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Biomedical subjects

Y Hayashida

Publications and source records attributed to Y Hayashida.

At least 37 records · Page 2Linked to original sources
PubMed2001

[Effects of topical prostaglandin analogues on the aqueous flare intensity in rabbit eyes at an early phase of endotoxin-induced uveitis].

PURPOSE: We examined the effects of prostaglandin analogues on the blood-aqueous barrier(BAB) permeability in rabbit eyes at an early phase of endotoxin-induced uveitis(EIU). SUBJECTS AND METHODS: One drop of 0.005% latanoprost or 0.12% unoprostone were applied to rabbit eyes. Escherichia coli lipopolysaccharides were injected to induce uveitis. The changes in flare intensity in normal eyes and EIU eyes after application of eye drops were evaluated. The effect of cyclooxygenase inhibitor on the flare intensity changes caused by the application of unoprostone was also examined. RESULTS: Flare intensity increased significantly after a single instillation of unoprostone, and the increase was not prevented by pretreatment with cyclooxygenase inhibitor. In eyes with EIU, unoprostone caused an additional increase of flare intensity to uveitis induced flare change. Latanoprost had no effects on BAB in eyes with normal and with uveitic conditions. CONCLUSION: Latanoprost and unoprostone did not cause an excessive inflammatory reaction in rabbit eyes at an early phase of EIU.

Animals↗
PubMed2000

Two novel first exons in the prolactin receptor gene are transcribed in a tissue-specific and sexual maturation-dependent manner to encode multiple 5'-truncated transcripts in the testis of the chicken.

Cloning and sequencing of the chicken prolactin receptor (PRLR) gene segment from the transmembrane domain to the box 2 motif revealed the presence of the two testis-specific first exons, TSE-1 and TSE-2, encoding the unique 5'-end sequences of the reported and newly identified multiple 5'-truncated PRLR transcripts containing only the cytoplasmic domain in the testis. TSE-1 was located downstream of the exon encoding the transmembrane domain and TSE-2 presented downstream of the exon encoding the box 1 motif. These findings indicate that the box 1-containing 5'-truncated transcripts are generated by the utilization of TSE-1 as the first exon with distinct splicing donor sites to the box 1-containing exon, and that the utilization of TSE-2 as the first exon and its splicing to the box 2-containing exon results in the generation of the box 1-lacking transcript. Three transcription initiation sites for the box 1-containing 5'-truncated transcripts and two transcription initiation sites for the box 1-lacking transcript were detected by the RNase protection assays. Reverse transcription-polymerase chain reaction analysis showed that the expression levels of all these 5'-truncated PRLR transcripts are simultaneously increased during sexual maturation, accompanying the decrease of the amount of the canonical full-length transcript for PRLR.

Animals↗
PubMed2000

Integrative effects of nitric oxide and endothelium-derived hyperpolarizing factor induced by acetylcholine and bradykinin in rat hindquarter perfusion.

We investigated the roles of endothelium-derived vasodilative factors in rat hindquarter perfusion using a system for the direct measurement of nitric oxide (NO). Acetylcholine (ACh) induced the dose-dependent release of NO with a concomitant decrease in perfusion pressure. Under the influence of N(G)-monomethyl-l-arginine (l-NMMA), NO release in response to ACh was blocked, while the perfusion pressure still decreased. In the presence of tetraethylammonium (TEA), the decrease in perfusion pressure in response to ACh was attenuated compared to the control value. The decrease in perfusion pressure in response to ACh was almost abolished in the presence of both l-NMMA and TEA or with deendothelialization. Bradykinin (BK) also induced NO release and biphasic effects on the perfusion pressure. The perfusion pressure decreased with a lower concentration of BK and increased with a higher concentration. l-NMMA and TEA each abolished the decrease in perfusion pressure induced by BK. Furthermore, in the presence of both l-NMMA and TEA, the perfusion pressure actually increased in response to BK. These results suggest that ACh and BK induce vasodilation through NO release and a potassium channel dependent mechanism via endothelium.

Acetylcholine↗
PubMed2000

Laryngeal endocrine cells: topographic distribution and adaptation to chronic hypercapnic hypoxia.

The morphology, topographic distribution, effects of denervation, and exposure to hypercapnic hypoxia of endocrine cells were examined in rat larynx. The endocrine cells, which were immunoreactive for protein gene product 9.5 (PGP 9.5) and calcitonin gene-related peptide (CGRP), were observed within the epithelial layer of the laryngeal cavity and in the laryngeal gland, while solitary endocrine cells with apical and/or basal cytoplasmic processes appeared near the glottis. After denervation of the left cervical vagosympathetic trunk and the superior laryngeal nerve, the number of mucosal endocrine cells in the denervated side was not significantly different from that in the intact side. After exposure to hypercapnic hypoxia for 3 months, the number of endocrine cells with PGP 9.5 and CGRP was markedly increased. In conclusion, the secretion of laryngeal endocrine cells may be stimulated by CO2 rather than O2. Furthermore, the endocrine cells and the sensory and autonomic nervous system may regulate each other by an axon reflex mechanism. Endocrine cells appear to play a very important role in the local regulation of the laryngeal mucosa.

Animals↗
PubMed2000

Metastatic gastrinoma to the liver 20 years after primary resection.

Gastrinoma is a rare endocrine tumor that is frequently associated with liver metastasis. The liver metastasis is usually seen simultaneously or soon after a primary operation. A 47-year-old woman who had had a total gastrectomy 20 years earlier developed liver metastasis. An interval of this length between surgery and metastasis is extremely rare. The total gastrectomy prevented the patient from developing the usual symptoms of hypergastrinemia that would have enabled early diagnosis of the metastasis. Laboratory examinations on admission revealed a high serum gastrin concentration (1500 pg/ml). Computed tomography showed an irregularly enhanced mass lesion with an uneven, low-density central area in the right anterior inferior segment of the liver. An extended right hepatectomy was performed. Intraoperative ultrasonography showed no abnormalities in the remnant pancreas. Examination of the cut surface of the specimen revealed a yellow, firm, elastic tumor, 55 mm in diameter. The interior of the tumor appeared necrotic. Histopathologically, the tumor was composed of cells with hyperchromatic, dysplastic nuclei arranged in a trabecular pattern with nest formation. Gastrin staining was positive. A histologic diagnosis of metastatic gastrinoma was made. The patient's gastrin concentration returned to normal and she was well at 2-year follow-up.

Female↗
PubMed2000

Stereocontrol in cyclophane synthesis: a photochemical method to overlap aromatic rings.

To overlap aromatic rings in cyclophanes, the inter- and intramolecular [2 + 2] photocycloaddition of vinylarenes has been developed. It gives cyclophanes, naphthalenophanes, phenanthrenophanes, thiophenophanes, and carbazolophanes in reasonable to excellent yields. The structures and properties of cyclophanes obtained are reviewed; especially the excimer emission of phenanthrenophanes, naphthalenophanes, and carbazolophanes stressed that many intriguing cyclophanes can be obtained through the fine molecular design of precursors.

Cyclobutanes↗
PubMed2000

Calbindin D-28k immunoreactive nerve fibers in the carotid body of normoxic and chronically hypoxic rats.

The distribution and ultrastructural characteristics of calbindin D-28k immunoreactive nerve fibers were examined in the carotid body of the normoxic control rats by light and electron microscopy, and the abundance of calbindin D-28k fibers in the carotid body was compared in normoxic and chronically hypoxic rats (10% O2 and 3.0-4.0% CO2 for 3 months). Calbindin D-28k immunoreactivity was recognized in nerve fibers within the carotid body. Calbindin D-28k immunoreactive nerve fibers appeared as thin processes with many varicosities. They were distributed around clusters of glomus cells, and around blood vessels. Immunoelectron microscopy revealed that the calbindin D-28k immunoreactive nerve terminals are in close apposition with the glomus cells, and membrane specialization is visible in some terminals. Some dense-cored vesicles in the glomus cells were aggregated in this contact region. The chronically hypoxic carotid bodies were found to be enlarged several fold, and a relative abundance of calbindin D-28k fibers was lesser than in the normoxic carotid bodies. When expressed by the density of varicosities per unit area of the parenchyma, the density of calbindin D-28k fibers associated with the glomus cells in chronically hypoxic carotid bodies was decreased by 70%. These immunohistochemical findings indicate a morphological basis for involvement of calcium binding protein in the neural pathway that modulates carotid body chemoreception.

Animals↗
PubMed2000

Changes in the immunoreactivity of substance P and calcitonin gene-related peptide in the laryngeal taste buds of chronically hypoxic rats.

The distribution of substance P (SP)- and calcitonin gene-related peptide (CGRP)-immunoreactive nerve fibers in the taste buds of the epiglottis and aryepiglottic folds was compared between normoxic control and chronically isocapnic hypoxic rats (10% O2 and 3-4% CO2 for 3 months). In the normoxic laryngeal taste buds, SP- and CGRP-immunoreactive fibers were detected within the taste buds, where they appeared as thin processes with many varicosities. Most CGRP fibers showed coexistence with SP, but a few fibers showed the immunoreactivity of CGRP only. The density of intra- and subgemmal SP and CGRP fibers penetrating into the laryngeal taste buds was significantly higher in chronically hypoxic rats than in normoxic control rats. Water intake in the hypoxic rats was significantly lower than in the normoxic rats. These results indicate that the increased density of SP- and CGRP-containing nerve fibers within the laryngeal taste buds is a predominant feature of hypoxic adaptation. The altered peptidergic innervation and reduced water intake support the hypothesis that the laryngeal taste buds are involved in water reception, and that the water reception may be under the control of peptidergic innervation.

Animals↗
PubMed2000

Riedel's lobe of the liver evaluated by multiple imaging modalities.

An 81-year-old Japanese woman visited our hospital because of abdominal discomfort. Physical examination revealed that she had an abdominal mass. A combination of ultrasonography, computed tomography, magnetic resonance imaging (MRI), and hepatic asialoglycoprotein scintigraphy was utilized to make a diagnosis. We found that she had a downward elongated hepatic lobe or Riedel's lobe which did not appear to be common in our district. The prevalence of Riedel's lobe in the Asian population has not been studied. Furthermore, this is the first report that describes the MRI and hepatic asialoglycoprotein scintigraphy features of Riedel's lobe of the liver.

Abdominal Pain↗
PubMed1999

Effect of magnesium deficiency on autonomic circulatory regulation in conscious rats.

A close relationship between magnesium and cardiovascular function has been reported; however, the effect of magnesium deficiency on autonomic cardiovascular regulation has not been clarified. We investigated the effect of magnesium deficiency on the autonomic regulation of oscillations of the R-R interval, arterial blood pressure (BP), and renal sympathetic nerve activity (RSNA) by using the maximum entropy method in conscious rats. Its effect on baroreflex control of RSNA and heart rate were also investigated with a logistic function curve. Mean BP in magnesium-deficient rats was higher than that in control rats (mean+/-SE, 114.0+/-4.3 versus 101.6+/-3.4 mm Hg; P<0.05), and urinary excretion of catecholamine was increased by 2.4-fold. The fraction of low-frequency oscillation of RSNA was reduced (31.7+/-0.9% versus 36.2+/-1.5%, P<0.05) and the correlation between low-frequency oscillations of BP and RSNA was weakened in magnesium-deficient rats. There was no difference in high-frequency oscillation of the R-R interval, which is related to vagal tone, whereas sympathetic tone became dominant (square root of low-frequency/high-frequency ratio of R-R interval, 1.00+/-0.05 versus 0.67+/-0.05, P<0.0001) in magnesium-deficient rats. The maximal gain in the BP-RSNA relation tended to be reduced in magnesium-deficient rats (-7.7+/-1.1% versus -12.2+/-1.9%/mm Hg, P=0. 07); however, that in the BP-heart rate relation was increased (-8. 1+/-0.7 versus -4.5+/-0.5 bpm/mm Hg, P<0.01). These results suggest that magnesium deficiency induces sympathetic excitation, which results in hypertension but attenuates the baroreflex-related response of sympathetic nerves, whereas magnesium deficiency enhances the sensitivity of the sinus node to autonomic regulation.

Animals↗
PubMed1999

Changes in the distribution of the substance P and calcitonin gene-related peptide immunoreactive nerve fibers in the laryngeal mucosa of chronically hypoxic rats.

The distribution and abundance of substance P (SP) and calcitonin gene-related peptide (CGRP) immunoreactive nerve fibers in four different regions of the laryngeal mucosa were compared between normoxic and chronically hypoxic rats (10% O2 and 3.0-4.0% CO2 for 3 months). In the chronically hypoxic laryngeal mucosa, the number of SP and CGRP fibers within and just beneath the epithelium, and around the laryngeal gland was increased in comparison with those in the normoxic controls. Especially in the epiglottic and arytenoid regions, the number of intraepithelial SP fibers was increased remarkably. Most intraepithelial SP and CGRP fibers penetrated into the epithelium to extend to the luminal surface. There was no distinct difference in the distribution and abundance of these peptidergic fibers in the mucosa of the normoxic and chronically hypoxic vocal cord regions. These results suggest that the increased density of SP and CGRP fibers within the epithelium of the upper laryngeal mucosa is a predominant feature of hypoxic adaptation, and this may be involved in airway protection, swallowing, and other functions in the chronically hypoxic environment. In addition, the increased SP and CGRP fibers around the laryngeal gland suggest an enhanced mucous secretion, and this may participate in the airway defense mechanism in low O2 conditions.

Animals↗
PubMed1999

Influence of rewarming conditions after hypothermia in gerbils with transient forebrain ischemia.

OBJECT: Recently, several studies have demonstrated that hypothermia has a beneficial effect on clinical outcome; however, it is difficult to determine the appropriate rewarming conditions in clinical use. The purpose of the present study was to examine the influence of rewarming conditions in gerbils with transient forebrain ischemia. METHODS: Ischemia was induced in the gerbils by a 5-minute bilateral common carotid artery occlusion, after which the animals were immediately subjected to moderate or deep hypothermia. After moderate hypothermia (30.5 degrees C for 4 hours) the animals were rewarmed over standard, fast, or slow time periods. After deep hypothermia (24 degrees C for 2 hours) the animals were rewarmed in a standard, fast, slow, or stepwise manner. Cerebral blood flow (CBF), extracellular glutamate, and lactate were monitored. Hippocampal CA I cell damage was assessed 7 days after induction of ischemia. In animals treated with moderate hypothermia, the rewarming rate had no influence on the number of surviving neurons. However, fast rewarming from deep hypothermia (to 37 degrees C for 30 minutes) failed to provide the neuroprotective effect of hypothermia. Furthermore, this group showed a poor recovery of CBF (p < 0.01) and, consequently, an increase in extracellular glutamate (p < 0.01) and lactate (p < 0.01) in the hippocampus. CONCLUSIONS: The results of this study indicate a transient uncoupling of CBF and cerebral metabolism during fast rewarming from deep hypothermia, whereas slow and stepwise rewarming periods were found to be useful for protection against uncoupling of CBF and cerebral metabolism during rewarming.

Animals↗
PubMed1999

Epidermal growth factor-mediated cell maturation and apoptosis in RGM-1 rat gastric mucosal cells.

Epidermal growth factor (EGF) and heparin-binding EGF-like growth factor (HB-EGF) exert their activities through the same cell surface receptor. In the present study, the role of EGF in cell kinetics of rat gastric epithelial cell line, RGM-1, in which HB-EGF is known to function in an autocrine fashion, was investigated. EGF stimulated the mucus glycoprotein synthesis which is characterized with cell maturation, but competed with HB-EGF for cell proliferation. By flow cytometric analysis, EGF inhibited G2/M transition by 48 h after stimulation and induced apoptosis manifested by hypodiploid DNA by 72 h after stimulation. Consistent with this, DNA ladder formation together with the histone-associated DNA fragments was found in EGF-treated cells. These results indicate that EGF and HB-EGF possess different functions in RGM-1 cells and that EGF acts as a mediator of both cell maturation and apoptosis in these cells.

Animals↗
PubMed1999

Detection of hepatitis B virus X-region DNA in liver tissue from patients with hepatitis C virus-associated cirrhosis who subsequently developed hepatocellular carcinoma.

The risk of hepatocellular carcinoma (HCC) in patients chronically infected by hepatitis C virus (HCV) is relatively higher in Japan than in Western countries. The presence of hepatitis B virus X (HBX)-DNA in the liver tissue samples obtained on enrollment from 69 patients with HCV-associated cirrhosis who were subsequently followed in our hospital was analyzed by polymerase chain reaction (PCR). During the follow-up period of 5.7+/-3.2 years (mean +/- SD), 52 (75%) of 69 patients developed HCC. The PCR analysis indicated that the HBX-DNA sequence was detected in 25 (48%) of 52 patients who developed HCC during follow-up, but in only 3 (18%) of 17 patients who did not (P<0.05). These results suggest that HBX, a hepatitis B viral product relevant to hepatocarcinogenesis, is involved in development of HCC in some patients chronically infected by HCV in Japan.

Adult↗