI/glucose ratio on postoperative day 1 was significantly less in Group E than in Group G, suggesting that insulin sensitivity after surgery was higher in Group E. The postoperative course was uneventful in all subjects. These results suggest that the endocrine-metabolic response to major upper abdominal surgery can be inhibited by epidural analgesia.

Anesthesia, Epidural↗
PubMed1983

An experimental study of the combined effects of n-hexane and methyl ethyl ketone.

This study was intended to determine whether or not methyl ethyl ketone (MEK) enhances the neurotoxicity of n-hexane at low concentration and after long term exposure. Separate groups of eight rats were exposed to 100 ppm n-hexane, 200 ppm MEK, 100 ppm n-hexane plus 200 ppm MEK, or fresh air in an exposure chamber for 12 hours a day for 24 weeks. The body weight, motor nerve conduction velocity (MCV), distal motor latency (DL), and mixed nerve conduction velocities (MNCVs) were measured before exposure and after four, eight, 12, 16, 20, and 24 weeks' exposure. One rat of each group was histopathologically examined after 24 weeks' exposure. Exposure of 100 ppm n-hexane did not significantly decrease the functions of the peripheral nerve throughout the experiment. Exposure to 200 ppm MEK significantly increased MCV and MNCVs and decreased DL after four weeks' exposure, but at this later stage no significant changes were found throughout the experiment by comparison with the controls. Mixed exposure to 100 ppm n-hexane plus 200 ppm MEK significantly decreased by comparison with the controls. On histopathological examination of the tail nerve, however, no changes were found in any of the exposed groups or the controls. These results suggest that MEK might enhance the neurotoxicity of n-hexane at a low concentration, and mixed exposures to n-hexane and MEK should be avoided.

Animals↗
PubMed1983

Immunohistochemical study on the distribution of serotonin-containing cell bodies in the brain stem of the dog.

The distribution of serotonin-containing neurons in the brain of the dog was studied by use of PAP immunohistochemistry. The lower brain stem was endowed with extensively scattered serotonergic cell bodies, a large portion of which was located in the raphe nuclei. At the same time, prominent distribution of serotonergic neurons in lateral areas outside the raphe nuclei was also demonstrated. Our observations on the brain stem were, in principle, consistent with those on rats, cats and monkeys, with only minor differences.

Animals↗
PubMed1983

Carbon tetrachloride-induced hepatotoxicity in rats: evidence for different susceptibilities of rat liver lobes.

The hepatotoxic effect of carbon tetrachloride (CCl4), reflected by augmented blood aspartate aminotransferase and alanine aminotransferase activities and the extent of histological liver damage, was observed following oral administration of CCl4 to rats. A marked increase of blood transaminase activities and severe degeneration of hepatocytes in the centrilobular region were detected 1-2 days after the administration, while the cytochrome P-450 content and the drug metabolizing activity in livers were depressed immediately after the administration. Based on these results, the effect of CCl4 on hepatic cytochrome P-450 and the histological pattern of liver cells was observed using tissue samples obtained from various liver lobes of rats given CCl4 24 hr previously. Dose-dependent inactivation of cytochrome P-450 by the administration of CCl4 was observed throughout the liver, with the most extensive decrease in the cytochrome content in the median lobe. The extent of liver damage (hydropic swelling degeneration and central necrosis in lobule) was also greater in the median and right liver lobes than in the left lobe. When a small amount of CCl4 was administered, degeneration of liver cells was detected only in the median and right lobes with only slight degeneration in the left lobe. These results indicate different susceptibilities of rat liver lobes to CCl4.

Alanine Transaminase↗